NYSE: ANRO

While personalized medicine has made significant advances in other areas, most notably in oncology, neuropsychiatry drug development and patient treatment remain largely untargeted. Alto was founded in 2019 to drive innovation in psychiatry and disrupt the traditional, all-comer approach to central nervous system, or CNS, drug development and clinical care. Our precision approach harnesses deep neurobiological insights to identify and develop personalized, highly effective and clinically differentiated treatment options in stratified populations to improve patient outcomes. We believe the opportunity across our portfolio represents a potential to impact over 25 million patients in the United States alone.

Our Platform

Our Platform employs modern tools for measuring human neurobiology and rigorous data science analytics. By combining inputs and expertise across multiple domains, we designed a platform that enables the integration and in-depth analysis of disparate data sets from a variety of sources. The initial development and refinement process involved specialists in data science, software engineering, neuroscience, and psychiatry; and we continue to expand and improve our Platform as we collect additional data across our clinical-stage programs. We believe the neuropsychiatry domain expertise leveraged to develop our Platform provides a distinct advantage in our ability to discover and develop biomarkers that are highly relevant to underlying brain circuit function.

Using our Platform, we collect and analyze data from neurocognitive assessments, electroencephalography, or EEG, and wearable devices. We also collect data from genetic and genomic samples. With our Platform, we employ quantitative analytics, including machine learning, to discover and evaluate unique biomarkers. Our approach aims to avoid the need for interpretation of biomarker data by a clinician, thereby enabling seamless integration into current clinical practice. The Platform is designed for commercial scalability, emphasizing the use of reliable and reproducible biomarkers that can be easily collected in any patient care setting without significant logistical or financial burden. The potential scalability of our Platform has been demonstrated through biomarker collection across more than 70 unique clinical sites and from over 2,000 participants.

We continue to expand our platform. In 2025, we identified and prospectively replicated an EEG biomarker that captures brain activity patterns in people with MDD that are more likely to elicit a larger response to placebo. We believe this biomarker can be used throughout the development of novel medicines for depression to reduce the signal-to-noise ratio and improve the detection of true therapeutic response.

Our Strategy

We are building a leading precision psychiatry company with a mission to redefine neuropsychiatric care with personalized and highly effective treatment options. We intend to accomplish our mission by implementing the following key strategies.

Leverage our Platform to advance the first biomarker-driven pipeline for neuropsychiatric indications

•Our Platform generates biological and clinical insights that are rarely, if ever, gained through traditional CNS drug development approaches, which directly guide each phase of the drug development process.

•We aim to use these unique insights to advance our current pipeline products and increase the probability of success for our portfolio of differentiated drug candidates designed to target independent, biomarker-defined patient populations with high unmet needs.

Discover and prospectively replicate objective biomarkers for patient selection

•Our proprietary approach relies on rigorous analytics using patient-derived data to discover, and prospectively replicate, biomarker signatures for likely drug responders. In addition to identifying likely drug responders, we deploy our Platform in early-stage clinical development to characterize drug effects on the brain.

Leverage our internal clinical operations and software development expertise

•We believe our in-house model creates synergies between trials, and enables us to conduct multiple studies simultaneously, reduce cost, and apply learnings across programs to enhance execution.

•Our approach to data oversight enables us to design software tools, such as Spectra, TechCheck, and Altoscope, which are tailored to the requirements of our biomarker data collection with an understanding of how these data will ultimately be gathered in clinical practice.

Expand our pipeline by strategically evaluating in-licensing and acquisition opportunities

•We plan to seek opportunities to in-license, acquire, or partner on new product candidates in clinical indications where we are able to offer unique expertise to potentially enhance the product candidate’s value and potentially streamline development through targeted patient selection.

Selectively partner our product candidates to maximize their value to patients and our stockholders

•As we advance the development of our product candidates, in addition to internal commercial capabilities that we may establish, we may also selectively partner with global pharmaceutical companies to maximize the value of our targeted product candidates and robust intellectual property portfolio.

•We may seek partnerships where the efficiency of development and/or the commercial infrastructure required is best achieved through external capabilities.

Our Product Candidates

Our clinical-stage product candidates are being advanced based on extensive preclinical and clinical data that suggest the potential to bring significant improvements to patient populations not adequately treated with current standard-of-care medications.

Our pipeline of clinical-stage product candidates is depicted below:

ALTO-207

ALTO-207 is a fixed-dose combination of pramipexole, a dopamine D3-preferring D3/D2 agonist, approved for the treatment of Parkinson’s disease with demonstrated antidepressant effect through multiple robust randomized, placebo-controlled clinical trials, and ondansetron, an antiemetic, selective 5-HT3 receptor antagonist. As a fixed-dose combination, ALTO-207 is designed to enable rapid titration and higher dosing by mitigating the dose-limiting adverse events typically experienced with pramipexole. ALTO-207 is being developed to address the significant unmet need for patients with TRD. The planned Phase 2b trial of ALTO-207, which has the potential to serve as a pivotal trial subject to U.S. Food and Drug Administration, or FDA, feedback and review of data, is expected to initiate in the first half of 2026. Following an FDA meeting in October 2025, we also expect to initiate a Phase 3 trial by early 2027 following Phase 3 readiness work and alignment with the FDA on the planned trial design.

In May 2025, we acquired ALTO-207 (formerly known as CTC-501) from Chase Therapeutics Corporation, or Chase. See “—License and Other Agreements—Chase Asset Purchase Agreement” for additional information. Prior to the acquisition, Chase completed a randomized, placebo-controlled Phase 2a clinical trial evaluating CTC-501 in 32 patients with depression. CTC-501 met the primary and secondary endpoints in this trial, demonstrating statistically significant and clinically meaningful improvements on the Montgomery Åsberg Depression Rating Scale, or MADRS, compared to placebo. Patients randomized to receive CTC-501 reached a mean dose of 4.1mg per day. Real-world data demonstrate that it is challenging to achieve doses above 1mg per day of pramipexole. CTC-501 was generally well tolerated in the maintenance period of the study with an adverse event rate similar to placebo.

Our acquisition of ALTO-207 was motivated by the results from the PAX-D study conducted by the University of Oxford. Results, which were recently published in The Lancet Psychiatry, showed pramipexole augmentation of antidepressant treatment, at a target dose of 2.5mg, demonstrated a large (Cohen’s d=0.87) reduction in symptoms relative to placebo at 12 weeks (and continuing through 48 weeks), but was associated with a high rate of adverse effects.  We believe the profile of ALTO-207 will enable higher dosing of pramipexole while mitigating the significant rates of nausea and vomiting that have limited its use for depression. The graph below depicts the effects of pramipexole and placebo over the 48-week treatment period in the PAX-D study on the left, and the dropouts due to adverse events on the right.

About the Completed Phase 2a Trial for CTC-501

Chase completed a randomized, placebo-controlled Phase 2a clinical trial evaluating CTC-501 in 32 patients with depression. The study consisted of two periods, a dose titration period in which patients were dosed with increasing dose levels of CTC-501 or placebo at increments of 1 mg/day (or matching placebo) until the maximum allowed dose (or first intolerable dose) was reached. Patients were then maintained for an eight-week treatment period at either the maximum allowed dose or their maximum tolerated dose (1 mg/day lower than their first intolerable dose in the titration period). The primary endpoint in the study was defined as overall tolerability and achievement of higher dose levels of pramipexole when combined with ondansetron. Clinical efficacy was evaluated as a secondary exploratory endpoint in the study.

The primary endpoint was achieved in the study. Patients randomized to receive CTC-501 reached a mean dose of 4.1mg per day with 67% of patients achieving the highest allowable dose of 5mg/day. CTC-501 was generally well tolerated in the maintenance period of the study.

The clinical efficacy measures were evaluated as secondary endpoints and across measures CTC-501 demonstrated large, clinically meaningful, effects. CTC-501 demonstrated statistically significant and clinically meaningful improvements from baseline compared to placebo on depression symptoms as measured by the MADRS (LSM Δ vs. placebo at Week 8 = -8.2, p=0.025, Cohen’s d=1.1). CTC-501 also demonstrated a significantly greater improvement compared to placebo on the Clinician Global Impression Scale of Severity, or CGI-S (LSM Δ vs. placebo at Week 8 = -0.76, p=0.04, Cohen’s d=1.0). The results on the clinical efficacy measures are depicted below.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-207.

ALTO-300

Overview

ALTO-300 is an investigational oral, small molecule melatonergic (MT1 and MT2) agonist and serotonergic (5-HT2C) antagonist with antidepressant properties. We are developing ALTO-300 as an adjunctive treatment in the United

States for patients with MDD, characterized by an EEG biomarker. The compound has been approved as an antidepressant in Europe and Australia with the International Nonproprietary Name agomelatine at both 25mg and 50mg, but has not been approved in the United States.

We are currently evaluating ALTO-300 in a six-week, double-blind, placebo-controlled, randomized Phase 2b clinical trial in patients with MDD characterized by an EEG biomarker signature. We expect to enroll approximately 200 biomarker positive patients in the final analysis sample, which is therefore expected to result in approximately 320 patients enrolled in the study in total (inclusive of biomarker negative patients and patients not included in the final analysis sample as a result of the completed blinded site and patient case review). Patients are randomized to receive either 25mg of ALTO-300 once daily before bedtime, or QHS, or placebo in addition to a background antidepressant, to which they have had inadequate response, over a six-week treatment period. Patients are then enrolled into an eight-week open-label extension in which they receive 25mg QHS of ALTO-300. The primary endpoint in the trial is the change in MADRS score from baseline to week six in the EEG biomarker positive group. We expect to report topline data from this trial in mid-2026.

The ALTO-300 biomarker—a measure of reduced neural signaling stability—has been replicated and reverse translated to animals to elucidate a mechanistic link. In the preclinical model, administration of a 5-HT2C agonist led to a dose-related increase in EEG irregularity using the same measure as the human biomarker. Building on these results, we have now demonstrated the successful standardization of EEG enrichment marker acquisition through a platform that facilitates the identification of patients potentially most likely to respond to ALTO-300. Given the prevalence of patients with the biomarker profile observed in our clinical trials to date, we estimate approximately 50% of patients with MDD to be eligible candidates for potential treatment with ALTO-300 if approved.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-300.

MDD Background

MDD is a psychiatric disorder characterized by key symptoms such as low mood, anhedonia, poor concentration and decision-making, and changes in sleep and appetite. It is one of the most common and debilitating medical disorders and, according to the World Health Organization, is a leading cause of disability worldwide. According to the National Institute of Mental Health, an estimated 8.3% of adults in the United States experienced one major depressive episode in 2021.

Given the extensive utilization of antipsychotic medications in depression, which are typically poorly tolerated, and the favorable tolerability profile of agomelatine, we believe the opportunity for a treatment with a novel mechanism in an adjunctive treatment population could provide a substantial benefit to patients and providers.

Background on ALTO-300 (Agomelatine) and History of Clinical Development

ALTO-300 is a product candidate known as agomelatine, initially developed by Servier. Agomelatine is a melatonergic (MT1 and MT2) agonist and serotonergic (5-HT2C) antagonist that is approved and commercially available in Europe (for the treatment of major depressive episodes in adults) and Australia (for the treatment of major depression in adults including prevention of relapse). As illustrated in the figure below, its MT1/2 agonism is thought to elevate mood through effects on circadian rhythms, while its 5-HT2C antagonism is thought to elevate mood by disinhibiting dopamine and norepinephrine release, particularly in the frontal cortex. This unique pattern of pharmacological activity is thought to contribute to agomelatine’s favorable tolerability data, characterized by a low reported incidence of canonical antidepressant side effects such as gastrointestinal intolerability, anxiety, sleep disturbance, and sexual dysfunction. Compared to other adjunctive treatments, agomelatine has demonstrated similar all-comer efficacy and favorable tolerability, with no difference in dropout due to adverse events, unlike many antipsychotics. Further, agomelatine has been shown to better treat anhedonia symptoms as compared to selective serotonin reuptake inhibitors, or SSRIs, or serotonin-norepinephrine reuptake inhibitors, or SNRIs, in third-party clinical trials.

Agomelatine has been studied in thousands of patients globally, including a Phase 3 clinical development program for MDD in the United States by Novartis. In these studies, the observed antidepressant effects of 25mg and 50mg agomelatine were approximately similar. However, higher rates of reversible liver enzyme elevation have been observed in the 50mg relative to the 25mg dose, both in Servier’s studies and in clinical practice. We are developing only 25mg agomelatine as ALTO-300.  In comparison to the 50mg dose of agomelatine, the 25mg dose has been shown to have equivalent antidepressant efficacy and has not been associated with reversible, low liver enzyme elevations observed with the 50mg dose. A published meta analysis including more than 58,000 patients demonstrated that agomelatine is not associated with elevated aspartate transferase, or AST, or alanine transaminase, or ALT, unlike certain other commonly used antidepressants. In our development program, including our completed Phase 2a and ongoing Phase 2b study, we have observed low rates of liver function test, or LFT, elevations (greater than 3 times the upper limit of normal, or ULN) with the 25mg dose which supports our strategy of developing only the 25mg dosage strength.

Interim Analysis Outcome from Ongoing Phase 2b Trial in MDD

In February 2025, we announced a favorable outcome from the planned interim analysis for the Phase 2b trial of ALTO-300 as an adjunctive treatment for patients with MDD. The interim analysis resulted in a recommendation to continue the study with a total targeted biomarker positive population of approximately 200 patients in the final analysis sample. The original target sample was 150 biomarker positive patients. We believe increasing the biomarker positive sample improves the overall probability of success of this trial.

Prior to the interim analysis, a blinded committee conducted an in-depth site and patient eligibility review that resulted in the prospective exclusion of sites and patients from the analysis population. Following the eligibility review, the biomarker positive population in the interim analysis consisted of 87 patients.

Our Completed ALTO-300 Phase 2a Trial in MDD

We completed an exploratory Phase 2a clinical trial of ALTO-300 as an adjunctive treatment in patients with MDD who experienced inadequate response to an antidepressant. The eight-week clinical trial was conducted across more than 20 sites in the United States and enrolled 239 patients with MDD between the ages of 18-74 years old to evaluate potential predictive biomarkers as well as the efficacy and safety of ALTO-300. Patients remained on a background antidepressant and were administered 25mg of ALTO-300 once daily before bedtime. A total of 110 of these patients underwent EEG recordings, of which 105 met pre-specified eligibility requirements to be included in the EEG analyses. The primary analysis was change in depressive symptoms as measured by MADRS at week four.

The Phase 2a trial identified a reproducible, readily scalable, and easily administered machine learning-derived EEG biomarker, which was further validated through prospective replication. Significantly more biomarker-characterized patients (n=55) than patients without the biomarker (n=50) achieved clinical response (defined as ≥50% reduction in depression symptoms) at week four (47% vs. 28%), week six (58% vs. 34%), and week eight (62% vs. 48%) of treatment. Overall, we observed a robust clinical response in biomarker positive patients. Further, the predictive biomarker is specific

to patients receiving ALTO-300, as it is not predictive of response in patients taking either placebo or standard-of-care SSRI/SNRIs based on data from separate studies in which EEG measurements allowed Alto to differentiate between patients with or without this EEG biomarker.

ALTO-300 was well tolerated in the Phase 2a trial among 239 patients, with no treatment-related serious adverse events reported. Importantly, we did not observe any incidents of LFT elevations across aspartate transaminase or alanine transaminase greater than three times the upper limit of normal.

ALTO-100

Overview

ALTO-100 is a novel small molecule that has shown evidence of a pro-neurogenesis/neuroplasticity mechanism of action, and we believe binds a receptor not targeted by other CNS therapeutics, which would make it first-in-class if approved.

We are currently evaluating ALTO-100 in a Phase 2b trial in patients with BPD, in which patients are assigned to take ALTO-100 as adjunctive treatment to a stable dose of a background mood stabilizing treatment over a 6-week treatment period. BPD is associated with memory, cognitive, and neuroplasticity abnormalities at similar or greater rates than seen in MDD. Much like MDD, poor memory and cognition patients typically experience greater treatment resistance and disability, with overall worse outcomes. Moreover the only currently approved therapies are antipsychotics. We believe the pro-neuroplasticity mechanism of ALTO-100 has the potential to address the high unmet need in this important patient population. The design of the trial is depicted below.

A blinded pharmacokinetic, or PK, analysis from the first cohort of patients in this trial demonstrated that 96% of samples for ALTO-100 qualified as PK positive. A sample was considered PK positive if observed drug levels were above a pre-specified minimum threshold. We believe these results underscore the effectiveness of the operational adjustments made to trial design and execution following the completion of the ALTO-100 MDD Phase 2b trial. Enrollment in this trial is ongoing, with a target of approximately 200 patients, and we expect to report topline data from the study in the second half of 2026.

In July 2024 we reported that this Phase 2b study is supported in part by a funding award from The Wellcome Trust Limited. See “—License and Other Agreements—The Wellcome Trust Limited Convertible Grant Agreement” for additional information.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-100.

Background on ALTO-100

Deficits in neuroplasticity lead to reductions in an individual’s ability to effectively adapt to their environment, which in patients with depression reinforces negative thought and behavioral patterns. Reductions in plasticity-promoting signaling molecules, such as brain derived neurotrophic factor, or BDNF, are also seen in the hippocampus of patients with depression, giving rise to a “neurotrophin hypothesis of depression” in which a central component is the resulting hippocampal neuroplasticity impairment. BDNF plays key roles in neuroplasticity at the synaptic and cellular levels, as well at the level of hippocampal neurogenesis, or the process of forming new neurons in the adult brain. ALTO-100 has demonstrated enhanced hippocampal neuroplasticity at the synaptic and cellular levels, along with neurogenesis, which we

believe suggests the potential to ameliorate depression symptoms in patients with this disruption, identified clinically as deficits in hippocampus-dependent verbal memory.

Our Completed ALTO-100 Phase 2b Trial in MDD

In October 2024, we announced that our Phase 2b study of ALTO-100 in patients with MDD did not meet its primary endpoint, assessed by a change from baseline in MADRS compared to placebo. The topline results included the primary and key secondary analyses in the biomarker positive modified-intent-to-treat, or mITT, population which included monotherapy and adjunctive treatment populations combined (n=196) and the monotherapy population alone (n=135). We further reported that the favorable safety and tolerability profile of ALTO-100 was consistent with previously reported studies. Overall, placebo response was well-managed, and the biomarker did not enrich for a larger placebo response in the study. The primary and pre-specified key secondary analyses are depicted in the table below.

ALL ANALYSIS POPULATION SAMPLE SIZE (N) MEAN BASELINE MADRS (SD) WEEK 6 LSM MADRS CHANGE (SE) COHEN’S D P

ALTO-100

Placebo

ALTO-100

Placebo
ALTO-100
Placebo

ALL BIO + MITT

(PRIMARY)
97 99 31.2(5.4) 31.5(5.4) -10.3(1.0) -9.8(1.0) 0.05 >0.1

MONOTHERAPY BIO + MITT

(KEY SECONDARY)
67 68 31.0(4.8) 32.2(5.3) -9.9(1.2) -11.1(1.1) -0.13 >0.1

ADJUNCTIVE BIO + MITT

(PRE-SPECIFIED SECONDARY, NOT POWERED)
30 31 31.5(6.6) 30.1(5.4) -11.5(1.8) -7.3(1.7) 0.47 0.09

LSM: Least Squares Mean; SD: Standard Deviation; SE: Standard Error; BIO+: Biomarker Positive; MITT: Modified Intention to treat

In a pre-specified analysis of biomarker positive patients taking ALTO-100 or placebo adjunctively to a stable background antidepressant (n=61), ALTO-100 demonstrated a clinically meaningful effect compared to placebo at week 6 (Cohen’s d=0.47, p=0.09). The pre-specified analysis of this population was not powered to achieve statistical significance.

We believe the inconsistency of the ALTO-100 effect between the monotherapy population and the adjunctive population was due to a higher than anticipated level of non-compliance with study medication in the monotherapy group, while the adjunctive group demonstrated a high level of compliance (56% in monotherapy vs. 100% in adjunctive). The graph above (right panel) demonstrates the difference in compliance (as measured by detectable levels of ALTO-100 in blood samples) between the monotherapy and adjunctive populations.

In the subset of patients that had evidence of taking ALTO-100 through blood sample analysis, a greater improvement was observed with ALTO-100 compared to placebo in the patients with the cognitive biomarker (shown below on left), and the patients with the cognitive biomarker demonstrated a greater improvement than those without the biomarker (right). The analyses in the PK positive sample are supportive of the overall potential efficacy of ALTO-100 in patients with the cognitive biomarker.

We believe the clinically meaningful signal in the adjunctive subgroup, combined with the evidence of biomarker enrichment in the compliant subset of patients, supports continuing the Phase 2b trial of ALTO-100 as an adjunctive treatment in BPD. Further, we believe the evidence across analyses of the ALTO-100 Phase 2b MDD trial broadly supports our enrichment approach as having the potential to identify patients that could demonstrate a better response to treatment.

ALTO-101

Overview

ALTO-101 is an investigational brain-penetrant phosphodiesterase 4, or PDE4, inhibitor that we are developing in a novel transdermal formulation for the treatment of Cognitive Impairment Associated with Schizophrenia, or CIAS. Through this unique formulation, ALTO-101 is designed to retain the desired brain effects shown with the oral formulation and avoid tolerability challenges and adverse effects known to be associated with PDE4 inhibitors. In our completed Phase 1 trial, we observed robust effects of ALTO-101 on cognitive processing, measured with EEG, and cognitive test performance. We are currently evaluating ALTO-101 in a Phase 2 proof-of-concept, or POC, trial, which consists of a cross-over, double-blind, placebo-controlled, dose-escalating treatment. We recently completed enrollment of 83 participants in this trial and we expect to complete the trial and report topline data around the end of the first quarter of 2026.

The primary endpoint in the trial is the effect of ALTO-101 on theta band activity, the EEG measure shown to be best related to CIAS in replicated analyses of large schizophrenia datasets. Objective cognitive performance will also be evaluated. In September 2025, we announced positive results from an independent, prospective replication study evaluating EEG biomarkers in people with schizophrenia. The study successfully replicated previous findings, demonstrating that event-related theta-band responses, particularly theta-band inter-trial coherence, or ITC, robustly differentiates people with schizophrenia from healthy individuals. The results support the use of this objective, brain-based measurement in evaluating drug activity in this patient population.

In October 2025, the FDA granted Fast Track designation to ALTO-101 for the treatment of CIAS.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-101.

CIAS Background

Schizophrenia afflicts more than 2.8 million people in the United States alone. The hallmark symptoms of schizophrenia include hallucinations, delusions, irrational/illogical thoughts, and movement disorders. In addition to these positive symptoms, which are the target of all currently approved medications, approximately 90% of patients with schizophrenia also experience cognitive and/or negative symptoms. Cognitive symptoms include memory disturbances, inability to process information and make decisions, and trouble focusing or paying attention. Negative symptoms entail blunting of affect and are more akin to other affective disorders such as depression. Cognitive and negative symptoms of schizophrenia are also often more predictive of impairment in daily function than positive symptoms. Despite significant need for interventions to treat these aspects of schizophrenia, there are no currently approved treatments for the cognitive and negative symptoms.

Background on ALTO-101

ALTO-101 is a brain-penetrant small molecule that inhibits the PDE4 enzyme. PDE4 inhibition is relevant across numerous high-need therapeutic areas. However, available medications are non-brain penetrant with substantial tolerability and dosing limitations.

PDE4 normally acts to break down cyclic adenosine monophosphate, or cAMP, terminating its ability to drive downstream signaling. Post-mortem and genetic studies of patients with cognitive disorders, including schizophrenia, have demonstrated reduction in a key neuroplasticity-related second messenger signaling pathway involving cAMP. This pathway has been extensively studied in humans and a wide range of preclinical models, with findings indicating that reduction in cAMP signaling has been observed to be associated with impaired cognition and mood, while increasing cAMP has been shown to rescue deficits in animal models of a variety of neuropsychiatric disorders. While several drugs that increase cAMP levels by inhibiting the breakdown of this second messenger are approved for non-CNS indications (e.g., psoriasis), none have yet been approved in the United States to treat neuropsychiatric disorders. By inhibiting PDE4, ALTO-101 is designed to elevate cAMP levels, which in the hippocampus has enhanced neuroplasticity and improved various forms of memory in preclinical models. ALTO-101 has demonstrated pro-cognitive effects in vivo at doses as low as five micrograms per kilogram. The figure below illustrates the potential mechanism of action of ALTO-101.

Our Completed ALTO-101 Phase 1 Study in Healthy Subjects

In order to understand the pharmacodynamic effects of ALTO-101 and neurocognitive outcomes relevant to CIAS, we completed a dose mapping trial in healthy subjects using our platform. Specifically, 40 individuals completed a three-condition cross-over design study, with each participant receiving single doses of placebo, 0.5mg, and 1.5mg of ALTO-101 orally at seven-day intervals. Key outcomes on EEG, event-related potentials, and neurocognitive task performance measures relevant to schizophrenia and other cognitive disorders were assessed. Compared to placebo, we observed significant effects in a dose response relationship for ALTO-101 on multiple measures including decreases in EEG resting theta power, which is known to be elevated in multiple cognitive and psychiatric disorders; increases in stimulus-driven gamma-band phase locking, which is known to be reduced in schizophrenia patients; and increases in mismatch negativity, which is known to be blunted in patients with schizophrenia. We also observed statistically significant, dose-dependent increases in information processing speed, a core cognitive domain important to multiple higher-level functions, as well as promising effects on a global cognition composite. We believe that these results support the potential utility of ALTO-101 as a pro-cognitive agent.

Higher doses of PDE4 inhibitors, broadly, have been associated with increased rates of nausea, which we believe is associated with peak concentrations in the brain after oral dosing. In our Phase 1 study, we likewise observed a dose-dependent increase in nausea (2.4% at 0.5mg and 28% at 1.5mg), dizziness (4.8% and 23.3%), and lightheadedness (2.4% and 14%), though only 2.3% of patients discontinued due to an adverse event. No serious treatment emergent adverse events, or TEAEs, were identified. The vast majority of these TEAEs occurred near Tmax, or the time it takes to reach peak drug concentration in the brain. Given the potency of ALTO-101, and our observation of its dose-response pharmacodynamic effects on brain biomarkers of cognition, we reformulated ALTO-101 to be delivered transdermally. The transdermal formulation, being developed in partnership with MedRx Co., Ltd., or MedRx, is designed to deliver a consistent and pharmacodynamically relevant dose while avoiding the peaks in blood concentration typical of immediate release oral drugs. See “—License and Other Agreements—License Agreement with MedRx” for further discussion.

We completed a Phase 1 trial in healthy subjects designed to evaluate the safety, tolerability, pharmacokinetics, and adhesion properties of a proprietary transdermal formulation of ALTO-101 compared to oral administration of ALTO-101 in healthy subjects. The transdermal formulation achieved similar maximum concentration as the oral formulation with a greater overall duration of exposure. The area under the curve was 62% and 170% higher on day 1 and day 2 respectively for the transdermal relative to oral administration (day 1 p=0.01; day 2 p<0.001). Further, the transdermal formulation was well-tolerated with no discontinuations. All adverse events reported in the study were mild in severity, and there were no reported serious adverse events. The transdermal formulation demonstrated favorable adhesion properties and there were no application site reactions that led to removal or intolerance. Taken together, our novel transdermal formulation of ALTO-101 exhibited greater systemic drug exposure than orally administered ALTO-101 while also demonstrating a reduction in typical class-related adverse events.

ALTO-203

Overview

ALTO-203 is an investigational, novel, oral small molecule histamine H3 receptor inverse agonist. We are currently advancing ALTO-203 for the treatment of patients with MDD associated with increased levels of anhedonia.

In June 2025, we announced the completion of our exploratory Phase 2 POC trial of ALTO-203 in MDD with elevated levels of anhedonia and the resulting identification of a patient selection biomarker and positive pharmacodynamic results. The exploratory Phase 2 POC trial, which enrolled 69 patients, was conducted in two sequential, double-blind, placebo-controlled periods. The trial was designed to characterize the pharmacodynamic, pharmacokinetic, safety, and tolerability profile of ALTO-203 across two dose levels compared to placebo in a crossover design. In the first period, patients received a single-dose of ALTO-203 or placebo, and the outcome measure was designed to evaluate pharmacodynamic effects. An acute change in positive emotion was assessed by the alertness and mood components of the Bond-Lader Visual Analog Scale (BL-VAS), an established scale of subjective emotion also used in a prior Phase 1 trial of ALTO-203. In the second period, patients received ALTO-203 or placebo once daily over a 28-day treatment period to evaluate the clinical activity and safety of ALTO-203. The study was powered based on the outcomes being evaluated in the first period and was not powered to detect statistical significance on traditional depression outcome scales (e.g., MADRS).

The profile exhibited by ALTO-203 in the exploratory POC trial demonstrated clear effects on objective measures of attention and wakefulness, with observed improvements linked to changes in the EEG theta/beta ratio—a biomarker indexing cortical arousal and attentional control. This biomarker is FDA-cleared for use alongside clinical evaluation in the diagnosis of attention-deficit/hyperactivity disorder or ADHD, reinforcing its clinical relevance. These findings replicate results from the Phase 1 study in healthy volunteers, where ALTO-203 treatment led to improvements in sustained attention and reductions in the EEG theta/beta ratio. Baseline EEG theta/beta ratio predicted attentional benefits of ALTO-203 in both the Phase 1 study and exploratory Phase 2 POC trial. A higher-than-expected placebo response was observed on Bond & Lader measurements, therefore no significant separation of subjective effects between ALTO-203 and placebo were observed.

Additionally, we presented data in early 2026 demonstrating the potential benefits of ALTO-203 in indications with excessive daytime sleepiness/hypersomnolence and/or impairments in sustained attention. We continue to evaluate the best indication to pursue with ALTO-203, and expect to provide further details on planned development in the future.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-203.

Background on ALTO-203 

The histamine H3 receptor, unlike other histamine receptors, is located predominantly in the brain and acts as a master regulator, inhibiting the release of a number of other major neurotransmitters including histamine, dopamine, acetylcholine, and norepinephrine. By inhibiting the “brake” driven through tonic activity the H3 receptor, levels of these neurotransmitters are thought to increase. Use of an H3 inverse agonist may therefore be important given its potential to block both histamine-induced and basal levels of receptor activity. The figure below illustrates the potential mechanism of action of ALTO-203.

Despite these theoretical effects of blocking H3 receptors, as well as the action of many H3 inverse agonists on cortical dopamine release, prior data on several H3 inverse agonists have failed to demonstrate any effects on dopamine release in

the nucleus accumbens. This lack of an effect on dopamine is particularly notable for the only approved H3 inverse agonist, pitolisant, which is indicated for the treatment of excessive daytime sleepiness in narcolepsy. In a preclinical study conducted by ALTO-203’s originator, ALTO-203 demonstrated an elevation of dopamine in the nucleus accumbens, a region of the brain thought to be particularly implicated for reward and motivation. We believe this activity in the nucleus accumbens differentiates ALTO-203 from other H3 inverse agonists given that the ability to drive dopamine release may be critical for mood enhancement. Further, in a Phase 1 trial completed by its originator, ALTO-203 acutely increased subjective positive emotions by levels equivalent to or greater than modafinil, an FDA approved drug acting through dopamine release. The approach to treating depression through a dopamine-enhancing treatment, like modafinil or armodafinil, has been successful in third-party clinical trials in MDD and BPD.

Previously Completed ALTO-203 Phase 1 Study in Healthy Volunteers

ALTO-203 was previously studied in a Phase 1 study and demonstrated significant acute benefits on a scale of subjective positive emotion, compared to placebo. The magnitude of this effect was shown to be equivalent to, or better than modafinil, an active comparator with demonstrated antidepressant activity in clinical trials.

ALTO-202

Overview

ALTO-202 is an investigational orally bioavailable antagonist of the GluN2B subunit of the NMDA receptor. NMDA receptors are receptors for glutamate, the major excitatory neurotransmitter in the brain, and its excessive release is associated with excitotoxicity-induced brain injury. This involvement of the glutamatergic system in depression is supported by the antidepressant effects of NMDA receptor antagonists, like ketamine and its enantiomer, esketamine. Given the evidence of antidepressant activity of NMDA receptor antagonists, and the drawbacks of those currently used, we plan to develop ALTO-202 in MDD as an oral GluN2B antagonist. We are currently in the process of planning the next phase of clinical development for ALTO-202.

Background on ALTO-202

Prior to our licensing of ALTO-202, it was evaluated by Merck and Cerecor across 10 clinical trials, including five Phase 1 safety and PK trials and two Phase 2 trials in MDD, a pilot study in treatment resistant depression, and two Phase 1b trials in patients with Parkinson’s disease. Specifically, the originator conducted a 115-patient clinical trial using a sequential parallel comparison design, wherein patients received a sequential single dose regimen of 12 mg or 20 mg of ALTO-202 or placebo. The primary endpoint in the trial was the HDRS-6, using the average change across day two and day four post-dosing. ALTO-202 did not demonstrate statistically significant changes compared to placebo on the primary endpoint, but potentially clinically meaningful differences were observed on total HDRS score change at day two compared to placebo in a prespecified secondary analysis. Based on these results, we believe ALTO-202 may have potential rapid-onset antidepressant effects that could potentially be elucidated in a well-powered study. Across the trials, ALTO-202 was well tolerated with the most common adverse events being increased blood pressure, dizziness, somnolence, and paresthesia (numbness or tingling feeling). There were no treatment related serious adverse events observed in the prior studies of ALTO-202.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to ALTO-202.

ALTO-208

ALTO-208 is a fixed-dose combination of pramipexole and aprepitant, an antiemetic, neurokinin-1 (NK-1) receptor antagonist. We plan to develop ALTO-208 for patients with Parkinson’s disease, or PD. In May 2025, we acquired ALTO-208 (formerly known as CTC-413) from Chase. See “—License and Other Agreements—Chase Asset Purchase Agreement” and “—Intellectual Property—Product Candidate Patent Portfolio” for additional information.

About the Completed Phase 2a Trial for CTC-413

Chase completed a blinded Phase 2a clinical trial evaluating CTC-413 (pramipexole co-administered with aprepitant) in 13 patients with PD. The study consisted of two periods. Patients in the treatment group were initially titrated to the maximum allowed dose of standard pramipexole extended release (4.5 mg/day). Patients were then switched to CTC-413 until the

maximum allowed dose of 9mg/day (or first intolerable dose) was reached. Following three months of maintenance, patients returned to their pre-study regimen for final assessment.

The mean tolerated dose of CTC-413 significantly exceeded pramipexole (p<0.001). Six subjects (67%) tolerated CTC-413 at the maximum dose of 9.0mg/day and all but one remained on that dose throughout the final three-month treatment period. CTC-413 demonstrated favorable safety and tolerability with no unexpected, serious or persistent issues.

License and Other Agreements

License Agreement with Stanford University

In December 2019, we entered into an exclusive license agreement with equity, or the Stanford Agreement, with the Board of Trustees of the Leland Stanford Junior University, or Stanford, which was subsequently amended in May 2020 and December 2023.

Under the terms of the Stanford Agreement, we obtained a worldwide, royalty-bearing license, with the right to sublicense during the exclusive term only, under certain patent rights in five patent families relating to brain stimulation, electroencephalogram and functional MRI that we could use to guide treatment of psychiatry patients, or the Stanford Licensed Patents, and under certain technology relating to the inventions covered by the Stanford Licensed Patents, or Stanford Licensed Technology, to make, have made, use, sell, offer for sale and import licensed products for use in any indication. Our rights under the Stanford Licensed Patents are exclusive until December 2029, at which time it will become non-exclusive, and our rights under the Stanford Licensed Technology are non-exclusive. Some of the Stanford Licensed Patents are jointly owned by the United States Department of Veterans Affairs and/or the Board of Regents of the University of Texas System, or the UT Board, but all the Stanford Licensed Patents are exclusively managed by Stanford under invention management agreements between Stanford and those other institutions. Stanford retained the right for itself and all other non-profit research institutions to practice the Stanford Licensed Patents and use the Stanford Licensed Technology for any non-profit purpose, including sponsored research and collaborations. Additionally, the United States Government has the nonexclusive, nontransferable, irrevocable, royalty-free, paid-up right to practice or have practiced the Stanford Licensed Patents throughout the world by or on behalf of the United States Government and on behalf of other governments or organizations, and requires us to manufacture the licensed product substantially in the United States.

As partial consideration to acquire these license rights, we paid Stanford an upfront fee of $20,000 and reimbursed Stanford approximately $80,000 of prior patent prosecution expenses related to the licensed patents. Additionally, we are required to pay a low five-digit annual license maintenance fee beginning on each anniversary of the effective date through the term of the Stanford Agreement. We also issued an aggregate of 104,348 shares of our common stock to Stanford, the UT Board and five inventors, including Amit Etkin, M.D., Ph.D., our Chief Executive Officer. We additionally granted to Stanford a right to participate in subsequent private financings of our equity securities, pursuant to which Stanford has purchased an aggregate of 627,189 shares of our Series Seed and Series A convertible preferred stock. This purchase right terminated upon the closing of the IPO.

We are required to diligently develop, manufacture and offer to sell licensed products and to diligently develop markets for licensed products, in addition to meeting certain specified development and commercial diligence milestones. We do not owe any milestone payments to Stanford in connection with our development and commercialization of products or services covered by the Stanford Licensed Patents, however beginning with our first commercial sale of the licensed products, we owe Stanford royalties on aggregate annual net sales of all licensed products by us, our affiliates or sublicensees at a very low single digit percentage. We are also required to pay Stanford mid-teen to low-mid double digit percentages of any sublicensing consideration that we receive from third parties to whom we sublicense rights under the Stanford Licensed Patents, depending on the timing of entry into the applicable sublicense.

Unless terminated earlier, the Stanford Agreement will expire upon the expiration of the last Stanford Licensed Patent. Stanford has the right to terminate the Stanford Agreement on thirty days’ written notice upon our uncured material breach of the Stanford Agreement, including failure to achieve the specified diligence milestones by the specified dates, as well as for certain other specified breaches. We have the right to terminate the Stanford Agreement for any reason upon specified prior written notice to Stanford.

License Agreement with Sanofi

In May 2021, we entered into a license agreement, or the Sanofi Agreement, with Sanofi, pursuant to which we obtained an exclusive, worldwide, royalty-bearing license, with the right to sublicense, under certain patent rights and know-how of

Sanofi relating to a PDE4 inhibitor compound, now known as ALTO-101, to use, have used, develop, have developed, manufacture, have manufactured, commercialize, have commercialized or otherwise exploit ALTO-101 and products incorporating ALTO-101, or the Sanofi Licensed Products, for all human therapeutic, prophylactic and diagnostic uses. We also obtained a non-exclusive, worldwide license to use certain other specified know-how licensed to Sanofi by a specified third party to exploit Sanofi Licensed Products solely with respect to Parkinson’s disease. During a time period that ends at a specified point in late-stage clinical development for the first Sanofi Licensed Product, Sanofi retains a limited right of first negotiation to negotiate to obtain from us, on an indication-by-indication basis, exclusive worldwide rights to exploit such Sanofi Licensed Product in such indication. If we do not agree upon terms for such exclusive license with Sanofi within a specified negotiation period, we are free to continue the development and commercialization of the Sanofi Licensed Product ourselves or via the grant of rights to any third party, subject to certain specified limitations on the grant of such rights, and the reinstatement of Sanofi’s right of first negotiation after a specified period.

We are required to use commercially reasonable efforts to develop Sanofi Licensed Products and to obtain regulatory approval for Sanofi Licensed Products in at least one indication in each of the United States, a major European country, the United Kingdom and Japan or China, and to commercialize any Sanofi Licensed Product for which we obtain regulatory approval. We paid Sanofi an upfront fee of $0.5 million upon the entry into the Sanofi Agreement, and will be required to pay Sanofi up to an aggregate amount in the low-mid double digit millions upon the achievement of certain one-time development and regulatory approval milestones for the first Sanofi Licensed Product to achieve the specified milestone events. In addition, if we grant sublicenses under the patents and know how licensed to us under the Sanofi Agreement, we are required to pay sublicense revenue to Sanofi at tiered percentages ranging from low-mid double-digit percentages down to the very low double-digit percentages, reducing based on the time of entry into the applicable sublicense agreement.

If we achieve regulatory approval for one or more Sanofi Licensed Products, we will owe Sanofi certain commercial milestone payments for the achievement of specified levels of aggregate, annual worldwide net sales of all Sanofi Licensed Products, up to an aggregate amount of $102.0 million for all Sanofi Licensed Products. Beginning with our first commercial sale of a Sanofi Licensed Product, we will also be required to pay Sanofi a tiered royalty on aggregate, annual, worldwide net sales of Sanofi Licensed Products at percentages ranging from the mid-to-high single digits, subject to certain customary reductions that are applicable on a product-by-product and country-by-country basis, and a customary overall royalty floor. Royalties are payable, on an aggregate basis for all licensed products and all countries, with the royalty term commencing on a Sanofi Licensed Product-by-Sanofi Licensed Product and country-by-country basis on the first commercial sale of a Sanofi Licensed Product in such country, until the latest to occur of (a) expiration of the last valid claim of either a licensed patent or certain patents filed by us after the effective date of the Sanofi Agreement that claim the know-how licensed to us by Sanofi, (b) the expiration of any regulatory exclusivity for such Sanofi Licensed Products in such country, and (c) the tenth anniversary of the first commercial sale of such Sanofi Licensed Product in such country, or the Sanofi Royalty Term. Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms.

In addition, if we use specified know-how licensed to Sanofi by the specified third party to exploit the Sanofi Licensed Products for Parkinson’s disease, we will pay an additional premium at a mid-single digit percentage on all fees, milestone payments and royalties payable by us to Sanofi under the Sanofi Agreement, which premium will be payable by Sanofi directly to the specified third party.

Unless terminated earlier, the Sanofi Agreement will expire with respect to each licensed product, on a country-by-country basis, upon the expiration of the Sanofi Royalty Term, and with respect to the agreement in its entirety upon the expiry of the Sanofi Royalty Term for the last licensed product for which there has been a first commercial sale. Either we or Sanofi may terminate the Sanofi Agreement upon 60 days’ prior written notice for the uncured material breach of the Sanofi Agreement by the other party. Sanofi also has the right to terminate the Sanofi Agreement for our insolvency or if we bring or otherwise participate in a patent challenge against any licensed patents. We may terminate the Sanofi Agreement for any reason upon specified prior written notice to Sanofi.

License Agreement with Cerecor

In May 2021, we entered into a patent and know-how license agreement, or the Cerecor Agreement, with Cerecor Inc. (n/k/a Avalo Therapeutics, Inc.), or Cerecor, pursuant to which we obtained an exclusive worldwide, royalty-bearing license, with the right to sublicense, under certain patent rights and know-how owned or controlled by Cerecor relating to an NR2B inhibitor compound now known as ALTO-202, including certain rights licensed to Cerecor by Essex Chemie AG, or Merck, to research, develop, make, have made, use, import, offer for sale and sell ALTO-202 and products

incorporating ALTO-202, or Cerecor Licensed Products, for the prevention, diagnosis and/or treatment of all diseases in humans. Merck and its affiliates retained a co-exclusive, worldwide right under Merck’s patent rights and know-how sublicensed to us by Cerecor to research, make, have made, use and import ALTO-202 and Cerecor Licensed Products solely for non-human, non-commercial purposes, and we received a non-exclusive worldwide, royalty-bearing license, with the right to sublicense, under certain patent rights covering improvements made by Merck through its exercise of such retained right. We are required to use commercially reasonable efforts to develop and commercialize at least one Cerecor Licensed Product in the licensed field in the United States, a major European country or Japan, whether ourselves or through an affiliate or licensee.

As partial consideration for the licenses granted by Cerecor, we paid Cerecor an upfront fee of $0.5 million. We will be required to pay Cerecor or Merck, depending on the specific milestone as set forth in the Cerecor Agreement, up to an aggregate of $59.1 million per Cerecor Licensed Product if we achieve certain development, regulatory approval and first commercial sale milestones for such Cerecor Licensed Product in up to a specified number of indications. If we successfully commercialize Cerecor Licensed Products, we will also be required to pay to Merck sales milestones totaling up to $15.0 million for all Cerecor Licensed Products, for the achievement of certain specified levels of worldwide annual aggregate net sales of all Cerecor Licensed Products. Beginning on the date of our first commercial sale of a Cerecor Licensed Product, on a Cerecor Licensed Product-by-Cerecor Licensed Product and country-by-country basis, we will also be obligated to pay Merck and Cerecor tiered royalties on aggregate annual worldwide net sales of such Cerecor Licensed Product at percentages in the high single digits in the aggregate, until the later of (a) the expiration of the last valid claim within the licensed patents covering such Cerecor Licensed Product in such country and (b) 10 years after the first commercial sale of such Cerecor Licensed Product in such country, or the Cerecor Royalty Term. Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms. If we develop and commercialize a companion diagnostic as a standalone product in connection with a Cerecor Licensed Product, we will be required to make a one-time milestone payment to Cerecor upon the achievement of a specified level of net sales of such companion diagnostic product, at an amount in the very low single digit millions.

The Cerecor Agreement will remain in force, unless earlier terminated, until the expiration of the Cerecor Royalty Term. Either we or Cerecor may terminate the Cerecor Agreement upon 60 days’ prior written notice for an uncured material breach of the Cerecor Agreement by the other party, or in the case of an insolvency event of the other party. We may terminate the agreement for any reason upon specified prior written notice to Cerecor.

Teva Asset Purchase Agreement

In October 2021, we entered into an asset purchase agreement, or the Teva Agreement, with Teva Pharmaceutical Industries, Ltd. and its affiliate Cephalon, Inc., or, together Teva, pursuant to which we acquired patents, know-how and other rights to ALTO-203 and a specified related compound, or Teva Acquired Compounds, and we assumed all post-acquisition liabilities related thereto. Pursuant to the Teva Agreement, we are required to use commercially reasonable efforts to research, register, manufacture, develop, and commercialize the acquired assets, including exploiting products that incorporate a Teva Acquired Compound, or Teva Products.

As partial consideration for the acquisition of these rights, we paid Teva an upfront fee of $0.5 million. For the first Teva Product that we develop pursuant to the Teva Agreement, we are required to pay Teva up to an aggregate of $27.0 million upon the achievement of certain development and regulatory approval milestones ($0.5 million of which was paid to Teva in connection with the initiation of our Phase 2 POC trial evaluating ALTO-203), and up to $35.0 million in the aggregate for the achievement of certain tiered sales milestones for such Teva Product. In addition, if we successfully achieve regulatory approval, then beginning with first commercial sale, on a Teva Product-by-Teva Product and country-by-country basis, we will be required pay Teva tiered royalties on worldwide annual net sales of Teva Products at percentages ranging from the mid-single-digit to ten percent, until the latest to occur of (a) expiration of the last valid claim of an acquired patent covering the composition of matter, or use or formulation of the composition of matter of a Teva Acquired Compound incorporated in or comprising such Teva Product in such country, (b) the expiration of new chemical entity data and/or market exclusivity for such Teva Product in such country and (c) the 10th anniversary of the date of first commercial sale of such Teva Product in such country. Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms.

Palisade Asset Purchase Agreement

In October 2021, we entered into an asset transfer agreement, or the Palisade Agreement, with Palisade Bio, Inc., or Palisade, pursuant to which we acquired all patent, know-how and other rights to ALTO-100.

As partial consideration for the acquisition of these rights, we paid Palisade an upfront fee of $0.5 million. In addition, we will be required to pay Palisade up to an aggregate of $4.5 million upon the achievement of certain development and regulatory approval milestones for ALTO-100 (or a product containing ALTO-100 or otherwise derived from the acquired assets), or Palisade Acquired Products. If we sell or grant to a third party a license to the patents, know-how and other rights included in the acquired assets prior to the achievement of a specified clinical development milestone, we will be required to pay to Palisade a low-double digit percentage of any consideration received by us from such license or sale, provided that the maximum aggregate consideration we will be required to pay to Palisade under the Palisade Agreement, including the upfront payment and all potential milestones and transaction-related payments, will not exceed $5.0 million.

In connection with the transactions effected by the Palisade Agreement, Palisade also transferred and assigned to us all right, title, and interest in, to, and under an exclusive license agreement, or the Dow Agreement, between Dow Agrosciences LLC, or Dow, and Palisade (f/k/a Neuralstem, Inc.), dated as of December 1, 2016, as a result of which we obtained an exclusive, sublicensable license under certain patent rights of Dow to make, have made, use, and have used, certain compounds covered by such patent rights and to make, have made, offer for sale, sell, import, and have imported, products using such compounds, including Palisade Acquired Products, for the development, synthesis, and commercialization of such products as prescription human pharmaceutical in the United States. The patent rights licensed to us under the Dow Agreement cover an intermediate compound in the manufacturing process for ALTO-100.

Under the Dow Agreement, we are required to pay Dow an annual license maintenance fee that is customary for a license of this nature and not material to us. Additionally, we are required to pay Dow a single milestone payment that is customary for a license of this nature in the range of several million dollars upon the achievement of the first commercial sale of a product containing ALTO-100 (including any Palisade Acquired Product) in the United States. In addition, if we continue to manufacture ALTO-100 using a process that includes the manufacturing step covered by the patents included in the Dow Agreement, we will be required to pay Dow tiered royalties calculated as a percentage of any cash or non-cash consideration payable to us by our commercial partners that arise from net sales of products covered by the Dow patent rights, including Palisade Acquired Products, by such commercial partners, at percentages in the single digits. Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms.

Unless earlier terminated, the Dow Agreement will expire upon the last to expire valid claim of the licensed patent rights in the United States. Either we or Dow may terminate the Dow Agreement for the uncured material breach of this Agreement by the other party following a specified notice period.

License Agreement with MedRx

In September 2023, we entered into a joint development and license agreement, or the MedRx Agreement, with MedRx Co., Ltd., or MedRx, pursuant to which we obtained an exclusive, sublicensable, worldwide license, with the right to sublicense, under certain patent rights and know-how of MedRx relating to transdermal drug delivery to develop (excluding any pre-clinical development), manufacture, and commercialize transdermally delivered pharmaceutical products comprising MedRx’s transdermal patch technology and our ALTO-101, or MedRx Licensed Products, for all therapeutic, prophylactic, and diagnostic uses. We granted MedRx an exclusive, sublicensable, worldwide license under certain patent rights and know-how relating to ALTO-101 owned or controlled by us, including certain patents and know how licensed to us pursuant to the Sanofi Agreement, solely to conduct pre-clinical development and manufacturing of the MedRx Licensed Products for us in accordance with the MedRx Agreement and a separate manufacturing and supply agreement to be entered into between us and MedRx. During the term of the MedRx Agreement, we agreed that we will not, directly or indirectly, develop, manufacture, or commercialize any pharmaceutical product that is a transdermal patch formulation containing similar active pharmaceutical ingredients as ALTO-101 and that is used in the same field and labeled for the same indications as the MedRx Licensed Products, or MedRx Competitive Product. MedRx agreed that it will not, directly or indirectly, exploit any patch formulations of PDE4-inhibitor drugs for use within CNS disorders or exploit any MedRx Competitive Product, provided that if certain specified development or first commercial sale milestones are not achieved by certain specified dates, then MedRx has the right to cause the non-compete restrictions on both parties to lapse.

Under the MedRx Agreement, MedRx will be solely responsible for conducting all pre-clinical development of the MedRx Licensed Products to support IND and institutional review board filing, and we will be solely responsible for all other development (including non-clinical studies and clinical studies) necessary to obtain regulatory approval for the licensed products and subsequent commercialization of MedRx Licensed Products. We are obligated to use commercially reasonable efforts to commercialize the MedRx Licensed Products in each of the following countries in which we have

obtained regulatory approval: the United States; at least two of Germany, Spain, France, Italy or the United Kingdom; and one of China or Japan.

Pursuant to the MedRx Agreement, we paid MedRx an upfront fee of $150,000. We are required to pay MedRx up to an aggregate of $11.0 million for the achievement of certain development and first commercial sale milestones for the first MedRx Licensed Product to achieve such milestones with respect to a first indication, and an additional milestone in the mid-single digit millions for each additional approved distinct indication for such first MedRx Licensed Product or a subsequent MedRx Licensed Product. In addition, we will be required to pay MedRx sales milestones based on the achievement of specified thresholds of aggregate annual worldwide net sales of all MedRx Licensed Products of up to $110.0 million in the aggregate, if all such sales thresholds are achieved. In April 2024, we achieved a milestone under the MedRx Agreement and paid MedRx $0.75 million in cash and issued MedRx 46,875 shares of our common stock.

Commencing on the first commercial sale of a MedRx Licensed Product, we will also be obligated to pay MedRx a mid-single digit royalty on annual, worldwide net sales of all MedRx Licensed Products, subject to certain customary reductions and a royalty floor. Royalties will be payable, on a MedRx Licensed Product-by-MedRx Licensed Product and country-by-country basis, until the latest to occur of (a) expiration of the last valid claim of certain specified patent rights covering such MedRx Licensed Products in such country, (b) the expiration of any regulatory exclusivity for such MedRx Licensed Product in such country, (c) the first approval of a specified generic product referencing such MedRx Licensed Product in such country, and (d) the tenth anniversary of the first commercial sale of such MedRx Licensed Product in such country, or the MedRx Royalty Term.

The MedRx Agreement will expire with respect to each MedRx Licensed Product, on a country-by-country basis, upon the expiration of the MedRx Royalty Term, and with respect to the entire MedRx Agreement upon the expiry of the last-to-expire MedRx Royalty Term for the last MedRx Licensed Product for which there has been a first commercial sale. Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms. Either we or MedRx may terminate the MedRx Agreement in its entirety or on a MedRx Licensed Product-by-MedRx Licensed Product basis upon an uncured material breach by the other party or in connection with an insolvency event of such party. In addition, if we or MedRx bring or otherwise participate in a patent challenge against any patents licensed by the other party, such other party may terminate the MedRx Agreement immediately. We have the right to terminate the MedRx Agreement in its entirety or on a MedRx Licensed Product-by-MedRx Licensed Product basis for any reason upon specified prior written notice to MedRx provided that the effective date of such termination will not be earlier than the completion date of a specified development event. We also have the right to terminate the MedRx Agreement with respect to a MedRx Licensed Product immediately upon our reasonable determination of a material safety issue with respect to such MedRx Licensed Product.

The Wellcome Trust Limited Convertible Grant Agreement

In July 2024, we entered into a convertible loan agreement, or the Convertible Grant Agreement, with The Wellcome Trust Limited, or Wellcome. The Convertible Grant Agreement provides for an unsecured convertible loan, or the Convertible Loan, from Wellcome of up to approximately $11.7 million, payable in six tranches. As of December 31, 2025, we had drawn down $2.0 million under the Convertible Grant Agreement, and the remainder will be funded upon draw down of payments following the completion of certain milestones as set forth in the Convertible Grant Agreement, subject to certain conditions described therein, which may or may not be met in a timely manner or at all. In addition to the funds that we have drawn down as of December 31, 2025, we have achieved clinical milestones that allow us to draw down an incremental $3.0 million under the Convertible Grant Agreement.

We may use proceeds from the Convertible Loan solely to advance development of ALTO-100 in bipolar depression. In addition, if we do not exploit or develop ALTO-100 (other than for safety or efficacy concerns) within a specified period following the completion of our Phase 2b clinical trial evaluating ALTO-100 in patients with bipolar depression, the Convertible Grant Agreement provides Wellcome with a limited right to exploit ALTO-100, solely in bipolar depression, subject to a revenue share between Wellcome and us of any proceeds arising from Wellcome’s exploitation. Outstanding amounts under the Convertible Loan accrue interest at an annual rate equal to the Sterling Overnight Index Rate plus 2%, subject to potential adjustment if such interest rate equals or exceeds 9% at any time. At any time after the second anniversary of the effective date of the Convertible Grant Agreement or in connection with an event of default, Wellcome has the right, at its election, to convert some or all of the Convertible Loan into shares of our common stock at a price per share equal to a 20% discount to the thirty-day volume-weighted average price of Common Stock on the New York Stock Exchange at the date of such conversion. The Convertible Grant Agreement provides that in no event shall the aggregate number of shares of our common stock issued pursuant to conversion of the Convertible Loan exceed 5,363,326, which is

equal to 19.9% of the number of shares of our common stock outstanding as of the date of the Convertible Grant Agreement. At any time after the fifth anniversary of the date of the Convertible Grant Agreement or in connection with an event of default, Wellcome may require repayment of the Convertible Loan in full, together with accrued interest, to the extent not converted as described above.

Chase Asset Purchase Agreement

In May 2025, we entered into an asset purchase agreement, or the Chase Agreement, with Chase Therapeutics Corporation, or Chase, pursuant to which we acquired all patent, know-how and other rights to ALTO-207, ALTO-208, and certain related asset, or the Acquired Chase Compounds. On the May 31, 2025 closing date, or the Chase Closing Date, we made an initial payment of $1.8 million in cash and reimbursed Chase $1.2 million to offset certain expenses incurred by Chase in connection with the Chase Agreement. We are obligated to pay Chase up to an aggregate of $71.5 million after the Chase Closing Date, or the Chase Milestone Payments, upon the achievement of certain clinical, regulatory, and sales milestones related to the Acquired Chase Compounds, or the Chase Milestone Events. Of the potential Chase Milestone Payments, $41.0 million in aggregate are tied to commercial success of the product candidates. Other than with respect to the first Chase Milestone Event, Chase may elect to receive the Chase Milestone Payments for each Chase Milestone Event either as cash or as restricted shares of our common stock, subject to an overall limitation of a maximum of 5,387,353 shares of common stock that may be issued pursuant to the Chase Agreement (representing 19.9% of the outstanding shares of the common stock as of the Chase Closing Date). No additional milestones or royalties were paid or accrued during the year ended December 31, 2025 related to this agreement.

The number of shares of common stock issuable for a Chase Milestone Payment paid in restricted shares of common stock will be determined by dividing the Chase Milestone Payment by the applicable Company Stock Price (as defined below), rounded down to the nearest share. The Company Stock Price is defined as the five-day volume-weighted average price per share of common stock as reported by Bloomberg and calculated during regular trading hours over the five consecutive trading day period ending on: (a) with respect to a Chase Milestone Payment pursuant to Chase’s election to receive a Chase Milestone Payment as common stock, the first trading day immediately following an Achievement Notice (as defined in the Chase Agreement); and (b) with respect a Deadline Milestone Payment (as defined below), the first trading day immediately following the applicable anniversary of the Closing Date.

We must use commercially reasonable efforts to develop, seek Regulatory Approval (as defined in the Chase Agreement) for, and commercialize products containing or comprising the Acquired Chase Compounds in the United States. If we fail to achieve certain Chase Milestone Events by an agreed date, we must either pre-pay a portion of the relevant Chase Milestone Payment associated with that Chase Milestone Event, or a Deadline Milestone Payment, which pre-payment obligation may be paid in restricted shares of Common Stock, or transfer the related Acquired Chase Compound back to Chase, in our sole discretion.

Please refer to the section titled “—Intellectual Property—Product Candidate Patent Portfolio” for details of certain patent terms related to the Acquired Chase Compounds.

Intellectual Property

Overview

We strive to protect and enhance the proprietary technology, inventions and improvements that are commercially important to our business, including by seeking, maintaining, enforcing and defending patent rights, whether developed internally or licensed from our collaborators or other third parties. Our policy is to seek to protect our proprietary position by, among other methods, filing patent applications in the United States and in jurisdictions outside of the United States related to our proprietary technology, inventions, improvements and product candidates that are important to the development and implementation of our business. We also rely, in part, on trade secrets and know-how relating to our proprietary technology and product candidates, continuing innovation, and in-licensing opportunities to develop, strengthen and maintain our proprietary position in the field of precision psychiatry and neuropsychiatric drug development; however, trade secrets are difficult to protect and provide us with only limited protection. Our commercial success will depend in part on our ability to obtain and maintain patent and other proprietary protection for our technology, inventions and improvements; to preserve the confidentiality of our trade secrets; to maintain our licenses to use intellectual property owned by third parties; and to defend and enforce our proprietary rights, including any patents that we own or may obtain in the future. Intellectual property rights may not address all potential threats to our competitive advantage.

As of December 31, 2025, we owned, co-owned, or have an exclusive license to approximately 235 patents and pending patent applications in the United States and foreign jurisdictions, including 35 issued U.S. patents and 97 issued foreign patents, with expected expiry dates between 2026 and 2046, without taking into account potentially available patent term adjustments or extensions in the United States and other countries, and assuming payment of all appropriate maintenance, renewal, and annuity fees.

Product Candidate Patent Portfolio

As of December 31, 2025, we owned, co-owned, or have an exclusive license to approximately 167 patents and pending patent applications in the United States and foreign jurisdictions relating to our product candidates, including 18 issued U.S. patents and 63 issued foreign patents. Patents and patent applications directed to our most advanced programs are summarized below.

ALTO-207

With respect to ALTO-207, as of December 31, 2025, we owned one issued U.S. patent, 10 issued foreign patents, 10 pending U.S. patent applications, 10 pending foreign applications, and two pending international application with claims directed to the ALTO-207 formulation and a method of treating depression. Any patents covering the ALTO-207 formulation or method of treating depression that have or may issue are expected to expire in 2038 or 2046, respectively, and in each case, without taking into account any possible patent term adjustment or extensions or terminal disclaimers, and assuming payment of all appropriate maintenance, renewal, and annuity fees. Our foreign patents and pending patent applications are filed in jurisdictions including Australia, Brazil, Canada, China, European Patent Office, Hong Kong, Israel, India, Japan, South Korea, Macau, Mexico, and Taiwan.

ALTO-300

With respect to ALTO-300, as of December 31, 2025, we owned one issued U.S. patent, two U.S. pending patent applications and one pending international application with claims directed to a method of treating depression in patients with certain EEG measurements. Any patents that issue from such pending patent applications are expected to expire in 2044, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees.

ALTO-100

With respect to ALTO-100, as of December 31, 2025, we owned four issued U.S. patents, 18 issued foreign patents, five pending U.S. patent applications, and 20 pending foreign applications with claims directed to composition of matter, method of manufacturing, and method of treating depression. The patents covering the method of manufacturing ALTO-100 are expected to expire in 2030. We in-license one patent from Dow directed to certain intermediate compounds useful in the manufacturing ALTO-100, which patent is expected to expire in 2029. Any patents covering the method of treating depression that may issue from such pending patent applications are expected to expire in 2042 or 2043, in each case, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. Our foreign patents and pending patent applications are filed in jurisdictions including Australia, Brazil, Canada, China, Israel, India, Japan, South Korea, Mexico, Philippines, Singapore, Hong Kong, Czech Republic, Germany, Spain, France, United Kingdom, Ireland, and Italy.

ALTO-101

With respect to ALTO-101, as of December 31, 2025, we owned two U.S. pending patent applications and two pending international applications with claims directed to method of treatment of neuropsychiatric disorders. Any patents that issue from these applications would be expected to expire in 2044 or 2045, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. We also exclusively in-license from Sanofi one issued U.S. patent and three issued foreign patents in Germany, France, and United Kingdom, which are expected to expire in 2033, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. Additionally, we exclusively in-license from MedRx one issued U.S. patent, eight issued foreign patents in Germany, Spain, France, United Kingdom, Italy, Japan and China, as well as one pending U.S. patent applications. The issued U.S. and foreign patents that are in-licensed from MedRx are expected to expire in 2034, and any patent issued from the pending patent application is expected to expire in 2034, without taking into account any possible

patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. We also co-own one pending international patent application with MedRx and two pending U.S. applications which are directed to an ALTO-101 formulation, which is expected to expire in 2044 or 2046, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees.

ALTO-203

With respect to ALTO-203, as of December 31, 2025, we owned three issued U.S. patents with claims directed to composition of matter and method of treatment for cognition/cognitive disorders. These patents are expected to expire in 2027, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. In addition, we own one U.S. application and one international application with claims directed to a method of treating a psychiatric or neurological disorder in a patient who has anhedonia with ALTO-203. These patents are expected to expire in 2044, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. We also own a U.S. patent application directed to a method of treating disorders in patients exhibiting a particular biomarker with ALTO-203. This patent is expected to expire in 2046, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees.

ALTO-202

With respect to ALTO-202, as of December 31, 2025, we in-licensed from Cerecor one issued U.S. patent (owned by Merck and licensed to Cerecor) with claims directed to the composition of matter (ALTO-202 compound), which is expected to expire in 2026. We also in-licensed from Cerecor (co-owned with Merck) four issued U.S. patents and nine foreign issued patents or pending applications in Australia, Canada, China, Germany, Spain, France, India, United Kingdom, and Italy, with claims directed to composition of matter (polymorphic forms of ALTO-202). These patents are expected to expire in 2035, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees.

ALTO-208

With respect to ALTO-208, as of December 31, 2025, we owned one issued US patent, 16 issued foreign patents, and three pending foreign applications with claims directed to a method of treating Parkinson’s disease. Any patents covering the method of treating Parkinson’s disease that have or may issue are expected to expire in 2038 in each case, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. Our foreign patents and pending patent applications are filed in jurisdictions including Australia, Canada, China, European Patent Office, Switzerland, Spain, United Kingdom, Hungary, Ireland, Monaco, Norway, Israel, Japan, Mexico and Taiwan.

Precision Psychiatry Platform Patent Portfolio

With respect to our Platform, as of December 31, 2025, we owned one pending U.S. patent application with claims directed to a method of predicting the response of a patient to a placebo or sham treatment which relates to one aspect of our Platform. If issued, this patent is expected to expire in 2046, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. We also exclusively in-license from Stanford six issued U.S. patents and four U.S. pending patent application with claims directed to machine learning techniques for identifying treatable patient populations, or placebo responders. The issued patents are expected to expire between 2037 and 2040, and any patents that issue from the pending patent application are expected to expire in 2039, without taking into account any possible patent term adjustment or extensions or terminal disclaimers and assuming payment of all appropriate maintenance, renewal, and annuity fees. These Stanford patents may be relevant to future iterations of our Platform.

Trademarks

We also protect our brands, including through the procurement of trademark registrations. As of December 31, 2025, we owned U.S. trademark registrations and pending applications for our house mark ALTO NEUROSCIENCE and our Brain logo, and UK trademark applications for our house mark ALTO NEUROSCIENCE and our Brain logo.

Intellectual Property Protection

We continue to assess the extent to which we may seek additional patent protection for aspects of our product candidates. The term of individual patents depends upon the date of filing of the patent application, date of patent issuance and the legal term of the patents in the countries in which they are obtained. In most countries in which we file, the patent term is 20 years from the earliest date of filing of the first non-provisional application to which priority is claimed. Outside of the United States, the duration of patents varies in accordance with applicable local law, but typically is also 20 years from the earliest non-provisional filing date. In the United States, patent term may be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the United States Patent and Trademark Office, or USPTO, in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over an earlier-filed patent. Moreover, in the context of approved products, there may be additional exclusivity for the patents covering such approved products. In the United States, the term of a patent that covers an FDA-approved drug may also be eligible for a patent term extension of up to five years under the Hatch-Waxman Act, which is designed to compensate for the patent term lost during the FDA regulatory review process. The length of the patent term extension is calculated based on the length of time it takes for regulatory review. A patent term extension under the Hatch-Waxman Act cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, only one patent applicable to an approved drug may be extended and only those patents with claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended. Patent term extension is available only for the first approved use of the drug, and thus, no extension is available if a product is approved for a subsequent use. Moreover, a patent can only be extended once, and thus, if a single patent is applicable to multiple products, it can only be extended based on one product. Similar provisions are available in Europe and certain other foreign jurisdictions to extend the term of a patent that covers an approved drug.

We intend to pursue, in the normal course of business and when possible, composition, method of use, process, dosing and formulation patent protection for the product candidates we develop and commercialize. We may also pursue patent protection with respect to manufacturing and other technologies. When available to expand market exclusivity, we intend to strategically obtain or license additional intellectual property related to current or contemplated product candidates.

In some instances, we submit patent applications directly to the USPTO as provisional patent applications. Corresponding non-provisional patent applications must be filed within 12 months after the provisional application filing date. The corresponding non-provisional application may be entitled to the benefit of the earlier provisional application filing date(s), and the patent term of the finally issued patent is calculated from the later non-provisional application filing date. Provisional applications for patents were designed to provide a lower-cost first patent filing in the United States. This system allows us to obtain an early priority date, add material to the patent application(s) during the priority period, obtain a later start to the patent term and to delay prosecution costs.

The PCT system allows a single application to be filed within 12 months of the original priority date of the patent application, and to designate all of the PCT member states in which national or regional patent applications can later be pursued based on the international patent application filed under the PCT. The PCT searching authority performs a patentability search and issues a non-binding patentability opinion which can be used to evaluate the chances of success for the national or regional applications prior to having to incur the filing fees and prosecution costs. Although a PCT application does not issue as a patent, it allows the applicant to seek protection in any of the member states through national/regional-phase applications. At the end of the period of two and a half years from the first priority date of the patent application, separate patent applications can be pursued in any of the PCT member states either by direct national filing or, in some cases by filing through a regional patent organization, such as the European Patent Office. The PCT system delays expenses, allows a limited evaluation of the chances of success for national/regional patent applications and enables substantial savings where applications are abandoned within the first two and a half years of filing. We intend to file U.S. nonprovisional applications and PCT applications that claim the benefit of the priority date of earlier filed provisional applications, when applicable.

For all patent applications, we determine claiming strategy on a case-by-case basis. Advice of counsel, country-specific patent laws and our business model and needs are always considered. We may file patents containing claims for protection of all useful applications of our proprietary product candidates, as well as all new applications and/or uses we discover for existing product candidates, assuming these are strategically valuable. We continuously reassess the number and type of patent applications in our portfolio, as well as the pending and issued patent claims, to help ensure that maximum coverage and value are obtained for our processes, and compositions, given existing patent office rules and regulations. Further, claims may be modified during patent prosecution, to the extent allowed, to meet our intellectual property and business needs.

There can be no assurance that we will be able to obtain, maintain, enforce and defend all patents and other intellectual property rights necessary to conduct our business. The patents we in-license, or patents that issue from our owned patent applications, if any, may be challenged by third parties, may not effectively prevent third parties from commercializing competitive technologies or may not otherwise provide us with a competitive advantage. For more information regarding the risks related to our intellectual property, see the section titled “Risk Factors—Risks Related to Collaborations, Intellectual Property, and Related Agreements.”

Sales, Marketing, and Commercialization

We do not currently have a commercial organization for the marketing, sales, and distribution of products. We intend to build our global commercialization capabilities internally over time, such that we are able to commercialize any product candidate for which we may obtain regulatory approval. We expect to manage sales, marketing, and distribution through internal resources and third-party relationships. In addition, we will opportunistically explore commercialization partnerships, particularly with entities that have strong capabilities in geographies outside the United States. As our current and future product candidates progress through clinical development, our commercial plans may change. Clinical data, the size of the development programs, the size of our target markets, the size of the requisite commercial infrastructure, and manufacturing needs may all influence our commercialization strategies.

Manufacturing

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We have engaged, and expect to continue to rely on, well-established third-party contract manufacturing organizations, or CMOs, to supply our product candidates for use in our preclinical studies and clinical trials. Because we rely on contract manufacturers, we employ personnel with extensive technical, manufacturing, analytical, and quality experience to oversee contract manufacturing and testing activities, and to compile manufacturing and quality information for our regulatory submissions. We believe our current manufacturers have the scale, systems, and experience to supply our currently planned clinical trials.

Additionally, we intend to rely on third-party CMOs for later-stage development and commercial manufacturing, if our product candidates receive marketing approval. As our lead product candidates advance through clinical development, we expect to enter into longer-term commercial supply agreements to fulfill and secure our production needs. While the drug substances used in our product candidates are manufactured by more than one supplier, the number of manufacturers is limited. In the event it is necessary or advisable to acquire supplies from an alternative supplier, we might not be able to obtain them on commercially reasonable terms, if at all. It could also require significant time and expense to redesign our manufacturing processes to work with another company. If we need to change manufacturers during the clinical or development stage for product candidates or after commercialization for our product candidates, if approved, the FDA and corresponding foreign regulatory agencies must approve these new manufacturers in advance, which will involve testing and additional inspections to ensure compliance with FDA regulations and standards and may require significant lead times and delay.

To adequately meet our projected commercial manufacturing needs, our CMOs will need to scale-up production, or we will need to secure additional suppliers. Processes for producing drug substances and drug product for commercial supply are currently being developed, with the goal of achieving reliable, reproducible, and cost-effective production. We believe the drug substance and drug product processes for our current product candidates can be appropriately scaled.

Competition

The biopharmaceutical industry is characterized by the rapid innovation and intense competition. While we believe that our innovative precision psychiatry approach and pipeline of clinical assets provide us with competitive advantages, we face competition from multiple biopharmaceutical and biotechnology companies that are similarly working to develop therapeutics targeting neuropsychiatry and CNS disorders, as well as from academic institutions, governmental agencies, and public and private research institutions. Many of our potential competitors, either alone or with collaboration partners, have significantly greater financial resources than we do, as well as equal or greater experience in the discovery and development of product candidates, obtaining FDA and other regulatory approvals of products, and the commercialization of those products. Accordingly, our potential competitors may be more successful than we are in achieving regulatory approvals and commercializing their products. We anticipate that we will face intense and increasing competition from existing, approved drugs, as well as new drugs entering the market and emerging technologies that become available. In particular we are developing our product candidates in the areas of major depressive disorder, treatment resistant

depression, bipolar depression, and schizophrenia. Notable examples of companies with either approved therapies or product candidates in development in areas that may be competitive in our areas of focus are AbbVie Inc.; Atai Beckley, Inc.; Axsome Therapeutics, Inc.; Compass Pathways, Inc.; Neumora Therapeutics, Inc.; Neurocrine Biosciences, Inc.; and Xenon Pharmaceuticals, Inc., among others. We believe the key competitive factors affecting the success of our product candidates that we develop to address MDD, TRD, BPD, schizophrenia, and other CNS disorders, if approved, are likely to be efficacy, safety, convenience, price, the level of generic competition, and the availability of reimbursement from government and other third-party payors.

Government Regulation

Government authorities in the United States, at the federal, state and, local level, and other countries extensively regulate, among other things, the research, development, testing, manufacture, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, marketing, and export and import of drug products. We, along with any third-party contractors, will be required to navigate the various preclinical, clinical and commercial approval requirements of the governing regulatory agencies of the countries in which we wish to conduct studies or seek approval of our products and product candidates. The process of obtaining regulatory approvals and the subsequent compliance with applicable federal, state, local, and foreign statutes and regulations require the expenditure of substantial time and financial resources.

U.S. Drug Development Process

In the United States, the FDA regulates drugs under the federal Food, Drug, and Cosmetic Act, or the FDCA, and its implementing regulations. A new drug must be approved by the FDA through the New Drug Application, or the NDA, process before it may be legally marketed in the United States. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local and foreign statutes and regulations require the expenditure of substantial time and financial resources. The process required by the FDA before a drug may be marketed in the United States generally involves the following:

•completion of preclinical laboratory tests, animal studies and formulation studies in accordance with FDA’s Good Laboratory Practice, or GLP, regulations and other applicable requirements;

•submission to the FDA of an IND which must become effective before human clinical trials may begin;

•approval by an independent Institutional Review Board, or IRB, or ethics committee at each clinical site before each trial may be initiated;

•performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practices, or GCP, regulations to evaluate the safety and efficacy of the proposed drug for its intended use;

•preparation of and submission to the FDA of an NDA after completion of all pivotal trials;

•a determination by the FDA within 60 days of its receipt of an NDA to file the application for review;

•satisfactory completion of an FDA advisory committee review, if applicable;

•satisfactory completion of an FDA inspection of the manufacturing facility or facilities at which the drug is produced to assess compliance with current Good Manufacturing Practice, or cGMP, regulations to assure that the facilities, methods and controls are adequate to preserve the drug’s identity, strength, quality and purity, and a potential inspection of selected clinical investigation sites to assess compliance with GCP regulations; and

•FDA review and approval of the NDA to permit commercial marketing of the product for particular indications for use in the United States.

Once a product candidate is identified for development, it enters the preclinical development stage. The preclinical developmental stage generally involves laboratory evaluations of chemistry, formulation, and stability, as well as studies to evaluate the product candidate’s toxicity in animals, in an effort to support subsequent clinical testing. The conduct of preclinical studies is subject to federal regulations and requirements, including GLP regulations for certain studies.

Prior to beginning the first clinical trial with a product candidate in the United States, the trial sponsor must submit the results of preclinical/nonclinical testing in animals, together with manufacturing information and analytical data, to the FDA as part of an IND. An IND is a request for authorization from the FDA to administer an investigational drug product to humans. The central focus of an IND submission is on the general investigational plan and the protocol(s) for clinical trials, detailing, among other things, the objectives of the clinical trial, the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated, if the trial includes an efficacy evaluation. The IND also includes results of animal and in vitro studies assessing the toxicology, pharmacokinetics, pharmacology, and pharmacodynamic characteristics of the product candidate, chemistry, manufacturing, and controls information, and any available human data or literature to support the use of the product candidate. Some preclinical testing may continue even after the IND is submitted. An IND must become effective before human clinical trials may begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, places the IND on clinical hold. In such case, the IND sponsor and the FDA must resolve any outstanding concerns or questions before the clinical trial can begin. Submission of an IND therefore may or may not result in FDA authorization to begin a clinical trial. Clinical holds also may be imposed by the FDA at any time after submission of clinical trials to FDA due to safety concerns about ongoing or proposed clinical trials or non-compliance with specific FDA requirements, and the trials may not begin or continue until the FDA notifies the sponsor that the hold has been lifted.

Clinical trials involve the administration of the investigational product to human subjects under the supervision of one or more qualified investigators, generally physicians not employed by or under the trial sponsor’s control, in accordance with GCP regulations, which include, among other things, the requirement that all research subjects provide their informed consent in writing for their participation in any clinical trial. Clinical trials must be conducted under protocols detailing, among other things, the objectives of the trial, dosing procedures, subject selection and exclusion criteria, and the safety and effectiveness criteria to be evaluated. Each protocol must be submitted to the FDA as part of the IND, and a separate submission to the existing IND must be made for each successive clinical trial conducted during product development and for any subsequent protocol amendments. While the IND is active, progress reports summarizing the results of the clinical trials and nonclinical studies performed since the last progress report, among other information, must be submitted at least annually to the FDA, and written IND safety reports must be submitted to the FDA and investigators for serious and unexpected adverse events suspected to be related to the drug’s use, findings from other studies suggesting a significant risk to humans exposed to the same or similar drugs, findings from animal or in vitro testing suggesting a significant risk to humans, and any clinically important increased incidence of a serious suspected adverse reaction compared to that listed in the protocol or investigator brochure.

Furthermore, an independent IRB at each institution participating in the clinical trial must review and approve each protocol before a clinical trial commences at that institution and must also approve the consent form that must be signed by each trial subject or his or her legal representative, monitor the study until completed, and otherwise comply with IRB regulations. Regulatory authorities, the IRB or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the trial is unlikely to meet its stated objectives. In addition, some clinical trials also include oversight by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board or committee. Depending on its charter, this group may determine whether a trial may move forward at designated check points based on access to certain data from the trial. There are also requirements governing the reporting of ongoing clinical studies and clinical trial results to public registries, including clinicaltrials.gov.

Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

•Phase 1: The product candidate is initially introduced into healthy human subjects or patients and tested for safety, dosage tolerance, absorption, metabolism, excretion, and distribution of the investigational product in humans, the side effects associated with increasing doses, and, if possible, to gain an early indication of its effectiveness.

•Phase 2: The product candidate is administered to a limited patient population with a specified disease or condition to identify possible adverse effects and safety risks, to preliminarily evaluate the efficacy of the product candidate for specific targeted diseases and to determine dosage tolerance and appropriate dosage.

•Phase 3: The product candidate is administered to an expanded patient population to further evaluate dosage, to provide substantial evidence of efficacy and to further test for safety, generally at multiple geographically dispersed clinical trial sites and can be longer term duration. These clinical trials are intended to establish the overall risk-benefit ratio of the product candidate and provide an adequate basis for product labeling.

In some cases, the FDA may require, or sponsors may voluntarily pursue, additional clinical trials after a product is approved to gain more information about the product. These clinical trials, sometimes referred to as Phase 4 studies, may be conducted after initial marketing approval, and may be used to gain additional experience from the treatment of patients in the intended therapeutic indication. In certain instances, the FDA may mandate the performance of Phase 4 clinical trials as a condition of approval of an NDA.

During the development of a new drug, sponsors are given opportunities to meet with the FDA at certain points. These points may be prior to submission of an IND, at the end of Phase 2, and before an NDA is submitted. Meetings at other times may be requested. These meetings can provide an opportunity for the sponsor to share information about the data gathered to date, for the FDA to provide advice, and for the sponsor and the FDA to reach alignment on the next phase of development.

Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the drug and finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the manufacturer must develop methods for testing the identity, strength, quality, and purity of the final drug. In addition, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

U.S. Review and Approval Process

The results of product development, preclinical and other non-clinical studies and clinical trials, along with descriptions of the manufacturing process, analytical tests conducted on the chemistry of the drug, proposed labeling and other relevant information are submitted to the FDA as part of an NDA requesting approval to market the product. The submission of an NDA is subject to the payment of substantial user fees, unless a waiver or exemption applies.

The FDA conducts a preliminary review of all NDAs within the first 60 days after submission, before accepting them for filing, to determine whether they are sufficiently complete to permit substantive review. The FDA may request additional information rather than accept an NDA for filing. In this event, the NDA must be resubmitted with the additional information. The resubmitted application also is subject to review before the FDA accepts it for filing. As part of the preliminary review and prior to filing, FDA also determines whether the NDA will be categorized as a standard or priority review. Priority reviews are given to drugs that treat serious conditions that offer a significant improvement in safety or effectiveness over existing treatments. Once filed, the FDA reviews an NDA to determine, among other things, whether a product is safe and effective for its intended use and whether its manufacturing is cGMP-compliant to assure and preserve the product’s identity, strength, quality, and purity. Under the Prescription Drug User Fee Act, or PDUFA, guidelines that are currently in effect, the FDA has a goal of ten months from the filing date to complete a standard review of an NDA for a drug that is a new molecular entity. This review typically takes twelve months from the date the NDA is submitted to FDA because the FDA has approximately two months to make a “filing” decision after the application is submitted.

The FDA may refer an application for a novel drug to an advisory committee. An advisory committee is a panel of independent experts, including clinicians and other scientific experts, that reviews, evaluates and provides a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

Before approving an NDA, the FDA will typically inspect the facility or facilities where the product is manufactured. Additionally, before approving an NDA, the FDA may inspect one or more clinical trial sites to assure compliance with GCP regulations.

After the FDA evaluates an NDA and conducts inspections of manufacturing facilities where the investigational product and/or its drug substance will be produced, the FDA may issue an approval letter or a Complete Response Letter, or CRL. An approval letter authorizes commercial marketing of the drug with prescribing information for specific indications. A CRL indicates that the review cycle of the application is complete, and the application will not be approved in its present form. A CRL usually describes the specific deficiencies in the NDA identified by the FDA and may require additional clinical data, such as an additional clinical trial or other significant and time-consuming requirements related to clinical trials, nonclinical studies or manufacturing. If a CRL is issued, the sponsor must resubmit the NDA addressing all of the deficiencies that the FDA has identified in the letter, or withdraw the application. Even if such data and information are

submitted, the FDA may decide that the NDA does not satisfy the criteria for approval. As of 2025, FDA publishes a redacted form of the CRL to the public.

If a product receives regulatory approval, the approval may be significantly limited to specific diseases and dosages or the indications for use may otherwise be limited, which could restrict the commercial value of the product. In addition, the FDA may require a sponsor to conduct additional testing in the form of a post-marketing commitment (PMC) or post-marketing requirement (PMR), which involves nonclinical and/or clinical trials designed to further assess a drug’s safety and effectiveness after NDA approval, and may require testing and surveillance programs to monitor the safety of approved products which have been commercialized. The FDA may also place other conditions on approval including the requirement for a risk evaluation and mitigation strategy, or REMS, to assure the safe use of the drug. If the FDA concludes a REMS is needed, the sponsor of the NDA must submit a proposed REMS. The FDA will not approve the NDA without an approved REMS, if required. A REMS could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. Any of these limitations on approval or marketing could restrict the commercial promotion, distribution, prescription or dispensing of products.

In addition, the Pediatric Research Equity Act, or PREA, requires a sponsor to conduct pediatric clinical trials for most drugs, for a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration. Under PREA, original NDAs and supplements must contain a pediatric assessment unless the sponsor has received a deferral or waiver. The required assessment must evaluate the safety and effectiveness of the product for the claimed indications in all relevant pediatric subpopulations and support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The sponsor or FDA may request a deferral of pediatric clinical trials for some or all of the pediatric subpopulations. A deferral may be granted for several reasons, including a finding that the drug is ready for approval for use in adults before pediatric clinical trials are complete or that additional safety or effectiveness data needs to be collected before the pediatric clinical trials begin. The FDA must send a non-compliance letter to any sponsor that fails to submit the required assessment, keep a deferral current or fails to submit a request for approval of a pediatric formulation.

505(b)(1) vs 505(b)(2)

The Federal Food, Drug and Cosmetic Act provides two pathways for the approval of NDAs. Drugs that follow the 505(b)(1) follow the standard path where the NDA sponsor provides all the required data for review of the NDA (Clinical, Nonclinical and CMC/Quality). NDAs submitted as part of the 505(b)(2) pathway are allowed to rely upon the FDA’s conclusions of safety or efficacy for prior drug approvals if appropriate bridging studies are performed to connect the drug under review to the previously approved reference listed drug. Published clinical studies may also be used in a 505(b)(2) NDA.

Fixed Combination Drug Rule

The FDA’s regulation governing fixed combination drug products provides that two or more drugs may be combined in a single dosage form when each component contributes to the claimed effects and the dosage of each component (amount, frequency, duration) is such that the combination is safe and effective for a significant patient population requiring such concurrent therapy as defined in the labeling for the drug. This rule is meant to ensure that any fixed-dose combination drug provides an advantage to the patient over and above that obtained when one of the individual ingredients is used in the usual safe and effective dose. ALTO-207 will be required to comply with the requirements of the fixed combination drug rule.

Regulation of Patch Formulations of Drugs as Combination Products in the United States

Certain products are comprised of components, such as drug components and device components intended for drug delivery, which would normally be subject to different regulatory frameworks by the FDA and frequently regulated by different centers at the FDA. These products are known as combination products. Under the FDCA, the FDA is charged with assigning a center with primary jurisdiction, or a lead center, for review of a combination product. The determination of which center will be the lead center is based on the “primary mode of action” of the combination product. Thus, if the primary mode of action of a drug-device combination product is attributable to the drug product, the FDA center responsible for premarket review of the drug product would have primary jurisdiction for the combination product. We believe that any patch formulation of a product candidate that we develop would have a drug primary mode of action. A combination product with a primary mode of action attributable to the drug component generally would be reviewed and

approved pursuant to the drug approval processes set forth in the FDCA. In reviewing the NDA for such a product, however, FDA reviewers would consult with their counterparts in the FDA’s Center for Devices and Radiological Health to ensure that the device component of the combination product met applicable requirements regarding safety, effectiveness, durability, and performance. In addition, under FDA regulations, combination products are subject to cGMP requirements applicable to both drugs and devices, including the Quality Management System Regulation, or QMSR, applicable to medical devices.

Expedited Development and Review Programs

The FDA offers a number of programs intended to expedite the development or review of a marketing application for an investigational drug. For example, the Fast Track designation program is intended to expedite or facilitate the process for developing and reviewing product candidates that are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast Track designation applies to the combination of the product candidate and the specific indication for which it is being studied. The sponsor of a Fast Track product candidate has opportunities for more frequent interactions with the applicable FDA review team during development and, once an NDA is submitted, the application may be eligible for priority review. An NDA for a Fast Track product candidate may also be eligible for rolling review, where the FDA may consider for review sections of the NDA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the NDA, the FDA agrees to accept sections of the NDA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the NDA.

A product candidate intended to treat a serious or life-threatening disease or condition may also be eligible for Breakthrough Therapy designation to expedite its development and review. A product candidate can receive Breakthrough Therapy designation if preliminary clinical evidence indicates that the product candidate, alone or in combination with one or more other drugs, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the Fast Track program features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product candidate, including involvement of senior managers.

Any marketing application for a drug submitted to the FDA for approval, including a product candidate with a Fast Track designation and/or Breakthrough Therapy designation, may be eligible for other types of FDA programs intended to expedite the development and review processes, such as priority review and accelerated approval. An NDA is eligible for priority review if the product candidate is designed to treat a serious condition, and if approved, would provide a significant improvement in safety or efficacy compared to available therapies for such disease or condition. The FDA will attempt to direct additional resources to the evaluation of a NDA designated for priority review in an effort to facilitate the review. For new-molecular-entity NDAs, priority review designation means the FDA’s goal is to take action on the marketing application within six months of the 60-day filing date, as compared to ten months for review of new-molecular-entity NDAs under its current PDUFA review goals.

Additionally, product candidates studied for their safety and effectiveness in treating serious or life-threatening diseases or conditions may be eligible for accelerated approval upon a determination that the product candidate has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefits, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. As a condition of continued approval, the FDA will generally require the sponsor of a drug receiving accelerated approval to perform adequate and well-controlled confirmatory clinical studies to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefits, and may require that such confirmatory trials be underway prior to granting accelerated approval. Products receiving accelerated approval may be subject to expedited withdrawal procedures if the sponsor fails to conduct the required confirmatory studies in a timely manner or if such studies fail to verify the predicted clinical benefit. In addition, the FDA currently requires as a condition for accelerated approval pre-approval of promotional materials, which could adversely impact the timing of the commercial launch of the product.

Fast Track designation, Breakthrough Therapy designation, priority review, and accelerated approval do not change the standards for approval, but may expedite the development or approval process. Even if a product candidate qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

Post-Approval Requirements

Any products manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to record-keeping, reporting of adverse experiences, periodic reporting, product sampling and distribution, and advertising and promotion of the product. After approval, most changes to the approved product, such as adding new indications, certain manufacturing changes and additional labeling claims, are subject to further FDA review and approval. There also are continuing, annual program fees for any marketed products. Drug manufacturers and other entities involved in the manufacture and distribution of approved drugs are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMP requirements and other laws and regulations. Changes to the manufacturing process are strictly regulated, and, depending on the significance of the change, may require prior FDA approval before being implemented. FDA regulations also require investigation and correction of any deviations from cGMP requirements and impose reporting requirements. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain compliance with cGMP requirements and other aspects of regulatory compliance.

The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of requirements for post-market studies or clinical studies to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

•restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or product recalls;

•fines, warning letters, or untitled letters;

•clinical holds on ongoing or planned clinical studies;

•refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of product approvals;

•product seizure or detention, or refusal to permit the import or export of products;

•consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs;

•mandated modification of promotional materials and labeling and the issuance of corrective information;

•the issuance of safety alerts, Dear Healthcare Provider letters, press releases and other communications containing warnings or other safety information about the product; or

•injunctions or the imposition of civil or criminal penalties.

The FDA closely regulates the marketing, labeling, advertising and promotion of drug products. A company can make only those claims relating to safety and efficacy that are approved by the FDA and in accordance with the provisions of the approved label. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses. Failure to comply with these requirements can result in, among other things, adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe, in their independent professional medical judgment, legally available products for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use of their products. However, companies may share truthful and not misleading information that is otherwise consistent with a product’s FDA-approved labeling.

Marketing Exclusivity

Market exclusivity provisions under the FDCA can delay the submission or the approval of certain marketing applications. The FDCA provides a five-year period of non-patent data exclusivity within the United States to the first applicant to obtain approval of an NDA for a new chemical entity. A drug is a new chemical entity if the FDA has not previously

approved any other new drug containing the same active moiety, which is the molecule or ion responsible for the action of the drug substance. During the exclusivity period, the FDA may not accept for review an abbreviated new drug application, or ANDA, or an NDA submitted under Section 505(b)(2) (505(b)(2) NDA) submitted by another company for another drug referencing the approved application, regardless of whether the drug is intended for the same indication as the original innovative drug or for another indication, where the applicant does not own or have a legal right of reference to all the data required for approval. However, an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement to one of the patents listed with the FDA by the innovator NDA holder.

The FDCA alternatively provides three years of marketing exclusivity for an NDA, or supplement to an existing NDA if new clinical investigations, other than bioavailability studies, that were conducted or sponsored by the applicant are deemed by the FDA to be essential to the approval of the application, for example new indications, dosages or strengths of an existing drug. This three-year exclusivity covers only the modification for which the drug received approval on the basis of the new clinical investigations and does not prohibit the FDA from approving ANDAs or 505(b)(2) NDAs referencing the approved application for drugs containing the active agent for the original indication or condition of use. Five-year and three-year exclusivity will not delay the submission or approval of a full NDA that does not reference the approved application. However, an applicant submitting a full NDA would be required to conduct or obtain a right of reference to all of the preclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and effectiveness.

Pediatric exclusivity is another type of marketing exclusivity available in the United States. Pediatric exclusivity provides for an additional six months of marketing exclusivity attached to another period of exclusivity if a sponsor conducts clinical trials in children in response to a written request from the FDA. The issuance of a written request does not require the sponsor to undertake the described clinical trials.

FDA Regulation of Companion Diagnostics and Clinical Decision Support Software

If safe and effective use of a therapeutic depends on a device intended to identify patients most likely to benefit from the therapeutic, then the FDA generally will require approval or clearance of that device, known as a companion diagnostic, at the same time that the FDA approves the therapeutic product. Approval or clearance of the companion diagnostic will ensure that the companion diagnostic has been adequately evaluated and has adequate performance characteristics in the intended population. The review of companion diagnostics in conjunction with the review of our therapeutic product candidates will, therefore, likely involve coordination of review by the FDA’s Center for Drug Evaluation and Research and the FDA’s Center for Devices and Radiological Health.

We currently anticipate that certain of our therapeutic product candidates will require us to develop and obtain FDA approval of a companion diagnostic for such therapeutic product candidates. This includes certain software applications, such as software that we are developing to identify biomarkers, that may also meet the definition of a medical device and be subject to FDA premarket authorization, depending on its classification and software function. FDA guidance adopts international principles established by the International Medical Device Regulators Forum for the clinical evaluation of software as a medical device, or SaMD, which refers to software that is intended to be used for one or more medical purposes that perform these purposes without being part of a hardware medical device.

The 21st Century Cures Act, or Cures Act, clarified the FDA’s authority to regulate software functions as medical devices by amending the definition of “device” in the FDCA to exclude certain software functions, including clinical decision support software, or CDS, that meet certain criteria. Under the Cures Act and FDA CDS guidance, certain software functions are excluded from the FDCA’s definition of “device” when they meet all the following criteria:

•not intended to acquire, process, or analyze a medical image or a signal from an in vitro diagnostic device or a pattern or signal from a signal acquisition system;

•intended for the purpose of displaying, analyzing, or printing medical information about a patient or other medical information (such as peer-reviewed clinical studies and clinical practice guidelines);

•intended for the purpose of supporting or providing recommendations to a healthcare professional about prevention, diagnosis, or treatment of a disease or condition; and

•intended for the purpose of enabling such healthcare professional to independently review the basis for such recommendations that such software presents so that it is not the intent that such healthcare professional rely primarily on any of such recommendations to make a clinical diagnosis or treatment decision regarding an individual patient.

As a result, certain software functions may not be subject to FDA review pursuant to the Cures Act and related FDA CDS guidance. However, SaMD that does not meet the criteria set forth above generally will require marketing clearance or approval from the FDA prior to commercialization as described below.

In the United States, the laws and regulations governing the marketing of companion diagnostics are evolving, extremely complex, and in many instances, there are no significant regulatory or judicial interpretations of these laws and regulations. The FDCA defines a medical device to include any instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related article, including a component part, or accessory, intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals. The FDCA and its implementing regulations, and other federal and state statutes and regulations govern, among other things, the design and development, research, preclinical and clinical testing, manufacturing, safety, labeling, storage, recordkeeping, premarket clearance or approval, registration and listing, advertising and promotion, sales and distribution, export and import, and post-market surveillance of medical devices in the United States.

Unless an exemption applies, both hardware and SaMD companion diagnostics are regulated as medical devices by the FDA, and will require marketing clearance or approval from the FDA prior to commercialization. The two primary types of FDA marketing authorization applicable to a medical device are approval of an application for premarket approval, or PMA, and clearance of a premarket notification, or 510(k) clearance. There is also a third route to market for novel, low-to-moderate risk devices, called the de novo classification pathway.

On August 6, 2014, the FDA issued a final guidance document addressing the development and approval process for “In Vitro Companion Diagnostic Devices.” According to the guidance, for novel product candidates, a companion diagnostic device and its corresponding drug candidate should be approved or 510(k)-cleared contemporaneously by the FDA for the use indicated in the labeling of the therapeutic product.

PMA Pathway

Companion diagnostics, including both hardware and SaMD, are regulated by the FDA as medical devices. The FDA categorizes medical devices into one of three classes—Class I, II, or III—based on the risks presented by the device and the regulatory controls necessary to provide a reasonable assurance of the device’s safety and effectiveness. Class I includes devices with the lowest risk to the patient and are those for which safety and effectiveness can be assured by adherence to the FDA’s General Controls for medical devices, which include compliance with the applicable portions of the QSR facility registration and product listing, reporting of adverse medical events, and truthful and non-misleading labeling, advertising, and promotional materials. Class II devices are subject to the FDA’s General Controls, and special controls as deemed necessary by the FDA to ensure the safety and effectiveness of the device. Special controls are established by the FDA for a specific device type and often include specific labeling provisions, performance metrics, and other types of controls that mitigate risks of the device (usually incorrect results for an in-vitro diagnostic device, or IVD). Devices deemed by the FDA to pose the greatest risks, such as life sustaining, life supporting or some implantable devices, or devices that have a new intended use, or use advanced technology that is not substantially equivalent to that of a legally marketed device, are placed in Class III, requiring approval of a PMA. Some pre-amendment devices are unclassified, but are subject to the FDA’s premarket notification and clearance process in order to be commercially distributed.

Class III devices generally require PMA approval before they can be marketed. Obtaining PMA approval requires the submission of “valid scientific evidence” to the FDA to support a finding of a reasonable assurance of the safety and effectiveness of the device. A PMA must provide complete analytical and clinical performance data and also information about the device and its components regarding, among other things, device design, manufacturing and labeling. Following receipt of a PMA, the FDA determines whether the application is sufficiently complete to permit a substantive review. If the FDA accepts the application for review, it has 180 days under the FDCA to complete its review of a PMA, although in practice, FDA’s review often takes significantly longer, and can take up to several years. An advisory panel of experts from outside the FDA may be convened to review and evaluate the application and provide recommendations to the FDA as to the approvability of the device. The FDA may or may not accept the panel’s recommendation. As part of the FDA’s review of a PMA, the FDA will typically inspect the manufacturer’s facilities for compliance with QSR requirements, which impose requirements related to design controls, manufacturing controls, documentation and other quality assurance procedures. The user fee costs and the length of FDA review time for obtaining PMA approval are significantly higher than for a 510(k) notification or a de novo classification.

The FDA will approve the new device for commercial distribution if it determines that the data and information in the PMA constitute valid scientific evidence and that there is reasonable assurance that the device is safe and effective for its intended use(s). The FDA may approve a PMA with post-approval conditions intended to ensure the safety and effectiveness of the device, including, among other things, restrictions on labeling, promotion, sale and distribution, and collection of long-term follow-up data from patients in the clinical study that supported PMA approval or requirements to conduct additional clinical studies post-approval. The FDA may condition PMA approval on some form of post-market surveillance when deemed necessary to protect the public health or to provide additional safety and efficacy data for the device in a larger population or for a longer period of use. In such cases, the manufacturer might be required to follow certain patient groups for a number of years and to make periodic reports to the FDA on the clinical status of those patients. Failure to comply with the conditions of approval can result in material adverse enforcement action, including withdrawal of the approval.

Certain changes to an approved device, such as changes in manufacturing facilities, methods, or quality control procedures, or changes in the design performance specifications, which affect the safety or effectiveness of the device, require submission of a PMA supplement. PMA supplements often require submission of the same type of information as a PMA, except that the supplement is limited to information needed to support any changes from the device covered by the original PMA and may not require as extensive clinical data or the convening of an advisory panel. Certain other changes to an approved device require the submission of a new PMA, such as when the design change causes a different intended use, mode of operation, and technical basis of operation, or when the design change is so significant that a new generation of the device will be developed, and the data that were submitted with the original PMA are not applicable for the change in demonstrating a reasonable assurance of safety and effectiveness.

510(k) Notification Pathway

To obtain 510(k) clearance, a manufacturer must submit a premarket notification demonstrating to the FDA’s satisfaction that the proposed device, including both hardware and SaMD, is “substantially equivalent” to another legally marketed device that itself does not require PMA approval (a predicate device). A predicate device is a legally marketed device that is not subject to premarket approval, i.e., a device that was legally marketed prior to May 28, 1976 (pre-amendments device) and for which a PMA is not required, a device that has been reclassified from Class III to Class II or I, or a device that was found substantially equivalent through the 510(k) process. The FDA’s 510(k) clearance process usually takes from three to twelve months, but often takes longer. FDA may require additional information, including clinical data, to make a determination regarding substantial equivalence. In addition, the FDA collects user fees for certain medical device submissions and annual fees and for medical device establishments.

If the FDA agrees that the device is substantially equivalent to a lawfully marketed predicate device, it will grant 510(k) clearance to authorize the device for commercialization. If the FDA determines that the device is “not substantially equivalent” to a previously cleared device, the device is automatically designated as a Class III device. The device sponsor must then fulfill more rigorous PMA requirements, or can request a risk-based classification determination for the device in accordance with the de novo process, which is a route to market for novel medical devices that are low to moderate risk and are not substantially equivalent to a predicate device, discussed below.

After a device receives 510(k) clearance, any modification that could significantly affect its safety or effectiveness, or that would constitute a major change or modification in its intended use, will require a new 510(k) clearance or, depending on the modification, PMA approval. The FDA requires each manufacturer to determine whether the proposed change requires submission of a 510(k) or a PMA in the first instance, but the FDA can review any such decision and disagree with a manufacturer’s determination. Many minor modifications are accomplished by a “letter to file” in which the manufacturer documents the rationale for the change and why a new 510(k) is not required. However, if the FDA disagrees with a manufacturer’s determination, the FDA can require the manufacturer to cease marketing and/or request the recall of the modified device until 510(k) marketing clearance or PMA approval is obtained. Also, in these circumstances, the manufacturer may be subject to significant regulatory fines or penalties.

If no legally marketed predicate can be identified for a new device to enable use of the 510(k) pathway, the device is automatically classified under the FDCA into Class III, which generally requires PMA approval. However, the FDA can reclassify or seek de novo classification for a device that meets the FDCA standards for a Class I or Class II device, permitting the device to be marketed without PMA approval. To grant such a reclassification, the FDA must determine that the FDCA’s general controls alone, or general controls and special controls together, are sufficient to provide a reasonable assurance of the device’s safety and effectiveness. The de novo classification route is generally less burdensome than the PMA approval process.

De Novo Classification

Medical device types, including both hardware and SaMD, that the FDA has not previously classified as Class I, II or III are automatically classified under the FDCA into Class III regardless of the level of risk they pose. Low to moderate risk medical devices that are automatically placed into Class III due to the absence of a predicate device may utilize the “Request for Evaluation of Automatic Class III Designation,” or the de novo classification procedure. This procedure allows a manufacturer whose novel device is automatically classified into Class III to request down-classification of its medical device into Class I or Class II on the basis that the device presents low or moderate risk, rather than requiring the submission and approval of a PMA application. Manufacturers may request de novo classification directly without first submitting a 510(k) premarket notification to the FDA and receiving a not substantially equivalent determination. If the manufacturer seeks reclassification into Class II, the manufacturer must include a draft proposal for special controls that are necessary to provide a reasonable assurance of the safety and effectiveness of the medical device. In addition, the FDA may reject the request if it identifies a legally marketed predicate device that would be appropriate for a 510(k) notification, determines that the device is not low to moderate risk, or that general controls would be inadequate to control the risks and special controls cannot be developed. After a device receives de novo classification, any modification that could significantly affect its safety or efficacy, or that would constitute a major change or modification in its intended use, will require a new 510(k) clearance or, depending on the modification, another de novo request or even PMA approval.

Investigational Device Exemption Process

Clinical trials are almost always required to support a PMA and are sometimes required to support a 510(k) submission. All clinical investigations of investigational devices to determine safety and effectiveness must be conducted in accordance with the FDA’s investigational device exemption, or IDE, regulations which govern investigational device labeling, prohibit promotion of the investigational device, and specify an array of recordkeeping, reporting and monitoring responsibilities of study sponsors and study investigators. If the device presents a “significant risk” to human health, the FDA requires the device sponsor to submit an IDE application to the FDA, which must become effective prior to commencing human clinical trials. A significant risk device is one that presents a potential for serious risk to the health, safety or welfare of a patient and either is implanted, used in supporting or sustaining human life, substantially important in diagnosing, curing, mitigating or treating disease or otherwise preventing impairment of human health, or otherwise presents a potential for serious risk to a subject. An IDE application must be supported by appropriate data, such as animal and laboratory test results, showing that it is safe to test the device in humans and that the testing protocol is scientifically sound. The IDE will automatically become effective 30 days after receipt by the FDA, unless the FDA notifies the company that the investigation may not begin. If the FDA determines that there are deficiencies or other concerns with an IDE for which it requires modification, the FDA may permit a clinical trial to proceed under a conditional approval.

In addition, the study must be approved by, and conducted under the oversight of, an IRB for each clinical site. The IRB is responsible for the initial and continuing review of the IDE, and may pose additional requirements for the conduct of the study. If an IDE application is approved by the FDA and one or more IRBs, human clinical trials may begin at a specific number of investigational sites with a specific number of patients, as approved by the FDA. If the device presents a non-significant risk to the patient, a sponsor may begin the clinical trial after obtaining approval for the trial by one or more IRBs without separate approval from the FDA, but must still follow abbreviated IDE requirements, such as monitoring the investigation, ensuring that the investigators obtain informed consent, and labeling and record-keeping requirements. Acceptance of an IDE application for review does not guarantee that the FDA will allow the IDE to become effective and, if it does become effective, the FDA may or may not determine that the data derived from the trials support the safety and effectiveness of the device or warrant the continuation of clinical trials. An IDE supplement must be submitted to, and approved by, the FDA before a sponsor or investigator may make a change to the investigational plan that may affect its scientific soundness, study plan or the rights, safety or welfare of human subjects.

During a study, the sponsor is required to comply with the applicable FDA requirements, including, for example, trial monitoring, selecting clinical investigators and providing them with the investigational plan, ensuring IRB review, adverse event reporting, record keeping, and prohibitions on the promotion of investigational devices or on making safety or effectiveness claims for them. The clinical investigators in the clinical study are also subject to FDA regulations and must obtain patient informed consent, rigorously follow the investigational plan and study protocol, control the disposition of the investigational device, and comply with all reporting and recordkeeping requirements. Additionally, after a trial begins, we, the FDA or the IRB could suspend or terminate a clinical trial at any time for various reasons, including a belief that the risks to study subjects outweigh the anticipated benefits.

Expedited Development and Review Programs for Medical Devices

The FDA has implemented a Breakthrough Devices Program, which is a voluntary program offering manufacturers of certain devices an opportunity to interact with the FDA more frequently and efficiently as they develop their products with the goal of expediting commercialization of such products to help patients have more timely access. The program is available to medical devices that meet certain eligibility criteria, including that the device provides more effective treatment or diagnosis of life-threatening or irreversibly debilitating diseases or conditions, and constitutes a device (i) that represents a breakthrough technology, (ii) for which no approved or cleared alternatives exist, (iii) that offer significant advantages over existing approved or cleared alternatives, or (iv) the availability of which is in the best interest of patients. Devices granted Breakthrough Device designation are eligible to rely on certain features of the Breakthrough Device Program, including interactive and timely communications with FDA staff, use of post-market data collection, when scientifically appropriate, to facilitate expedited and efficient development and review of the device, opportunities for efficient and flexible clinical study design and priority review of premarket submissions.

Postmarket Regulation of Medical Devices

After a device is cleared or approved by the FDA for marketing, numerous and pervasive regulatory requirements continue to apply. These include:

•establishment registration and device listing with the FDA;

•QMSR requirements, which require manufacturers, including third-party manufacturers, to follow stringent design, testing, control, documentation and other quality assurance procedures during all aspects of the design and manufacturing process;

•labeling regulations and FDA prohibitions against the promotion of “off-label” uses of cleared or approved products;

•requirements related to promotional activities;

•clearance or approval of product modifications to 510(k)-cleared devices that could significantly affect safety or effectiveness or that would constitute a major change in intended use of cleared devices, or approval of certain modifications to PMA-approved devices;

•medical device reporting regulations, which require that a manufacturer report to the FDA if a device it markets may have caused or contributed to a death or serious injury, or has malfunctioned and the device or a similar device that it markets would be likely to cause or contribute to a death or serious injury, if the malfunction were to recur;

•correction, removal, and recall reporting regulations, which require that manufacturers report to the FDA field corrections and product recalls or removals if undertaken to reduce a risk to health posed by the device or to remedy a violation of the FDCA that may present a risk to health;

•The FDA’s recall authority, whereby the agency can order device manufacturers to recall from the market a product that is in violation of governing laws and regulations; and

•post-market surveillance activities and regulations, which apply when deemed by the FDA to be necessary to protect the public health or to provide additional safety and effectiveness data for the device.

Device manufacturing processes subject to FDA oversight are required to comply with the applicable portions of the QSR, which cover the methods and the facilities and controls for the design, manufacture, testing, production, processes, controls, quality assurance, labeling, packaging, distribution, installation, and servicing of finished devices intended for human use. The QMSR also requires, among other things, maintenance of a device master file, device history file, and complaint files. Manufacturers are subject to periodic scheduled or unscheduled inspections by the FDA. A failure to maintain compliance with the QMSR requirements could result in the shut-down of, or restrictions on, manufacturing operations and the recall or seizure of products. The discovery of previously unknown problems with products, including unanticipated adverse events or adverse events of increasing severity or frequency, whether resulting from the use of the device within the scope of its clearance or off-label by a physician in the practice of medicine, could result in restrictions on the device, including the removal of the product from the market or voluntary or mandatory device recalls.

The FDA has broad regulatory compliance and enforcement powers. If the FDA determines that a manufacturer has failed to comply with applicable regulatory requirements, it can take a variety of compliance or enforcement actions, including the following:

•issuance of warning letters, untitled letters, fines, injunctions, consent decrees, and civil penalties;

•requesting or requiring recalls, withdrawals, or administrative detention or seizure of our products;

•imposing operating restrictions or partial suspension or total shutdown of production;

•refusing or delaying requests for 510(k) marketing clearance or PMA approvals of new products or modified products;

•withdrawing 510(k) clearances or PMA approvals that have already been granted;

•refusal to grant export approvals for our products; or

•criminal prosecution.

Healthcare Reform

In the United States, there have been, and continue to be, legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of product candidates, restrict or regulate post-approval activities, and affect the profitable sale of product candidates, and similar healthcare laws and regulations exist in the European Union, or EU, and other jurisdictions. Among policy makers and payors in the United States, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and/or expanding access. In the United States, the pharmaceutical industry has been a particular focus of these efforts and has been significantly affected by major legislative initiatives.

By way of example, in March 2010, the Patient Protection and Affordable Care Act, or the ACA, was passed, which substantially changed the way healthcare is financed by both governmental and private insurers, and significantly affected the pharmaceutical industry.

Since its enactment, there have been judicial, executive and political challenges and amendments to certain aspects of the ACA. For example, on August 16, 2022, the Inflation Reduction Act of 2022, or the IRA, was signed into law, which, among other things, extends enhanced subsidies for individuals purchasing health insurance coverage in ACA marketplaces through plan year 2025. It is unclear how other healthcare reform measures, if any, will impact our business.

Moreover, heightened governmental scrutiny is likely to continue over the manner in which manufacturers set prices for their marketed products, which already has resulted in several Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for pharmaceutical products. Most recently, among other things, the IRA requires manufacturers of certain drugs that have been on the market for at least seven years to engage in price negotiations with Medicare (beginning in 2026), imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023), and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). Manufacturers that fail to comply with the IRA may be subject to various penalties, including civil monetary penalties. The IRA permits the Secretary of the Department of Health and Human Services, or HHS, to implement many of these provisions through guidance, as opposed to regulation, for the initial years. HHS has and will continue to issue and update guidance as these programs as implemented.

The current administration is pursuing policies to reduce regulations and expenditures across government including at HHS, the FDA, the Centers for Medicare & Medicaid Services, or CMS, and related agencies. These actions, presently directed by executive orders or memoranda from the Office of Management and Budget, may propose policy changes that create additional uncertainty for our business. For example, the current administration has announced agreements with several pharmaceutical companies that require the drug manufacturers to offer, through a direct to consumer platform, U.S. patients and Medicaid programs prescription drug Most-Favored Nation pricing equal to or lower than those paid in other developed nations, with additional mandates for direct-to-patient discounts and repatriation of foreign revenues. Other recent actions, for example, include (1) directives to reduce agency workforce and cut programs; (2) directing HHS and other agencies to lower prescription drug costs through a variety of initiatives, including by improving upon the Medicare

Drug Price Negotiation Program and establishing Most-Favored-Nation pricing for pharmaceutical products; (3) imposing tariffs on imported pharmaceutical products; and (4) as part of the Make America Healthy Again, or MAHA, Commission’s recent Strategy Report, working across government agencies to increase enforcement on direct-to-consumer pharmaceutical advertising. These actions and policies may significantly reduce U.S. drug prices, potentially impacting manufacturers’ global pricing strategies and profitability, while increasing their operational costs and compliance risks. In June 2024, the U.S. Supreme Court’s Loper Bright decision greatly reduced judicial deference to regulatory agencies, which could increase successful legal challenges to federal regulations affecting our operations. Congress may introduce and ultimately pass health care related legislation that could impact the drug approval process and make changes to the Medicare Drug Price Negotiation Program created under the IRA.

Individual states in the United States have also become increasingly active in implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine which drugs and suppliers will be included in their healthcare programs Furthermore, there has been increased interest by third-party payors and governmental authorities in reference pricing systems and publication of discounts and list prices.

We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand for our products once approved or additional pricing pressures. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability or commercialize our product candidates.

Other U.S. Healthcare Laws and Compliance Requirements

In the United States, our current and future operations are subject to regulation by various federal, state and local authorities in addition to the FDA, including but not limited to, CMS, other divisions of HHS, (e.g., the Office of Inspector General, Office for Civil Rights and the Health Resources and Service Administration), the U.S. Department of Justice, or DOJ, and individual U.S. Attorney offices within the DOJ, and state and local governments. For example, our business practices, including our clinical research program and any future sales, marketing and scientific/educational grant programs may be required to comply with the anti-fraud and abuse provisions of the Social Security Act, the false claims laws, transparency requirements, and similar state laws, each as amended, as applicable.

The federal Anti-Kickback Statute prohibits, among other things, any person or entity, from knowingly and willfully offering, paying, soliciting or receiving any remuneration, directly or indirectly, overtly or covertly, in cash or in kind, to induce or in return for purchasing, leasing, ordering or arranging for the purchase, lease or order of any item or service reimbursable, in whole or in part, under Medicare, Medicaid or other federal healthcare programs. The term remuneration has been interpreted broadly to include anything of value. In addition, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation. Rather, if “one purpose” of the remuneration is to induce referrals, the federal Anti-Kickback Statute is violated. The federal Anti-Kickback Statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on one hand and prescribers, purchasers, and formulary managers on the other. There are a number of statutory exceptions and regulatory safe harbors protecting some common activities from prosecution. The exceptions and safe harbors are drawn narrowly and practices that involve remuneration that may be alleged to be intended to induce prescribing, purchasing or recommending may be subject to scrutiny if they do not qualify for an exception or safe harbor. Failure to meet all of the requirements of a particular applicable statutory exception or regulatory safe harbor does not make the conduct per se illegal under the Anti-Kickback Statute. Instead, the legality of the arrangement will be evaluated on a case-by-case basis based on a cumulative review of all of its facts and circumstances. Our practices may not in all cases meet all of the criteria for protection under a statutory exception or regulatory safe harbor.

The civil monetary penalties statute imposes penalties against any person or entity who, among other things, is determined to have presented or caused to be presented a claim to, among others, a federal healthcare program that the person knows or should know is for a medical or other item or service that was not provided as claimed or is false or fraudulent.

The federal false claims laws, including the federal False Claims Act, or FCA, impose significant penalties and can be enforced by private citizens through civil qui tam actions, prohibit, any person or entity from, among other things, knowingly presenting, or causing to be presented, a false or fraudulent claim for payment to, or approval by, the federal

government, including federal healthcare programs such as Medicare and Medicaid, or knowingly making, using, or causing to be made or used a false record or statement material to a false or fraudulent claim to the federal government. As a result of a modification made by the Fraud Enforcement and Recovery Act of 2009, a claim includes “any request or demand” for money or property presented to the U.S. government. For instance, historically, pharmaceutical and other healthcare companies have been prosecuted under these laws for allegedly providing free product to customers with the expectation that the customers would bill federal programs for the product. Other companies have been prosecuted for causing false claims to be submitted because of the companies’ marketing of the product for unapproved, off-label, and thus generally non-reimbursable, uses. In addition, a claim that includes items or services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the FCA.

Health Insurance Portability and Accountability Act of 1996, or HIPAA, created additional federal criminal statutes that prohibit, among other things, knowingly and willfully executing, or attempting to execute, a scheme to defraud or to obtain, by means of false or fraudulent pretenses, representations or promises, any money or property owned by, or under the control or custody of, any healthcare benefit program, including private third-party payors, willfully obstructing a criminal investigation of a healthcare offense, and knowingly and willfully falsifying, concealing or covering up by trick, scheme or device, a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services. Like the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.

HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, or HITECH, and its implementing regulations, also imposes certain obligations, including mandatory contractual terms, with respect to safeguarding the privacy and security of individually identifiable health information of covered entities subject to the rule, including health plans, healthcare clearinghouses and certain healthcare providers and their business associates, independent contractors of a covered entity that perform certain services involving the use or disclosure of individually identifiable health information for or on their behalf, as well as their covered subcontractors.

Additionally, the federal Physician Payments Sunshine Act, or the Sunshine Act, and its implementing regulations, require that certain manufacturers of drugs, devices, biological and medical supplies for which payment is available under Medicare, Medicaid or the Children’s Health Insurance Program (with certain exceptions) report information related to certain payments or other transfers of value made or distributed to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician practitioners (such as physician assistants and nurse practitioners), and teaching hospitals, or to entities or individuals at the request of, or designated on behalf of, the physicians and teaching hospitals and to report annually to CMS certain ownership and investment interests held by physicians and their immediate family members. Failure to report accurately could result in penalties. In addition, many states also govern the reporting of payments or other transfers of value, many which differ from each other in significant ways, are often not pre-empted, and may have a more prohibitive effect than the Sunshine Act, thus further complicating compliance efforts.

Also, many states have similar, and typically more prohibitive, fraud and abuse statutes or regulations that apply to items and services reimbursed under Medicaid and other state programs, or, in several states, apply regardless of the payor. In order to distribute products commercially, we must comply with state laws that require the registration of manufacturers and wholesale distributors of drug and biological products in a state, including, in certain states, manufacturers and distributors who ship products into the state even if such manufacturers or distributors have no place of business within the state. Some states also impose requirements on manufacturers and distributors to establish the pedigree of product in the chain of distribution, including some states that require manufacturers and others to adopt new technology capable of tracking and tracing product as it moves through the distribution chain. Several states have enacted legislation requiring pharmaceutical and biotechnology companies to establish marketing compliance programs, file periodic reports with the state, make periodic public disclosures on sales, marketing, pricing, clinical trials and other activities, and/or register their sales representatives, as well as to prohibit pharmacies and other healthcare entities from providing certain physician prescribing data to pharmaceutical and biotechnology companies for use in sales and marketing, and to prohibit certain other sales and marketing practices.

Ensuring business arrangements with third parties comply with applicable healthcare laws and regulations is a costly endeavor. If our operations are found to be in violation of any of the federal and state healthcare laws described above or any other current or future governmental regulations that apply to us, we may be subject to significant penalties, including without limitation, civil, criminal and/or administrative penalties, damages, fines, disgorgement, individual imprisonment, exclusion from participation in government programs, such as Medicare and Medicaid, injunctions, private “qui tam” actions brought by individual whistleblowers in the name of the government, or refusal to allow us to enter into

government contracts, contractual damages, reputational harm, administrative burdens, diminished profits and future earnings, additional reporting requirements and/or oversight if we become subject to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with these laws, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations.

Coverage, Pricing, and Reimbursement

Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we obtain regulatory approval. In the United States and markets in other countries, sales of any products for which we receive regulatory approval for commercial sale will depend, in part, on the extent to which third-party payors provide coverage, and establish adequate reimbursement levels for such products. In the United States, third-party payors include federal and state healthcare programs, private managed care providers, health insurers and other organizations.

The process for determining whether a third-party payor will provide coverage for a product may be separate from the process for setting the price of a product or for establishing the reimbursement rate that such a payor will pay for the product. Third-party payors may limit coverage to specific products on an approved list, or also known as a formulary, which might not include all of the FDA-approved products for a particular indication. Third-party payors are increasingly challenging the price, examining the medical necessity and reviewing the cost-effectiveness of medical products, therapies and services, in addition to questioning their safety and efficacy. We may need to conduct expensive pharmaco-economic studies in order to demonstrate the medical necessity and cost-effectiveness of our products, in addition to the costs required to obtain the FDA approvals. Our product candidates may not be considered medically necessary or cost-effective. A payor’s decision to provide coverage for a product does not imply that an adequate reimbursement rate will be approved. In addition, one payor’s determination to provide coverage for a product does not assure that other payors will also provide coverage for the product. Further, obtaining reimbursement for our product may be particularly difficult because of the higher prices often associated with branded drugs and drugs administered under the supervision of physicians. Adequate third-party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our investment in product development. In addition, companion diagnostic tests require coverage and reimbursement separate and apart from the coverage and reimbursement for their companion pharmaceutical or biological products. Similar challenges to obtaining coverage and reimbursement, applicable to pharmaceutical or biological products, will apply to companion diagnostics.

We may develop products that, once approved, may be administered by a physician. Under currently applicable U.S. law, certain products not usually self-administered (including injectable drugs) may be eligible for coverage under Medicare through Medicare Part B. Medicare Part B is part of original Medicare, the federal health care program that provides health care benefits to the aged and disabled, and covers outpatient services and supplies, including certain biopharmaceutical products, that are medically necessary to treat a beneficiary’s health condition. As a condition of receiving Medicare Part B reimbursement for a manufacturer’s eligible drugs, the manufacturer is required to participate in other government healthcare programs, including the Medicaid Drug Rebate Program and the 340B Drug Pricing Program. The Medicaid Drug Rebate Program requires pharmaceutical manufacturers to enter into and have in effect a national rebate agreement with the Secretary of HHS as a condition for states to receive federal matching funds for the manufacturer’s outpatient drugs furnished to Medicaid patients. Under the 340B Drug Pricing Program, the manufacturer must extend discounts to entities that participate in the program.

Different pricing and reimbursement schemes exist in other countries. In the EU, governments influence the price of pharmaceutical products through their pricing and reimbursement rules and control of national health care systems that fund a large part of the cost of those products to consumers. Some jurisdictions operate positive and negative list systems under which products may only be marketed once a reimbursement price has been agreed. To obtain reimbursement or pricing approval, some of these countries may require the completion of clinical trials that compare the cost-effectiveness of a particular product candidate to currently available therapies. Other EU member states allow companies to fix their own prices for medicines, but monitor and control company profits. In addition, in some countries, cross-border imports from low-priced markets exert a commercial pressure on pricing within a country.

In addition, some EU Member States may require the completion of additional studies that compare the cost-effectiveness of a particular medicinal product candidate to currently available therapies. This Health Technology Assessment, or HTA, process is the procedure according to which the assessment of the public health impact, therapeutic impact and the economic and societal impact of use of a given medicinal product in the national healthcare systems of the individual country is conducted. The outcome of HTA regarding specific medicinal products will often influence the pricing and reimbursement status granted to these medicinal products by the competent authorities of individual EU Member States. In

December 2021, Regulation No 2021/2282 on Health Technology Assessment, or HTA Regulation, was adopted. The HTA Regulation is intended to boost cooperation among EU Member States in assessing health technologies, including new medicinal products, and providing the basis for cooperation at EU level for joint clinical assessments in these areas. The HTA Regulation entered into application on January 12, 2025 through a phased implementation based on the type of product (i.e. oncology and advanced therapy medicinal products as of 2025, orphan medicinal products as of 2028, and all other medicinal products by 2030) and is intended to harmonize the clinical benefit assessment of HTA across the EU and is intended to harmonize the clinical benefit assessment of HTA across the EU.

The marketability of any product candidates for which we receive regulatory approval for commercial sale may suffer if the government and third-party payors fail to provide adequate coverage and reimbursement. The downward pressure on the rise in healthcare costs in general and pharmaceutical products in particular has become intense. As a result, in the EU, increasingly high barriers are being erected to the entry of new products. In the United States, the emphasis on managed care, the increasing influence of health maintenance organizations, and additional legislative changes has increased and we expect will continue to increase the pressure on product pricing. In addition, coverage policies and third-party reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

Foreign Government Regulation

To market any product outside of the United States, we would need to comply with numerous and varying regulatory requirements of other countries governing, among other things, clinical trials, marketing authorization, commercial sales and distribution of our products.

Whether or not we obtain FDA approval of a product, we must obtain the requisite approvals from regulatory authorities in foreign countries prior to the commencement of clinical trials or marketing of the product in those countries. Approval by one regulatory authority does not ensure approval by regulatory authorities in other jurisdictions. The approval process varies from country to country, can involve additional testing beyond that required by FDA, and may be longer or shorter than that required for FDA approval. The requirements governing the conduct of clinical trials, product licensing, pricing, promotion, and reimbursement vary greatly from country to country. Failure to comply with applicable foreign regulatory requirements, may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Regulation of Medicinal Products in the United Kingdom

The Medicines and Healthcare products Regulatory Agency, or MHRA, is the United Kingdom’s standalone regulator for medicinal products and medical devices.

The United Kingdom’s regulatory framework in relation to clinical trials is governed by the Medicines for Human Use (Clinical Trials) Regulations 2004, as amended. On April 10, 2025, the Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2024 came into force, with a 12-month implementation period before entering into force on April 28, 2026. These amendments modernize the UK clinical trials framework and introduce significant changes including: (i) a risk-proportionate approach whereby low-risk trials can receive faster approval through automatic authorization without prior regulatory review; (ii) a combined review process integrating ethics committee and regulatory approvals into a single streamlined approval pathway; (iii) enhanced transparency requirements mandating registration of clinical trials in a public registry and publication of trial results within 12 months of trial completion; (iv) provisions to streamline approvals and enable innovation in clinical trial design; and (v) measures to promote patient and public involvement in clinical trials.

Marketing authorizations in the United Kingdom are governed by the Human Medicines Regulations (SI 2012/1916), as amended. In order to obtain a United Kingdom MA to commercialize products in the United Kingdom, an applicant must be established in the United Kingdom and must follow one of the United Kingdom national authorization procedures or one of the remaining post-Brexit international cooperation procedures. Applications are made electronically through the MHRA Submissions Portal. The MHRA has introduced changes to national licensing procedures, including procedures to prioritize access to new medicines that will benefit patients, a 150-day assessment (subject to clock-stops) and a rolling review procedure. The rolling-review procedure permits the separate or joint submission of quality, non-clinical, and clinical data to the MHRA which can be reviewed on a rolling basis. After an application under the rolling-review procedure has been validated, the decision should be received within 100 days (subject to clock-stops).

In addition, since January 1, 2024, the MHRA may rely on the International Recognition Procedure, or IRP, when reviewing certain types of MAAs. Pursuant to the IRP, the MHRA will take into account the expertise and decision-making of trusted regulatory partners (e.g., the regulatory in Australia, Canada, Switzerland, Singapore, Japan, the U.S.A. and the EU). The MHRA will conduct a targeted assessment of IRP applications but retain the authority to reject applications if the evidence provided is considered insufficiently robust. The IRP allows medicinal products approved by such trusted regulatory partners that meet certain criteria to undergo a fast-tracked MHRA review to obtain and/or update a MA in the United Kingdom. Applications should be decided within a maximum of 60 days if there are no major objections identified that cannot be resolved within such 60 day period and the approval from the trusted regulatory partner selected has been granted within the previous two years or, if there are such major objections identified or such approval has not been granted within the previous two years, within 110 days. Applicants can submit initial MAAs to the IRP but the procedure can also be used throughout the lifecycle of a product for post-authorization procedures including line extensions, variations and renewals.

Existing EU marketing authorizations for centrally authorized products were automatically converted into United Kingdom’s marketing authorizations, effective in Great Britain only, free of charge on January 1, 2021, unless the marketing authorization holder opted-out of this possibility. On January 1, 2025, the Windsor Framework came into effect, reintegrating Northern Ireland under the regulatory authority of the MHRA with respect to medicinal products and introducing a UK-wide licensing process for medicines.

Regulation of Companion Diagnostics in the United Kingdom

Companion diagnostics are regulated as in vitro diagnostic medical devices which are regulated under the Medical Devices Regulations 2002, as amended. These rules implement requirements derived from the former EU In Vitro Diagnostic Medical Devices Directive. The MHRA is responsible for the regulation of IVDs in the United Kingdom. Manufacturers must demonstrate conformity with applicable essential requirements, including analytical and clinical performance, before placing IVDs on the UK market. From July 1, 2023, the UK has required UKCA marking for IVDs placed on the Great Britain market, though CE marking continues to be recognized during a transitional period. Manufacturers must appoint a UK Responsible Person if they are not established in the United Kingdom.

The United Kingdom is developing a new regulatory framework for IVDs based on a risk-based approach similar to the EU's In Vitro Diagnostic Regulation (EU) 2017/746 with the stated aim of reducing regulatory burden, with UK-specific modifications. The new regime will include enhanced clinical evidence requirements, increased scrutiny by UK-approved bodies for higher-risk devices, and strengthened post-market surveillance. The MHRA will provide transitional arrangements for compliance, though specific timelines remain subject to regulatory development and parliamentary approval.

The Foreign Corrupt Practices Act

The Foreign Corrupt Practices Act, or FCPA, prohibits any U.S. individual or business from paying, offering, or authorizing payment or offering of anything of value, directly or indirectly, to any foreign official, political party or candidate for the purpose of influencing any act or decision of the foreign entity in order to assist the individual or business in obtaining or retaining business. The FCPA also obligates companies whose securities are listed in the United States to comply with accounting provisions requiring the company to maintain books and records that accurately and fairly reflect all transactions of the corporation, including international subsidiaries, and to devise and maintain an adequate system of internal accounting controls for international operations.

Additional Regulation

In addition to the foregoing, state, federal, and foreign laws regarding environmental protection and hazardous substances, including the Occupational Safety and Health Act, the Resource Conservancy and Recovery Act and the Toxic Substances Control Act, affect our business. These and other laws govern our use, handling and disposal of various biological, chemical and radioactive substances used in, and wastes generated by, our operations. If our operations result in contamination of the environment or expose individuals to hazardous substances, we could be liable for damages and governmental fines. We believe that we are in material compliance with applicable environmental laws and that continued compliance therewith will not have a material adverse effect on our business. We cannot predict, however, how changes in these laws may affect our future operations.

Data Privacy and Security

In the ordinary course of our business, we may process personal data and sensitive personal data. Accordingly, we are, and may in the future become, subject to numerous data privacy and security obligations, including federal, state, local, and foreign laws, regulations, guidance, and industry standards related to data privacy, security, and protection. Such obligations may include, without limitation, the Federal Trade Commission Act, the California Consumer Privacy Act of 2018, or CCPA, the European Union’s General Data Protection Regulation 2016/679, or EU GDPR, and the EU GDPR as it forms part of United Kingdom law by virtue of section 3 of the European Union (Withdrawal) Act 2018, or UK GDPR, or collectively, GDPR. Several states within the United States have enacted or proposed data privacy laws. Additionally, we are, or may become, subject to various U.S. federal and state consumer protection laws which require us to publish statements that accurately and fairly describe how we handle personal data and choices individuals may have about the way we handle their personal data.

Numerous U.S. states have enacted comprehensive privacy laws that impose certain obligations on covered businesses, including providing specific disclosures in privacy notices and affording residents with certain rights concerning their personal data. As applicable, such rights may include the right to access, correct, or delete certain personal data, and to opt-out of certain data processing activities, such as targeted advertising, profiling, and automated decision-making. The exercise of these rights may impact our business and ability to provide our products and services. Certain states also impose stricter requirements for processing certain personal data, including sensitive information, such as conducting data privacy impact assessments. These state laws allow for statutory fines for noncompliance.

Outside the United States, under the GDPR, companies may face temporary or definitive bans on data processing and other corrective actions; fines of up to 20 million Euros under the EU GDPR, 17.5 million pounds sterling under the UK GDPR or, in each case, 4% of annual global revenue, whichever is greater; or private litigation related to processing of personal data brought by individuals or classes of data subjects or consumer protection organizations authorized at law to represent their interests. See the section titled “Risk Factors – Risks Related to Government Regulation – We and the third parties with whom we work are subject to stringent and evolving U.S. and foreign laws, regulations, and rules, contractual obligations, industry standards, policies and other obligations related to data privacy and security. Actual or perceived failures to comply with applicable data protection, privacy and security laws, regulations, standards, and other requirements could adversely affect our business, results of operations, and financial condition” for additional information about the laws and regulations to which we are or may become subject and about the risks to our business associated with such laws and regulations.

Our use of artificial intelligence and machine learning may also be subject to evolving laws and regulations regarding security and privacy, as well as controlling for data bias and anti-discrimination. Privacy and security laws, regulations and other obligations are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing.

Our use of artificial intelligence and machine learning may also be subject to evolving laws and regulations regarding security and privacy. Several jurisdictions around the globe, including Europe and certain U.S. states, have proposed enacted, or are considering laws governing the development and use of AI. We expect other jurisdictions will adopt similar laws. These laws, regulations and other obligations related to AI are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing

Employees and Human Capital Resources

As of December 31, 2025, we had 68 total employees, including 66 in the United States and two in Australia. Of our 68 employees, 16 hold Ph.D. and/or M.D. degrees and 54 were engaged in research and development. None of our employees is subject to a collective bargaining agreement. We consider our relationship with our employees to be good.

We recognize that our continued ability to attract, retain, and motivate exceptional employees is vital to ensuring our long-term competitive advantage. Our employees are critical to our long-term success and are essential to helping us meet our goals. Our human capital resources objectives include, as applicable, identifying, recruiting, retaining, incentivizing, and integrating our existing and additional employees. The principal purposes of our equity incentive plans are to attract, retain, and motivate selected employees, consultants, and directors through the granting of stock-based compensation awards and cash-based performance bonus awards.

Corporate Information and Trademarks

Alto Neuroscience, Inc. was incorporated under the laws of the State of Delaware in March 2019. Our principal executive office is located at 650 Castro Street, Suite 450, Mountain View, CA 94041. Our telephone number is (650) 200-0412. Our website address is www.altoneuroscience.com. Information contained in, or accessible through, our website does not constitute a part of, and is not incorporated into, this Annual Report.

The Alto Neuroscience logo, the name Alto Neuroscience, and other trademarks of Alto Neuroscience, Inc. appearing in this Annual Report are the property of Alto Neuroscience, Inc. Solely for convenience, trade names, trademarks, and service marks contained in this Annual Report may appear without the “®” or “™” symbols. Such references are not intended to indicate, in any way, that the respective owners will not assert, to the fullest extent possible under applicable law, their rights to those trade names, trademarks, and service marks.

Additional Information

Our Internet website address is www.altoneuroscience.com. On our website, we make available, free of charge, our annual, quarterly and current reports, including amendments to such reports, as soon as reasonably practicable after the company electronically files such material with, or furnishes such material to, the SEC. The SEC maintains a website at www.sec.gov that contains reports, proxy and information statements and other information regarding us and other companies that file materials with the SEC electronically.

Also available on our website is information relating to our corporate governance and our board of directors, including our corporate governance guidelines; our code of business conduct (for our directors, officers and employees); and our board committee charters. We will provide any of the foregoing information without charge upon written request to our Corporate Secretary, 650 Castro Street, Suite 450, Mountain View, CA 94041.