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MICVO is currently being studied as monotherapy in recurrent and metastatic head and neck squamous cell carcinoma (R/M HNSCC) and in combination with KEYTRUDA® (pembrolizumab) in 1L/2L+ R/M HNSCC and other solid tumors.

MICVO Monotherapy

PYX-201-101 Phase 1 (Part 1) Monotherapy Dose Escalation Study

As part of our Phase 1 monotherapy study, referred to as PYX-201-101, we conducted a dose escalation study to evaluate MICVO monotherapy in patients with advanced solid tumors known to express EDB+FN. In November 2024, we reported positive preliminary results from the dose escalation study, which included a total of 80 patients dosed across nine solid tumor types at doses ranging from 0.3 mg/kg to 8 mg/kg, with a data cut-off of October 4, 2024. Of the nine solid tumor types included in the study, the strongest tumor regression response was observed in R/M HNSCC. Among the six efficacy evaluable heavily pre-treated patients with R/M HNSCC, the confirmed objective response rate (ORR) was 50% per RECIST v1.1 at the therapeutically active dose response range of 3.6 mg/kg – 5.4 mg/kg administered intravenously every three weeks (IV Q3W), including one confirmed complete response (CR) and two confirmed partial responses (PRs), with a disease control rate (DCR) of 100%. Based on observations from the dose-escalation study, 5.4 mg/kg IV Q3W presented an optimal benefit-risk profile within the efficacious dose range and was selected for dose expansion. Subsequent translational data indicated reduction in ctDNA TF after treatment with MICVO, particularly at the 5.4 mg/kg dose, supported a positive molecular response to MICVO, providing further validation of the dose selection strategy for dose expansion.

PYX-201-101 Phase 1 (Part 2) Monotherapy Dose Expansion in R/M HNSCC

In January 2025, we initiated the dose expansion portion (Part 2) of the Phase 1 PYX-201-101 monotherapy study to further evaluate MICVO as a monotherapy at a dose of 5.4 mg/kg IV Q3W and to assess preliminary efficacy in R/M HNSCC. The Part 2 dose-expansion phase includes the following two cohorts:

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Arm 1: MICVO monotherapy for second line (2L) and third line (3L) R/M HNSCC patients who have received prior platinum-based chemotherapy and prior PD-(L)1 inhibitor therapy; and

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Arm 2: MICVO monotherapy for 2L and 3L R/M HNSCC patients who have received prior epidermal growth factor receptor (EGFR) directed therapy and prior PD-(L)1 inhibitor therapy.

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In December 2025, we reported positive preliminary data from our ongoing Phase 1 monotherapy study evaluating MICVO in patients with 2L+ R/M HNSCC, based on a data cut-off date of November 3, 2025, which included all R/M HNSCC patients dosed at 5.4 mg/kg total body weight (TBW) in Part 1 and in Part 2. As of the data cut-off, 18 R/M HNSCC patients had been treated and 13 patients were efficacy evaluable. All treated patients had received prior systemic therapy, with a median of three prior lines of therapy. All treated patients had received prior platinum-based and checkpoint inhibitor therapies while 67% of treated patients had received prior taxanes and 50% of treated patients had received prior EGFR-targeted therapies, specifically cetuximab. Among the 13 efficacy evaluable patients, the confirmed ORR was 46% (6/13, one patient confirmed response after November 3, 2025 data cut-off) per RECIST v1.1, including one confirmed complete response. Confirmed responses were observed in both dose-expansion cohorts, including patients previously treated with platinum-based therapy and anti-PD(L)1 therapy (Arm 1) and patients previously treated with an EGFR inhibitor and/or anti-PD(L)1 therapy (Arm 2), and were observed in patients regardless of HPV status. The preliminary data also showed a DCR of 92%, with 12 of 13 efficacy evaluable patients demonstrating significant tumor regression or tumor control.

Preliminary data reported in December 2025 indicated that MICVO was generally well tolerated. No Grade 4 ADC payload treatment-related adverse events (TRAEs) of interest were observed, and no Grade 5 events occurred. TRAEs were reported in 89% (16/18) of patients, with Grade ≥3 TRAEs reported in 56% (10/18) of patients. TRAEs leading to treatment discontinuation occurred in 28% (5/18) of patients. We observed a higher discontinuation rate and incidence of Grade ≥3 TRAEs in high body weight patients (defined as at least 10% above adjusted ideal body weight, or AIBW). In the preliminary dataset, all patients (5/5) who experienced TRAEs leading to treatment discontinuation had high body weight. Several approved ADCs have demonstrated comparable associations among patient body weight, systematic drug exposure, and tolerability profiles. Many of these ADCs, such as Padcev, Adcetris, and Elahere, have addressed such observations through dosing modifications that resulted in an improved tolerability profile while sustaining efficacy, including through capping the maximum allowable dose or employing AIBW dosing. We are actively evaluating both of these approaches to optimize MICVO’s benefit-risk profile.

MICVO Combination Therapy

In November 2024, we announced a Clinical Trial Collaboration and Supply Agreement with Merck & Co, Inc. or Merck (known as MSD outside of the United States and Canada), for a Pyxis Oncology-sponsored study of MICVO in combination with Merck’s anti-PD-1 therapy, KEYTRUDA® (pembrolizumab). In January 2025, we initiated the Phase 1/2 combination study with KEYTRUDA®, PYX-201-102, and are actively enrolling and dosing patients in this study. PYX-201-102 is a Phase 1/2 open label, global, multicenter dose escalation and dose expansion study designed to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary efficacy of MICVO in combination with pembrolizumab in patients with advanced solid tumors. Patients with histologically or cytologically confirmed advanced solid tumors, including 1L R/M HNSCC, 2L+ R/M HNSCC, cervical cancer, gastric cancer, HR+/HER2- breast cancer, and locally advanced or metastatic triple-negative breast cancer (TNBC), are eligible to enroll.

PYX-201-102 Phase 1/2 Preliminary Combination Data in R/M HNSCC

In December 2025, we reported positive preliminary data from this study, evaluating MICVO at 3.6 mg/kg and 4.4 mg/kg IV Q3W, each administered in combination with a fixed 200 mg dose of pembrolizumab Q3W, in patients with 1L/2L+ R/M HNSCC. As of the data cut-off date of November 3, 2025, seven patients had been treated, including four patients at 3.6 mg/kg and three patients at 4.4 mg/kg of MICVO, each in combination with pembrolizumab. All treated patients had received prior systemic therapy, including four patients with 1L R/M HNSCC (median of one prior systemic therapy administered in the neoadjuvant or adjuvant setting) and three patients with 2L+ R/M HNSCC (median of three prior lines of therapy, some of which were administered prior to the R/M setting). Among the seven efficacy-evaluable patients, the confirmed ORR was 71% (5/7, one patient confirmed response after November 3, 2025 data cut-off) and the DCR was 100% (7/7), with all seven patients demonstrating meaningful tumor regression. Responses were observed across a range of PD-L1 combined positive scores (CPS), from CPS≥1 to CPS>20, and included responses in patients who had previously received checkpoint inhibitor treatment and had experienced disease progression while receiving checkpoint inhibitor treatment. Preliminary safety data indicated that MICVO in combination with pembrolizumab was generally well tolerated, with no Grade 3 or Grade 4 ADC payload TRAEs of interest and no Grade 5 events reported. TRAEs were reported in 86% (6/7) of patients. No TRAEs led to treatment discontinuation, and, as of the data cut-off date, no overlapping toxicities between MICVO and pembrolizumab (KEYTRUDA®) had been observed.

We believe the totality of our preliminary data supports continued clinical development of both MICVO monotherapy expansion and combination therapy trials.

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Our Clinical Pipeline

The following table summarizes our clinical pipeline:

MICVO Monotherapy Pipeline

The dose expansion phase of our PYX-201-101 monotherapy study is ongoing with the objective of further evaluating the preliminary safety, efficacy and durability signals observed with MICVO in R/M HNSCC at the 5.4mg/kg dose. We completed target enrollment of approximately 40 patients in the Phase 1 monotherapy dose expansion study of MICVO in 2L+ R/M HNSCC in the first quarter of 2026 and are actively treating patients in two monotherapy R/M HNSCC cohorts at the 5.4 mg/kg IV Q3W dose. The dose expansion phase includes the following R/M HNSCC cohorts across sites in the United States (US), European Union (EU) and other countries:

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MICVO monotherapy for 2L and 3L R/M HNSCC patients who have received prior platinum-based chemotherapy and prior PD-(L)1 inhibitor therapy. We expect to enroll approximately 20 patients in this expansion cohort at the 5.4 mg/kg IV Q3W dose and anticipate reporting updated clinical data from this cohort in mid-2026; and

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MICVO monotherapy for 2L and 3L R/M HNSCC patients who have received prior epidermal growth factor receptor (EGFR) directed therapy and prior PD-(L)1 inhibitor therapy. We expect to enroll approximately 20 patients in this expansion cohort at the 5.4 mg/kg IV Q3W dose and anticipate reporting updated clinical data from this cohort in mid-2026.

MICVO Phase 1 monotherapy data in 2L+ R/M HNSCC expected in mid-year 2026 will include patients dosed at 5.4 mg/kg IV Q3W with a dose cap for patients with higher body weight, as well as patients previously dosed at 5.4 mg/kg IV Q3W based on total body weight. The results are expected to include detailed analyses of the effect of the modified weight-based dosing strategy on safety and efficacy. AIBW dosing, which has demonstrated improved tolerability without apparent loss of activity in clinical studies of other antibody-drug conjugates, is being implemented in ongoing clinical studies as well.

During the fourth quarter of 2025, we obtained feedback and alignment from the U.S. Food and Drug Administration (FDA) regarding the clinical trial design for a planned pivotal monotherapy study in 2L+ R/M HNSCC.

MICVO Combination Therapy Pipeline

Our Phase 1/2 combination study with KEYTRUDA® (PYX-201-102) is ongoing and we are conducting the dose escalation phase of PYX-201-102 across multiple tumor types with the objective of identifying the Recommended Phase 2 Dose (RP2D) of MICVO in combination with pembrolizumab. We are currently enrolling and dosing patients across several dose levels between 3.6 mg/kg and 5.4 mg/kg of MICVO, in combination with pembrolizumab at the fixed dose of 200 mg IV Q3W, in order to accurately characterize the RP2D for MICVO in combination with pembrolizumab, subject to ongoing safety review, enrollment progress, and clinical data evaluation.

We expect to report updated data from the PYX-201-102 study in patients with 1L/2L+ R/M HNSCC in the second half of 2026.

Our Team

Pyxis Oncology was founded in 2018 and began operations in 2019 with a mission to address difficult-to-treat cancers. We have assembled a multidisciplinary team with experience across core oncology research and development functions and corporate and administrative operations. Collectively, our team brings experience spanning early- through late-stage development and, in certain cases, commercialization, across biotechnology and pharmaceutical organizations.

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Our Strategy

Our goal is to improve the lives of patients with difficult-to-treat cancers. Key elements of our strategy include:

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Building a leading ADC oncology company. We believe our team, with its deep oncology knowledge, functional biology expertise, ADC modality technical know-how and biologics development capabilities, positions us to build a leading ADC-focused oncology company.

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Successfully developing our lead product candidate, MICVO, to address significant unmet need in R/M HNSCC. We are prioritizing development of our lead product candidate, MICVO, for R/M HNSCC, where we believe there is significant unmet need for durable therapeutic options. HNSCC is among the most common cancers, and it has been estimated that approximately one million new cases could occur worldwide annually by 2030. Our prioritization reflects, among other factors, the unmet need in this patient population and the preliminary activity observed to date in the PYX‑201‑101 monotherapy and PYX-201-102 combination program.

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Selectively forging alliances to provide strategic or financial support to our lead MICVO program. We intend to seek strategic collaborations to facilitate the capital efficient development of our pipeline. We believe various potential alliance structures including collaborations, licenses and future agreements could potentially provide significant funding to advance our pipeline and could allow us to benefit from the additional resources, development and commercialization expertise of our collaborators.

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Maximize value from our intellectual property and technology platforms. We continue to engage in discussions with potential partners regarding opportunities to monetize elements of our intellectual property portfolio, including certain programs that are not currently being actively resourced. We also seek to maximize the value of our biologics technology platforms, including our Flexible Antibody Conjugation Technology (FACT) platform for ADC development and our APXiMAB platform for antibody discovery and development.

Unmet Need in Head and Neck Cancer and Treatment Paradigm

Head and Neck Cancer (HNC) is the seventh most common cancer in the world (Source: NIH), with 940,000 new cases and 480,000 deaths from HNC per 2022 GLOBOCAN estimates. GLOBOCAN is a cancer surveillance branch of the World Health Organization’s International Agency for Research on Cancer (Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC12507627/). Squamous Cell Carcinoma presents as the most common HNC subtype and is derived from the mucosal lining of the oral cavity, oropharynx, hypopharynx and larynx. It is estimated that by 2030 there will be approximately one million new cases of HNSCC worldwide annually per 2022 GLOBOCAN estimates. HNC accounts for approximately 4.5% of cancer diagnoses and deaths globally with over 90% of cases presenting with squamous cell origin.

HNSCC commonly originates in the mouth and throat, from the mucosa of the oral cavity, oropharynx, hypopharynx and larynx. There are approximately 60,000 cases of HNSCC each year in the U.S. with a 13% 5-year survival rate in the R/M (Stage IVC) setting. 15% of HNSCC patients are diagnosed with de novo metastatic disease and almost 50% of locally advanced cases will suffer a recurrence post initial treatment and/or become metastatic. There are approximately 31,000 cases of R/M HNSCC each year in the U.S. with ~67% (~21,000) of patients progressing from 1L to 2L and facing a sharp decline in survival. The median Overall Survival (OS) for patients with 1L R/M HNSCC ranges from 9 months (HPV unrelated) to about 14 months (HPV+). The overall incidence of HNSCC is expected to rise with a predicted 30% increase annually by 2030. The increase has been associated with multiple factors, including but not limited to tobacco use, alcohol consumption, a rise in HPV infections and other environmental catalysts. Approximately 80% of patients in the U.S. with R/M HNSCC are HPV unrelated. Globally, these numbers vary with higher rates of HPV+ cancers in countries such as New Zealand and parts of Northern Europe. The vast majority of HPV+ HNSCC cases are detected in the oropharyngeal cavity versus other locations (oral cavity, pharynx, larynx etc.) with approximately 5,500 cases of virally driven tumors diagnosed in the U.S. each year. Furthermore, HPV+ HNSCC is also on the rise in the U.S. with a greater number of oropharyngeal cancer cases diagnosed every year, suggesting potential shifts in how patients will be diagnosed and treated based on possible HPV segmentation.

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Current Treatment Paradigm of R/M HNSCC

The standard of care (SOC) first line therapy for R/M HNSCC globally is determined by the Combined Positive Score (CPS) which corresponds to the number of PD-L1 positive cells in relation to the total number of viable tumor cells. Patients with high CPS scores tend to respond better to PD-(L)1 checkpoint inhibitors, as observed across multiple tumor types. In R/M HNSCC, pembrolizumab monotherapy (was previously approved for CPS≥20) is recommended for patients with a CPS>1 post label expansion based on KEYNOTE-048 (KN_048) (~26,000 addressable patients). However, addition of platinum-based chemotherapy is strongly considered in these patients if they are symptomatic or present with aggressive disease. Pembrolizumab combined with platinum and 5-fluorouracil is recommended for patients with any PD-L1 status of CPS≥1 essentially providing a monotherapy or combo option to all patients considered PD-L1+ with different treatment options adopted by region worldwide. While approved, the chemo combination is not always reimbursed by the health authorities in certain parts of Europe but is the most commonly used regimen in the U.S. The addition of chemotherapy to pembrolizumab increases the response rate; however, it also significantly reduces the duration of response while increasing toxicity and leads to roughly equivalent median overall survival (OS) with both treatments. For patients with a CPS<1 and no PD-L1 expression, the typical standard of care is the EXTREME regimen (not in the U.S.), a combination of cetuximab and chemotherapy, which has low response rates and survival (10 months), as well as a difficult tolerability profile. The EXTREME regimen is more commonly used in Europe and other ex-US countries with less than 5% usage in the U.S. Patients with CPS<1 in the US receive a chemotherapy combination consisting of platinum (cisplatin or carboplatin) with 5-fluorouracil to lower toxicity associated with addition of cetuximab. While the 1L R/M HNSCC treatment paradigm is well defined, globally, limited options are available for patients that fail therapy and move into 2L and beyond. If patients are treated with immuno-oncology (IO) in 1L, they are not eligible for re-treatment and the only therapy approved is chemotherapy. Cetuximab (with or without chemo) does not have an approved FDA or EMA label post IO but is recommended by certain clinical practice and regulatory guidelines set forth by some countries including the NCCN in the US. Patients that are platinum refractory or not treated with IO in 1L are eligible for pembrolizumab or nivolumab monotherapy in 2L but progression free survival (mPFS) benefit remains modest at 2-3 months, highlighting need for a more efficacious option in these patients.

The Phase 3 KN-048 trial conducted by Merck investigated pembrolizumab as a monotherapy or in combination with chemotherapy, compared to cetuximab with chemotherapy in first line R/M HNSCC. The pembrolizumab monotherapy and pembrolizumab and chemotherapy combination response rates of 19% and 36%, respectively, were comparable to the 36% ORR for cetuximab and chemotherapy combination in patients with CPS>1. In these patients, pembrolizumab monotherapy and in combination with chemotherapy led to median OS of 12.3 and 13.0 months, respectively, compared to 10.7 months in the active control arm. While this represents a step forward, there remains significant unmet need in R/M HNSCC for more efficacious therapies that can extend survival, especially for chemotherapy-free alternatives with superior tolerability and also differentiated treatment modalities that can serve the emerging unmet need populations as the treatment paradigms may evolve. Patients that are not eligible for 1L pembrolizumab (CPS<1) represent ~3500 patients and lack efficacious treatment options that offer durable survival and quality of life. Furthermore, pembrolizumab was also recently approved in the adjuvant and neo-adjuvant setting allowing subsets of localize/locally advanced patients to benefit from IO in the peri-operative setting. Use of IO in earlier disease may impact use in the R/M setting which may result in additional shifts to the R/M HNSCC landscape.

HPV status also does not play a role in patient segmentation and treatment choices based on approved SOC but a shift may occur as emerging therapies may prove to be superior in one patient segment versus another. This could open up newer patient groups with unmet needs that may not be fulfilled by current or emerging therapies, particularly in the 2L+ setting given that HPV+ patients have historically shown poor response rates to EGFR therapies.

Emerging Treatment Landscape of R/M HNSCC

Currently, several companies are innovating next-generation EGFR assets and bi-specific antibodies to address the needs of HNSCC patients, including Genmab A/S (Genmab) via its acquisition of Merus N.V (Merus), Bicara Therapeutics Inc. (Bicara) and Johnson & Johnson (JNJ). Genmab, Bicara and JNJ have ongoing clinical trials evaluating antibodies targeting EGFR - petosemtamab, ficerafusp alfa (BCA101), and RYBREVANT FASPRO™ (amivantamab and hyaluronidase-lpuj), respectively, as a monotherapy or as a combination therapy with pembrolizumab for the treatment of R/M HNSCC solid tumors, with a focus on combination therapy for 1L. All assets have been granted breakthrough designation (BTD) by the U.S. Food and Drug Administration (FDA) in R/M HNSCC. Genmab has two Phase 3 clinical trials ongoing, 1L treatment of R/M PD-L1+ (CPS≥1) HNSCC in combination with pembrolizumab and 2L/3L R/M HNSCC monotherapy. Bicara has ongoing trials for the treatment of 1L R/M HNSCC, including a Phase 2/3 combination trial with pembrolizumab in HPV unrelated patients only (1L, CPS>1). JNJ also has ongoing trials for the treatment of 1L R/M HNSCC in HPV unrelated patients only. Aside from these next-generation EGFR assets, Corbus Pharmaceuticals has ongoing clinical trials evaluating a Nectin-4 targeting ADC, CRB-701, for the treatment of 2L+ R/M HNSCC with monotherapy and 1L R/M HNSCC in combination with pembrolizumab. Additionally, other agents like Nanobiotix’s radioenhancer, NBTRX3, are in clinical development and may be used earlier in the treatment sequence such as in localized or locally advanced settings. Other modalities including but not limited to T cell engagers may segment market further into HPV+ specific treatments along with other emerging segmentations that may trigger a change in clinical practice. These evolving shifts naturally result in the development of new patient populations (particularly in the R/M setting) that are left with limited treatments and generate a new unmet need. For example, the use of IO in the surgical setting may limit its use in the 1L segments while the use of next-generation of EGFRi in 1L may create a growing need for therapies post IO and EGFRi. Emerging therapies may be potentially limited to specific patient segments such as HPV+ or HPV unrelated patients or CPS>1 only. Furthermore, patients that fail existing and emerging therapies are more likely to have poor performance status, which will necessitate that the next tranche of treatment options be tolerable so patients can stay longer on the treatment and derive a survival benefit.

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Our Solution: MICVO, a Novel ADC

MICVO is an investigational novel ADC that is designed to uniquely target the splice variant of fibronectin, EDB+FN, a non-cellular structural component of the ECM in the TME. The TME is a complex ecosystem consisting of cancer cells, stroma, immune cells, blood vessels and secreted factors like cytokines. The tumor stroma consists of cancer-associated fibroblasts (CAFs) and ECM which is interspersed throughout the TME. The tumor ECM consists of many proteins like fibronectin and some, not all, fibronectin proteins in the tumor ECM are EDB+FN.

Fibronectin is a key component of healthy ECM and is involved in the regulation of cell adhesion, migration, differentiation and wound healing. In tumors, fibronectin strands within the ECM, along with other proteins and polysaccharides, form a complex scaffold that gives the tumor shape and play critical roles in the tumor ECM remodeling process to promote progression and metastasis. EDB+FN is an isoform of fibronectin present in tumors and negligibly expressed in normal adult tissues resulting from alternative splicing, a process that occurs when ribonucleic acid (RNA) is re-arranged to produce multiple variants of the same protein. EDB+FN facilitates cancer progression by playing multiple roles including promoting cell proliferation, adhesion, and migration, activating the integrin signaling pathway, stimulating angiogenesis and vascular remodeling, driving epithelial-mesenchymal transition (EMT), and establishing the pre-metastatic niche. The localization of EDB+FN in the tumor ECM is illustrated in Figure 1 below.

Figure 1

The tumor ECM can form an effective barrier to entry of therapeutic agents such as some chemotherapies. Although the tumor ECM plays a significant role in the initiation, growth, survival, invasion and drug resistance of solid tumors, few therapeutics specifically target tumor-specific ECM proteins.

Our ADC, MICVO, consists of a fully human IgG1 monoclonal antibody that is site-specifically conjugated to a cleavable linker with an optimized auristatin (Aur0101) microtubule polymerization inhibitor payload. MICVO was developed using the Flexible Antibody Conjugation Technology (FACT) Platform, developed by Pfizer, to produce an ADC designed to be highly stable with a predictable and homogenous drug-to-antibody ratio (DAR) of four. The complementarity determining regions of the EDB+FN antibody used in MICVO, which is the part of the antibody responsible for binding to EDB+FN, is well characterized and has been tested clinically in the form of a radiolabel-conjugated antibody for tumor imaging demonstrating a high degree of tumor-directed specificity. Unlike conventional ADCs which bind to an antigen on the surface of a cancer cell, MICVO is designed to bind to EDB+FN in the tumor ECM, where extracellular proteases under acidic conditions cleave the linker to release the Aur0101 payload. The payload diffuses through the membrane of cancer cells to kill them directly, which is the first component of MICVO’s three-pronged MOA. The dying cancer cells release the payload which diffuses into nearby cancer cells and kills them via the bystander effect, representing the second component of MICVO’s MOA. The dying cancer cells also release neoantigens which trigger immunogenic cell death (ICD), the final component of its MOA. Together with its purpose-built design and postulated three pronged MOA, MICVO has the potential for improved stability and anti-tumor activity compared to conventional ADCs. The MOA for MICVO is illustrated in Figure 2 below.

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Figure 2

EDB+FN is highly expressed in a variety of cancers, including, but not limited to, cancers of the head and neck, breast, lung, ovary, pancreas, and thyroid as compared to a matched set of normal tissues. EDB+FN expression is detectable as early as stage 1 of cancer progression and increases in more advanced stages. Furthermore, EDB+FN expression is maintained in distant metastasis in human cancer. The broad expression of EDB+FN protein in the ECM of the tumor of many cancer types as compared to negligible expression in normal adult tissues is shown in Figure 3 below.

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Figure 3

We believe EDB+FN is a compelling target for cancer therapeutics as the physiological expression of EDB+FN is very low in healthy adult tissues, yet it is found to be highly expressed in a variety of solid tumors. By targeting EDB+FN in the tumor ECM, our goal is to deliver a cytotoxic payload directly to the tumor and be released extracellularly within the acidic tumor ECM to permeate the tumor, diffuse into and kill cancer cells and stimulate an immune response to further enhance cancer cell killing, all without requiring the ADC itself to reach the cancer cell and be internalized. Additionally, MICVO may also remodel the TME to destabilize the barrier that protects, feeds and provides structure to the tumor while sparing healthy cells.

MICVO is designed to exhibit anti-tumor activity through three distinct modes of action:

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Direct cancer cell killing activity: MICVO targets EDB+FN within the tumor ECM where active extracellular proteases in an acidic microenvironment cleave the linker and release the cytotoxic chemotherapy payload which then diffuses into and kills the cancer cells.

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Additional bystander killing: Dying cancers cells release the free payload which then diffuses into and kills nearby cancer cells via the bystander effect.

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Immunogenic cell death: Lastly, dying cancer cells release neoantigens which stimulate immune cell activation and induce immunogenic cell death.

Preclinical Data

In April 2025, we presented preclinical data at the 2025 American Association for Cancer Research (AACR) Annual Meeting in Chicago, Illinois. We observed broad anti-tumor activity for MICVO across ten solid tumor indications in PDX models. Tumor responsiveness to the optimized cytotoxic Auristatin0101 payload did not correlate with EDB+FN target expression but did associate with gene expression signatures indicative of proteolytic activity for MICVO linker cleavage. The preclinical data are summarized below and shown in Figure 4:

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45% of models demonstrated strong to very strong tumor growth inhibition (TGI%) activity (70%<TGI<90% or TGI>90% respectively), with only 25% of models showing no response (TGI<25%).

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PDX models with very strong activity (TGI>90%) were found across nine out of ten solid tumor indications.

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Complete responses to MICVO (tumor volume reached 0mm3 for at least two consecutive measurements) were found across several tumor indications, consistent with previous analysis.

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MICVO was observed to be well-tolerated (3mg/kg, Q4Dx4).

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Figure 4

We also performed differential gene expression analysis, which enabled us to identify gene signatures linked to anti-tumor activity consistent with our extracellular linker cleavage ADC hypothesis. We observed that enzyme and tumor stroma gene signatures were the gene sets with the greatest number of differentially expressed genes. Further, the preclinical data showed upregulation of certain proteases that may contribute to increased linker cleavage and subsequent increased anti-tumor activity for MICVO, supporting our extracellular linker cleavage hypothesis.

We also conducted preclinical studies combining a mouse analog of MICVO with anti-PD-1 therapy in a syngeneic mouse model of triple negative breast cancer (EMT6) known to be sensitive to PD-1 blockade. The combination of a mouse analog of MICVO with anti-PD-1 therapy inhibited EMT6 tumor growth and improved survival compared to either treatment alone, suggesting potential benefit for combination therapy to deepen anti-tumor responses in solid tumors. The preclinical studies combining a mouse analog of MICVO with anti-PD-1 therapy are summarized below:

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Monotherapy of mouse analog of MICVO inhibited dose-dependent tumor outgrowth of EDB+FN expressing EMT6 tumors and was well-tolerated at 6 mg/kg.

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The mouse analog of MICVO boosted the immune response by activating dendritic cells and increasing CD45+ immune cell infiltration, including PD-1+ T cells, into tumors, transforming EMT6 tumors into immune-infiltrated, "hot" tumors.

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Significant TGI observed with mouse analog of MICVO (TGI=94%) and anti-PD-1 therapy (TGI=54%) as monotherapies.

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The combination of the mouse analog of MICVO and anti-PD-1 therapy resulted in TGI of 91% and complete response was seen in 9/15 animals – greater tumor regression and clearance than either treatment alone.

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Mouse analog of MICVO in combination with anti-PD-1 therapy induced lasting immunological memory, enhancing tumor clearance and protecting against tumor recurrence in rechallenged mice.

The preclinical data indicated MICVO alone may be eliciting immune responses in immune excluded/immunologically cold tumors, as observed with the infiltration of T cells into the tumor, representing potential for MICVO to drive immunogenic cell death (ICD). Together, these preclinical data further support the three-pronged mechanism of action of MICVO driving anti-tumor activity via direct tumor killing, bystander effect and ICD.

Recent Translational Data

In October 2025, we presented translational data at the European Society of Medical Oncology (ESMO) Congress 2025 in Berlin, Germany and at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in Boston, Massachusetts. Data presented build on preclinical data previously presented in April 2025 at AACR Annual Meeting in Chicago.

The poster presentations at the ESMO and AACR-NCI-EORTC meetings provide deeper insights into the pharmacodynamic responses of tumors to MICVO as well as MICVO’s unique mechanism of action and its potential to exert anti-tumor activity through three mechanisms: direct cancer cell killing, bystander killing and ICD. These translational findings highlight MICVO’s effects on TME remodeling, immune activation and tumor infiltration, further reinforcing the potential benefit of MICVO as both monotherapy and in combination with anti-PD-1 therapy.

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Additional data supporting MICVO’s MOA indicate this ADC binds very specifically to EDB+FN in the TME, an important trait for the non-cellular tumor ECM targeting MOA, locally delivering the ADC close to the malignant cells for cancer cell killing after extracellular linker cleavage. Data also indicate MICVO binds strongly to EDB+FN, which enables the ADC to stay anchored in the TME longer allowing more time for extracellular linker cleavage by proteases. In vitro data presented indicate MICVO’s linker can be cleaved extracellularly via specific cathepsins and pH conditions that exist in the TME, which allows the payload to be released extracellularly to then diffuse into cancer cells.

Multiple posters supported MICVO’s ability to induce ICD and a mouse analog of MICVO (maMICVO) stimulated an immune response in tumors from a syngeneic triple negative breast cancer model (4T1) that had been refractory to anti-PD-1. Synergistic antitumor activity was observed in this anti-PD-1 refractory model when maMICVO was combined with anti-PD-1. The preclinical studies combining maMICVO with anti-PD-1 therapy in the 4T1 model are summarized below:

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Mouse anti-PD-1 alone had no effect on tumor growth, consistent with published studies.

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maMICVO alone inhibited 4T1 tumor growth.

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Synergistic anti-tumor activity was observed when both treatments were combined.

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maMICVO induced the infiltration of progenitor exhausted T cells (Tpex) into 4T1 tumors.

Observations of translational data from clinical samples include changes in circulating tumor DNA (ctDNA) tumor fraction (TF) after treatment with MICVO to the vast majority of 37 clinical samples tested from the monotherapy dose escalation study. Notably, reduction in ctDNA TF after treatment with MICVO, particularly in HNSCC and at the 5.4 mg/kg dose, supported a positive molecular response to MICVO and strengthened rationale for continued development of this tumor type and dose in the monotherapy dose expansion study. Analysis of baseline tumor tissues from participants in the monotherapy dose escalation trial showed EDB+FN protein level did not directly correlate with sensitivity to MICVO, which was consistent the preclinical PDX study. However, features observed in nonclinical samples of the stromal architecture detected using digital pathology may correlate with sensitivity to MICVO, a finding that may be unique compared to tumor cell surface targeting ADCs, due to MICVO’s targeting of a non-cellular structural component of the tumor ECM. Preliminary analysis of clinical tumor biopsy samples revealed that MICVO remodeled the TME as well as induced an immune response, consistent with observations in tumors from the preclinical syngeneic EMT6 mouse model. The findings observed from the clinical biopsy studies are summarized below:

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Histological evaluation of a limited set of matched pair biopsies from participants treated with MICVO demonstrated pharmacodynamic effects on both cancer cells and stromal remodeling across clinical responses, reflective of the mechanism of action of this novel non-cellular targeting ADC.

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MICVO reduced cellular density in both tumor epithelium and stroma compartments after two cycles of treatment but did not deplete EDB+FN expression in the cancer stroma, maintaining target expression.

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Pharmacodynamic effects of MICVO on stroma included increased FN fluorescence intensity and changes in stromal cell composition, reflective of stromal remodeling.

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MICVO increased the density of non-immunosuppressive T-cells in the tumor parenchyma, with increased infiltration associated with better clinical response (see example in Figure 5 below).

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Greater MICVO-induced T-cell infiltration was correlated with longer time on study.

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MICVO increased immune gene expression signatures within tumors.

Figure 5

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Figure 5 shows a representative image of multiplex immunofluorescence CD3 density maps on a matched baseline and on-treatment tumor biopsy pair from a MICVO monotherapy trial participant with ovarian cancer showing increased density of CD3 cells in the tumor after treatment with MICVO.

Taken together, we believe that MICVO may generate a multi-pronged attack on difficult-to-treat cancers by specifically targeting the ADC to the tumor ECM where the extracellularly released cytotoxic payload can permeate the tumor and directly kill cancer cells, impact ECM remodeling and mobilize an anti-tumor immune response (as illustrated in Figure 2 above). Further, we believe that the non-cellular approach targeting the tumor ECM may potentially avoid the primary cause of drug resistance identified for therapeutics targeting cell surface receptors. Downregulated expression of therapeutic targets on cancer cells such as HER2 and EGFR has been demonstrated to be a resistance mechanism for therapies targeting these cell-surface proteins. Given the non-cellular expression profile of EDB+FN, we believe this resistance mechanism does not apply to MICVO and is supported by the observed maintenance of target expression in on-treatment biopsies evaluated thus far.

Upcoming Translational Data

In March 2026, we announced the publication of an abstract at the 2026 AACR Annual Meeting describing the anti-tumor activity of a murine analog of MICVO (maMICVO) in the poorly immunogenic and immunotherapy-refractory mouse oral carcinoma 2 (MOC2) syngeneic HNSCC model. The abstract also reported that image analysis suggested modulation of the tumor immune microenvironment following maMICVO treatment, which provided a scientific rationale for evaluating maMICVO in combination with anti-PD-1 in this refractory model. We expect to present this preclinical data at the AACR Annual Meeting in San Diego, CA, in April 2026.

Clinical Development of MICVO

PYX-201-101 Monotherapy Phase 1 Trial of MICVO

We are conducting a multi-part Phase 1 trial of MICVO, referred to as PYX-201-101, which initiated patient dosing in March 2023. The study is evaluating MICVO as a monotherapy in patients with advanced solid tumors known to express EDB+FN. PYX-201-101 (Part 1) is an open-label, multicenter, dose-escalation Phase 1 trial designed to assess the safety and tolerability of MICVO, characterize its PK and PD profile, evaluate preliminary anti-tumor activity, and identify recommended dose levels for further clinical development. Eligible patients include those with relapsed or refractory advanced solid tumors, including patients with R/M HNSCC, hepatocellular carcinoma (HCC), hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer, locally advanced or metastatic non-small cell lung cancer (NSCLC), ovarian cancer, pancreatic ductal adenocarcinoma (PDAC), renal cell carcinoma (RCC), sarcoma, thyroid cancer, and TNBC. Information regarding this clinical trial is available at ClinicalTrials.gov under identifier NCT05720117.

PYX-201-101 Phase 1 Dose Escalation (Part 1) Preliminary Clinical Data

In November 2024, we reported positive preliminary data from Part 1 of our Phase 1 dose escalation study of PYX-201-101. A total of 80 patients were enrolled and treated with MICVO in the Part 1 dose-escalation portion of the study, as of the data cut-off of October 4, 2024, at dose levels ranging from 0.3 mg/kg to 8.0 mg/kg IV Q3W across multiple advanced solid tumor types. We identified a therapeutically active dose response range of 3.6 mg/kg – 5.4 mg/kg IV Q3W where we observed clinical benefit and a manageable safety profile. The dose-escalation schema and the number of patients treated at each dose level from trial initiation in March 2023 through the October 4, 2024 data cut-off are summarized in Figure 6 below.

Figure 6

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The preliminary efficacy analysis dataset included 65 patients, of whom 44 patients were treated within the dose range of 3.6 mg/kg to 5.4 mg/kg IV Q3W. As illustrated in Figure 7 below, tumor regression from baseline was observed across all nine tumor types evaluated in the study. Reductions in target lesion measurements were observed in multiple tumor types, with more pronounced responses noted in six tumor types of interest: including R/M HNSCC, HR+/HER2- breast cancer, NSCLC, ovarian, sarcoma and TNBC, at the therapeutically active dose response range of 3.6 mg/kg – 5.4 mg/kg IV Q3W.

Figure 7

The R/M HNSCC patients demonstrated the strongest tumor regression response in the dataset. Among the six efficacy-evaluable, heavily pre-treated patients with R/M HNSCC, at the therapeutically active dose response range of 3.6 mg/kg – 5.4 mg/kg IV Q3W, the confirmed ORR was 50% (3/6) as assessed per RECIST v1.1, including one confirmed CR and two confirmed PRs with a DCR of 100%. The R/M HNSCC patients had received a median of four prior lines of systemic therapy in the advanced disease setting. Additionally, clinical activity was observed in patients with either HPV+ or HPV unrelated tumors as illustrated in Figure 8 below.

Figure 8

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PYX-201-101 Phase 1 Dose Expansion (Part 2) Monotherapy Study

In January 2025, we initiated the dose expansion portion (Part 2) of the Phase 1 PYX-201-101 monotherapy study (NCT05720117). Part 2 is designed to further evaluate MICVO as a monotherapy at a dose of 5.4 mg/kg IV Q3W and to assess preliminary efficacy in R/M HNSCC. Based on observations from the dose-escalation study, 5.4 mg/kg IV Q3W presented an optimal benefit-risk profile within the efficacious dose range and was selected for dose expansion. Subsequent translational data indicated reduction in ctDNA TF after treatment with MICVO, particularly at the 5.4 mg/kg dose, supported a positive molecular response to MICVO, providing further validation of the dose selection strategy for dose expansion. In February 2025, the FDA granted Fast Track designation to MICVO for the monotherapy treatment of adult patients with R/M HNSCC whose disease has progressed following treatment with platinum-based chemotherapy and an anti-PD-(L)1 antibody. Fast Track designation is intended to facilitate the development and expedite the review of drugs that treat serious conditions and fill an unmet medical need.

We completed target enrollment of approximately 40 patients in the Phase 1 monotherapy dose expansion study of MICVO in 2L+ R/M HNSCC in the first quarter of 2026 and are actively treating patients in two monotherapy R/M HNSCC cohorts at the 5.4 mg/kg IV Q3W dose. The dose expansion phase includes the following R/M HNSCC cohorts across sites in the United States (US), European Union (EU) and other countries:

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Arm 1: MICVO monotherapy for 2L and 3L R/M HNSCC patients who have received prior platinum-based chemotherapy and prior PD-(L)1 inhibitor therapy. We expect to enroll approximately 20 patients in this expansion cohort at the 5.4 mg/kg IV Q3W dose; and

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Arm 2: MICVO monotherapy for 2L and 3L R/M HNSCC patients who have received prior epidermal growth factor receptor (EGFR) directed therapy and prior PD-(L)1 inhibitor therapy. We expect to enroll approximately 20 patients in this expansion cohort at the 5.4 mg/kg IV Q3W dose.

The clinical trial design of MICVO monotherapy in R/M HNSCC is summarized in Figure 9 below.

Figure 9

PYX-201-101 Phase 1 Dose Expansion Monotherapy Study (Part 2) Preliminary Clinical Data

In December 2025, we reported positive preliminary data from our ongoing Phase 1 monotherapy study evaluating MICVO in patients with 2L+ R/M HNSCC, based on a data cut-off date of November 3, 2025, which included all R/M HNSCC patients dosed at 5.4 mg/kg in Part 1 and in Part 2. As of the data cut-off date, 18 patients had been treated at the 5.4 mg/kg IV Q3W dose level, and 13 patients were efficacy-evaluable. All treated patients had received prior systemic therapy, including platinum-based chemotherapy, checkpoint inhibitor therapy, taxanes, and EGFR-targeted therapies. Patients had received a median of three prior lines of systemic therapy in the advanced disease setting. Patient demographics and the prior treatment characteristics of treated patients are illustrated in Figure 10 below.

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Figure 10

Preliminary Efficacy

The preliminary efficacy analysis dataset consisted of 13 efficacy-evaluable Part 1 and Part 2 patients with R/M HNSCC treated at 5.4 mg/kg IV Q3W. Figures 11 and 12 below present waterfall plots depicting the percentage change in target lesion size from baseline for individual patients, including stratification by expansion cohort (Arm 1 and Arm 2) and HPV status. Among the 13 efficacy-evaluable patients with R/M HNSCC treated at 5.4 mg/kg IV Q3W, the confirmed ORR was 46% (6/13) (one patient confirmed response after November 3, 2025 data cut-off), as assessed per RECIST v1.1, including one confirmed complete response. Confirmed responses were observed in both dose-expansion cohorts and in patients regardless of HPV status. The preliminary data also showed a DCR of 92% (12/13). One out of the 13 efficacy-evaluable patients experienced progressive disease. This patient had a verrucous subtype of HNSCC, a histologic variant that is generally managed with surgery and may demonstrate limited responsiveness to systemic therapy.

Figure 11

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Figure 12

Safety and Tolerability

The preliminary safety data in Figure 13 summarizes key TRAEs observed as of the November 3, 2025 data cut-off date. Preliminary data indicated that MICVO was generally well tolerated. As of the data cut-off, 18 patients had been treated with MICVO at 5.4 mg/kg IV Q3W. TRAEs were reported in 89% (16/18) of patients. Grade 3 or higher TRAEs were reported in 56% (10/18) of patients. No Grade 4 ADC Payload treatment-related adverse events (TRAEs) of interest were observed, and no Grade 5 events occurred. TRAEs leading to treatment discontinuation occurred in 28% (5/18) of treated patients as of the November 3, 2025 data cut-off date.

Figure 13

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Impact of Body Weight on MICVO Tolerability and Dosing Optimization Strategies

We observed a higher discontinuation rate and incidence of Grade ≥3 TRAEs at the 5.4 mg/kg dose level in high body weight patients (defined as at least 10% above AIBW). In the preliminary dataset, all patients (5/5) who experienced TRAEs leading to treatment discontinuation had high body weight, as shown in Figure 14. Several approved ADCs have demonstrated comparable associations among patient body weight, systematic drug exposure, and tolerability profiles.

Figure 14

Following the November 3, 2025, data cut-off date and based on an integrated assessment of safety, pharmacokinetic, and exposure-response data, we implemented modified dosing strategies for MICVO in the ongoing study with the goal of mitigating adverse events and improving tolerability in higher body weight patients while preserving clinical efficacy. These strategies include dose capping and AIBW-based dosing, both intended to reduce variability in systemic drug exposure among heavier patients. Such approaches are consistent with precedent established by approved ADCs.

For example, Padcev and Adcetris, which both have auristatin payloads similar to MICVO, incorporated dose caps for patients weighing more than 100 kg and have demonstrated improved tolerability while maintaining efficacy. Similarly, Elahere and Pfizer’s PDL1V ADC in clinical development, have implemented AIBW-based dosing to address tolerability findings in higher bodyweight patients.

We believe the higher frequency of TRAEs observed in higher bodyweight patients treated with ADCs is primarily attributable to the nonlinear relationship between body weight and drug clearance. Due to this nonlinearity, higher bodyweight patients may experience disproportionately greater systemic exposure, creating an opportunity to enhance the benefit–risk profile through dose reduction without materially compromising efficacy. Preliminary PK/PD modeling presented in Figure 15 below, indicate both dose capping and AIBW dosing for MICVO effectively mitigate exposure in heavier patients. We plan to present clinical data in 2026 that informs this hypothesis with the intention of optimizing MICVO’s benefit-risk profile.

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Figure 15

MICVO Monotherapy Next Milestone

During the fourth quarter of 2025, we received feedback from the U.S. FDA regarding the clinical trial design for a planned pivotal monotherapy study in patients with 2L+ R/M HNSCC. Based on these interactions, we believe we have alignment with the FDA on key elements of the proposed study design.

Our Part 2 dose-expansion phase of the PYX-201-101 monotherapy study has completed target enrollment of approximately 40 patients in 2L+ R/M HNSCC in the first quarter of 2026. We are continuing patient follow-up, monitoring clinical outcomes, and conducting related study activities. Updated MICVO Phase 1 monotherapy data in 2L+ R/M HNSCC are expected in mid-year 2026 and will include patients dosed at 5.4 mg/kg IV Q3W with a dose cap for patients with higher body weight, as well as patients previously dosed at 5.4 mg/kg IV Q3W TBW. The results are expected to include detailed analyses of the effect of the modified weight-based dosing strategy on safety and efficacy. AIBW dosing, which has demonstrated improved tolerability without apparent loss of activity in clinical studies of other antibody-drug conjugates, is being implemented in ongoing clinical studies as well.

PYX-201-102 Combination Therapy Phase 1/2 Trial

In November 2024, we entered into a Clinical Trial Collaboration and Supply Agreement with Merck & Co., Inc. (“Merck”) (known as MSD outside of the United States and Canada), pursuant to which we are conducting a Pyxis Oncology-sponsored clinical study evaluating MICVO in combination with Merck’s anti-PD-1 therapy, KEYTRUDA® (pembrolizumab). Under the terms of the agreement, we are responsible for conducting and funding the study, and Merck is supplying pembrolizumab for use in the trial with no cost to us. The agreement does not provide Merck with any rights to MICVO outside of the collaboration study.

In January 2025, we initiated the Phase 1/2 combination study with KEYTRUDA®, PYX-201-102, and we are actively enrolling patients. PYX-201-102 is a Phase 1/2, open label, global, multicenter, dose-escalation and dose-expansion study to evaluate the safety, tolerability, PK, PD, and preliminary efficacy of MICVO in combination with pembrolizumab in patients with advanced solid tumors. Eligible patients include those with histologically or cytologically confirmed advanced solid tumors, including 1L R/M HNSCC, 2L+ R/M HNSCC, cervical cancer, gastric cancer, HR+/HER2- breast cancer, and locally advanced or metastatic TNBC. The Phase 1 portion of the trial consists of a dose-escalation phase designed to determine the recommended Phase 2 dose of MICVO in combination with pembrolizumab. The Phase 2 portion includes dose-expansion cohorts in selected tumor types to further evaluate safety and preliminary efficacy. Information regarding this study is available at ClinicalTrials.gov under identifier NCT06795412. The clinical trial design of the MICVO combination therapy in R/M HNSCC and other tumor types is summarized in Figure 16 below.

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Figure 16

We are currently conducting the Part 1 dose-escalation portion of the PYX-201-102 Phase 1/2 study. Part 1 is designed to evaluate escalating dose levels of MICVO administered Q3W in combination with a fixed standard dose of pembrolizumab (200 mg IV Q3W). Three planned dose levels of MICVO are being evaluated in combination with pembrolizumab, ranging from 3.6 mg/kg to 5.4 mg/kg. The primary objective of the dose-escalation portion is to assess safety and tolerability and to identify the RP2D for further evaluation in the Phase 2 dose-expansion cohorts. Dose-escalation decisions are based on an evaluation of safety, dose-limiting toxicities, pharmacokinetics, and other clinical data.

The study initiated dose escalation at 3.6 mg/kg of MICVO administered in combination with pembrolizumab 200 mg IV Q3W. The DESC has reviewed available safety data and cleared escalation through the 3.6 mg/kg and 4.4 mg/kg MICVO dose levels, each administered in combination with the fixed 200 mg dose of pembrolizumab. We are currently enrolling and dosing patients across several dose levels between 3.6 and 5.4 mg/kg of MICVO, in combination with pembrolizumab at the fixed dose of 200 mg IV Q3W, in order to accurately characterize the RP2D for MICVO in combination with pembrolizumab, subject to ongoing safety review, enrollment progress, and clinical data evaluation.

PYX-201-102 Phase 1/2 Combination Therapy Preliminary Clinical Data

In December 2025, we reported positive preliminary data from our ongoing MICVO Phase 1/2 combination study, PYX-201-102, evaluating MICVO at doses of 3.6 mg/kg and 4.4 mg/kg, each administered IV Q3W in combination with a fixed 200 mg dose of pembrolizumab, in patients with 1L/2L+ R/M HNSCC. The data were based on a cut-off date of November 3, 2025. As of the data cut-off, seven patients had been treated in the dose-escalation portion of the study, including four patients treated at 3.6 mg/kg and three patients treated at 4.4 mg/kg of MICVO, each in combination with pembrolizumab 200 mg IV Q3W.

All treated patients had received prior systemic therapy. The patient population included:

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Four patients with 1L R/M HNSCC, with a median of one prior systemic therapy administered in the neoadjuvant or adjuvant setting and

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Three patients with 2L+ R/M HNSCC, with a median of three prior lines of therapy, some of which were received prior to the R/M setting.

As shown in Figure 17 below, among the four patients with 1L R/M HNSCC, all had previously received platinum-based therapy administered with radiation in the adjuvant or definitive setting, and one patient had also received a prior taxane in the neoadjuvant setting. Among the three patients with 2L+ R/M HNSCC, all had previously received platinum-based therapy and prior checkpoint inhibitor therapy, and one patient had additionally received prior taxane therapy.

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Figure 17

Preliminary Efficacy

Among the seven response-evaluable patients as of the November 3, 2025 data cut-off, the confirmed ORR was 71% (5/7, one patient confirmed response after November 3, 2025 data cut-off) per RECIST v1.1. Responses were observed across a range of PD-L1 CPS, including patients with CPS≥1 and patients with CPS>20. Responses were also observed in patients who had previously received checkpoint inhibitor therapy and experienced disease progression while receiving checkpoint inhibitor treatment. All seven efficacy-evaluable patients demonstrated tumor regression from baseline measurements. Figures 18 and 19 below present waterfall plots depicting the percentage change in target lesion size from baseline for individual patients, including subgroup stratification by line of therapy (1L or 2L+ R/M HNSCC) and CPS score.

Figure 18

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Figure 19

Safety and Tolerability

Figure 20 presents TRAEs reported as of the November 3, 2025 data cut-off date. Based on preliminary safety data from the seven patients treated in the dose-escalation cohorts evaluated at 3.6 mg/kg and 4.4 mg/kg of MICVO in combination with pembrolizumab, TRAEs were reported in 86% (6 of 7) of patients. No Grade 5 adverse events were reported. No Grade 3 or Grade 4 treatment-related adverse events associated with the ADC payload of MICVO were observed as of the data cut-off date. No TRAEs resulted in permanent treatment discontinuation. As of the data cut-off date, no overlapping toxicities between MICVO and pembrolizumab had been observed.

Figure 20

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MICVO Combination Therapy Next Milestone

We are currently enrolling and dosing patients across several dose levels between 3.6 mg/kg and 5.4 mg/kg of MICVO, in combination with a fixed 200 mg IV Q3W, in order to accurately characterize the RP2D for MICVO in combination with pembrolizumab, subject to ongoing safety review, enrollment progress, and clinical data evaluation. We expect to report updated data from the PYX-201-102 study in patients with 1L/2L+ R/M HNSCC in the second half of 2026.

Assets and Programs Available for Partnership or Collaboration

In addition to MICVO, we have certain clinical programs, assets, and preclinical programs that are currently paused. While these programs and assets are paused, we are focusing our development efforts and resources towards the clinical development of MICVO. We are seeking partnership opportunities that maximize potential value of these programs for patients and for our shareholders.

PYX-106 is an investigational fully human IgG1 Siglec-15-targeting antibody designed to block Siglec-15 mediated suppression of T-cell proliferation and function. PYX-106 has high binding affinity to a unique epitope and high potency. By binding and blocking Siglec-15 activity on myeloid cells and tumors, our Siglec-15 targeting antibody is designed to enhance immune cell mediated tumor cell killing. We licensed worldwide rights other than in Greater China (mainland China, Hong Kong, Macau and Taiwan) to PYX-106 from Biosion. In December 2024, after analysis of the program, PYX-106 was deprioritized and resources were reallocated toward advancing MICVO. At the time of deprioritization, the Phase 1 study of PYX-106, called PYX-106-101, was not complete. PYX-106-101 enrolled 45 patients with advanced solid tumors, with 41 patients being evaluable, and PYX-106 was observed as generally safe and well-tolerated across all tested doses, ranging from 0.5 mg/kg – 22.5 mg/kg. At the time of deprioritization, MTD had not been established, we decided to suspend further clinical investment in PYX-106 and not to open Part 2 dose expansion phase of the study.

Sotigalimab or PYX-107, acquired as part of the acquisition of Apexigen Inc. (Apexigen), is a CD40 agonist with demonstrated anti-cancer activity in patients with several cancer indications. PYX-107 has been evaluated in more than 500 patients in clinical trials and demonstrated strong activity, including rapid, deep and durable responses and a favorable tolerability profile, across multiple difficult-to-treat tumor types. In a Phase II trial, PYX-107 in combination with nivolumab has demonstrated strong activity in melanoma patients who are refractory to anti-PD-(L)1, with a 15.2% PR rate and a 30.3% stable disease rate along with a favorable tolerability profile. The FDA has granted Orphan Drug Designation for PYX-107 for the treatment of soft tissue sarcoma (STS), esophageal and gastroesophageal junction (EGJ) cancers and PDAC.

PYX-203, licensed from Pfizer, is an investigational ADC that targets and binds to the interleukin-3 receptor, also known as CD123, a rapidly internalizing target that is overexpressed in hematologic cancers by leukemic blasts and stem cells. After internalization, its highly potent cyclopropylpyrroloindoline (CPI) payload is enzymatically released and trafficked to the nucleus, where it crosslinks DNA. CPI is engineered for enhanced tolerability and may allow PYX-203 to reach a broader patient population. CPI is resistant to drug efflux pumps and could confer superior cancer-killing activity. The antibody is also engineered to have a modified Fc region to mitigate off-tumor toxicity.

PYX-102 is an investigational immune-therapeutic that targets killer cell lectin-like receptor subfamily G member 1 (KLRG1), an inhibitory receptor expressed on T cells and NK cells. Its ligands, E- and N-cadherin are expressed in numerous solid cancers. By blocking KLRG1 signaling, PYX-102 may relieve immune inhibition in these tumors while rescuing KLRG1-mediated suppression of human CD8+ T cells. PYX-102 has significant potential as a monotherapy and in combination treatment strategies.

Our Technology Platforms

We are capitalizing on years of industry innovation and advancement in ADC platforms to develop and design our product candidates. Our MICVO product candidate was built utilizing the FACT Platform, initially licensed from Pfizer in December 2020, before securing an exclusive license to the FACT Platform in October 2022. The FACT Platform leverages over a decade of investment by Pfizer in refining the technical components of ADCs to improve the clinical properties of ADCs. Using our expertise in site-specific antibody conjugation, we are developing next-generation ADCs with customized linker-payload combinations aimed at increasing stability and, consequently, a reduced off target side-effect profile potentially enhancing the Therapeutic Index (TI).

The acquisition of Apexigen enhanced our ADC capabilities with the addition of Apexigen’s antibody-discovery platform (APXiMAB) Platform, to use with our FACT Platform to support and potentially accelerate our existing ADC initiatives and our end-to-end capabilities to design and produce novel next-generation ADC candidates with improved potency, stability and tolerability.

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The APXiMAB Platform was used to enable the discovery of multiple protein therapeutic product candidates against a variety of molecular targets, including targets that are difficult to generate antibodies with conventional antibody technologies. In addition to certain product candidates that we wholly own, several product candidates that were discovered through the use of the APXiMAB Platform are in clinical development by our licensees. The most advanced of these programs is Novartis’ Beovu® (brolucizumab-dbll) product, which received FDA approval in 2019 and is marketed in over 70 countries. For the Simcere suvemcitug/Enzeshu® program, during the year, the Company has sold its royalty rights under Simcere Royalty Agreement. Other than already approved programs (i.e. Simcere’s Enzeshu®, Novartis’ Beovu®) there is no guarantee that any of the other product candidates discovered using our APXiMAB Platform, whether developed by us or our licensees, will receive regulatory approval.

Target Catalog and Discovery Efforts

We have a large proprietary target catalog that we have assembled through both our own discovery activities and through an exclusive license from the University of Chicago for the work on immunotherapy targets out of Dr. Thomas Gajewski’s laboratory. We are also building a large “cold” tumor target discovery database leveraging several human tumor databases.

The target catalog is based upon findings from an in vivo mouse model system which examined tumor tissue for functional and dysfunctional T cells based on the ability of the T cells to produce the cytokine IL-2. Furthermore, since 4-1BB and LAG3 positive T cells do not secrete IL-2, the CD8+ T cells were sorted based on cell surface marker expression i.e., 4-1BB and LAG3, which further defined functional or dysfunctional T cells. Gene expression analysis identified upregulated cell surface molecules in dysfunctional cells which included well established markers such as PD1, CTLA4, and TIM3 and many other novel targets were identified based on bioinformatics and deep biological rationale.

Our cold tumor target discovery database used RNA-seq transcriptome analysis of human tumor databases to identify potential novel targets involved in regulation of T cell function and/or infiltration leading to cold tumors. We have supplemented this database with additional resources which we continue to mine to identify additional novel targets for immunomodulation. These cold tumor targets are potentially dominant immune suppressors that are expressed across a variety of tumor associated cells, including immune cells, tumors cells, and stroma, offering the potential to uncover novel immuno-oncology (IO) mechanisms and additional novel targets for our ADC platform.

We have large opportunities to advance product candidates based on the target catalog, however, we have chosen not to conduct additional discovery efforts to refocus our development efforts and resources toward clinical development of MICVO.

Competition

The development and commercialization of therapeutic biological products is highly competitive. We compete with a variety of multinational biopharmaceutical companies and specialized biotechnology companies, as well as technology being developed at universities and other research institutions. Our competitors have developed, are developing or will develop product candidates and processes competitive with our product candidate. Competitive therapeutic treatments include those that have already been approved or licensed and accepted by the medical community and any new treatments that enter the market. We believe that a significant number of products are currently under development, and may become commercially available in the future, for the treatment of conditions for which we may try to develop product candidates. Biotechnology and pharmaceutical industries, including the oncology subsector, are characterized by rapidly evolving technologies, intense competition and strong defense of intellectual property and proprietary technologies. Any product candidate that we successfully commercialize may be competitive with currently marketed therapies and any new therapies commercialized in the future.

We are aware of several companies that are developing cancer immunotherapies and ADCs. Many of these companies are well-capitalized, have significant clinical experience, and may include our existing or future collaborators. In addition, these companies compete with us in recruiting scientific and managerial talent and the patient pool available for participation in clinical trials which could negatively impact our ability to execute our business plan.

If our product candidate is licensed, it will compete with a range of therapeutic treatments that are either in development or currently marketed. Many companies are active across various stages of development in the oncology subsector and are marketing and developing products that employ similar ADC and immunotherapy approaches. As of February 2026, there were approximately 900+ ADCs in clinical or preclinical development worldwide, of which the vast majority are being developed for the treatment of various cancer indications. Additionally, there are several large and small companies working on various immunotherapy approaches for treatment of cancer. Multiple companies are also involved in the development of ADC therapeutics and immunotherapies, including, but not limited to, AbbVie Inc., Abcure, Inc., ADC Therapeutics SA, Alligator Bioscience AB, Astellas Pharma, Inc., AstraZeneca plc, Celldex Therapeutics, Inc., Daiichi Sankyo Company, Ltd., Eucure Biopharma, a subsidiary of Biocytogen, Genentech, Inc., Gilead Sciences, Inc, GlaxoSmithKline, plc, Johnson & Johnson, Lyvgen Biopharma, Nextcure, Inc., Pfizer, Philogen S.p.A., Merck Sharpe & Dohme (MSD), Corbus Pharmaceuticals, and Rakuten Medical, Inc.

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We may also face competition from alternative therapeutic modalities, such as cell therapies, bispecific antibodies, vaccines, radiopharmaceuticals and small molecules that are being developed for the same cancer types that we are targeting with our pipeline candidate. These approaches could achieve regulatory approval before our product candidate or prove to be more effective, safer, or convey other advantages over any products resulting from our technology. They could potentially result in shifts in treatment paradigms eroding or reducing the addressable market available to our product candidate.

We could also face competition with respect to specific targets, including the target of our ADC, MICVO, EDB+FN, by Philogen S.p.A., a Swiss based Biotechnology company, focused on generating antibody-cytokine fusions (immunocytokines) against cancers, using the L19 antibody specific to the EDB domain of Fibronectin fused to TNF, a potent inflammatory cytokine, which could pursue similar indications targeting EDB and stand out as the first non-ADC therapy pursuing EDB+FN.

There are other emerging agents in key indications of interest including R/M HNSCC. Genmab’s EGFR and LGR5 targeting biclonal, petosemtamab, Bicara’s EGFR/TGF-beta targeting bifunctional, ficerafusp alfa (BCA101), and Johnson and Johnson’s EGFR and cMET bispecific antibody, amivantamab, are notable competitors that are targeting patient populations of interest to MICVO and pose a potentially significant threat to our clinical development strategy. Additionally, Corbus Pharmaceutical’s nectin-4 targeting ADC, CRB-701 has shown preliminary efficacy data and is a direct competitor given similarity in payload (MMAE) to MICVO, and comparable patient populations and clinical development timelines in R/M HNSCC.

Other competitors may also include agents targeting specific segments such as HPV+ HNSCC, namely NeoTrail Therapeutics (formerly Hookipa)’s and PDS Biotech’s vaccines and agents such as Nanobiotix’s radioenhancer that may be used earlier in the treatment sequence. With the approval of pembrolizumab in the peri-operative setting based on Keynote-689, use of IO in the neoadjuvant and adjuvant settings may shift how HPV patients are treated in earlier lines of therapy. The implementation of using IO in the earlier disease settings could impact patient segmentation and treatment choices in the R/M setting.

Furthermore, ADCs such as Gilead’s TROP-2 ADC, sacituzumab govitecan, Pfizer’s Nectin-4 targeting ADC, enfortumab vedotin and AZ’s AZD9592, a dual targeting ADC against EGFR and cMET are in clinical development in HNSCC. Enfortumab vedotin is currently pursuing a 1L HNSCC trial in combination with pembrolizumab thus adding to the crowded landscape of combo studies in the frontline setting. Additional competition may arise from other combination regimens being evaluated including but not limited to ficlatuzumab + cetuximab (2L), ivonescimab + ligufalimab (1L, CPS>1) and LN-145 + pembrolizumab (1L). Additionally, there is a wide array of activity in the development of immunotherapies for oncology which may be competitive with our preclinical discovery programs. Furthermore, if our product candidate is approved in oncology indications such as breast cancer, hematological and other cancers, they may compete with existing approaches to treating cancer including surgery, radiation, and drug therapy, including conventional chemotherapy, biological products, and targeted drug small molecule therapies.

Our competitors may possess greater scientific, research and development capabilities, as well as greater financial, technical, manufacturing, marketing, sales and supply resources or experience than we do. These competitors may compete with us on the basis of establishing clinical trial sites and patient registration, recruiting and retaining qualified scientific and management personnel, and acquiring new technologies that may be complementary to, or necessary for, our programs. If we achieve regulatory approval, commercial opportunity for our product candidate may be dependent on the ability of our competitors to develop new products that may be more effective, safer, or less expensive than any products that we may develop. Our competitors may succeed in developing competing products before we do, obtaining marketing approval for products and gaining acceptance for such products in the same markets that we are targeting. Smaller or earlier-stage companies that seek collaborative arrangements with large and established companies, may prove to be significant competitors. In addition, our ability to compete may be affected by the availability of reimbursement from government and other third party payors. Competitive factors affecting the success of our programs, if approved, will likely be based on their safety and effectiveness, the timing and scope of marketing approvals, the availability and cost of supply, the depth of marketing and sales capabilities, and reimbursement coverage, among other considerations. Competitive products may make any products we develop obsolete owing to treatment paradigm shifts or noncompetitive, reducing the addressable market before we recover the expense of developing and commercializing our product candidate. Such competitors could also recruit our employees, which could negatively impact our level of expertise and our ability to execute our business plan.

We believe that our ability to successfully compete will depend on, among other things:

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our ability to develop and protect therapeutics that are more effective and safer than competing products;

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our ability to innovate with rapidly evolving technologies;

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the ease with which our products can be administered and the extent to which patients accept relatively new routes of administration;

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the timing and scope of regulatory licenses for these products;

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the price of our product candidate and whether coverage and adequate levels of reimbursement are available under health insurance plans;

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our ability to utilize any abbreviated licensure pathways; and

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the length of time we are granted market exclusivity for any product candidate we may develop that is licensed as a biological product under a Biologics License Application (BLA).

Chemistry, Manufacturing and Controls

The manufacture of our ADCs and monoclonal antibodies requires significant scientific expertise, specialized technical capabilities, and substantial financial and operational resources. We do not own or operate any current Good Manufacturing Practice (cGMP)-compliant manufacturing facilities and currently have no plans to establish such facilities. Accordingly, we rely, and expect to continue to rely, on third-party contract development and manufacturing organizations (CDMOs) for the manufacture of our product candidates for preclinical and clinical development and, if approved, for commercial supply.

Our reliance on third-party manufacturers limits our direct control over manufacturing capacity, production schedules, costs, and compliance with cGMP and other regulatory requirements. Although we maintain quality agreements and technical oversight processes, we are dependent on the performance and compliance of our CDMOs. If any of our third-party manufacturers fail to comply with applicable regulatory requirements, experience quality or performance issues, encounter capacity constraints, or cease operations, our development timelines and potential commercialization efforts could be materially and adversely affected.

In addition, certain raw materials, components, and intermediates used in the manufacture of our product candidates may be sourced from single suppliers, and we may not maintain fully qualified alternate suppliers for all materials or manufacturing steps. Any interruption in the supply of such materials, including due to manufacturing failures, regulatory actions, business disruptions, or geopolitical events, could delay development activities or increase costs.

The manufacture of ADCs, in particular, involves complex multi-step processes, including monoclonal antibody production, linker and payload synthesis, and conjugation. Variability in process performance, including deviations in raw material specifications or process parameters, may result in reduced yields, batch failures, or the need for investigations and corrective actions. Such events could require additional manufacturing runs, process optimization, or comparability analyses and may necessitate regulatory notifications or submissions.

As part of our product development strategy, we rely on our internal scientific expertise and proprietary know-how, as well as the technical capabilities and trade secrets of our third-party manufacturing partners. We maintain agreements with our CDMOs that include customary confidentiality, intellectual property, and quality provisions designed to protect our proprietary rights and ensure compliance with applicable regulatory standards.

We believe that outsourcing manufacturing enables us to maintain a capital-efficient and flexible operating model by avoiding the significant investment required to build and operate our own manufacturing facilities and infrastructure. At the same time, we have established internal personnel and governance processes with experience in technical development, manufacturing sciences, analytical development, quality assurance, cGMP compliance, and project management to oversee our CDMOs and to manage manufacturing data and regulatory documentation in support of our development and potential commercialization activities.

Commercialization Plans

We currently retain worldwide rights to our lead product and while we intend to commercialize this asset upon FDA approval in the US, we may have opportunities to leverage partnerships to extend the reach of our products into geographies outside the US. We currently have no sales, marketing, or commercial product distribution capabilities. We intend to build our own specialized sales and marketing organization over time to support the commercialization of any approved product candidate. We may also pursue collaboration, co-promotion, distribution and/or other marketing arrangements with one or more third parties to commercialize our product candidate in the United States, and potentially other regions. We may also pursue these arrangements for situations in which a larger sales and marketing organization is necessary to realize the full commercial value of any approved wholly owned or collaboration product candidate.

Licensing and Collaboration Agreements

The University of Chicago Agreement

In April 2020, we entered into a license agreement (the University License Agreement) with the University of Chicago (the University) to obtain an exclusive license under certain patents resulting from research performed, in-part, by our scientific founder, Dr. Thomas Gajewski, as well as a non-exclusive license to certain know-how and materials. Under the terms of the license, we have the exclusive global right to develop and commercialize products that are covered by a valid claim of a licensed patent, incorporate or use the licensed know-how and materials or are known to assess, modulate or utilize the activity of certain specified biological targets.

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In partial consideration for the license from the University, we issued to the University 48,919 shares of our common stock in 2020. Pursuant to the University License Agreement, we are obligated to pay to the University an annual maintenance fee of $10,000 commencing on the third anniversary of the effective date, potential development and commercial milestones of up to an aggregate of $7.7 million as well as running royalties on net sales of licensed products at varying rates ranging from less than a percent to the low single digits, subject to a minimum annual royalty ranging from $1.0 million to $3.0 million during certain years following the first commercial sale of a licensed product. The Company assessed the milestone and royalty events under the University License Agreement as of December 31, 2025 and 2024, and determined that no such amounts were required. Our royalty obligations apply on a licensed product-by-licensed product and country-by-country basis until: (1) for licensed products covered by a valid claim of a licensed patent in a given country, the expiration of such valid claims; and (2) for all other licensed products, 10 years from the first commercial sale of a licensed product in a given country. We are also obligated to pay the University a percentage of certain sublicensing revenue ranging from low- to mid-teens based on the date of entering into the applicable sublicense.

Under the University License Agreement, we are obligated to use commercially reasonable efforts to develop and bring licensed products to market, meet certain preclinical and clinical development milestones by specific dates, and promote and sell licensed products after receipt of regulatory approval, subject to certain free and payment-based extensions. The University controls prosecution of the licensed patents at our cost and we have the first right to enforce the licensed patents subject to the University’s backup enforcement rights.

The University License Agreement will remain in effect on a licensed product-by-licensed product basis until the expiration of all royalty obligations with respect to a licensed product, unless terminated in accordance with the following: (1) by the University upon 30 days’ prior written notice for any uncured payment breaches or 90 days’ prior written notice for all other uncured breaches; (2) by the University upon certain insolvency events or dissolution by us or any affiliate; or (3) by us in full or with respect to a particular licensed product at the end of the calendar quarter following the calendar quarter when we provide written notice of termination.

Pfizer Inc. Agreement

In December 2020, the Company entered into a license agreement (as amended, the “Pfizer License Agreement”) with Pfizer Inc. (“Pfizer”) for worldwide development and commercialization rights to ADC product candidates directed to certain licensed targets, including MICVO and PYX-203, and products containing the ADC product candidates. The Company’s rights are exclusive with respect to certain patents owned or controlled by Pfizer covering the licensed ADCs. The initial licensed targets include CD123 and EDB+FN and the Company has the option to expand the scope of its license to add additional licensed targets that have not been licensed to a third party or are not the subject of a Pfizer ADC development program. The Pfizer License Agreement became effective in March 2021 and the Company paid a combined $25.0 million for the license fee, consisting of an upfront cash payment of $5.0 million and issued 12,152,145 shares of Series B convertible preferred stock, which was converted into 1,911,015 shares of its common stock upon the initial public offering (“IPO”) in October 2021, with a value of $20.0 million to Pfizer.

On October 6, 2022, the Company entered into an amended and restated license agreement (the “A&R License Agreement”) with Pfizer, which amends and restates the Pfizer License Agreement. Pursuant to the A&R License Agreement, Pfizer granted to the Company exclusive worldwide rights under Pfizer’s FACT Platform technology to develop and commercialize ADC product candidates directed to certain licensed targets, including MICVO and PYX-203, and products containing the ADC product candidates. Additional ADC targets may be licensed for a nominal upfront payment and milestones. In accordance with the terms of the A&R License Agreement, the Company issued 2,229,654 shares of its common stock to Pfizer in October 2022, paid $8.0 million to Pfizer in January 2023 and issued 1,811,594 shares of its common stock to Pfizer in March 2023.

Further, pursuant to the A&R License Agreement, the Company is obligated to pay future contingent payments including development, regulatory and commercial milestones as well as running royalties on net sales of licensed products at varying rates. The Company assessed the milestone and royalty events under the A&R License Agreement as of December 31, 2025 and 2024, and determined that no such amounts were required.

We are also obligated to pay future contingent payments, including development, regulatory, and commercial milestone up to an aggregate of $665 million for the first four licensed ADCs. In addition, we are required to pay future contingent payments including development, regulatory and commercial milestones for ADCs to each additional licensed target beyond the first four licensed ADC targets developed and commercialized via the FACT Platform. Additionally, if ADC licensed products are launched, we will pay Pfizer tiered royalties on net sales of licensed products in varying royalty rates ranging from low single digits to mid-teens. Our royalty obligations apply on a licensed product-by-licensed product and country-by-country basis from first commercial sale until the latest to occur of: (1) 12 years from first commercial sale; (2) the expiration of all regulatory or data exclusivity; and (3) the expiration of the last valid claim of a licensed patent covering the licensed product in a country. We are also obligated to pay Pfizer a percentage of certain sublicensing revenue ranging from low-double digits to twenty percent based on the stage of development of the licensed product at the time of entering into the applicable sublicense.

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Under the Pfizer License Agreement, we are obligated to use commercially reasonable efforts to nominate a clinical candidate within four years of a target becoming a licensed target. We are also required to use commercially reasonable efforts to develop and seek regulatory approval for at least one licensed product directed to each licensed target in the United States and at least one other major market country (France, Germany, Italy, Japan, Spain and the United Kingdom), and to commercialize any licensed product in each such country after receiving regulatory approval. We control prosecution and enforcement with respect to any exclusively licensed patents, and Pfizer has prosecution and enforcement rights if we elect not to exercise such rights.

The Pfizer License Agreement will remain in effect until the expiration of the last to expire royalty term, unless terminated in accordance with the following: (1) by either party for the other party’s material breach if such party fails to cure such breach within the specified cure period; (2) by either party upon certain insolvency events of the other party; or (3) prior to receipt of the first regulatory approval for a licensed product, by us for any reason upon 90 days’ prior written notice, or after receipt of the first regulatory approval for a licensed product, by us for any reason upon one year’s prior written notice.

License Agreement with Biosion USA, Inc.

On March 28, 2022, we entered into a license agreement (the Biosion License Agreement) with Biosion USA, Inc. (Biosion) pursuant to which we obtained an exclusive, worldwide (other than Greater China (mainland China, Hong Kong, Macau and Taiwan)), license for development, manufacturing and commercialization rights for BSI-060T, a Siglec-15 targeting antibody, an IO product candidate (now referred to as PYX-106), and products containing the licensed compound. Under the terms of the Biosion License Agreement, each party granted to the other party a right of first offer to obtain an exclusive license in the other party’s territory (Greater China for Biosion and the rest of the world for us) to develop, manufacture and commercialize any bi-specific or multi-specific antibody any antibody-drug conjugate controlled by a party or its affiliate that inhibits, modulates or binds to Siglec-15 as an intended mechanism of action.

Pursuant to the Biosion License Agreement, we paid an upfront fee of $10.0 million in March 2022 and are obligated to pay future contingent payments including development, regulatory and commercial milestones up to an aggregate of $217.5 million in case of normal approval and $222.5 million in case of Accelerated Approval. Additionally, if products are launched, we will pay Biosion tiered royalties on net sales of licensed products in varying royalty rates ranging from low single digits to low teens. In December 2024, the Company paused the clinical development of PYX-106. The Company assessed the milestone and royalty events involving the Biosion License Agreement as of December 31, 2025 and 2024, and determined that no such amounts were required. Our royalty obligations apply on a licensed product-by-licensed product and country-by-country basis from first commercial sale until the latest to occur of: (1) 12 years from first commercial sale; (2) the expiration of all regulatory or data exclusivity; and (3) the expiration of the last valid claim of a licensed patent covering the licensed product in a country. We are also obligated to pay Biosion a percentage of certain sublicensing revenue ranging from low-double to mid-double digits based on the stage of development of the licensed product at the time of entering into the applicable sublicense.

Under the Biosion License Agreement, we are obligated to use commercially reasonable efforts to clinically develop and seek regulatory approval for at least one licensed product in the licensed territory, and to commercialize such licensed product following receipt of regulatory approval. We control prosecution and enforcement with respect to the licensed patents in the licensed territory.

The Biosion License Agreement will remain in effect on a licensed product-by-licensed product and country-by-country basis until the expiration of the applicable royalty term, unless terminated in accordance with the following: (1) by either party for the other party’s material breach if such party fails to cure such breach within the specified cure period; (2) by either party upon certain insolvency events of the other party; (3) by us for scientific or safety reasons; (4) any time following completion of our first clinical trial for a licensed product, by us for convenience; or (5) by Biosion if we cease development and commercialization activities for licensed products for a specified period of time, subject to certain exceptions.

Out-License Relationships

In August 2023, we completed the acquisition of Apexigen contemplated by the Merger Agreement, with Apexigen surviving as a wholly owned subsidiary of the Company. Upon the Merger Agreement, we assumed all out-licensing agreements of Apexigen. The assumed agreements consist of licenses with several biopharmaceutical companies that are developing product candidates that were discovered using our APXiMAB platform, which has been important to prosecuting the full value of our platform. We believe the licenses for the programs for the development of product candidates we have generate and demonstrate the productivity and utility of our platforms and position us to receive meaningful milestone and royalty payments if those product candidates are approved and successfully commercialized.

Described below are the out-license relationships and the related agreements under which we may receive milestone or royalty payments.

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Simcere License and Collaboration Agreement

In December 2008, Epitomics (Apexigen’s predecessor) and Jiangsu Simcere Pharmaceutical R&D Co., Ltd. (Simcere) entered into a license and collaboration agreement (the Simcere Agreement) for the development and commercialization of suvemcitug (BD0801) for oncology in China. Suvemcitug is a humanized anti-VEGF monoclonal antibody molecule derived from APXiMAB technology. Simcere is responsible for conducting the development and commercialization of suvemcitug in China at its cost. Under the terms of the Simcere Agreement, Apexigen had, and now we have, reserved the right to develop and commercialize suvemcitug outside of China at our discretion. If we develop and commercialize suvemcitug outside of China, we will share with Simcere costs incurred and revenue earned outside of China. Under the Simcere Agreement, Simcere has an exclusive, royalty-bearing license (without the right to sublicense) to Apexigen's rights in certain intellectual property to develop and commercialize suvemcitug in the field of oncology therapeutics in China.

Simcere granted Apexigen a non-exclusive, royalty-free, worldwide license (without the right to sublicense) to improvements derived from suvemcitug using the intellectual property licensed to Simcere for any purpose outside of China and for purposes outside of oncology therapeutics in China. Intellectual property created in the collaboration program with Simcere is jointly owned by Apexigen and Simcere.

In January 2024, Simcere announced that the Phase 3 clinical trial of suvemcitug for injection combined with chemotherapy in patients with recurrent, platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal cancer met its primary endpoints of the progression-free survival. In March 2024, Simcere announced the New Drug Application (NDA) for suvemcitug for injection was accepted by the China National Medical Products Administration (NMPA).

On June 30, 2025, the National Medical Products Administration (NMPA) of China (formerly SFDA) granted final regulatory approval for suvemcitug in China. Upon suvemcitug approval by the NMPA, the Company received a $3 million regulatory approval milestone under the Simcere Agreement.

On December 2025, we entered into an amendment to the License and Collaboration Agreement (the Simcere Royalty Agreement) with Simcere, pursuant to which we relinquished our rights to future royalties on the net sales of Enzeshu® to Simcere for a one-time amount of $11.0 million and four semi-annual installments of $175,000 each. Notwithstanding the foregoing amendment, the Simcere Agreement otherwise remains in full force and effect.

T-Mab/Mabwell Agreement

In May 2008, Epitomics and Jiangsu T-Mab Biotechnology Ltd., Co. (T-Mab) entered into a license, co-development and contract manufacture agreement (the T-Mab Agreement) for the development and commercialization of therapeutic candidates in two therapeutic programs, each directed to a specified target for specified fields, including VEGF for the treatment of ocular diseases, in China. The Company assessed the milestone and royalty events involving Mabwell as of December 31, 2025 and determined that no such amounts were receivable. Mabwell (Shanghai) Bioscience Co., Ltd. (Mabwell) acquired T-Mab in 2015. Mabwell is responsible for conducting the development and commercialization of the therapeutic candidates in China. We may, at our discretion, develop and commercialize such therapeutic candidates outside of China; however, we must pay Mabwell a royalty on sales of such therapeutic candidates made outside of China if we do so.

Under the T-Mab Agreement, Mabwell was granted an exclusive, royalty-bearing, perpetual license (without the right to sublicense) to its rights in certain intellectual property that it licensed from Epitomics to develop and commercialize such therapeutic candidates. Mabwell is obligated to pay us a mid-single-digit percentage royalty on net sales of such therapeutic candidates in China. If we choose to commercialize such therapeutic candidates outside of China, we would be obligated to pay Mabwell a mid-single-digit percentage royalty on net sales of such therapeutic candidates outside of China that we sell directly to end users and a mid-single-digit percentage of revenue we receive as sublicense fees, milestone payments and royalties related to the sale of such therapeutic candidate. Each party’s obligations to pay royalties to the other party continue until 15 years after the first commercial sale of licensed product in each party’s respective territory. The term of the T-Mab Agreement expired in May 2013; however, Mabwell’s royalty payment obligations under the agreement survive expiration. The royalty term for 9MW0211, an anti-VEGF antibody licensed under the T-Mab Agreement, will begin with the first commercial sale in China and end after a low two-digit number of years.

Mabwell is currently in Phase 3 development of 9MW0211.

Toray Sublicense Agreement

In May 2012, Apexigen and Toray Industries, Inc. (Toray), entered into a non-exclusive sublicense agreement (the Toray Agreement) under which Apexigen granted Toray a non-exclusive, worldwide sublicense, with the right to grant further sublicenses, to develop and commercialize drug product candidates that Toray developed using antibodies created using the APXiMAB platform that target certain molecules to use in the development of its drug product candidates. Under the Toray Agreement, Toray paid an upfront fee and agreed to pay certain development- and regulatory-related milestone payments and a low single-digit percentage royalty on net sales of licensed products by Toray or its affiliates. The Company assessed the milestone and royalty events involving Toray as of December 31, 2025 and determined that

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no such amounts were receivable. Toray is also obligated to pay us a mid-teens percentage of certain payments Toray receives from sublicensees under the Toray Agreement, which payments may limit Toray’s obligations to pay the milestone payments described above. Subject to certain termination rights, including Toray’s right to terminate the agreement for convenience upon 60 days’ prior written notice, the Toray Agreement continues on a product-by-product and country-by-country basis until 10 years after the first commercial sale of such product in such country. Upon expiration or early termination of the agreement, Toray’s sublicense and any further sublicenses granted by Toray will automatically terminate.

Toray is currently in Phase 2 development of TRK-950, an antibody licensed under the Toray Agreement.

Intellectual Property

Our intellectual property is critical to our business, and we strive to protect it, including by obtaining and maintaining patent protection in the U.S. and internationally for our product candidates, new therapeutic approaches, platform technologies, potential methods of use in our indications of interest and other inventions that are important to our business. We also rely on trade secrets and proprietary know-how to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

Our patent portfolio includes patents and patent applications that are exclusively licensed from the University of Chicago, Pfizer and Biosion, and patents and patent applications that are wholly owned by us. Our patent portfolio includes patents and patent applications that cover our product candidates MICVO (formerly PYX-201), PYX-203, PYX-106, PYX-107 and PYX-102, and the use of these candidates for therapeutic purposes in certain territories. Our proprietary technology has been developed primarily through internal development efforts and relationships with academic institutions, Pfizer, Biosion and contract research organizations.

For our product candidates, we will, in general, initially pursue patent protection covering compositions of matter and methods of use. Throughout the development of our product candidates, we seek to identify additional means of obtaining patent protection that would potentially enhance commercial success, including through additional methods of use for particular indications, process of making, formulation and dosing regimen-related claims.

For all patent applications, we determine claiming strategy on a case-by-case basis. Advice of counsel and our business model and needs are always considered. We file patent applications containing claims for protection of useful applications of our proprietary technologies and any products, as well as new applications and/or uses we discover for existing technologies and products, assuming these are strategically valuable. We continuously reassess the number and type of patent applications, as well as the existing patent claims to 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 meet our intellectual property and business needs.

We recognize that the ability to obtain patent protection and the degree of such protection depends on a number of factors, including the extent of the prior art, the novelty and non-obviousness of the invention, and the ability to satisfy the enablement requirement of the patent laws. The patent positions of immuno-oncology companies like ours are generally uncertain and involve complex legal, scientific and factual questions. Consequently, we may not obtain or maintain adequate patent protection for any of our current or future product candidates or for our platform technologies. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or whether the claims of any issued patents will provide sufficient proprietary protection from competitors. Any patents that we hold may be challenged, circumvented or invalidated by third parties.

Regardless of the coverage we seek under our existing patent applications, there is always a risk that an alteration to the product or process may provide sufficient basis for a competitor to avoid infringement claims. In addition, the coverage claimed in a patent application can be significantly reduced before a patent is issued, and courts can reinterpret patent scope after issuance. Moreover, many jurisdictions, including the United States, permit third parties to challenge allowed or issued patents in administrative proceedings, which may result in further narrowing or even cancellation of patent claims. Moreover, we cannot provide any assurance that any patents will be issued from our pending or any future applications or that any current or future issued patents will adequately protect our products.

In total, our patent portfolio, including patents licensed from the University of Chicago, Pfizer and Biosion, and patents owned by us, comprises 29 different patent families, filed in various jurisdictions worldwide, including families directed to compositions of matter for antibodies and antibody-drug conjugates, families directed towards the compositions, manufacture, and use, of antibodies and antibody-drug conjugates generally, families directed towards methods of identifying patients for treatment with compositions of antibodies and antibody-drug conjugates and subsequently treating said patients, and families directed to methods of treating cancer and identifying potential targets.

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MICVO (formerly PYX-201) Patent Families, Status, and Potential Expiration

MICVO is covered by a growing portfolio of patent families, some of which are in-licensed from Pfizer, some of which we have sole ownership of, and one of which we co-own. Details, status, and potential expiration dates of MICVO patent families are summarized below:

MICVO Antibody-Drug Conjugate Composition of Matter (Drug Product) Patent Coverage

MICVO Related Patent Families – Constructs, Methods, and Components

MICVO Anti-EDB+FN Antibody-Drug Conjugate Composition of Matter and Methods of Using the Same. We have exclusively licensed from Pfizer a patent family for antibodies and antibody-drug conjugates that bind to the extra domain B splice variant of fibronectin, including the composition of matter for MICVO and methods of using MICVO in treating certain cancer including NSCLC, colorectal cancer, PDAC and generic breast cancer, that includes granted patents in Australia, Austria, Belgium, Brazil, Bulgaria, China, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Great Britian, Greece, Hong Kong, Hungary, India, Ireland, Israel, Italy, Japan, Latvia, Lithuania, Mexico, Netherlands, Norway, Poland, Portugal, Romania, Russia, Serbia, Singapore, Slovak Republic, Slovenia, South Korea, Spain, Sweden, Switzerland, Turkey, and the United States, and pending applications in Australia, Brazil, Canada, China, European Patent Organization (Europe), Hong Kong, Israel, Japan, Mexico, Singapore, South Africa, and the United States. The 20-year term of the patents in this family runs through 2037, absent any available patent term adjustments or extensions.

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Methods of using MICVO - Constructs and Compositions for Treating EDB+FN Expressing Disease and Disorders in Certain Cancer Indications. We have sole ownership of a patent family for constructs, compositions, and methods of treating EDB+FN expressing diseases and disorders, including but not limited to HNSCC, sarcoma, TNBC, HR+ breast cancer, ovarian cancer, and thyroid cancer, with MICVO and similar constructs, that includes a pending PCT application. The 20-year term of this patent family runs through 2045, absent any available patent term adjustments or extensions.

Dosage and Treatment Regimens of MICVO. We have sole ownership of a patent family for dosage and treatment regimens of MICVO and similar constructs, that includes a pending PCT application. The 20-year term of this patent family runs through 2045, absent any available patent term adjustments or extensions.

Combination Therapies including MICVO. We have sole ownership of two patent families for certain drug combinations with MICVO, that include four provisional patent applications. The 20-years terms for these patent families run through 2046, absent any available patent term adjustments or extensions.

Combination of MICVO and Pembrolizumab. We have joint ownership of a patent family for the combination of MICVO and pembrolizumab in certain cancer indications at certain dose levels. The 20-year term of this patent family runs through 2046, absent any available patent term adjustments or extensions.

Cytotoxic Peptides and Antibody-Drug Conjugates Thereof. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward cytotoxic pentapeptides, including the auristatin 0101 (Aur0101) payload and MC-VC-PABC-Aur0101 linker-payload (vc0101, pelidotin) found in MICVO, and to antibody-drug conjugates thereof, that includes granted patents in Argentina, Australia, Austria, Belgium, Brazil, Bulgaria, Canada, China, Colombia, Czech Republic, Denmark, Finland, France, Germany, Great Britain, Greece, Hong Kong, Hungary, Iceland, India, Indonesia, Ireland, Israel, Italy, Japan, Luxembourg, Malaysia, Mexico, Netherlands, New Zealand, Norway, Peru, Philippines, Poland, Portugal, Romania, Russia, Saudi Arabia, Singapore, Slovak Republic, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Taiwan, Turkey, and the United States. The 20-year term of the patents in this family runs through 2032, absent any available patent term adjustments or extensions.

Antibodies and Antibody Fragments for Site-Specific Conjugation. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward polypeptides, antibodies, and antigen-binding fragments thereof, that comprise a engineered cysteine for site-specific conjugation, including the K290C engineered cysteine found in MICVO, that includes granted patents in Australia, Canada, Colombia, India, Israel, Malaysia, Mexico, Saudi Arabia, South Africa, and Taiwan, and a pending application in Europe. The 20-year term of the patents in this family runs through 2036, absent any available patent term adjustments or extensions.

Engineered Antibody Constant Regions for Site-Specific Conjugation and Methods and Uses Therefor. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward antibodies, and antigen-binding portions thereof, engineered to introduce amino acids for site-specific conjugation, including the kK183C engineered cysteine found in MICVO, that includes granted patents in Canada, EPO (Unitary Patent), France, Germany, Great Britain, Ireland, Italy, Japan, Spain, Switzerland, and the United States, and a pending application in Canada and Japan. The 20-year term of the patents in this family runs through 2032, absent any available patent term adjustments or extensions.

Composition of Matter Patents for Additional Assets (excluding MICVO)

PYX-203 Anti-CD123 Antibody-Drug Conjugate. We have exclusively licensed from Pfizer a patent family for antibodies and antibody-drug conjugates that specifically bind to CD123, that includes granted patents in Australia, Canada, China, Colombia, Hong Kong, India, Israel, Japan, Mexico, Russia, South Korea, Taiwan, and the United States, and pending applications in Brazil, China, Europe, Japan, New Zealand, Singapore, South Africa, and the United States, that claim the composition of matter and certain methods of use with respect to PYX-203. The 20-year term of the patents in this family runs through 2038, absent any available patent term adjustments or extensions.

PYX-106 Anti-Siglec-15 Antibody. We have exclusively licensed from Biosion USA, Inc. a patent family for monoclonal antibodies that specifically bind human Siglec15, including PYX-106, that includes granted patents in Australia, Canada, China, Israel, Japan, Malaysia, New Zealand, Russia, Saudi Arabia, South Korea, and the United States, and pending applications in Australia, Brazil, Egypt, Europe, Hong Kong, India, Indonesia, Mexico, New Zealand, Philippines, Singapore, South Africa, United Arab Emirates, and the United States. The 20-year term of the patents in this family runs through 2041, absent any available patent term adjustments or extensions.

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PYX-107A/B “Sotigalimab” CD40 Agonist Antibodies. Through our acquisition of Apexigen, Inc. we have acquired sole ownership of two patent families for high affinity CD40 agonist monoclonal antibodies and related compositions, including PYX-107 (also known as sotigalimab) which may be used in any of a variety of therapeutic methods for the treatment of cancer and other diseases. The first patent family includes granted patents in Australia, Belgium, Brazil, Canada, China, France, Germany, Great Britain, Hong Kong, India, Italy, Japan, Mexico, New Zealand, Russia, Singapore, South Africa, South Korea, Spain, Switzerland, and the United States, with a pending application in Israel. The 20-year term of this first patent family runs through 2032, absent any available patent term adjustments or extensions. The second patent family includes granted patents in Australia, Belgium, China, Denmark, France, Germany, Great Britain, Hong Kong, India, Ireland, Italy, Japan, Netherlands, New Zealand, Norway, South Africa, South Korea, Spain, Sweden, Switzerland, and the United States, with pending applications in Canada, Europe, and the United States. The 20-year term of this second patent family runs through 2033, absent any available patent term adjustments or extension.

PYX-102 Anti-KLRG1 Antibody. We have sole ownership of a patent family for monoclonal antibodies that specifically bind human KLRG1, that includes a pending applications in Australia, Canada, China, Europe, Japan, and the United States. The 20-year term of this patent family runs through 2044, absent any available patent term adjustments or extensions.

PYX-205 Antibody-drug Conjugates and Methods of Use. We have sole ownership of a patent family for certain ADC compositions with payload optionality, that includes a pending provisional application in the United States. The 20-year term of this patent family, if converted, runs through 2047, absent any available patent term adjustments or extensions.

Certain Methods Patents Related to Compositions of Matter

PYX-107D Methods of Treating Cancer with CD-40 Agonists. Through our acquisition of Apexigen we have acquired sole ownership of a patent family for methods of identifying a sub-population of cancer patients amenable for a combination therapy with a CD40 agonist and one or more chemotherapy drugs and subsequently treating the sub-population of cancer patients with said combination therapy, that includes pending patent applications in Canada, China, Europe, Japan, and the United States. The 20-year term of the patents in this family runs through 2042, absent any available patent term adjustments or extensions.

PYX-107F Biomarkers for CD40 Agonist Therapy. Through our acquisition of Apexigen we have acquired sole ownership of a patent family for biomarkers and other characteristics for predicting tumor responsiveness to CD40 agonist therapy in melanomas, and related kits, compositions, and methods of treating said melanomas, including PD-(L)1 refractory melanomas, that includes pending applications in Europe and the United States. The 20-year term of the patents in this family runs through 2042, absent any available patent term adjustments or extensions.

PYX-002 Site Specific Ligand-Payload Conjugates. We have sole ownership of a patent family for ligand-payload conjugates, and compositions and use thereof for treating diseases, disorders, or conditions, such as cancers, autoimmune diseases, or infectious diseases, that includes pending applications in Europe and the United States. The 20-year term of the patents in this family runs through 2043, absent any available patent term adjustments or extensions.

Antibody-Drug Candidate Patent Rights

Purification of Antibody-Drug Conjugates Using a Sodium Phosphate Gradient. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture useful in antibody-drug conjugates generally, directed toward methods of removing high molecular weight species, in particular aggregates, from antibody-drug conjugate preparations, by contacting preparations of the antibody-drug conjugate reaction mixture with a hydroxyapatite resin and selectively eluting the antibody-drug conjugate from the resin using a gradient comprising sodium phosphate, that includes granted patents in France, Germany, Great Britain, Ireland, Italy, Spain, and the United States, and a pending application in the United States. The 20-year term of the patents in this family runs through 2036, absent any available patent term adjustments or extensions.

Platform Patent Rights

Stability-Modulating Linkers for Use with Antibody-Drug Conjugates. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward stability-modulating linker components used to make these stability-modulated antibody-drug conjugates, that includes granted patents in Australia, Brazil, Canada, China, France, Germany, Great Britain, India, Italy, Japan, Mexico, Russia, South Korea, Spain, and the United States, and a pending application in Mexico. The 20-year term of the patents in this family runs through 2035, absent any available patent term adjustments or extensions.

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Synergistic Auristatin Combinations. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward combinations of an auristatin or an auristatin-based antibody-drug conjugate with second active agents including PI3K/mTOR inhibitors, MEK inhibitors, taxanes, or other anti-cancer agents, that includes granted patents in the United States and Japan. The 20-year term of the patents in this family runs through 2035, absent any available patent term adjustments or extensions.

Capped and Uncapped Antibody Cysteines, and Their Use in Antibody-Drug Conjugation. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward antibody production process in which engineered unpaired cysteine residues are post-translationally modified and capped with particular chemical entities, which capped antibodies are well suited to further site-specific conjugation steps to form antibody-drug conjugates, that includes granted patents in Australia, Brazil, China, France, Germany, Great Britain, India, Ireland, Israel, Italy, Japan, Mexico, Russia, South Korea, Spain, Switzerland, and the United States, and pending applications in Canada and Europe. The 20-year term of the patents in this family runs through 2036, absent any available patent term adjustments or extensions.

Large Scale Production Process for Capped and Uncapped Antibody Cysteines and Their Use in Therapeutic Protein Conjugation. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward optimizing production of selectively capped, and uncapped, cysteines on antibodies by manipulation of cell growth conditions, that includes granted patents in South Korea and the United States, and no pending applications. The 20-year term of the patents in this family runs through 2038, absent any available patent term adjustments or extensions.

Bifunctional Cytotoxic Agents. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward cytotoxic dimers comprising CBI-based and/or CPI-based sub-units, and antibody-drug conjugates comprising such dimers, that includes granted patents in Argentina, Austria, Belgium, Brazil, Bulgaria, Canada, China, Colombia, Czech Republic, Denmark, Finland, France, Germany, Great Britain, Greece, Hong Kong, Hungary, Iceland, India, Indonesia, Ireland, Israel, Italy, Japan, Luxembourg, Malaysia, Mexico, Netherlands, New Zealand, Norway, Peru, Philippines, Poland, Portugal, Romania, Russia, Saudi Arabia, Singapore, Slovak Republic, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Taiwan, Turkey, the United States and Venezuela, and a pending application in Argentina. The 20-year term of the patents in this family runs through 2035, absent any available patent term adjustments or extensions.

Engineered Polypeptide Conjugates and Methods for Making Thereof Using Transglutaminase. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward engineered polypeptide conjugates comprising acyl donor glutamine-containing tags and amine donor agents, that includes granted patents in Canada, Japan, and the United States, and a pending application in Europe. The 20-year term of the patents in this family runs through 2031, absent any available patent term adjustments or extensions.

Antibody-Drug Conjugates with High Drug Loading. We have exclusively licensed from Pfizer, subject to certain reservations, a patent family for compositions, methods of use, and/or methods of manufacture related to the FACT Platform, directed toward transglutaminase-mediated antibody-drug conjugates with high anti-body-drug ratio, that includes granted patents in Australia, Austria, Belgium, Brazil, Bulgaria, Canada, China, Czech Republic, Denmark, Finland, France, Germany, Great Britain, Greece, Hong Kong, Hungary, India, Ireland, Israel, Italy, Japan, Luxembourg, Mexico, Netherlands, Poland, Portugal, Romania, Russia, Slovak Republic, Slovenia, South Korea, Spain, Sweden, Switzerland, Turkey, and the United States, and no pending application. The 20-year term of the patents in this family runs through 2035, absent any available patent term adjustments or extensions.

Methods in Immuno-Oncology

Methods and Compositions Related to T-Cell Activity. We have exclusively licensed from the University of Chicago a patent family for methods for treating patients with immunotherapy based on the identification of the patient as having non-anergic T cells after measuring expression levels of various genes that includes granted and pending patents in the United States. The 20-year term for patents in this family runs through 2034, absent any available patent term adjustments or extensions.

Beta-catenin Inhibitors in Cancer Immunotherapy. We have exclusively licensed from the University of Chicago a patent family for methods for treating solid tumor cancers that includes granted patents in the United States, and no pending applications. The 20-year term for patents in this family runs through 2036, absent any available patent term adjustments or extensions.

Dysfunctional Antigen-specific CD8+ T Cells in the Tumor Microenvironment. We have exclusively licensed from the University of Chicago a patent family for methods of treating cancer comprising administering an agent that specifically targets dysfunctional tumor antigen-specific CD8+T cells that includes pending applications in Canada, and Europe, and a granted patent in the United States. The 20-year term for patents in this family runs through 2038, absent any available patent term adjustments or extensions.

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Patent Term and Term Extensions

Individual patents have terms for varying periods depending on the date of filing of the patent application or the date of patent issuance and the legal term of patents in the countries in which they are obtained. Generally, utility patents issued for applications filed in the United States, and most countries around the world, are granted a term of 20 years from the earliest effective filing date of a non-provisional patent application. In addition, in certain instances, the term of a U.S. patent can be extended to recapture a portion of the United States Patent and Trademark Office (USPTO) delay in issuing the patent as well as a portion of the term effectively lost as a result of the FDA regulatory review period. However, as to the FDA component, the restoration period cannot be longer than five years, and is typically less, and the restoration period cannot extend the patent term beyond 14 years from FDA approval. In addition, only one patent applicable to an approved drug is eligible for the extension, and only those claims covering the approved drug, a method for using it, or a method of manufacturing may be extended. Similar provisions are available in Europe and other foreign jurisdictions to extend the term of a patent that covers an approved drug. We will, in general, pursue available patent term extensions in the U.S. and in foreign jurisdictions that provide for patent term extensions, however, there is no guarantee that the applicable authorities, including the FDA in the United States, will agree with our assessment of whether such extensions should be granted, and if granted, the length of such extensions. All taxes, annuities or maintenance fees for a patent, as required by the USPTO and various foreign jurisdictions, must be timely paid in order for the patent to remain in force during this period of time.

The actual protection afforded by a patent may vary on a product-by-product basis, from country to country, and can depend upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions and the availability of legal remedies in a particular country and the validity and enforceability of the patent.

Our patents and patent applications may be subject to procedural or legal challenges by others. We may be unable to obtain, maintain and protect the intellectual property rights necessary to conduct our business, and we may be subject to claims that we infringe or otherwise violate the intellectual property rights of others, which could materially harm our business. For more information, see the section titled “Risk Factors—Risks Related to Our Intellectual Property.”

Trademarks and Know-How

In connection with the ongoing development and advancement of our product candidate in the United States and various international jurisdictions, we seek to create protection for our marks and enhance their value by pursuing trademarks where available and when appropriate. In addition to patent and trademark protection, we rely upon trade secrets and know-how and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary information, in part, using confidentiality agreements with our commercial partners, collaborators, employees and consultants and invention assignment agreements with our employees and selected consultants. We also seek to preserve the integrity and confidentiality of our data and trade secrets by maintaining physical security of our premises and physical and electronic security of our information technology systems. While we have confidence in these individuals, organizations and systems, agreements or security measures may be breached, and our trade secrets and other proprietary information may be disclosed. We may not have adequate remedies for any breach and could lose our trade secrets and other proprietary information through such a breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors. To the extent that our consultants, contractors or collaborators use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting trade secrets, know-how and inventions.

Our commercial success will also depend in part on not infringing the proprietary rights of third parties. In addition, we have licensed rights under proprietary technologies of third parties to develop, manufacture and commercialize specific aspects of our future products and services. It is uncertain whether the issuance of any third party patent would require us to alter our development or commercial strategies, alter our processes, obtain licenses or cease certain activities. The expiration of patents or patent applications licensed from third parties or our breach of any license agreements or failure to obtain a license to proprietary rights that we may require to develop or commercialize our future technology may have a material adverse impact on us. If third parties prepare and file patent applications in the United States that also claim technology to which we have rights, we may have to participate in interference proceedings in the USPTO to determine priority of invention.

For more information regarding the risks related to our intellectual property, please see “Risk Factors—Risks Related to Our Intellectual Property.”

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Government Regulation

The research, development, testing, manufacture, quality control, approval, labeling, packaging, storage, record keeping, serialization and tracking, promotion, advertising, distribution and marketing, post approval or licensure monitoring and reporting, and export and import, among other things, of our product candidates are extensively regulated by governmental authorities in the United States and in other countries and jurisdictions, including the EU. In the United States, the FDA regulates biological products under the Federal Food, Drug, and Cosmetic Act (FDCA) and its implementing regulations, and the Public Health Service Act (PHSA) and its implementing regulations. Failure to comply with the applicable U.S. requirements may subject us to administrative or judicial sanctions, such as the FDA’s refusal to approve a Biologics License Application (BLA), warning letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions and/or criminal prosecution.

Preclinical Studies

Before testing any biologic product candidate in humans, the product candidate undergoes preclinical testing. Preclinical tests, also referred to as non-clinical studies, include laboratory evaluations of the product chemistry, pharmacology, toxicity and formulation, as well as animal studies to assess the pharmacokinetics, metabolism, bio-distribution, elimination and toxicity of the product candidate. The conduct of the preclinical tests and formulation of the compounds for testing must comply with federal regulations and requirements and certain preclinical trials must conform to the FDA’s Good Laboratory Practice requirements (GLP).

The results of preclinical testing, manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, among other things, must be submitted to the FDA as part of an IND that must be reviewed and cleared by the FDA before clinical testing can begin. The IND will become effective 30 days after the FDA receives the application, unless the FDA raises concerns or questions related to the investigations in the application and places the trial on clinical hold. In this situation, the IND sponsor must resolve any outstanding FDA concerns before clinical trials can proceed. As a result, submission of an IND may or may not result in the FDA authorizing clinical trials to commence.

Clinical Development

The FDA and comparable regulatory agencies in state and local jurisdictions and in foreign countries impose substantial requirements upon the clinical development, manufacture and marketing of pharmaceutical products. These agencies and other federal, state and local entities regulate, among other things, research and development activities and the testing, manufacture, export, import, quality control, marketing approval, safety, effectiveness, labeling, storage, record keeping, promotion, advertising, distribution and marketing and post-marketing safety reporting.

The process required by the FDA before product candidates may be marketed in the U.S. generally involves the following:

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non-clinical laboratory and animal tests, some of which must be conducted in accordance with GLP ;

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submission of an Investigational New Drug (IND) application, which contains results of non-clinical studies (e.g., laboratory evaluations of the chemistry, formulation, stability and toxicity of the product candidate), together with Investigator’s Brochure, manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, and must become effective before human clinical trials may begin;

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approval by an independent Institutional Review Board (IRB) or ethics committee for each clinical trial site before each trial may be initiated;

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adequate and well-controlled human clinical trials conducted in accordance with the protocol and Good Clinical Practice (GCP) to establish the safety and efficacy of the product candidate for its proposed intended use;

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for drug products, submission of a New Drug Application (NDA) to the FDA for commercial marketing, or generally of a supplemental New Drug Application (sNDA), for approval of a new indication if the product is already approved for another indication;

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for biotherapeutic products, submission of a Biologics License Application (BLA) to the FDA for commercial marketing, or generally a supplemental Biologics License Application (sBLA) for approval of a new indication if the product is already approved for another indication;

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pre-approval inspection of manufacturing facilities and selected clinical investigators, clinical trial sites and/or Pyxis Oncology as the clinical trial sponsor for their compliance with cGMP and GCP, respectively;

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payment of user fees for FDA review of an NDA or BLA unless a fee waiver applies;

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agreement with the FDA on the final labeling for the product and design and implementation of any required Risk Evaluation and Mitigation Strategy;

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if the FDA convenes an advisory committee, satisfactory completion of the advisory committee review; and

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FDA approval of the NDA or sNDA, or BLA or sBLA.

Clinical Trials

Clinical trials involve the administration of the biologic product candidate to volunteers or patients under the supervision of qualified investigators in accordance with GCP requirements, which include the requirement that all research patients provide their informed consent for their participation in any clinical trial. Clinical trials are conducted under protocols detailing the objectives of the study, dosing procedures, inclusion and exclusion criteria, study procedures, parameters to be used in monitoring safety and the effectiveness criteria to be evaluated.

Further, the study protocol and informed consent information for patients in clinical trials must also be submitted to an IRB for approval covering each institution at which the clinical trial will be conducted. The IRB will consider, among other requirements, rationale for conducting the trial, clinical trial design, patient informed consent, ethical factors, the safety and rights of human patients and the possible liability of the institution. The FDA can temporarily or permanently halt a clinical trial at any time, or impose other sanctions, if it believes that the clinical trial is not being conducted in accordance with FDA requirements or presents an unacceptable risk to the clinical trial patients. The IRB may also require the clinical trial at a particular site be halted, either temporarily or permanently, or impose other conditions, for failure to comply with GCP or the IRB’s requirements.

For purposes of NDA or BLA approval, human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

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Phase 1 clinical trials, which involve the initial introduction of a new drug product candidate into humans, are initially conducted in a small number of volunteers or patients to assess the product candidate for early tolerability, safety, pattern of drug absorption, distribution and metabolism, the mechanism of action in humans, and may include studies where investigational drugs are used as research to explore biological phenomena or disease processes.

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Phase 2 clinical trials typically are conducted in a limited patient population with a specific disease in order to provide enough data to evaluate the preliminary efficacy, optimal dosage, and common short-term side effects and risks associated with the drug. Multiple phase 2 clinical trials may be conducted to obtain information prior to beginning larger and more expensive phase 3 clinical trials.

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Phase 3 clinical trials typically are larger scale, multicenter, well-controlled trials conducted on patients with a specific disease to gather additional information about effectiveness and safety across a higher number of patients and evaluate the overall benefit-risk relationship of the product candidate following earlier phase evaluations, which will have provided preliminary evidence suggesting an effective dosage range and acceptable safety profile for the product candidate. Phase 3 trials are also intended to provide an adequate basis for the product labeling if it is approved.

Post approval clinical trials, sometimes referred to as Phase 4 clinical trials, may be conducted after initial marketing approval. These clinical trials may be conducted to fulfill mandatory conditions of product approval or used to gain additional experience from the treatment of patients in the intended therapeutic indication, particularly for long-term safety follow-up. The mandatory studies are used to confirm clinical benefit in the case of drugs approved under the accelerated approval regulations or to provide additional clinical safety or efficacy data for “full” approvals. Failure to promptly conduct and complete mandatory Phase 4 clinical trials could result in withdrawal of approval for products approved under accelerated approval regulations.

A therapeutic product candidate being studied in clinical trials may be made available for treatment of individual patients, intermediate-size patient populations, or for widespread treatment use under an expanded access protocol, under certain circumstances. Pursuant to the 21st Century Cures Act, or Cures Act, which was signed into law in December 2016, the manufacturer of one or more investigational products for the diagnosis, monitoring, or treatment of one or more serious diseases or conditions is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for individual patient access to such investigational product.

Additionally, on May 30, 2018, the Trickett Wendler, Frank Mongiello, Jordan McLinn, and Matthew Bellina Right to Try Act of 2017 was signed into law. The law, among other things, provides a federal framework for certain patients to access certain investigational new drug products that have completed a Phase 1 clinical trial and that are undergoing investigation for FDA approval. Under certain circumstances, eligible patients can seek treatment without enrolling in clinical trials and without obtaining FDA authorization under an FDA expanded access program; however, manufacturers are not obligated to provide investigational new drug products under the current federal right to try law.

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Disclosure of Clinical Trial Information

Under the PHSA, sponsors of certain clinical trials of FDA-regulated products are required to register and disclose certain clinical trial information. Information related to the product, patient population, phase of investigation, trial sites and investigators, and other aspects of the clinical trial are then made public as part of the registration on a public registry (clinicaltrials.gov) maintained by the U.S. National Institutes of Health (the NIH). Sponsors are also obligated to disclose the results of their clinical trials after completion. Competitors may use this publicly available information to gain knowledge regarding the progress of development programs. Information for certain clinical trials also must be publicly disclosed within certain time limits on the clinical trial registry and results databank maintained by the NIH.

Expedited Development and Review Programs

The FDA has a number of programs intended to expedite the process for developing and reviewing promising drugs, or to provide for the approval of a drug on the basis of a surrogate endpoint. Generally, drugs that are eligible for these programs are those for serious or life-threatening conditions, those with the potential to address unmet medical needs and those that offer meaningful benefits over existing treatments. Examples of such programs include Fast Track Designation, Breakthrough Therapy Designation, Priority Review designation and Accelerated Approval, and the eligibility criteria of and benefits of each program vary:

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Fast Track is a process designed to facilitate the development and expedite the review of drugs intended to treat a serious or life-threatening conditions that demonstrate the potential to address unmet medical needs, by providing, among other things, potential actions to expedite development and review, and rolling review, which allows submission of individually completed sections of an NDA for FDA review before the entire submission is completed. The FDA may revoke the Fast Track Designation if it believes that the designation is no longer supported by data emerging in the clinical trial process.

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Breakthrough Therapy Designation is a process designed to expedite the development and review of drugs intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence demonstrates that the drug may have substantial improvement on one or more clinically significant endpoints over existing therapies. Drugs designated as breakthrough therapies are also eligible for other actions to expedite review. The FDA will seek to ensure the sponsor of a Breakthrough Therapy product candidate receives intensive guidance on an efficient drug development program, intensive involvement of senior managers and experienced staff on a proactive, collaborative and cross-disciplinary review, and rolling review.

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Priority Review is designed to shorten the review period for drugs that are intended to treat a serious conditions and, if approved or licensed, would provide a significant improvement in safety or effectiveness. The FDA intends to take action on a Priority Review marketing application within six months of receipt, compared to 10 months for regular review submissions.

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Accelerated Approval provides for an earlier approval of a new drug intended to treat a serious or life-threatening disease or condition and that provides a meaningful therapeutic benefit over existing treatments and demonstrates an effect on a surrogate endpoint, or an intermediate clinical endpoint, which is considered reasonably likely to predict a clinical benefit. As a condition of approval, the FDA requires that a sponsor of a product candidate receiving Accelerated Approval perform post-marketing clinical trials or provide data on established clinical endpoints from the same trial to confirm the clinical benefit as predicted by the surrogate marker trial and may require that these studies be underway prior to approval. In addition, the FDA requires, as a condition for Accelerated Approval, the submission of promotional materials in advance, which could adversely impact the timing of the commercial launch of the product. The FDA can also withdraw an Accelerated Approval on an expedited basis provided it follows certain procedures.

Fast Track Designation, Breakthrough Therapy Designation, Priority Review and Accelerated Approval do not change the standards for licensure but may expedite the review process.

In February 2025, the FDA granted Fast Track Designation for use of MICVO for the treatment of adults with R/M HNSCC whose disease has progressed following treatment with platinum-based chemotherapy and an anti-PD-(L)1 antibody.

Additionally, with respect to oncology products, the FDA may review applications under the Real-Time Oncology Review (RTOR) program established by the FDA’s Oncology Center of Excellence. The RTOR program, which allows an applicant to pre-submit components of the NDA or BLA to allow the FDA to review clinical data before the complete filing is submitted, aims to explore a more efficient review process to ensure that safe and effective treatments are available to patients as early as possible, while maintaining and improving review quality. Drugs considered for review under the RTOR program must be likely to demonstrate substantial improvements over available

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therapy, which may include drugs previously granted breakthrough therapy designation for the same or other indications and must have straight-forward study designs and endpoints that can be easily interpreted.

Orphan Drugs

Under the Orphan Drug Act, the FDA may grant orphan drug designation to therapeutic candidates (drugs or biological products) intended to treat a disease or condition that affects fewer than 200,000 individuals in the U.S. (or for which there is no reasonable expectation that the cost of developing and making available in the U.S. for such disease or condition will be recovered from sales in the U.S.). To be eligible for orphan drug designation, the FDA must not have previously approved a drug considered the “same drug,” as defined in the FDA’s orphan drug regulations, for the same orphan-designated indication or the sponsor of the subsequent drug must provide a plausible hypothesis of clinical superiority over the previously approved same drug. Upon receipt of Orphan Drug Designation, the sponsor is eligible for tax credits for certain clinical trial expenses, waiver of pediatric studies, and an exemption from the BLA application fee.

In addition, upon marketing approval, an Orphan Drug Designation could be eligible for seven years of market exclusivity if no drug considered the same drug was previously approved for the same orphan condition (or if the subsequent drug is demonstrated to be clinically superior to any such previously approved same drug). Such orphan drug exclusivity, if awarded, would only block the approval of any drug considered the same drug for the same orphan indication. Orphan drug exclusivity does not prevent the FDA from approving a different biological product for the same disease or condition, or the same biological product for a different disease or condition.

In May 2023, the FDA granted Orphan Drug Designation for use of MICVO in the treatment of pancreatic cancer.

Additional controls for biologics

To help reduce the increased risk of the introduction of adventitious agents, the PHSA emphasizes the importance of manufacturing controls for products whose attributes cannot be precisely defined. The PHSA also provides authority to the FDA to immediately suspend biologics licenses in situations where there exists a danger to public health, to prepare or procure products in the event of shortages and critical public health needs, and to authorize the creation and enforcement of regulations to prevent the introduction or spread of communicable diseases within the United States.

After a BLA is approved, the product may also be subject to official lot release as a condition of approval. As part of the manufacturing process, the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official release by the FDA, the manufacturer submits samples of each lot of product to the FDA together with a release protocol showing a summary of the lot manufacturing history and the results of all of the manufacturer’s tests performed on the lot.

The FDA may also perform certain confirmatory tests on lots of some products, such as viral vaccines, before allowing the manufacturer to release the lots for distribution. In addition, the FDA conducts laboratory research related to the regulatory standards on the safety, purity, potency, and effectiveness of biological products. As with drugs, after approval of a BLA, biologics manufacturers must address any safety issues that arise, are subject to recalls or a halt in manufacturing, and are subject to periodic inspection after approval.

FDA Review of BLAs

After completion of the required clinical testing, a BLA is prepared and submitted to the FDA. FDA approval of the BLA is required before marketing of the product may begin in the United States. The BLA must include the results of all preclinical, clinical and other testing and a compilation of data relating to the product’s pharmacology, chemistry, manufacture and controls. The cost of preparing and submitting a BLA is substantial. The submission of most BLAs is additionally subject to a substantial application user fee, currently $4,682,003 for BLAs requiring clinical data for fiscal year 2026, and the manufacturer and sponsor under an approved BLA are also subject to annual program fees, currently $442,213 (fiscal year 2026) for each prescription product. Sponsors of applications for drugs granted Orphan Drug Designation are exempt from these user fees.

The FDA has 60 days from its receipt of a BLA to determine whether the application will be accepted for filing based on the Agency’s threshold determination that it is sufficiently complete to permit substantive review. The FDA may request additional information rather than accept a BLA for filing. In this event, the application must be resubmitted with the additional information. The resubmitted application is also subject to review before the FDA accepts it for filing. If the application is accepted for review, the FDA reviews the application to determine, among other things, whether a product is safe and effective for its intended use and whether the manufacturing controls are adequate to assure and preserve the product's identity, strength, quality, and purity.

The FDA has agreed to certain performance goals in the review of BLAs to encourage timeliness. Applications for standard review biological products are meant to be reviewed within ten months; applications for Priority Review drugs are meant to be reviewed in six months. Priority Review can be applied to biological products that the FDA determines offer major advances in treatment or provide a treatment where no adequate therapy exists. The review process for both standard and Priority Review may be extended by the FDA for three additional months (“major amendment”) to consider certain late-submitted information, or information intended to clarify information already provided in the submission.

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The FDA is required to refer an application for a novel biological product to an advisory committee or explain why such referral was not made. An advisory committee is typically a panel that includes clinicians and other experts—for review, evaluation and a recommendation as to whether the application should be approved. The FDA is not bound by the recommendation of an advisory committee, but it generally follows such recommendations.

Before approving a BLA, the FDA will typically inspect one or more clinical sites to assure compliance with GCP. Additionally, the FDA will inspect the facility or the facilities at which the drug is manufactured. The FDA will not license the product unless compliance with cGMP is satisfactory, and the application meets the appropriate standard. A BLA must include data that demonstrate that the biological product is safe, pure and potent.

After the FDA evaluates the BLA and accompanying information and the manufacturing facilities, it issues either an approval letter or a complete response letter. An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A complete response letter generally outlines the deficiencies in the submission and may require substantial additional testing, or information, in order for the FDA to reconsider the application. If, or when, those deficiencies have been addressed to the FDA’s satisfaction in a resubmission of the BLA, the FDA will issue an approval letter. The FDA has committed to reviewing such re-submissions in two or six months depending on the type of information included. Even with submission of this additional information, the FDA ultimately may decide that the application does not satisfy the regulatory criteria for approval.

If the FDA approves a product, it may limit the approved indications for use for the product; require that contraindications, warnings or precautions be included in the product labeling; require that post-marketing studies, including Phase 4 clinical trials, be conducted to further assess the drug’s safety after licensure; require testing and surveillance programs to monitor the product after commercialization; or impose other conditions, including distribution restrictions or other risk management mechanisms, which can materially affect the potential market and profitability of the product. As a condition of BLA licensure, the FDA may require a risk evaluation and mitigation strategy (REMS) to help ensure that the benefits of the biological product outweigh the potential risks. REMS can include medication guides, communication plans for healthcare professionals and elements to assure safe use (ETASU). ETASU can include, but are not limited to, special training or certification for prescribing or dispensing, dispensing only under certain circumstances, special monitoring and the use of patient registries. The requirement for a REMS can materially affect the potential market and profitability of the drug. Moreover, product licensure may require substantial post approval testing and surveillance to monitor the drug’s safety or efficacy. Once granted, product licenses may be withdrawn if compliance with regulatory standards is not maintained, or problems are identified following initial marketing.

The FDA may prevent or limit further marketing of a product based on the results of post-market studies or surveillance programs. Changes to some of the conditions established in an approved application, including changes in indications, labeling, or manufacturing processes or facilities, require submission and FDA approval, as applicable, of a new BLA or supplement before the change can be implemented. A BLA supplement for a new indication typically requires similar non-clinical and CMC data to that in the original application, and the FDA uses the same procedures and actions in reviewing supplements as it does in reviewing BLAs.

Post-Licensure FDA Requirements

Following approval of a new product, the manufacturer and the approved product are subject to continuing regulation by the FDA, including, among other things, monitoring and record keeping activities, reporting of adverse experiences, complying with promotion and advertising requirements, which include restrictions on promoting products for unapproved uses or patient populations (known as “off-label use”) and limitations on industry sponsored scientific and educational activities. Although physicians may prescribe legally available products for off-label uses, manufacturers may not market or promote such uses. Prescription drug and biologic promotional materials must be submitted to the FDA in conjunction with their first use. Further, if there are any modifications to the biologic, including changes in indications, labeling or manufacturing processes or facilities, the applicant may be required to submit and obtain FDA approval of a new BLA or sBLA, which may require the development of additional data or preclinical studies and clinical trials.

The FDA may also place other conditions on approvals including the requirement for a REMS to assure the safe use of the product. If the FDA concludes a REMS is needed, the sponsor of the BLA must submit a proposed REMS. The FDA will not approve the BLA 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. Product approvals may be withdrawn for non-compliance with regulatory standards or if problems occur following initial marketing.

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FDA regulations require that products be manufactured in specific facilities and in accordance with cGMP regulations. We rely, and expect to continue to rely, on third parties for the production of clinical and commercial quantities of our products in accordance with cGMP regulations. These manufacturers must comply with cGMP regulations that require, among other things, quality control and quality assurance, the maintenance of records and documentation and the obligation to investigate and correct any deviations from cGMP. Manufacturers and other entities involved in the manufacture and distribution of approved drugs or biologics 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, including applicable product tracking and tracing requirements. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain cGMP compliance. The discovery of violations, including failure to conform to cGMP regulations, could result in enforcement actions, and the discovery of post approval problems with a product may result in restrictions on a product, manufacturer or holder of an approved BLA, including recall.

Biosimilars and Reference Product Exclusivity

The Biologics Price Competition and Innovation Act of 2009 (BPCIA) created an abbreviated approval pathway for biological product candidates shown to be highly similar (“biosimilar”) to or interchangeable with an FDA licensed reference biological product. Biosimilarity, which requires there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency, can generally be shown through analytical studies, animal studies, and a clinical study or studies. Interchangeability requires that a product is biosimilar to the reference product, and the product must demonstrate that it can be expected to produce the same clinical results as the reference product in any given patient and, for products that are administered multiple times to an individual, the interchangeable biosimilar and the reference biological product may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biological product. A product shown to be biosimilar or interchangeable with an FDA-approved reference biological product may rely in part on the FDA’s previous determination of safety and effectiveness for the reference product for approval, which can potentially reduce the cost and time required to obtain approval to market the product. Complexities associated with the larger, and often more complex, structures of biological products, as well as the processes by which such products are manufactured, pose significant hurdles and have slowed implementation of the BPCIA by the FDA.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of reference product exclusivity, another company may obtain FDA licensure and market a competing version of the reference product if the FDA approves a full BLA for the competing product containing that applicant’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of its product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed “interchangeable” by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law.

The BPCIA is complex and continues to be interpreted and implemented by the FDA. In addition, government proposals have sought to reduce the 12-year reference product exclusivity period. Other aspects of the BPCIA, some of which may impact the BPCIA exclusivity provisions, have also been the subject of recent litigation. As a result, the ultimate implementation of the BPCIA remains subject to significant uncertainty.

Patent Term Extension

Depending upon the timing, duration, and specifics of the FDA approval and BLA licensure of the use of product candidates, some U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. The patent term restoration period is typically one-half the time between the effective date of an IND and the submission date of a BLA, plus the time between the submission date and approval of that application. The total patent term after the extension may not exceed 14 years from the product date of product licensure. Only one patent applicable to a licensed biological product is eligible for extension and the application for the extension must be submitted prior to the expiration of the patent and within 60 days of the product’s approval. The U.S. Patent and Trademark Office, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. Some, but not all, foreign jurisdictions possess patent term extension or other additional patent exclusivity mechanisms that may be more or less stringent and comprehensive than those of the United States.

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Other Regulatory Matters

Manufacturing, sales, promotion, and other activities of product candidates following product approval, where applicable, or commercialization are also subject to regulation by numerous regulatory authorities in the U.S. in addition to the FDA, which may include the Centers for Medicare & Medicaid Services (CMS), other divisions of the Department of Health and Human Services, the Department of Justice, the Drug Enforcement Administration, the Consumer Product Safety Commission, the Federal Trade Commission, the Occupational Safety & Health Administration, the Environmental Protection Agency, and state and local governments and governmental agencies.

Numerous state, federal and foreign laws and regulations govern the collection, dissemination, use, access to, privacy and security of personal information (including health-related information). Such laws and regulations that could apply to our operations or the operations of our partners include health information privacy and security laws (HIPAA), federal and state consumer protection laws and regulations (Section 5 of the Federal Trade Commission Act), state privacy laws, data breach notification laws, and the EU General Data Protection Regulation (GDPR).

In addition to regulations in the United States, we will be subject to a variety of foreign regulations governing clinical trials and commercial sales and distribution of our product candidate to the extent we choose to sell any products outside of the United States. Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities and, if required, from independent ethics committees in foreign countries before we can commence clinical trials as well as regulatory approvals prior to marketing the product candidate in those countries. The approval processes vary from country to country and the time may be longer or shorter than that required for FDA approval. The requirements governing the conduct of clinical trials, product licensing, pricing and reimbursement vary greatly from country to country. As in the United States, post approval regulatory requirements, such as those regarding product manufacture, marketing, or distribution would apply to any product that is approved outside the United States.

Any drug candidates that we develop must be approved by the FDA before they may be legally marketed in the United States and by the appropriate foreign regulatory agency before they may be legally marketed in those foreign countries. Generally, our activities in other countries will be subject to regulation that is similar in nature and scope as that imposed in the United States, although there can be important differences. Additionally, some significant aspects of regulation in the European Union (EU) are addressed in a centralized way, but country-specific regulation remains essential in many respects.

Healthcare and Data Privacy Regulation

Federal and state healthcare laws and regulations, including fraud and abuse and health information privacy and security laws, also govern our business. These laws and regulations 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.

Although we do not currently have any products on the market, in addition to FDA restrictions on marketing of pharmaceutical products, we are also subject to healthcare statutory and regulatory requirements and enforcement by the U.S. federal and state governments. Pharmaceutical companies and their products are subject to extensive regulation and enforcement. These laws include, without limitation:

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the federal Anti-Kickback Statute, a criminal statute which prohibits, among other things, persons and entities from knowingly and willfully soliciting, offering, paying, receiving or providing any remuneration (including any kickback, bribe, or certain rebate), directly or indirectly, overtly or covertly, in cash or in kind, to induce or reward, or in return for, either the referral of an individual for, or the purchase, order or recommendation of, any good or service, for which payment may be made, in whole or in part, under a federal healthcare program such as Medicare and Medicaid; a person or entity need not have actual knowledge of the federal Anti-Kickback Statute or specific intent to violate it in order to have committed a violation;

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the federal civil and criminal false claims laws, including the civil False Claims Act (the FCA), which prohibit individuals or entities from, among other things, knowingly presenting, or causing to be presented, to the federal government, claims for payment or approval that are false, fictitious or fraudulent; knowingly making, using, or causing to be made or used, a false statement or record material to a false or fraudulent claim or obligation to pay or transmit money or property to the federal government; or knowingly concealing or knowingly and improperly avoiding or decreasing an obligation to pay money to the federal government;

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manufacturers can be held liable under the FCA even when they do not submit claims directly to government payors if they are deemed to “cause” the submission of false or fraudulent claims. In addition, the government may assert that 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. The FCA also permits a private individual acting as a “whistleblower” to bring actions on behalf of the federal government alleging violations of the FCA and to share in any monetary recovery;

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the federal civil monetary penalties laws, which impose civil fines for, among other things, the offering or transfer or remuneration to a Medicare or state healthcare program beneficiary if the person knows or should know it is likely to influence the beneficiary’s selection of a particular provider, practitioner, or supplier of services reimbursable by Medicare or a state health care program, unless an exception applies;

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the federal criminal statute enacted under HIPAA, which imposes criminal and civil liability for knowingly and willfully executing a scheme, or attempting to execute a scheme, to defraud any healthcare benefit program, including private payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, willfully obstructing a criminal investigation of a healthcare offense, or falsifying, concealing or covering up a material fact or making any materially false statements in connection with the delivery of or payment for healthcare benefits, items or services. Similar to the federal Anti-Kickback Statute, a person or entity need not have actual knowledge of the statute or specific intent to violate it in order to have committed a violation;

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HIPAA, as amended, and the respective implementing regulations, which imposes, among other things, specified requirements on covered entities and their business associates relating to the privacy and security of individually identifiable health information including mandatory contractual terms and required implementation of technical safeguards of such information;

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the federal Physician Payments Sunshine Act, which requires manufacturers of drugs, devices, biologics, and medical supplies for which payment is available under Medicare, Medicaid, or the Children’s Health Insurance Program, to monitor and report annually certain transfers of value made to U.S.-licensed physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), physician assistants, nurse practitioners, clinical nurse specialists, certified registered nurse anesthetists, anesthesiologist assistants, certified nurse midwives, and U.S. teaching hospitals, as well as ownership and investment interests held by U.S.-licensed physicians and their immediate family members; and

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analogous state and foreign laws and regulations, such as state anti-kickback and false claims laws, which may apply to sales or marketing arrangements and claims involving healthcare items or services reimbursed by non-governmental third party payors, including private insurers, and may be broader in scope than their federal equivalents; state and foreign laws that require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government or otherwise restrict payments that may be made to healthcare providers; state and foreign laws that require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers, and restrict marketing practices or require disclosure of marketing expenditures and pricing information; state and local laws that require the registration of pharmaceutical sales representatives; and state and foreign laws that govern the privacy and security of health information in some circumstances.

Violations of any of these laws or any other applicable laws or regulations may result in significant penalties, including, without limitation, administrative, civil, and criminal penalties, damages, fines, disgorgement, the curtailment or restructuring of operations, integrity oversight and reporting obligations to resolve allegations of noncompliance; exclusion from participation in federal and state healthcare programs, such as Medicare and Medicaid; and imprisonment. Ensuring business arrangements comply with applicable healthcare laws, as well as responding to possible investigations by government authorities, can be time- and resource-consuming and can divert a company’s attention from its business.

Coverage and Reimbursement

Sales of any pharmaceutical product depend, in part, on the extent to which such product will be covered by third party payors, such as federal, state, and foreign government healthcare programs, commercial insurance and managed healthcare organizations, and the level of reimbursement for such product by third party payors. Decisions regarding the extent of coverage and amount of reimbursement to be provided are made on a payor-by-payor basis. These third party payors are increasingly reducing coverage and reimbursement for healthcare items (including drugs) and services. Moreover, for products administered under the supervision of a physician, obtaining coverage and adequate reimbursement may be particularly difficult because of the higher prices often associated with such drugs. Additionally, separate reimbursement for the product itself may or may not be available. Instead, the hospital or administering physician may be reimbursed only for providing the treatment or procedure in which our product is used. Decreases in third party reimbursement for any drug product or a decision by a third party payor not to cover a product could reduce physician usage and patient demand for the product and also have a material adverse effect on sales.

Healthcare Reform

The U.S. and some foreign countries are considering proposals or have enacted legislative and regulatory changes to the healthcare system that could affect our ability to sell our products profitably. Among policy makers and payers in the U.S. and elsewhere, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and/or expanding access.

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For example, in 2010, the U.S. enacted the ACA, which among other things, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; extended the Medicaid Drug Rebate program to utilization of prescriptions of individuals enrolled in Medicaid managed care organizations; subjected manufacturers to new annual fees and taxes for certain branded prescription drugs; and provided incentives to programs that increase the federal government’s comparative effectiveness research. Current laws, as well as other healthcare reform measures that may be adopted in the future, may result in more rigorous coverage criteria and additional downward pressure on the price for any approved products.

Since the enactment of the ACA, there have been, and continue to be, numerous legal challenges and Congressional actions to repeal and replace provisions of the law. For example, with enactment of the Tax Cuts and Jobs Act of 2017 (TCJA), Congress repealed the “individual mandate.” The repeal of this provision, which requires most Americans to carry a minimal level of health insurance, became effective in 2019. Further, on June 17, 2021, the U.S. Supreme Court dismissed a judicial challenge to the ACA brought by several states without specifically ruling on the constitutionality of the ACA. Litigation and legislation over the ACA are likely to continue, with unpredictable and uncertain results.

In August 2022, former President Biden signed the Inflation Reduction Act of 2022 (IRA), which introduced substantial changes to drug pricing, reimbursement and access support in the U.S., including enabling CMS to establish a “maximum fair price” for a fixed number of high expenditure pharmaceutical and biological products covered under Medicare Parts B and D following a price negotiation process with CMS (the Medicare Drug Price Negotiation Program). The IRA contains a limited exception for small biotech drug manufacturers, which applies on a drug-specific basis, and qualifying drugs will be exempt from possible pricing negotiation through 2028 and eligible for a lower limit (i.e., a price floor) on the potential maximum fair price in 2029 and 2030, if the manufacturers of those drugs continue to qualify each year (small biotech exception). Separately, in November 2023, CMS released final guidance on another program, the Medicare Part D Manufacturer Discount Program (Part D Discount Program), which will require manufacturers to take on more of the beneficiary cost previously subsidized by the federal government through the application of increased drug discounts. The IRA also imposes additional rebates for certain Part B and Part D drugs where relevant pricing metrics associated with the products increase faster than inflation. However, it is unclear how the IRA will be effectuated or changed under the new Trump Administration and the degree of impact that the IRA will ultimately have upon our business similarly remains unclear.

At the state level, legislatures and regulatory agencies have increasingly passed legislation and implemented regulations designed to control pharmaceutical and biotherapeutic product pricing, including restrictions on pricing or reimbursement at the state government level, limitations on discounts to patients, advance notices of price increases, marketing cost disclosure and transparency measures, and, in some cases, policies to encourage importation from other countries (subject to federal approval) and bulk purchasing. These laws may affect our sales, marketing, and other promotional activities by imposing administrative and compliance burdens on us. In addition, given the lack of clarity with respect to these laws and their implementation, our reporting actions could be subject to the penalty provisions of the pertinent state and federal authorities.

Employees and Human Capital Management

Our values of “Be Clever,” “Be of Service,” “Be Gutsy,” “Be Tenacious,” and “Be You,” are the foundation of our organization and drives our mission to improve the quality of life for patients and their families.

We believe that our continued success is directly due to the commitment, engagement and performance of our employees. We strive to attract and retain experienced operators, oncology experts, clinicians, and biopharma veterans with deep market knowledge and insights with an uncompromising vision of delivering solutions for patients. In order to achieve this, we provide an inclusive and empowering work environment, foster a culture that reward performance and leadership skills, and by offering competitive compensation and benefits programs.

Employees

As of March 20, 2026, we had 56 full-time permanent employees. Of these employees, 80% were engaged in research and development activities and 46% had advanced degrees including Ph.D., M.D., M.B.A. and J.D. More than half of our workforce is comprised of women. None of our employees are represented by a labor union or covered by a collective bargaining agreement. We consider our relationship with our employees to be good.

Culture and Employee Engagement

We place a high value in the experience and expertise of our team, to foster our culture of innovation. Our employees are guided by our Code of Conduct, which sets basic requirements for business conduct and serves as a foundation for our policies, procedures and guidelines, all of which provide additional guidance on expected employee behaviors.

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Hiring & Retention Risk

We compete with biotechnology and pharmaceutical companies for qualified personnel, particularly in clinical development, regulatory affairs and technical operations. We may not be able to attract or retain personnel on acceptable terms or in a timely manner, which could affect our ability to execute our development strategy.

Compensation, Benefits and Ongoing Professional Development

Drug development is a complex endeavor which requires deep expertise and experience across a broad array of disciplines. Biotechnology and pharmaceutical companies both large and small compete for a limited number of qualified applicants to fill specialized positions. As part of our total rewards philosophy, we offer competitive compensation and benefits to attract and retain top talent.

We are committed to fair and equitable treatment in our compensation and benefits for employees at all levels. We provide our employees with compensation packages that include competitive base salaries, incentive bonuses, and new hire and long-term incentive equity awards. We believe that providing employees with the opportunity to earn ownership interest in the company encourages employees to act in our long-term best interests, aligns the interests of our stockholders with our employees, and further strengthens the level of employee engagement. Employees can also participate in our Employee Share Purchase Plan (ESPP) which provides our employees with an opportunity to purchase shares of our common stock at a discount.

Our total rewards offerings also include an array of programs to support our employees' financial well-being, including retirement savings programs with matching contributions for eligible employees, health and welfare benefits, and paid time off. We have also created a flexible work policy to allow our employees to work remotely. For our facility-dependent employees, including those needed to maintain our research and development activities, we implemented comprehensive safety protocols designed to ensure a healthy environment.

We also provide reimbursement and time for employees to attend professional development courses ranging from technical training, competency-based workshops, and leadership development programs. Direct managers also take an active role in identifying individualized development plans to assist their employees in realizing their full potential and creating opportunities for promotions and added responsibilities that enhance the engagement and retention of our workforce. We are committed to maintaining and increasing our investment in our workforce as we grow, including improvements in the way we hire, develop, motivate and retain employees.

Board of Directors Oversight

Our Board of Directors (the Board) recognizes the critical importance of our team and innovative work environment that is centered around a values-based culture. Our Board meets regularly with management to discuss issues impacting our employees, and to focus on ways to support our workforce. Our focus on culture comes from our Board and flows throughout our company. In evaluating our Chief Executive Officer and management team, significant emphasis is placed on their contributions to our overall culture.

Our Board’s Compensation Committee is responsible for reviewing with management our human resources activities, which include, among other things, matters relating to employee development, management and engagement, pay equity, and our demographics.

Our Board’s Nominating and Corporate Governance Committee is responsible for developing and recommending to the Board any company program relating to corporate responsibility and sustainability, including environmental, social and governance matters. The Board receives periodic updates regarding workforce planning and organizational capability.

Corporate Information

We were incorporated in the state of Delaware on June 11, 2018, and launched with our first employee and Series A funding in July 2019. Our principal executive offices are located at 321 Harrison Avenue, Boston, MA 02118, and our telephone number is (617) 453-3596. Our website address is www.pyxisoncology.com. Our common stock is listed on The Nasdaq Global Market under the ticker symbol “PYXS.”

The information in, or that can be accessed through, our website is not a part of this Annual Report on Form 10-K. Our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 12(a) or 15(d) of the Exchange Act are available, free of charge, on or through our website as soon as reasonably practicable after such reports and amendments are electronically filed with or furnished to the U.S. Securities and Exchange Commission (SEC). The SEC maintains an Internet site that contains, reports, proxy and information statements and other information regarding our filings at sec.gov. The contents of these websites are not incorporated into this filing. Further, references to the URLs for these websites are intended to be inactive textual references only.

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