NASDAQ: APVO

Our ADAPTIR and ADAPTIR-FLEX platforms are designed to generate monospecific and multi-specific antibody candidates capable of enhancing the human immune system against cancer cells. Both are modular platforms, which give us the flexibility to potentially generate immunotherapeutic candidates with a variety of mechanisms of action. Multi-specifics are designed to help the immune system find and attack cancer. This flexibility in design allows us to generate novel therapeutic candidates that may provide effective strategies against difficult-to-treat, as well as, advanced forms of cancer. We have successfully designed and constructed numerous therapeutic candidates based on our ADAPTIR platform, which is designed to generate monospecific and bispecific immunotherapeutic proteins that specifically bind to one or more targets. This allows for the development of bispecific therapeutic molecules which may have structural and functional advantages over monoclonal antibodies. We have also developed preclinical candidates based on the ADAPTIR-FLEX platform which are advancing in our pipeline. The structural differences of

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ADAPTIR and ADAPTIR FLEX molecules over monoclonal antibodies allow for the development of immunotherapies that are designed to engage immune effector cells and disease targets to produce signaling responses that modulate the immune system to kill tumor cells. We believe we are skilled at candidate generation, validation, and subsequent preclinical and clinical development.

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STRATEGY

We seek to grow our business by, among other things:

Advancing our lead clinical blood cancer candidate, mipletamig, through clinical development to evaluate its therapeutic potential alone and in combination with other therapies. Based on the positive results from our Phase 1 dose escalation and dose expansion studies, we are conducting a dose optimization Phase 1b/2 trial, RAINIER, in frontline AML patients who are receiving a combination of mipletamig and the standard of care (venetoclax + azacitidine) for patients who are unfit for intensive chemotherapy to assess safety and efficacy of mipletamig and to determine a recommended Phase 2 dose (RP2D). Positive initial results from the frontline RAINIER trial show continued favorable efficacy and safety outcomes better than those observed in the completed dose expansion phase of the trial. These results have shown a strong remission rate across all cohorts. No cytokine release syndrome has been observed in frontline patients to date.

Advancing our lead solid tumor candidate, ALG.APV-527, developed in partnership with Alligator Bioscience AB (Alligator), in the clinic. Aptevo and Alligator continue to investigate ALG.APV-527 for the treatment of multiple solid tumor types with 5T4-tumor expressing antigens. The dose escalation trial, which included nineteen patients across five cohorts showed that 58% of patients achieved a best response of stable disease. Positive safety (no liver toxicity, a common and potentially serious side effect associated with similar treatments), tolerability, and clinical activity. ALG.APV-527 targets the 4-1BB co-stimulatory receptor (on T lymphocytes and NK cells) and 5T4 (solid tumor antigen) and is designed to promote anti-tumor immunity. Aptevo believes this compound has the potential to be clinically important because 4-1BB can stimulate tumor-specific T cells and NK cells involved in tumor control, making 4-1BB a particularly compelling target for cancer immunotherapy.

Advance our multi-specific antibody pipeline across both clinical and preclinical programs, with particular emphasis on our CD3-based portfolio, where emerging clinical experience supports the potential for a differentiated safety profile. This foundation, demonstrated by mipletamig, informs the continued development of additional CD3-containing candidates built on our unique and proprietary use and application of CRIS-7–derived binding domain utilizing our ADAPTIR and ADAPTIR-FLEX platforms. We are progressing a broad set of programs directed at well-validated tumor antigens and immune pathways, including PSMA, Nectin-4, CD40, PD-L1, 4-1BB, and OX40, as we advance assets through preclinical and IND-enabling activities.

Development of novel bispecific and multi-specific proteins for the treatment of cancer using our ADAPTIR and ADAPTIR-FLEX platforms. We have expertise in molecular and cellular biology, immunology, oncology, pharmacology, translational sciences, antibody engineering and the development of protein therapeutics. This includes target validation, preclinical proof-of-concept, cell line development, protein purification, bioassay and process development and analytical characterization. We focus on product development using our ADAPTIR and ADAPTIR-FLEX platforms. We plan to generate additional monospecific, bispecific, and multi-specific protein immunotherapies for development, potentially with other collaborative partners, to exploit the potential of the ADAPTIR and ADAPTIR-FLEX platforms. Our platforms can also support combination therapy in emerging modalities, including antibody-drug conjugates (ADC), radiopharmaceuticals, and potentially other modalities. We will select novel candidates that have the potential to demonstrate proof of concept early in development. We expect to continue to expand the ADAPTIR and ADAPTIR-FLEX product pipelines to address areas of unmet medical need. Bispecific therapeutics are increasingly recognized as potent anti-cancer agents. Information from FDA.gov shows that 15 bispecifics have been approved to date. Of these, 11 were approved as cancer treatments. Additionally, more than 100 bispecific drug candidates are currently in clinical development in the US. We believe our candidates in development and our future molecules derived from our ADAPTIR and ADAPTIR-FLEX platforms will be highly competitive in the market as they are rationally designed for safety and tolerability as well as efficacy.

Establishing collaborative partnerships to broaden our pipeline and provide funding for research and development. We intend to pursue collaborations with other biotechnology and pharmaceutical companies, academia, and non-governmental organizations to advance our product portfolio.

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PRODUCT CANDIDATES AND PLATFORM TECHNOLOGY PIPELINE

Product Portfolio

Our current product candidate pipeline is summarized in the table below:

Product Candidates

Our pipeline includes investigational clinical and preclinical stage anti-cancer drug candidates with potential for treating hematologic malignancies and solid tumors.

Mipletamig bispecific AML candidate

Mipletamig is a bispecific ADAPTIR that is designed to engage CD3 and CD123 to redirect T cells to destroy leukemia cells expressing the target CD123 molecule on their surface. This antibody-like recombinant protein therapeutic candidate is designed to simultaneously engage both leukemia cells and T cells of the immune system. T cells become activated via CD3 when crosslinked to CD123 resulting in the destruction of CD123-expressing cells. Importantly, CD123 is not only expressed on the leukemic blast cells but is also expressed on leukemic stem cells, making it an especially meaningful therapeutic target. Mipletamig has been engineered using our proprietary ADAPTIR platform technology and is uniquely designed to reduce the likelihood and severity of cytokine release syndrome (CRS). This differentiated safety profile can be attributed to our unique and proprietary use and application of the CRIS 7-derived CD3 pathway.

Mipletamig has received orphan drug designation (orphan status) for the treatment of AML from the U.S. Food and Drug Administration (FDA).

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We have completed a Phase 1a dose escalation trial to evaluate mipletamig as a single agent monotherapy treatment and a Phase 1b dose expansion clinical trial to evaluate mipletamig in adult patients with AML as monotherapy as well as in combination with current standard-of-care therapies. Additionally, our current RAINIER dose optimization trial is underway in frontline patients receiving mipletamig in combination with the standard-of-care for patients who are venetoclax naïve and unfit for intensive chemotherapy (venetoclax and azacitidine). We expect the trial to conclude in the second half of 2026.

Monotherapy Efficacy and Safety Data

Mipletamig was explored as a single agent monotherapy treatment in the Phase 1a dose escalation trial as well as in cohorts 3 and 5 of the Phase 1b dose expansion trial. We saw the following clinically meaningful results in a heterogenous AML patient population from our monotherapy efforts:

Phase 1a Dose Escalation Trial

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Approximately 1/2 of evaluable monotherapy patients in the dose escalation trial (49%) experienced clinical benefit (CR, CRi MLFS, PR or SD; 19 of 39 evaluable AML patients).

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Over 1/3 of evaluable monotherapy patients (36% - 12 of 33 evaluable patients) experienced substantial AML blast reductions (range of 17% to 88% reduced) compared to baseline. These results show clinical activity with single agent mipletamig in a heterogenous patient population and would not be achieved without the presence of an active drug.

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Two complete remissions were observed, one at the 12 mcg and the other at the 18 mcg dose level, which aligned with the two largest percent reductions in AML blast counts.

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Common adverse events in relapsed and refractory patients included cytokine release syndrome (26%) and infusion-related reactions (IRR, 30%), with most events being low-grade and manageable in the clinic.

Monotherapy Patients Included in Phase 1b Dose Expansion Trial

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In Cohort 3, 100% of patients experienced clinical benefit: of four evaluable patients who had AML and were treated with mipletamig as a single agent, one patient achieved MLFS and three achieved SD as their best overall response.

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In Cohort 5 (CR upon enrollment based on design criteria), two enrolled patients (N=2) maintained their disease status as best overall response compared to baseline for two months and three months.

In addition, in Cohort 2 of the Phase 1b dose expansion trial (N=19), one patient completed 4 cycles of the triple combination of venetoclax + azacitidine + mipletamig per study protocol and then received mipletamig only as single agent administration (monotherapy treatment) for the last 4 cycles. This patient maintained their remission status during the last 4 cycles (about 4 months) while receiving mipletamig only as a single agent administration before moving to another therapy as required by the study protocol.

These results clearly demonstrate clinical activity of mipletamig as a single agent establishing a strong foundation for combination strategies. This demonstrated in monotherapy efficacy data in the dose escalation expansion studies.

Combination Efficacy and Safety Data (in Combination with Venetoclax + Azacitidine)

Phase 1b Dose Expansion Trial

Mipletamig was generally well tolerated, with the highest response rate of 82% composite clinical remission (Composite CR) and 73% complete remission/complete remission with incomplete hematologic recovery (CR/CRi) observed in Cohort 2 in venetoclax naïve patients, where we saw 91% clinical benefit.

A potential complication associated with treatment using CD3 T cell-engaging bispecifics is a systemic inflammatory response known as CRS. CRS may occur within minutes to hours after infusion of the T cell-engager or emerge as a delayed onset complication after several days. Clinical manifestations of CRS may range from mild to severe including hypotension, hypoxia, and uncontrolled systemic inflammatory response with circulatory collapse, vascular leakage, peripheral and/or pulmonary edema, renal failure, cardiac dysfunction, heart failure, and fatal multiorgan system failure.

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CRS cases occurred in some mipletamig patients in both the dose escalation and the dose expansion phases. Most CRS cases were mild to moderate and clinically manageable without having to interrupt treatment. Mipletamig-treated patients who experienced CRS were effectively treated using standard CRS treatments, which includes the use of tocilizumab and dexamethasone, combined with standard supportive care. These cases were mostly mild and treatable in the clinic and outperformed the benchmarks from literature. The differentiated safety profile associated with mipletamig is attributed to our unique and proprietary use and application CRIS 7-derived CD3 binding domain engineered into our ADAPTIR platform.

On November 26, 2019, the FDA granted Orphan Drug Designation for mipletamig to treat acute myeloid leukemia, which grants the Company potential exclusive marketing and development rights, as well as eligibility for market exclusivity upon FDA approval of mipletamig.

The RAINIER Trial (Ongoing)

We believe that the data from the dose expansion supports continued development of mipletamig for frontline patients who are not fit for high intensity chemotherapy and are candidates for the standard of care combination with venetoclax + azacitidine.

RAINIER, a frontline AML study, is a Phase 1b/2 dose optimization, multi-center, multi-cohort, open label study of up to 51 patients (adults aged 18 or older, newly diagnosed with AML who are not eligible for intensive induction chemotherapy) being treated across five dose levels ranging from 9 mcg – 137 mcg in combination with the standard-of-care for this patient type, venetoclax + azacitidine. Phase 1b consists of 28-day cycles of treatment in five sequential cohorts and will be followed by a Phase 2 study that will be informed by the outcomes of the dose optimization portion.

Mipletamig Combined Frontline Patient Clinical Results

Among the evaluable frontline patient population treated to date (N=28), including 24 patients from the RAINIER trial and 4 patients from the completed dose expansion trial, mipletamig in combination with venetoclax and azacitidine has demonstrated:

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100% of frontline patients have remained free of cytokine release syndrome (CRS).

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86% clinical benefit rate.

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79% achieved CR or CRi.

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61% achieved CR.

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55% of patients who achieved CR/CRi had blast reductions that reached the important measurable residual disease-negative level, a result that is typically associated with stronger, more durable responses.

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35% of patients with remissions had the TP53 genetic mutation, a high-risk biomarker typically associated with poor prognosis in AML and for which most treatment options frequently fail.

These clinical data underscore mipletamig’s safety and combinability, potentially offering a superior treatment in the future. This safety profile is particularly important in frontline AML, where tolerability and combinability are essential for treating older patients and/or those with comorbidities.

ALG.APV-527 bispecific solid tumor candidate

ALG.APV-527 is a novel investigational bispecific ADAPTIR candidate, developed in partnership with Alligator Bioscience AB (Alligator), with a mechanism of action designed to simultaneously target 4-1BB (CD137) and 5T4, a tumor antigen overexpressed in several types of solid tumors. 4-1BB is a co-stimulatory receptor on T cells, known to enhance the immune response to cancer through activation of tumor-specific T cells, as well as tumor-killing NK cells, and is believed to be a promising target for new immunotherapeutic approaches. ALG.APV-527 could potentially have utility in the treatment of a broad spectrum of cancers over-expressing the 5T4 tumor antigen on the cell surface, including malignant pleural mesothelioma, non-small cell lung, gastric/gastro-esophageal, head and neck squamous cell carcinoma, pancreatic, renal, ovarian, prostate, breast, cervical, colorectal, endometrial, and bladder cancers.

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4-1BB is a particularly compelling target for cancer immunotherapy. We designed ALG.APV-527 to overcome limitations observed with the 1st generation 4-1BB monospecific antibodies developed by our competitors by improving the specificity to tumor compared to normal tissue. This was achieved through a requirement for 5T4-dependent crosslinking for 4-1BB signaling on T and NK cells within the tumor microenvironment.

The ALG.APV-527 Phase 1 dose escalation trial is a completed multi-center, multi-cohort, open-label dose-escalation trial that includes administration of ALG.APV-527 in up to six escalating dose levels in a 3+3 design*. The trial enrolled adult patients with multiple solid tumor types- likely to express the 5T4 antigen. ALG.APV-527 was administered intravenously once every two weeks. The trial assessed the safety and tolerability, pharmacokinetics, pharmacodynamics and preliminary anti-tumor activity of ALG.APV-527. (*The 3+3 design proceeds in cohorts of three patients treated at increasing dose levels. Dose escalation stops if at least two out of three or six patients experience dose limiting toxicities (DLTs) at that dose level).

Having concluded ALG.APV-527 Phase 1 dose escalation trial, we and our partner Alligator are evaluating next steps for the dose expansion trial.

Clinical Highlights

Safety and Tolerability

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No severe liver toxicity observed, a side effect associated with dose limiting toxicity.

Clinical Activity/Efficacy

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10 of 17 efficacy evaluable patients (59%) achieved stable disease (SD), 4 patients had long term SD of >10 cycles (5 months);

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The longest SD duration was in a breast cancer patient who entered the study with progressive disease, achieved stable disease and remained on study for >11 months. This patient successfully transitioned to a higher dose level twice.

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One colon cancer patient remained on study and in SD for six months.

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One prostate cancer patient in stable disease remained on study and in SD for more than four months.

Evidence of biological activity of ALG.APV-527

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ALG.APV-527 was detected in all evaluable patients. Measured levels of ALG.APV-527 were proportional to the administered dose.

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Analysis of biomarkers in the serum of treated patients including soluble 4-1BB indicate biological activity of ALG.APV-527.

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Analysis of biomarkers in biopsies showed that the tumor-specific target 5T4 was expressed on all evaluable tumors and that T cells were increased in a majority of biopsies following treatment. This data is consistent with the drug’s multi-tumor type utility and immune activation in the tumor microenvironment. These observations are consistent with ALG.APV-527's expected mechanism of action.

APVO603. APVO603 is a preclinical dual agonist bispecific ADAPTIR candidate designed to simultaneously target 4-1BB (CD137) and OX40 (CD134), both members of the TNF-receptor family. Dual targeting of 4-1BB and OX40 provides synergistic co-stimulation of immune cells with the potential to amplify the cytotoxic function of activated T cells and NK cells, potentially leading to robust anti-tumor responses. APVO603’s combined activation of both the 4-1BB and OX40 TNF receptors represents an attractive approach in potentially overcoming the immunosuppressive tumor microenvironment via promoting an important immunological cascade, enhancing T cell activation, prolonging T cell survival, and improving tumor cell killing. Of note, this product candidate is not dependent on any one tumor antigen and has the potential to treat multiple solid tumors. IND-enabling studies continue for APVO603.

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APVO442. APVO442 is a novel bispecific candidate based on the ADAPTIR-FLEX platform technology. APVO442 is engineered to address treatment challenges associated with later stage and castration resistant prostate cancer with its unique design that enables precise tumor targeting while activating the immune system in a controlled manner. The molecule binds to Prostate-Specific Membrane Antigen (PSMA) on prostate cancer cells where it activates T cells within the tumor and enhances targeted tumor cell killing. This is notable because the approach reduces the risk of harm to healthy cells. Preclinical studies have shown that the molecule readily localizes to solid tumors by avoiding unwanted binding to immune cells circulating in the bloodstream. This approach helps the treatment focus on fighting the tumor itself while reducing the risk of widespread side effects, making it both safer and more effective.

APVO711. APVO711 is a bispecific checkpoint inhibitor with added functionality, targets PD-L1 and CD40, and is designed to function to synergistically induce a biological response. This is achieved by simultaneously engaging in two clinically validated immune activating mechanisms: 1) blocking of PD-L1/PD-1 inhibitory pathway and 2) CD40 signaling augments APC maturation resulting in enhanced T cell stimulation. APVO711 is designed to activate CD40 only in the presence of PD-L1 binding for an improved safety profile. The Company believes APVO711 has the potential to positively impact the treatment paradigm of multiple solid tumor types for which there is currently significant unmet medical need.

APVO455. APVO455 is a preclinical Nectin-4 x CD3 bispecific T cell engager designed for tumors such as bladder, breast, NSCLC, and head and neck cancers, where Nectin-4 is highly expressed. Unlike other approaches that restrict activity to acidic tumor environments or rely on activated T cells, APVO455 is designed to avoid binding to or triggering T cell activation in the periphery and do so only in the presence of Nectin-4 positive tumor cells, offering the potential for a broader therapeutic window and more consistent immune activation.

APVO451. APVO451 incorporates trispecific design principles, targeting nectin-4, CD40, and CD3, and is intended for a broad range of solid tumors. This ADAPTIR-FLEX is engineered with a dual mechanism of action designed to overcome the suppressive solid tumor microenvironment. This is accomplished by providing synergistic co-stimulation to antigen presenting cells (APC) via CD40 while simultaneously stimulating T cells via CD3 to directly kill necin-4-expressing tumors. CD40 engagement promotes APC maturation, polarization and cytokine production, which in turn, enhances the antitumor response from T cells. Early data demonstrate potent, anti-cancer activity despite tumor suppressive influences (PD-L1-expressing tumors and immunosuppressive myeloid cells), increasing the opportunity to address critical unmet needs for multiple solid tumors. Demonstration of the in vitro efficacy was recently presented at the Society of Immunotherapy of Cancer (SITC) conference. Preclinical studies are ongoing.

APVO452. APVO452 targeting PSMA, CD40, and CD3, is designed similarly to APVO451 but with the intent to address prostate cancers via PSMA targeting. In preclinical studies, this trispecific approach was able to effectively kill PSMA-expressing tumor cells and, importantly for safety, only activated the immune system when tumor cells were present. As the mechanism of action intended, APVO452 promoted both APC co-stimulation and T cell killing of tumor. Preclinical studies continue.

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PLATFORM TECHNOLOGIES

Platform Technologies

ADAPTIR and ADAPTIR-FLEX Platform Technologies. The ADAPTIR and ADAPTIR-FLEX platform technologies can be used to produce monospecific, bispecific, and multi-specific immunotherapeutic proteins. These protein candidates bind to one or more targets on tumor cells, immune cells, or other cells in circulation to either amplify, suppress, or otherwise regulate the body’s defense mechanisms to treat cancer. We focus on developing drugs for treatment of oncology indications, but also may pursue other indications, including inflammatory diseases. We believe we are well positioned for the development of anti-cancer therapeutics, which are antibody-based molecules that can bind one or more targets of therapeutic interest, utilizing our innovative ADAPTIR (modular protein technology) and ADAPTIR-FLEX platform technologies. This allows us to take an innovative approach to cancer immunotherapy or treatment of other diseases.

Our position in the market is further solidified by a growing body of safety, tolerability, and clinical activity data for our clinical candidates, where results suggest our therapies demonstrate competitive, and in some cases superior, profiles compared to industry benchmarks. These outcomes reinforce our confidence in the potential impact of our therapies, positioning us as a leader in the bispecific oncology space.

Information from FDA.gov shows that 15 bispecifics have been approved to date. Of these, 11 were approved as cancer treatments.

ADAPTIR and ADAPTIR-FLEX molecules are similar to antibodies; they can exhibit similar therapeutic properties to an antibody but can be easily modified to either eliminate or incorporate activities, while maintaining a similar size, stability, half-life and manufacturing advantages of a monoclonal antibody. The ADAPTIR molecules are single-chain polypeptides comprising customized elements, including a protein domain that binds to one or more targets connected to the hinge domain and a set of antibody constant domains known as the fragment crystallizable region, or Fc region of a human antibody. A second protein binding domain can be connected to the Fc region using a linker. The antibody Fc region can elicit an immune response by binding to the corresponding Fc receptors found

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on various immune cells such as natural killer (NK) cells, and other cells bearing Fc receptors to mediate antibody-dependent cell cytotoxicity resulting in killing the target. With the ADAPTIR platform, the Fc region can be modified to enhance or eliminate these functions. Incorporation of the Fc region into the ADAPTIR platform also provides for an extended serum half-life by engaging recycling via the neonatal Fc receptor or FcRn. A longer serum half-life could potentially reduce dosing frequency and dose quantity. The ADAPTIR-FLEX molecules are comprised of at least two polypeptides that are comprised of customized elements similar to ADAPTIR candidates. The Fc region of these molecules can be modified to enable formation of a stable heterodimer. These candidates have similar mutations in the Fc region as ADAPTIR candidates to enable or eliminate binding to Fc receptors but retaining binding and recirculation to FcRn to provide for an extended serum half-life.

The ADAPTIR platform technology enables the design of both monospecific and bispecific bi-valent protein therapeutics.

Bispecific ADAPTIR molecules are similar in structure to monospecific ADAPTIR molecules, with the exception that they have two customized target binding domains on the ends of the Fc region. We have created several bispecific molecules that are able to redirect T cell cytotoxicity (RTCC). T cells are white blood cells that fight infections and tumor cells. RTCC ADAPTIR molecules are designed to activate T cells to specifically kill tumor cells. The RTCC ADAPTIR does so by binding to a common T cell component CD3, a receptor complex that activates T cells, when engaging a specific tumor antigen on a specific tumor via the second binding domain, thereby activating the T cell to kill the tumor cell. Additional immune stimulatory/inhibitory domains have been introduced (4-1BB, OX40, PD-L1 and CD40 to tailor the bispecific to an ideal mechanism of action.

Our ADAPTIR-FLEX platform technology extends advantages of ADAPTIR technology to create protein therapeutics with varied specificity and valency and potentially new modes of action.

These molecules are composed of two different polypeptides that form a hetero-dimer through modifying specific sequences in the Fc region of each polypeptide. Each end of the polypeptide may contain one or two different binding domains, enabling the ADAPTIR-FLEX molecules to bind up to four targets. In addition, the ADAPTIR-FLEX platform can be used to modify the valency of binding to each target, which means it can bind a target, through one binding domain or through multiple binding domains, to a specific target to enable modifying the strength of binding to a specific target. In 2026, trispecifics were introduced using our ADAPTIR-FLEX platform, adding to the breadth of our pipeline and extending our capabilities to target hard-to-treat solid tumors with immune suppressive characteristics.

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We believe that ADAPTIR and ADAPTIR-FLEX are promising platform technologies within the rapidly growing field of immuno-oncology therapeutics. The structural differences between ADAPTIR and ADAPTIR-FLEX molecules and monoclonal antibodies allow for the development of new immunotherapies that engage disease targets in a novel manner and produce a unique signaling response. By customizing the binding domains of our molecules, we can select the desired potency, half-life, toxicity and stability/manufacturability. We have the potential to develop products with mechanisms of action including, but not limited to, redirected T cell cytotoxicity (RTCC), modulating signals through immunostimulatory or immunoinhibitory receptors and targeted cytokine delivery. We believe we can expand our ADAPTIR and ADAPTIR-FLEX platforms to generate monospecifics, bispecifics, or multi-specifics that target tumor antigens in combination with co-stimulatory molecules, including TNF-Receptor family members and other activating or inhibitory signaling receptors. We believe the ADAPTIR and ADAPTIR-FLEX platform technologies may prove to have advantages over other immunotherapies and other bispecific T cell engaging technologies. In preclinical studies, our data indicates that mipletamig, a RTCC ADAPTIR bispecific that binds CD123, may have high potency and activity at low doses with reduced cytokine release compared to other bispecifics targeting the same tumor antigen and CD3. The ADAPTIR and ADAPTIR-FLEX monospecifics, bispecifics, and multi-specifics can be produced using standard manufacturing practices. Further clinical and preclinical studies may not confirm the anticipated benefits of this platform.

Our ADAPTIR and ADAPTIR-FLEX platform intellectual property (IP) portfolio consists of IP that we solely own and control, with the exception of non-exclusive licenses to Chinese hamster ovary (CHO) cell lines and related expression systems, and a non-exclusive license to certain transgenic rodents of Open Monoclonal Technology, Inc.’s (OMT) OmniAb platform, which we non-exclusively license from various third parties. See “Intellectual Property” for additional information about the ownership rights to ADAPTIR and ADAPTIR-FLEX platform intellectual property.

Competition

We face, and will continue to face, intense competition from both U.S.-based and foreign producers of both large and small molecule immune oncology products, some of which have lower cost structures, greater access to capital, greater resources for research and development, and sophisticated marketing capabilities. Any product candidate that we successfully develop and commercialize is likely to compete with currently marketed products, as well as other novel product candidates that are in development for the same indications.

Mipletamig: We anticipate that mipletamig would compete with other agents targeting both CD123 and non-CD123 that are in development for the treatment of AML if they are also approved. Competitors clinically developing antibody therapies targeting CD123 include: Affimed, ImmunoGen, Innate Pharma / Sanofi, Macrogenics / Gilead, MD Andersen CC / Xencor, Menarini Group, Molecular Partners / U of Bern, Lava, and Sanofi. Competitors developing non-CD123 antibody therapies include Cullinan, Novartis, Bio-Path, Shattuck Labs, Syros Pharma, Faron Pharma and ALX Oncology. Additionally, there are companies and institutions developing gene and CAR-T therapies that may potentially be competitive with mipletamig.

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ALG.APV-527: This asset targets 4-1BB in a bispecific format when cross-linked with the tumor antigen 5T4. We anticipate that ALG.APV-527 would compete with bispecifics targeting 5T4 and 4-1BB, which are currently in preclinical development such as by Crescendo Biologics. Companies in clinical development with 5T4-targeting drugs include Biotecnol / Chiome Biosciences’ 5T4 x CD3 and a number of anti-drug conjugates (ADC). In addition, other competitors include clinical bispecifics targeting 4-1BB in combination with other targets such as FAP (Boehringer Ingelheim, Molecular Partners / Amgen, and Hoffmann-La Roche). PD-L1 x 4-1BB is currently in Phase 3 clinical development by BioNTech / Genmab and Pieris / Servier / Palvella. Another bispecific targets 4-1BB x HER2, which is in phase 2 clinical development by Pieris for treatment of HER2+ solid tumors.

Furthermore, we face significant competition in the oncology market in general, including from the following: Affimed, AstraZeneca, Bristol Myers Squib, F-Star Biotechnology Ltd., Genentech Inc., (a subsidiary of F. Hoffmann-La Roche Ltd.), Genmab A/S, Gilead Sciences Inc., GlaxoSmithKline plc, ImmunoGen, Inc., Johnson & Johnson, Macrogenics, Inc., Sanofi-Aventis US LLC, Regeneron Pharma, Xencor, Inc. and Zymeworks Biopharmaceuticals, Inc. Additionally, there may be other potential competitors or companies developing competitive products such as ADCs that may not be known to us at this time.

COLLABORATIONS WITH ALLIGATOR BIOSCIENCE

On July 20, 2017, our wholly owned subsidiary Aptevo Research and Development LLC (Aptevo R&D), entered into a collaboration and option agreement (the Collaboration Agreement) with Alligator Bioscience AB, (Alligator), pursuant to which Aptevo R&D and Alligator are collaboratively developing ALG.APV-527, a lead bispecific antibody candidate simultaneously targeting 4-1BB (CD137).

Subject to certain exceptions for Aptevo R&D’s manufacturing and platform technologies, the parties jointly own intellectual property generated in the performance of the development activities under the Collaboration Agreement. Under the terms of the Collaboration Agreement, the parties intend to share revenue received from a third-party commercialization partner equally, or, if the development costs are not equally shared under the Collaboration Agreement, in proportion to the development costs borne by each party.

The Collaboration Agreement also contains several points in development at which either party may elect to “opt-out” (i.e., terminate without cause), including at the completion of the Phase 1a and Phase 1b clinical trials, and, following a termination notice period, cease paying development costs for this product candidate, which would be borne fully by the continuing party. Following an opt-out by a party, the continuing party will be granted exclusive rights to continue the development and commercialization of this product candidate, subject to a requirement to pay a percentage of revenue received from any future commercialization partner for this product, or, if the continuing party elects to self-commercialize, tiered royalties on the net sales of this product by the continuing party ranging from the low to mid-single digits, based on the point in development at which the opt-out occurs. The parties have also agreed on certain technical criteria or “stage gates” related to the development of this product that, if not met, will cause an automatic termination and wind-down of the Collaboration Agreement and the activities thereunder, provided that the parties do not agree to continue.

The Collaboration Agreement contains industry standard termination rights, including for material breach following a specified cure period, and in the case of a party’s insolvency.

INTELLECTUAL PROPERTY

We rely on a combination of patents, trademarks, trade secrets, and nondisclosure and non-competition agreements to protect our proprietary intellectual property and will continue to do so. We own or exclusively license the patents and patent applications in our patent portfolio that support the ADAPTIR-FLEX platform, ADAPTIR platform and pipeline products with the exception of certain cell line rights and other research tools, which we license on a non-exclusive basis. We practice patent life cycle management by filing patent applications to protect new inventions relating to meaningful improvements to our products and related methods. We primarily seek patent protection for inventions that support our products and product candidates, but from time to time, we may seek patent protection for inventions that could, for instance, support a potential business opportunity or block a competitor from designing around our existing patents.

In general, and where possible, we pursue patent protection in countries where we believe there will be a significant market for the corresponding product or product candidate. We generally do not seek patent protection in

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countries where we have reason to believe we would not be able to enforce patents. For instance, we tend to not file in countries that are frequently listed on the Priority Watch List of the Special 301 Report prepared by the Office of the United States Trade Representative, with the exception that we typically file patent applications in China. We may also decide to take a narrower filing approach for secondary and improvement type inventions as compared to inventions that are more foundational to our products. We do not seek patent protection in countries that are on the United Nations (U.N.) list of Least Developed Countries.

The term of protection for various patents associated with, and expected to be associated with, our marketed product and product candidates is typically twenty years from the filing date, but may vary depending on a variety of factors, including 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. The protection afforded by a patent varies on a product-by-product basis and country-to-country basis and depends upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions, the necessity for terminal disclaimers, the availability of legal remedies in a particular country, and the validity and enforceability of the patents.

In some cases, we may decide that the best way to protect our intellectual property is to retain proprietary information as trade secrets and confidential information, rather than to apply for patents, which would involve disclosure of proprietary information to the public. When determining whether to protect intellectual property as a trade secret, we consider many factors including, for instance, our ability to maintain the trade secret, the likelihood that a competitor will independently develop the information, our ability to patent protect the intellectual property and the likelihood we would be able to enforce a resulting patent.

We are a party to a number of license agreements under which we license patents, patent applications, and other intellectual property. These agreements impose various commercial diligence and financial payment obligations on us. We expect to continue to enter into these types of license agreements in the future.

ADAPTIR and ADAPTIR-FLEX Platforms. We protect the ADAPTIR platform technology through a combination of patents and trade secrets. We own all ADAPTIR and ADAPTIR-FLEX platform intellectual property, with the exception that we have licenses to certain intellectual property related to third-party research tools that we use in conjunction with our ADAPTIR platform technology such as cell lines, vectors, expression systems, and transgenic rodents. For instance, we have a non-exclusive commercial license and research license with Lonza Group AG (Lonza) related to its CHO cell lines and vectors. Under our Lonza research license, we have an option to take a license to use the GS System to develop and manufacture therapeutic proteins for our commercial purposes. We also have a non-exclusive license to certain transgenic rodents of OMT’s OmniAb platform.

The initial version of the ADAPTIR platform technology was originally developed by Trubion Pharmaceuticals, Inc. (Trubion) prior to its acquisition by Emergent BioSolutions Inc. (Emergent). A patent family supporting use of unique linkers in the homodimer (a molecule consisting of two identical halves) version of the ADAPTIR platform was invented jointly by Trubion and Wyeth Pharmaceuticals, Inc. (Wyeth) as part of a collaboration between the two companies. Wyeth assigned the rights it had in that platform patent family to Trubion. We subsequently received the rights to the platform patent family upon our spinoff from Emergent.

In order to differentiate our platform inventions from antibodies and other antibody-like constructs that have been publicly disclosed, many of our patents and patent applications are directed to unique aspects or components of our platform such as linkers, targets, or binding domains.

We have patents relating to the ADAPTIR platform issued in the United States, Australia, Canada, Hong Kong, Israel, Japan, Mexico, New Zealand, Russia, Singapore, South Africa and South Korea. We also have applications pending in Brazil. We plan to continue to improve our ADAPTIR platform and to file patent applications on those improvements. Our decision as to where to file any new ADAPTIR improvement inventions will be based in part on the significance of the improvement. If patents issue on the pending ADAPTIR patent applications, the patent term for those patents are estimated to expire between 2027 and 2039. As our ADAPTIR platform technology evolves, we may decide to allow patent applications and patents to expire if they contain claims that are limited to aspects of the platform that are no longer of value to Aptevo.

ADAPTIR-FLEX, our heterodimer platform, is covered by patent application under the Patent Cooperation Treaty (PCT) that we filed in 2021, which was nationalized in 2023 in various countries and territories including the United States, Australia, Brazil, Canada, China, Europe, Israel, Japan, Mexico, New Zealand, Singapore, and South

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Korea. If patents claiming priority to the pending ADAPTIR-FLEX patent application are issued, the resulting patents are estimated to expire in 2041.

We own patent families directed to use of particular binding domains in the ADAPTIR and ADAPTIR-FLEX platforms. For instance, we have some patents that cover the use of an ADAPTIR therapeutic to target CD3. We also have pending patent applications that cover ADAPTIR therapeutics containing our preferred humanized CD3 binding domain polypeptide sequences.

Mipletamig. We nationalized our core patent family, which covers the mipletamig product candidate in various countries and territories including the United States, Australia, Brazil, Canada, China, Colombia, Eurasia, Europe, Hong Kong, India, Indonesia, Israel, Japan, Macau, Malaysia, Mexico, New Zealand, Philippines, Singapore, South Africa, South Korea, Ukraine, and Vietnam.

ALG.APV-527. We co-own with Alligator a patent family corresponding to PCT application PCT/EP2018/069850, which covers the ALG.APV-527 product candidate. In January and February of 2020, this patent family was nationalized in various countries. Aptevo and Alligator also co-own U.S. patent 10,239,949, which relates to protein molecules that specifically bind to 5T4 and/or 4-1BB and U.S. patent 11,312,786, which relates to the 4-1BB binding domain.

In addition to the co-owned assets, Alligator owns a patent family corresponding to PCT application PCT/EP2017/059656, which also covers ALG.APV-527. Aptevo has an exclusive license from Alligator to this patent family for the development of the ALG.APV-527 product candidate.

Preclinical Therapeutic Candidates. We routinely file United States provisional patent applications and/or Patent Cooperation Treaty (PCT) patent applications on our preclinical therapeutic assets when we believe we have sufficient data to support a patent application filing. Aptevo owns pending patent applications for its APVO442, APVO603, and APVO711 therapeutic candidates, which were nationalized in various countries and territories, as well as APVO451, APVO452, AND APVO455 therapeutic candidates.

Trademarks owned by Aptevo Therapeutics Inc. and its subsidiaries. Where possible, we pursue registered trademarks for our marketed products in significant markets. We own trademark registrations and pending applications for the marks: APTEVO THERAPEUTICS, APTEVO BIOTHERAPEUTICS, APTEVO RESEARCH AND DEVELOPMENT, the Aptevo logo, ADAPTIR, and ADAPTIR-FLEX in relevant jurisdictions.

REGULATION

Regulations in the United States and other countries have a significant impact on our product development, manufacturing, and marketing activities. Government authorities in the United States, at the federal, state, and local level, and in other countries, extensively regulate, among other things, the research, development, testing, approval, manufacture, packaging, storage, recordkeeping, labeling, advertising, promotion, distribution, marketing, import, and export of biopharmaceutical products. In addition, sponsors of biopharmaceutical products participating in Medicaid and Medicare are required to comply with mandatory price reporting, discount, and rebate requirements. The processes for obtaining regulatory approvals in the United States and in foreign countries, along with compliance with applicable statutes and regulations, require the expenditure of substantial time and financial resources. In the United States, the FDA regulates biopharmaceutical products under the Federal Food, Drug, and Cosmetic Act, or FDCA, the Public Health Services Act, or PHSA, and their implementing regulations. FDA’s requirements and expectations with respect to product development are constantly evolving.

U.S. Product Development for Therapeutics

The process required by the FDA before a biologic may be marketed in the United States generally involves the following:

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completion of preclinical laboratory tests, animal studies according to Good Laboratory Practices (GLP);

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submission to the FDA of an investigational new drug application (IND), which must become effective before human clinical trials may begin;

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performance of adequate and well-controlled human clinical trials according to Good Clinical Practices, (GCP), to establish the safety and efficacy of the proposed drug or safety, purity and potency of the proposed biologic, for the intended use;

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preparation and submission to the FDA of biologics license application (BLA);

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

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satisfactory completion of an FDA inspection of the manufacturing facility or facilities at which the product, or components thereof, are produced to assess compliance with current Good Manufacturing Practices (cGMP);

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review of the product candidate by an FDA advisory committee, where appropriate and if applicable;

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payment of user fees for FDA review of the BLA (unless a fee waiver applies);

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FDA audits of some clinical trial sites to ensure compliance with GCP; and

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FDA review and approval of the BLA.

Preclinical Testing. Before beginning testing of any compounds with potential therapeutic value in human subjects in the United States, stringent government requirements for preclinical data must be satisfied. Preclinical testing includes both in vitro, or in an artificial environment outside of a living organism, and in vivo, or within a living organism, laboratory evaluation and characterization of the safety and efficacy of a drug and its formulation, as well as its chemistry, pharmacology, and toxicity. We perform preclinical testing on all of our product candidates before we initiate any human trials.

Investigational New Drug Application. Before clinical testing may begin, the results of preclinical testing, together with manufacturing information, analytical data and any other available clinical data or literature, must be submitted to the FDA, as part of an IND. The sponsor must also include an initial protocol detailing the first phase of the proposed clinical investigation, together with information regarding the qualifications of the clinical investigators. The provided data must provide an adequate basis for evaluating both the safety and the scientific rationale for the initial clinical studies in human volunteers. The IND automatically becomes effective 30 days after receipt by the FDA unless the FDA imposes a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. Clinical holds also may be imposed by the FDA at any time before or during trials due to safety concerns or non-compliance. As a result, submission of an IND may not result in FDA authorization to commence a clinical trial.

Clinical Trials. Clinical trials involve the administration of the drug to healthy human volunteers, or to patients with the target disease or disorder under the supervision of a qualified physician (also called an investigator) pursuant to an FDA-reviewed protocol. Human clinical trials typically are conducted in three sequential phases, although the phases may overlap with one another. Clinical trials must be conducted under protocols that detail the objectives of the study, the parameters to be used to monitor safety and the efficacy criteria, if any, to be evaluated. Each protocol, and any subsequent amendments, must be submitted to the FDA, as part of the IND, or comparable foreign regulatory authorities.

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Phase 1 clinical trials test for safety, dose tolerance, absorption, bio-distribution, metabolism, excretion, structure activity relationships, mechanism of action, and clinical pharmacology and, if possible, for early evidence regarding efficacy. Phase 1 studies may be conducted in healthy human volunteers or patients with the target disease or condition. Phase 1a is typically a dose escalation trial. Phase 1b may involve cohort expansion at one or more dose levels combinations, or in different populations to determine the recommended Phase 2 dose and strategy.

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Phase 2 clinical trials are controlled studies that involve a small sample of individuals with the target disease or disorder and seek to assess the efficacy of the drug for specific targeted indications to determine dose response and the optimal dose range and dose regimen and to gather additional information relating to safety and potential adverse effects.

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Phase 3 clinical trials are adequate and controlled studies that consist of expanded, large-scale studies of patients, at geographically dispersed sites, with the target disease or disorder to obtain definitive statistical evidence of the efficacy and safety of the proposed product and dosing regimen. The safety and efficacy

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data generated from Phase 3 clinical trials typically form the basis for FDA or comparable foreign regulatory authority approval of the product candidate, as well as product labeling. Typically, two Phase 3 trials are required by the FDA for product approval. Under some limited circumstances, however, the FDA may approve a BLA based upon a single Phase 3 clinical study plus confirmatory evidence or a single large multicenter trial without confirmatory evidence.

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Phase 4 clinical trials, if conducted, are conducted after a product has been approved. These trials can be conducted for a number of purposes, including to collect long-term safety information or to collect additional data about a specific population. As part of a product approval, the FDA or comparable foreign regulatory authorities may require that certain Phase 4 studies, which are called post-marketing commitment studies, be conducted post-approval. The results of Phase 4 studies can confirm or refute the effectiveness of a product candidate, and can provide important safety information.

In March 2022, the FDA released a final guidance entitled “Expansion Cohorts: Use in First-In-Human Clinical Trials to Expedite Development of Oncology Drugs and Biologics,” which outlines how drug developers can utilize an adaptive trial design commonly referred to as a seamless trial design in early stages of oncology drug development (i.e., the first-in-human clinical trial) to compress the traditional three phases of trials into one continuous trial called an expansion cohort trial. Information to support the design of individual expansion cohorts are included in IND applications and assessed by FDA. Expansion cohort trials can potentially bring efficiency to drug development and reduce developmental costs and time.

Additional kinds of data may also help to support a BLA or product development, such as patient experience and real-world evidence. For appropriate indications sought through supplemental BLAs, data summaries may provide marketing application support. For genetically targeted products and variant protein targeted products intended to address an unmet medical need in one or more patient subgroups with a serious or life threatening rare disease or condition, the FDA may allow a sponsor to rely upon data and information previously developed by the sponsor or for which the sponsor has a right of reference, that was submitted previously to support an approved application for a product that incorporates or utilizes the same or similar genetically targeted technology or a product that is the same or utilizes the same variant protein targeted drug as the product that is the subject of the application.

In addition, under the Pediatric Research Equity Act of 2003 (PREA) BLAs and supplements for a new active ingredient, indication, dosage form, dosage regimen, or route of administration must contain data to assess the safety and efficacy of the product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The FDA may grant deferrals for submission of data or full or partial waivers. Unless otherwise required by regulation, PREA does not apply to any drug or biologic for an indication for which orphan designation has been granted for the relevant indication except that PREA will apply to an original BLA for a new active ingredient that is orphan-designated if the biologic is a molecularly targeted cancer product intended for the treatment of an adult cancer and is directed at a molecular target that FDA determines to be substantially relevant to the growth or progression of a pediatric cancer.

Good Clinical Practice. All of the phases of clinical studies must be conducted in conformance with the FDA’s GCP or equivalent standards from comparable foreign regulatory authorities, which are ethical and scientific quality standards for conducting, recording and reporting clinical trials to assure that the data and reported results are credible and accurate and that the rights, safety and well-being of trial participants are protected. GCP include requirements that all research subjects provide their informed consent in writing for their participation in any clinical trial. Investigators must also provide certain information to the clinical trial sponsors to allow the sponsors to make certain financial disclosures to the FDA. In addition, an Institutional Review Board, or IRB, at each study site participating in the clinical trial or a central IRB must review and approve the plan for any clinical trial, informed consent forms, and communications to study subjects before a study commences at that site. An IRB considers, among other things, whether the risks to individuals participating in the trials are minimized and are reasonable in relation to anticipated benefits, and whether the planned human subject protections are adequate. The IRB must continue to oversee the clinical trial while it is being conducted. Once an IND is in effect, each new clinical protocol and any amendments to the protocol must be submitted to FDA for review, and to the IRB for approval. If a product candidate is being investigated for multiple intended indications, separate INDs may also be required. Progress reports detailing the results of the clinical trials must also be submitted at least annually to the FDA and the IRB and more frequently if serious and unexpected suspected adverse events are observed or other significant safety information is found, such as any findings from other studies or animal or in vitro testing that suggest a significant risk in humans exposed to the product. The sponsor must submit an IND safety report within 15 calendar days after the sponsor determines that the

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information qualifies for reporting. The sponsor also must notify the FDA of any unexpected fatal or life-threatening suspected adverse reaction within seven calendar days after the sponsor's initial receipt of the information.

Information about certain clinical trials, including a description of the study and study results, must be submitted within specific timeframes to the National Institutes of Health, or NIH, for public dissemination on their clinicaltrials.gov website. Sponsors or distributors of investigational products for the diagnosis, monitoring, or treatment of one or more serious diseases or conditions must also have a publicly available policy on evaluating and responding to requests for expanded access requests.

The manufacture of investigational biologics for the conduct of human clinical trials is subject to FDA’s current Good Manufacturing Practice, or cGMP requirements. Investigational biologics and therapeutic substances imported into the United States are also subject to regulation by the FDA. Further, the export of investigational products outside of the United States is subject to regulatory requirements of the receiving country as well as U.S. export requirements under the FDCA.

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

The FDA may order the temporary, or permanent, discontinuation of a clinical trial at any time, or impose other sanctions, if it believes that the clinical trial either is not being conducted in accordance with FDA requirements or presents an unacceptable risk to the clinical trial patients. An IRB may also require the clinical trial at the site to be halted, either temporarily or permanently, for failure to comply with the IRB’s requirements or if the trial poses an unexpected serious harm to subjects. The FDA or an IRB may also impose conditions on the conduct of a clinical trial. Clinical trial sponsors may also choose to discontinue clinical trials as a result of risks to subjects, a lack of favorable results, or changing business priorities.

Marketing Approval - Biologics

Biologics License Application. All data obtained from a comprehensive development program, including research and product development, manufacturing, preclinical and clinical trials, labeling and related information are submitted in a biologics license application (BLA) to the FDA and in similar regulatory filings with the corresponding agencies in other countries for review and approval. In most cases, the submission of a marketing application is subject to a substantial application user fee. These user fees must be paid at the time of the first submission of the application, even if the application is being submitted on a rolling basis. Fee waivers or reductions are available in certain circumstances. By example, product candidates that are designated as orphan products, which are further described below, are not subject to application user fees unless the application includes an indication other than the orphan indication.

The submission of an application is not a guarantee that the FDA will find the application complete and accept it for filing. The FDA may refuse to file the application and request additional information rather than accept the application for filing, in which case the application must be resubmitted with the supplemental information. The resubmitted application is also subject to review before the FDA accepts it for filing. The FDA has two months to review an application for its acceptability for filing.

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Once an application is accepted for filing, the FDA begins an in-depth substantive review. The Prescription Drug User Fee Act (PDUFA) establishes a two-tiered review system: Standard Review and Priority Review. When conducting Priority Review, the FDA has a goal to review and act on BLA submissions within six months from the date of the FDA’s acceptance for filing of the application, rather than the ten-month goal under a Standard Review. The FDA gives Priority Review status to product candidates that provide safe and effective therapies where no satisfactory alternative exists or to a product candidate that are intended to treat serious conditions and, if approved, would provide significant improvements in the safety or effectiveness of the treatment, diagnosis, or prevention of the serious condition. The PDUFA date is only a goal, thus, the FDA does not always meet its PDUFA dates. The review process and the PDUFA date may also be extended if the FDA requests or the sponsor otherwise provides substantial additional information or clarification regarding the submission.

The FDA may refer certain applications to an advisory committee. Before approving a product candidate for which no active ingredient (including any ester or salt of active ingredients) has previously been approved by the FDA, the FDA must either refer that product candidate to an external advisory committee or provide in an action letter, a summary of the reasons why the FDA did not refer the product candidate to an advisory committee. The FDA may also refer other product candidates to an advisory committee if FDA believes that the advisory committee’s expertise would be beneficial. An advisory committee is typically a panel that includes clinicians and other experts, which review, evaluate, and make a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

The FDA reviews applications to determine, among other things, whether a product candidate meets the agency’s approval standards and whether the manufacturing methods and controls are adequate to assure and preserve the product’s identity, strength, quality, potency, and purity. Before approving a marketing application, the FDA typically will inspect the facility or facilities where the product is manufactured, referred to as a Pre-Approval Inspection. The FDA will not approve an application unless it determines that the manufacturing processes and facilities, including contract manufacturers and subcontractors, are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. Additionally, before approving a marketing application the FDA will inspect one or more clinical trial sites to assure compliance with GCP.

In reviewing a BLA, the FDA may grant approval or deny the application through a complete response letter (CRL) if it determines the application does not provide an adequate basis for approval requesting additional information. A CRL indicates that the review cycle of the application is complete and the application is not ready for approval and describes all of the specific deficiencies that the FDA identified. A CRL generally contains a statement of specific conditions that must be met in order to secure final approval of the marketing application, and may require additional clinical or preclinical testing in order for the FDA to reconsider the application. The deficiencies identified may be minor, for example, requiring labeling changes; or major, for example, requiring additional clinical trials. If a CRL is issued, the applicant may either: resubmit the marketing application, addressing all of the deficiencies identified in the letter; withdraw the application; or request an opportunity for a hearing. Even if additional information outlined in a CRL is submitted, the FDA may ultimately decide that the BLA does not satisfy the criteria for approval.

The receipt of regulatory approval often takes many years, involving the expenditure of substantial financial resources. The speed with which approval is granted often depends on a number of factors, including the severity of the disease in question, the availability of alternative treatments and the risks and benefits demonstrated in clinical trials. The FDA may also impose conditions upon approval. For example, it may require a Risk Evaluation and Mitigation Strategy (REMS) for a product. This can include various required elements, such as publication of a medication guide, patient package insert, a communication plan to educate health care providers of the drug’s risks and/or restrictions on distribution and use, such as limitations on who may prescribe or dispense the drug. Following product approval, a REMS may also be required by the FDA if new safety information is discovered and the FDA determines that a REMS is necessary to ensure that the benefits of the product outweigh the risks.

The FDA may also significantly limit the indications or populations approved for a given product, require that contraindications, warnings, or precautions be included in the product labeling, including a boxed warning, and/or require, as a condition of approval, enhanced labeling, special packaging or labeling, post-approval clinical trials, distribution or other risk management mechanisms, expedited reporting of certain adverse events, pre-approval of promotional materials or restrictions on direct-to-consumer advertising, any of which could negatively impact the commercial success of a drug. The FDA may also not approve label statements that are necessary for successful commercialization and marketing.

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After approval, some types of changes to the approved product, such as adding new indications, manufacturing changes, and additional labeling claims, are subject to further testing requirements and FDA review and approval. The FDA may also withdraw the product approval if compliance with the pre- and post-marketing regulatory standards are not maintained or if problems occur after the product reaches the marketplace. Further, should new safety information arise, additional testing, product labeling, or FDA notification may be required.

Designated Platform Technology. Under the Food and Drug Omnibus Reform Act of 2022 (FDORA) a platform technology incorporated within or utilized by a biologic is eligible for designation as a designated platform technology if (1) the platform technology is incorporated in, or utilized by, a product approved under a BLA; (2) preliminary evidence submitted by the sponsor of the approved or licensed product, or a sponsor that has been granted a right of reference to data submitted in the application for such product, demonstrates that the platform technology has the potential to be incorporated in, or utilized by, more than one product without an adverse effect on quality, manufacturing, or safety; and (3) data or information submitted by the applicable person indicates that incorporation or utilization of the platform technology has a reasonable likelihood to bring significant efficiencies to the drug development or manufacturing process and to the review process. A sponsor may request the FDA to designate a platform technology as a designated platform technology concurrently with, or at any time after, submission of an IND application for a product that incorporates or utilizes the platform technology that is the subject of the request. If so designated, the FDA may expedite the development and review of any subsequent original BLA for a product that uses or incorporates the platform technology. Designated platform technology status does not ensure that a product will be developed or reviewed by the FDA more quickly or receive FDA approval. In addition, the FDA may revoke a designation if the FDA determines that a designated platform technology no longer meets the criteria for such designation.

Breakthrough Therapy. Under the provisions of the Food and Drug Administration Safety and Innovation Act (FDASIA) the FDA may designate a product as a breakthrough therapy if the product is intended, alone or in combination with one or more other products, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. Products designated as breakthrough therapies are also eligible for accelerated approval. A sponsor may request that a product candidate be designated as a breakthrough therapy concurrently with, or at any time after, the submission of an IND, and the FDA must determine if the candidate qualifies for breakthrough therapy designation within 60 days of receipt of the sponsor’s request. If so designated, the FDA must take certain actions, such as holding timely meetings and providing advice, intended to expedite the development and review of an application for approval of a breakthrough therapy. The FDA may rescind breakthrough therapy designation if the product candidate does not continue to meet the criteria for such designation.

Orphan Drugs. Under the Orphan Drug Act, an applicant can request the FDA to designate a product as an “orphan drug” in the United States if the drug is intended to treat an orphan, or rare, disease or condition. A disease or condition is considered orphan if it affects fewer than 200,000 people in the United States, or affecting more than 200,000 in the United States and for which there is no reasonable expectation that the cost of developing and making the product available in the United States will be recovered from United States sales. Additionally, sponsors must present a plausible hypothesis for clinical superiority to obtain orphan drug designation if there is a product already approved by the FDA that that is considered by the FDA to be the same as the already approved product and is intended for the same indication. This hypothesis must be demonstrated to obtain orphan exclusivity. Orphan drug designation must be requested before submitting a BLA. Products designated as orphan drugs are eligible for special grant funding for research and development, potential tax credits for research, waived user fees for marketing applications and a seven-year period of market exclusivity after marketing approval. The tax advantages, however, were limited in the 2017 Tax Cuts and Jobs Act.

Orphan drug exclusivity (afforded to the first applicant to receive approval for an orphan designated drug) prevents FDA approval of applications by others for the same drug for the designated orphan disease or condition. The FDA may approve a subsequent application from another applicant if the FDA determines that the application is for a different drug or different use, or if the FDA determines that the subsequent product is clinically superior, or that the holder of the initial orphan drug approval cannot assure the availability of sufficient quantities of the drug to meet the public’s need. A grant of an orphan designation is not a guarantee that a product will be approved. On November

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26, 2019, FDA granted Orphan Drug Designation to mipletamig, a bispecific antibody candidate, for the treatment of acute myelogenous leukemia.

Post-Approval Requirements. Any biologic for which we receive FDA approval will be subject to continuing regulation by the FDA, including, among other things, record keeping requirements, reporting of adverse experiences, reporting of deviations and shortages, providing the FDA with updated safety and efficacy information, product sampling and distribution requirements, cGMP, and restrictions on advertising and promotion. Adverse events that are reported after marketing approval can result in additional limitations being placed on the product’s distribution or use and, potentially, withdrawal or suspension of the product from the market. In addition, the FDA authority to require post-approval clinical trials and/or safety labeling changes if warranted. In certain circumstances, the FDA may impose a REMS after a product has been approved.

Facilities involved in the manufacture and distribution of approved products are required to register their establishments with the FDA and certain state agencies, list their manufactured products, and are subject to periodic unannounced inspections by the FDA for compliance with cGMP and other laws. Manufacturers and other parties involved in the supply chain for prescription drug products must also comply with product tracking and tracing requirements and for notifying the FDA of counterfeit, diverted, stolen and intentionally adulterated products or products that are otherwise unfit for distribution in the United States. Recently, the information that must be submitted to FDA regarding manufactured products was expanded through the Coronavirus Aid, Relief, and Economic Security (CARES) Act to include the volume of drugs produced during the prior year. Manufacturers must continue to expend time, money, and effort in the areas of production and quality-control to maintain compliance with cGMP. Regulatory authorities may withdraw product approvals, require label modifications, or request product recalls, among other actions, if a company fails to comply with regulatory standards, if it encounters problems following initial marketing, or if previously unrecognized problems are subsequently discovered.

The FDA also closely monitors advertising and promotional materials we may disseminate for our products for compliance with restrictions on off-label promotion and other laws. We may not promote our products for conditions of use that are not included in the approved package inserts for our products. Physicians, in their independent professional medical judgment, however, may prescribe legally available products for unapproved indications that are not described in the product’s labeling and that differ from those tested and approved by the FDA. Certain additional restrictions on advertising and promotion exist for products that have boxed warnings in their approved package inserts The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a company that is found to have improperly promoted off-label uses may be subject to significant liability, including, but not limited to, criminal and civil penalties under the FDCA and False Claims Act, exclusion from participation in federal healthcare programs, mandatory compliance programs under corporate integrity agreements, suspension and debarment from government contracts, and refusal of orders under existing government contracts.

Biosimilars and Exclusivity. The Biologics Price Competition and Innovation Act of 2009 (BPCIA) creates an abbreviated approval pathway for biological products shown to be highly similar to or interchangeable with an FDA-licensed reference biological product. Biosimilarity sufficient to reference a prior FDA-approved product requires a high similarity to the reference product notwithstanding minor differences in clinically inactive components, and no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency. Biosimilarity must be shown through analytical studies, animal studies, and at least one clinical trial, absent a waiver by the FDA. There must be no difference between the reference product and a biosimilar in mechanism of action, conditions of use, route of administration, dosage form, and strength. A biosimilar product may be deemed interchangeable with a prior approved product if it meets the higher hurdle of demonstrating that it can be expected to produce the same clinical results as the reference product and, for products administered multiple times, the biologic and the reference biologic may be switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic.

A reference biologic is granted 12 years of exclusivity from the time of first licensure, and no application for a biosimilar can be submitted for four years from the date of licensure. However, certain changes and supplements to an approved BLA, and subsequent applications filed by the same sponsor, manufacturer, licensor, predecessor in interest, or other related entity do not qualify for the twelve-year exclusivity period. The first biologic product submitted under the abbreviated approval pathway that is determined to be interchangeable with the reference product is eligible for a period of exclusivity against other biologics submitted under the abbreviated approval pathway during which time the FDA may not determine that another product is interchangeable with the same reference product for any condition of use. The FDA may approve multiple “first” interchangeable products so long as they are all approved

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on the same first day of marketing. This exclusivity period, which may be shared amongst multiple first interchangeable products, lasts for the lesser of (i) one year after the first commercial marketing, (ii) 18 months after approval if there is no legal challenge, (iii) 18 months after the resolution in the applicant’s favor of a lawsuit challenging the biologic’s patents if an application has been submitted, or (iv) 42 months after the application has been approved if a lawsuit is ongoing within the 42-month period. The PHSA also includes provisions to protect reference products that have patent protection. The biosimilar product sponsor and reference product sponsor may exchange certain patent and product information for the purpose of determining whether there should be a legal patent challenge. Based on the outcome of negotiations surrounding the exchanged information, the reference product sponsor may bring a patent infringement suit and injunction proceedings against the biosimilar product sponsor. The biosimilar applicant may also be able to bring an action for declaratory judgment concerning the patent.

In an effort to increase competition in the biologic product marketplace, Congress, the executive branch, and the FDA have taken certain legislative and regulatory steps. For example, in 2020, FDA finalized a guidance to facilitate drug and biologic product importation. Moreover, the 2020 Further Consolidated Appropriations Act included provisions requiring that sponsors of approved biologic products, including those subject to REMS, provide samples of the approved products to persons developing biosimilar products within specified timeframes, in sufficient quantities, and on commercially reasonable market-based terms. Failure to do so can subject the approved product sponsor to civil actions, penalties, and responsibility for attorney’s fees and costs of the civil action. This same bill also includes provisions with respect to shared and separate REMS programs for reference and generic drug products.

Patent Term Restoration If approved, biologic products may also be eligible for periods of U.S. patent term restoration. If granted, patent term restoration extends the patent life of a single unexpired patent that has not previously been extended, for a maximum of five years. The total patent life of the product with the extension also cannot exceed fourteen years from the product’ approval date. Subject to the prior limitations, the period of the extension is calculated by adding half of the time from the effective date of an IND to the initial submission of a marketing application, and all of the time between the submission of the marketing application and its approval. This period may also be reduced by any time that the applicant did not act with due diligence.

Regulation in the European Union. Product development, the regulatory approval process and safety monitoring of medicinal products and their manufacturers in the European Union proceed broadly in the same way as they do in the United States. Therefore, many of the issues discussed above apply similarly in the context of the European Union. In addition, drugs are subject to the extensive price and reimbursement regulations of the various EU member states. The Clinical Trial Regulation EU 536/2014 (CTR) repealed the Clinical Trials Directive 2001/20/EC, as amended (CTD) on January 31, 2022, subject to a three-year transition period. The CTR makes it possible within the EU for sponsors to submit a single harmonized electronic submission via a single online platform known as the Clinical Trials Information System (CTIS) for approval to conduct a clinical trial in several European countries and have a single assessment process for clinical trials conducted in multiple member states. Under the CTR, sponsors can use the CTIS from January 31, 2022 but are not obliged to use it immediately, in line with a three-year transition period Sponsors may use CTIS to apply to conduct a clinical trial under the CTR or may choose to apply to conduct a trial under the CTD until January 30, 2023 From January 31, 2023, sponsors need to use CTIS to apply to start a new clinical trial in the EU/EEA. From January 31, 2025, any trials approved under the CTD that continue running will need to comply with the CTR and their sponsors must have recorded information on such trials in CTIS.

Healthcare Fraud and Abuse and Anti-Corruption Laws

Various federal and state laws pertaining to health care “fraud and abuse” exist, including state and federal anti-kickback laws false claims laws, and patent privacy and security laws. Anti-kickback laws make it illegal for a drug manufacturer to knowingly and willfully solicit, offer, receive or pay any remuneration in exchange for, to induce, or in return for, the referral of business that may be reimbursed by a third-party payor (including Medicare and Medicaid), including the purchase, prescribing or recommendation of a particular drug. Due to the breadth of the statutory provisions, it is possible that our practices might be challenged under anti-kickback or similar laws. Civil and criminal false claims laws, false statement laws and civil monetary penalty laws prohibit, among other things, anyone from knowingly presenting, or causing to be presented for payment, to third-party payors (including Medicare and Medicaid) claims for reimbursed drugs or services that are false or fraudulent, claims for items or services not provided as claimed or claims for medically unnecessary items or services. Our activities relating to the sale and marketing of our products may be subject to scrutiny under these laws. Privacy and security laws, such as the Health Insurance

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Portability and Accountability Act of 1996, or HIPAA, create federal criminal and civil liability for executing a scheme to defraud any healthcare benefit program or knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services. Additionally, HIPAA, as amended by the Health Information Technology for Economic and Clinical Health, or HITECH, and their respective implementing regulations, impose certain requirements relating to the privacy, security, and transmission of individually identifiable health information.

In addition, as part of the Affordable Care Act, the federal government enacted the Physician Payment Sunshine Act. Manufacturers of drugs biologics and devices that are reimbursed by Medicare, Medicaid or the Children’s Health Insurance Program are required to annually report to CMS payments and transfers of value made to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors) and teaching hospitals, and ownership or investment interest held by physicians and their family members. Effective January 1, 2022, these reporting obligations extend to include transfers of value made to certain non-physician providers (physician assistants, nurse practitioners, clinical nurse specialists, certified registered nurse anesthetists and anesthesiologist assistants, and certified-nurse midwives).

Our operations are also subject to compliance with the U.S. Foreign Corrupt Practices Act (FCPA) which prohibits corporations and individuals from directly or indirectly paying, offering to pay, or authorizing the payment of anything of value to any foreign government official or employee, or any foreign political party or political candidate in an attempt to obtain or retain business or to otherwise influence such official, employee, party or candidate in his or her or its official capacity. Our operations are also subject to compliance with the U.K. Bribery Act of 2010, which applies to activities both in the public and private sector, Canada’s Corruption of Foreign Public Officials Act and similar laws and industry codes in other countries where we do business.

Other Regulation

Our present and future business has been and will continue to be subject to various other laws and regulations. Various laws, regulations and recommendations relating to safe working conditions, laboratory practices, the experimental use of animals, and the purchase, storage, movement, import, export, use and disposal of hazardous or potentially hazardous substances, including radioactive compounds and infectious disease agents used in connection with our product development, are or may be applicable to our activities.

HUMAN CAPITAL

Employees and Office Location

We employed 33 full-time and 3 contract persons as of December 31, 2025. The team is comprised of a dedicated group of accomplished professionals who bring a broad range of academic achievements combined with significant industry experience. We believe that our future success will depend in part on our continued ability to attract, hire and retain qualified personnel. To this end, we strive to maintain competitive base compensation structures and comprehensive benefits packages, and to engage our employees through ongoing development and training. None of our employees are represented by a labor union or covered by collective bargaining agreements. We believe our relationships with our employees are positive.

Our principal executive offices are located at 2401 4th Ave., Suite 1050, Seattle, Washington 98121. Our telephone number is (206) 838-0500.

Corporate Values

Leading by our core values unifies Aptevo and enables every employee to be an agent of positive culture. We believe that our success depends on creating an environment that is personally and professionally rewarding and creating opportunities for personal and professional development. These values, which are the foundation of our Company culture, are:

•
Professionalism

o
Act respectfully with all;

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o
Deal with each other directly, clearly, and transparently; and

o
Routinely seek feedback and receive it maturely.

•
Ownership

o
Work towards objectives with focus and speed without sacrificing quality;

o
Approach our work like business owners; and

o
Invest with the best interest of the Company in mind.

•
Empowerment

o
Assume all employees are capable and collegial adults;

o
Leaders enable employees to accept delegation; and

o
Bureaucracy and administrative tasks must be justified.

Workforce and Workplace Culture

We consider these values to be an integral part of our corporate goal setting and review process. We believe in empowering our employees and consider them as owners of the business. We treat each other with respect and maintain a high level of professionalism and accountability. Our Board of Directors and executive team continue to monitor and focus on our human capital resources to ensure we live by our core values.

Our employees are central to our operations and our ability to advance therapeutic product candidates. We focus on attracting, developing, and retaining highly qualified employees and maintaining a workplace that promotes professionalism, collaboration, and respect. We are an equal opportunity employer and are committed to fair and consistent employment practices. Our policies and practices support equal opportunity in hiring, compensation, promotion, and professional development. We maintain policies addressing workplace conduct, including anti-harassment and anti-retaliation standards, and seek to provide a safe and respectful working environment for all employees. We believe that building a strong team with a broad range of experiences and perspectives supports innovation in the development of therapeutic product candidates and enhances our ability to solve complex scientific and operational challenges.

Recruiting and Retention

We invest in resources to recruit, develop, and retain the talent needed to achieve our business goals. We believe in supporting our employees to reach their full potential and strive to promote internally. We have been successful in attracting and retaining talented personnel to support our business, though competition for personnel in our industry is intense.

Compensation and Benefits

Our compensation packages are designed to attract and retain talent, drive Company performance and achieve business goals. In setting appropriate compensation levels, we look at the average base pay rate for each position based on market data. We also offer an annual cash incentive program and long-term equity incentive plans designed to assist in attracting, retaining, and motivating employees and promoting the creation of long-term value for stockholders. Further, all employees are eligible for health insurance and other health benefits, paid and unpaid leaves, retirement benefits with Company match, and life and disability coverage/insurance. We have an unlimited paid time off policy that provides employees with considerable flexibility in scheduling time away from work.

Health & Safety

Employee safety and well-being is of paramount importance to us and was of continued focus in 2025. The Company maintains a hybrid working environment. Our essential employees, which mainly include our research and development team, work onsite, and non-essential employees work remotely or hybrid. We equip our employees working remotely or hybrid with necessary equipment and tools to continue to collaborate and remain productive.

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Additionally, we have an Environmental, Health and Safety program that focuses on implementing policies and training programs, as well as performing self-audits to enhance work safety.

ORGANIZATIONAL HISTORY

Aptevo was formed as a wholly-owned subsidiary of Emergent BioSolutions Inc. (Emergent) for the purpose of serving as the parent company for the development-based biotechnology business focused on novel oncology, hematology, and autoimmune and inflammatory therapeutics and was incorporated in Delaware in February 2016. On August 1, 2016, Emergent effectuated a spin-off of Aptevo into an independent publicly traded company and made a pro rata distribution of Aptevo common stock to Emergent’s stockholder base at that time. Accordingly, Aptevo has operated as an independent publicly traded company since August 1, 2016.

AVAILABLE INFORMATION

The Aptevo website is located at www.AptevoTherapeutics.com. Aptevo makes certain filings with the Securities and Exchange Commission (the SEC), including its Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, and all amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act available free of charge through its website as soon as reasonably practicable after we electronically file those reports with, or furnish them to, the SEC.

In addition, all disclosures that are required to be posted by applicable law, the rules of the SEC or the Nasdaq listing standards regarding any amendment to, or waiver of, our code of business conduct and ethics are available free of charge on our website. We intend to use our website as a means of disclosing material non-public information and for complying with our disclosure obligations under Regulation FD. Accordingly, investors should monitor our website, in addition to following our press releases, investor deck, SEC filings and public conference calls and webcasts. We have included our website address as an inactive textual reference only. The information contained on, or that can be accessed through, our website is not a part of, or incorporated by reference into, this Annual Report on form 10-K.

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