Celldex Therapeutics, Inc.: Form 10-Q for the period ended Sep 30, 2025

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995: This Quarterly Report on Form 10-Q contains forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 under Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements include statements with respect to our beliefs, plans, objectives, goals, expectations, anticipations, assumptions, estimates, intentions and future performance, and involve known and unknown risks, uncertainties and other factors, which may be beyond our control, and which may cause our actual results, performance or achievements to be materially different from future results, performance or achievements expressed or implied by such forward-looking statements. All statements other than statements of historical fact are statements that could be forward-looking statements. You can identify these forward-looking statements through our use of words such as “may,” “will,” “can,” “anticipate,” “assume,” “should,” “indicate,” “would,” “believe,” “contemplate,” “expect,” “seek,” “estimate,” “continue,” “plan,” “point to,” “project,” “predict,” “could,” “intend,” “target,” “potential” and other similar words and expressions of the future.

There are a number of important factors that could cause the actual results to differ materially from those expressed in any forward-looking statement made by us. These factors include, but are not limited to:

• our dependence on product candidates that are still in development stages;
• our ability to successfully complete research and further development, including preclinical and clinical studies;
• our anticipated timing for preclinical development, regulatory submissions, commencement and completion of clinical trials and product approvals;
• our ability to negotiate strategic partnerships, where appropriate, for our drug candidates;
• our ability to manage multiple clinical trials for a variety of drug candidates at different stages of development;
• the cost, timing, scope and results of ongoing preclinical and clinical testing;
• our expectations of the attributes of our product and development candidates, including pharmaceutical properties, efficacy, safety and dosing regimens;
• the cost, timing and uncertainty of obtaining regulatory approvals for our drug candidates;
• the availability, cost, delivery and quality of clinical management services provided by our clinical research organization partners;
• the availability, cost, delivery and quality of clinical and commercial-grade materials produced by our own manufacturing facility or supplied by contract manufacturers, suppliers and partners;
• our ability to commercialize our drug candidates and the growth of the markets for those drug candidates;
• our ability to develop and commercialize products before competitors that are superior to the alternatives developed by such competitors;
• our ability to develop technological capabilities, including identification of novel and clinically important targets, exploiting our existing technology platforms to develop new drug candidates and expand our focus to broader markets for our existing targeted therapeutics;
• the cost of paying the regulatory approval milestone under the merger agreement by which we acquired Kolltan and our related settlement agreement with Kolltan;
• our ability to raise sufficient capital to fund our preclinical and clinical studies and to meet our long-term liquidity needs, on terms acceptable to us, or at all. If we are unable to raise the funds necessary to meet our long-term liquidity needs, we may have to delay or discontinue the development of one or more programs, discontinue or delay ongoing or anticipated clinical trials, discontinue or delay our commercial manufacturing efforts, discontinue or delay our efforts to expand into additional indications for our drug product candidates, license out programs earlier than expected, raise funds at significant discount or on other unfavorable terms, if at all, or sell all or part of our business;
• our ability to protect our intellectual property rights and our ability to avoid intellectual property litigation, which can be costly and divert management time and attention;
• our ability to develop and commercialize products without infringing the intellectual property rights of third parties; and
• the risk factors set forth elsewhere in this Quarterly Report on Form 10-Q and the factors listed under the headings “Business,” “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2024 and other reports that we file with the SEC.

All forward-looking statements are expressly qualified in their entirety by this cautionary notice. You are cautioned not to place undue reliance on any forward-looking statements, which speak only as of the date of this report or the date of the document incorporated by reference into this report. We have no obligation, and expressly disclaim any obligation, to update, revise or correct any of the forward-looking statements, whether as a result of new information, future events or otherwise. We have expressed our expectations, beliefs and projections in good faith, and we believe they have a reasonable basis. However, we cannot assure you that our expectations, beliefs or projections will result or be achieved or accomplished.

OVERVIEW

We are a biopharmaceutical company dedicated to exploring the science of mast cell biology and developing therapeutic antibodies which have the ability to engage the human immune system and/or directly affect critical pathways to improve the lives of patients with severe inflammatory, allergic, autoimmune and other devastating diseases. Our drug candidates include monoclonal and bispecific antibodies designed to address mast cell mediated diseases for which available treatments are inadequate.

We are focusing our efforts and resources on the continued research and development of

• Barzolvolimab (also referred to as CDX-0159), a monoclonal antibody that specifically binds the KIT receptor and potently inhibits its activity, which is currently being studied across multiple mast cell driven diseases including
• Chronic Spontaneous Urticaria (CSU): We initiated Phase 3 studies in chronic spontaneous urticaria (CSU) in July 2024. In November 2023, we announced that our Phase 2 study in CSU achieved the primary efficacy endpoint (statistically significant mean change from baseline to Week 12 of urticaria activity score compared to placebo) and was well tolerated. Patients on study continued to receive barzolvolimab and, in September 2024, we reported data from 52 weeks of treatment—demonstrating sustained and deepening disease efficacy and a well tolerated long term safety profile. In June 2025, Celldex presented longer term follow up data from the study. At 76 weeks, 7 months after the completion of dosing with barzolvolimab, over 40% of patients (150 mg Q4W) continued to experience profound, sustained complete response and improved quality of life.
• Cold Urticaria (ColdU) and Symptomatic Dermographism (SD): In July 2024, we announced that our Phase 2 study being conducted in two forms of chronic inducible urticaria (CIndU), ColdU and SD, achieved the primary efficacy endpoint (statistically significant difference between the percent of patients with a negative provocation test compared to placebo at Week 12) and was well tolerated. 12 week data from the CIndU study were presented in October of 2024 and all secondary endpoints across the study were also met and were highly statistically significant and clinically meaningful. Patients on study continued to receive barzolvolimab and, in

November 2025, we reported data from 20 weeks of treatment—demonstrating sustained efficacy and a well tolerated safety profile over the longer treatment period;

• Prurigo Nodularis (PN): In April 2024, we initiated a Phase 2 study in PN and enrollment is ongoing; positive data from a Phase 1b study in PN was reported in November 2023; and
• Atopic Dermatitis (AD): A Phase 2 study in AD was initiated in December 2024 and enrollment is ongoing.
• Our next generation bispecific antibody platform to support pipeline expansion with additional candidates for inflammatory diseases. Targets are being selected based on new science as well as their compatibility to be used in bispecific antibody formats with our existing antibody programs. Development is focused on emerging, important pathways controlling inflammatory diseases.
• CDX-622 (TSLP & SCF): Our first bispecific candidate for inflammatory diseases is CDX-622 which targets two complementary pathways that drive chronic inflammation, potently neutralizing the alarmin thymic stromal lymphopoietin (TSLP) and depleting mast cells via stem cell factor (SCF) starvation. In November 2024, a Phase 1a dose-escalation study in healthy volunteers was initiated and enrollment is ongoing. Positive data from the single ascending dose portion of the study was presented in October 2025.

More detail on these programs is provided in the Clinical Development Programs section.

Our goal is to build a fully integrated, commercial-stage biopharmaceutical company that develops important therapies for patients with unmet medical needs. We believe our program assets provide us with the strategic options to either retain full economic rights to our innovative therapies or seek favorable economic terms through advantageous commercial partnerships. This approach allows us to maximize the overall value of our technology and product portfolio while best ensuring the expeditious development of each individual product.

The expenditures that will be necessary to execute our business plan are subject to numerous uncertainties. Completion of clinical trials may take several years or more, and the length of time generally varies substantially according to the type, complexity, novelty and intended use of a drug candidate. It is not unusual for the clinical development of these types of drug candidates to each take five years or more, and total development costs could exceed hundreds of millions of dollars for each drug candidate. We estimate that clinical trials of the type we generally conduct are typically completed over the following timelines:

The duration and the cost of clinical trials may vary significantly over the life of a project as a result of differences arising during the clinical trial protocol, including, among others, the following:

• the number of patients that ultimately participate in the trial;
• the duration of patient follow-up that seems appropriate in view of results;
• the number of clinical sites included in the trials;
• the length of time required to enroll suitable patient subjects; and
• the efficacy and safety profile of the drug candidate.

We test potential drug candidates in numerous preclinical studies for safety, toxicology and immunogenicity. We may then conduct multiple clinical trials for each drug candidate. As we obtain results from trials, we may elect to discontinue or delay clinical trials for certain drug candidates in order to focus our resources on more promising drug candidates.

An element of our business strategy is to pursue the discovery, research and development of a broad portfolio of drug candidates. This is intended to allow us to diversify the risks associated with our research and development expenditures. To the extent we are unable to maintain a broad range of drug candidates, our dependence on the success of one or a few drug candidates increases.

Regulatory approval is required before we can market our drug candidates as therapeutic products. In order to proceed to subsequent clinical trial stages and to ultimately achieve regulatory approval, the regulatory agencies must conclude that our clinical data demonstrate that our product candidates are safe and effective. Historically, the results from preclinical testing and early clinical trials (through Phase 2) have often not been predictive of results obtained in later clinical trials. A number of new drugs and biologics have shown promising results in early clinical trials but subsequently failed to establish sufficient safety and efficacy data to obtain necessary regulatory approvals.

Furthermore, our business strategy includes the option of entering into collaborative arrangements with third parties to complete the development and commercialization of our drug candidates. In the event that third parties take over the clinical trial process for one of our drug candidates, the estimated completion date would largely be under control of that third party rather than us. We cannot forecast with any degree of certainty which proprietary products, if any, will be subject to future collaborative arrangements, in whole or in part, and how such arrangements would affect our development plan or capital requirements. Our programs may also benefit from subsidies, grants, contracts or government or agency-sponsored studies that could reduce our development costs.

As a result of the uncertainties discussed above, among others, it is difficult to accurately estimate the duration and completion costs of our research and development projects or when, if ever, and to what extent we will receive cash inflows from the commercialization and sale of a product. Our inability to complete our research and development projects in a timely manner or our failure to enter into collaborative agreements, when appropriate, could significantly increase our capital requirements and could adversely impact our liquidity. These uncertainties could force us to seek additional, external sources of financing from time to time in order to continue with our business strategy. Our inability to raise additional capital, or to do so on terms reasonably acceptable to us, would jeopardize the future success of our business.

During the past five years through December 31, 2024, we incurred an aggregate of $459.7 million in research and development expenses. The following table indicates the amount incurred for each of our significant research programs and for other identified research and development activities during the nine months ended September 30, 2025 and 2024. The amounts disclosed in the following table reflect direct research and development costs and an allocation of indirect research and development costs to each program.

(In thousands)

Clinical Development Programs

Barzolvolimab (also referred to as CDX-0159)

Barzolvolimab is a humanized monoclonal antibody that specifically binds the receptor tyrosine kinase KIT and potently inhibits its activity. KIT is expressed in a variety of cells, including mast cells, and its activation by its ligand SCF regulates mast cell growth, differentiation, survival, chemotaxis and degranulation. Barzolvolimab is designed to block KIT activation by disrupting both SCF binding and KIT dimerization. By targeting KIT, barzolvolimab has been shown to inhibit mast cell activity and decrease mast cell numbers, which we believe could provide potential clinical benefit in mast cell related diseases.

Barzolvolimab was initially studied in chronic spontaneous urticaria (CSU) and chronic inducible urticaria (CIndU), diseases where mast cell degranulation plays a central role in the onset and progression of the disease. In July 2024, we initiated two Phase 3 studies in CSU. In July 2023, we announced that enrollment was complete in the ongoing Phase 2 CSU study. In November 2023, we reported that barzolvolimab achieved the primary efficacy endpoint in this study, with a statistically significant mean change from baseline to Week 12 of UAS7 (weekly urticaria activity score) compared to placebo and was well tolerated. In September 2024, we presented 52 week treatment data from the CSU study, demonstrating sustained and deepening disease efficacy and a well tolerated long term safety profile. In June 2025, we presented follow up data from this study through Week 76, 7 months after the completion of dosing with barzolvolimab, demonstrating ongoing profound, sustained complete response and improved quality of life. The study is complete. In April 2024, we announced enrollment was complete in the ongoing Phase 2 CIndU study. In July 2024, we announced that our Phase 2 study in CIndU achieved the primary efficacy endpoint, (statistically significant difference between the percent of patients with a negative provocation test compared to placebo at Week 12) and was well tolerated. 12 week data from the CIndU study were presented in October of 2024 and all secondary endpoints across the study were also met and were highly statistically significant and clinically meaningful. Patients on study continued to receive barzolvolimab for 20 weeks of treatment and were then followed for up to 24 additional weeks without treatment. In November 2025, data from the 20 week placebo controlled treatment period were presented, demonstrating sustained efficacy and a favorable safety profile. Patients with returning or continuing symptoms were eligible to enroll into an open label extension (OLE). The study was recently completed and data from the OLE are expected to be presented in the first quarter of 2026.

Based on the positive results reported in urticaria, we expanded development of barzolvolimab into additional indications where mast cells are believed to play an important role. We are conducting ongoing Phase 2 studies in prurigo nodularis (PN), atopic dermatitis (AD) and eosinophilic esophagitis (EOE; further development discontinued). We continue to assess potential opportunities for barzolvolimab in other diseases where mast cells play an important role, such as dermatologic, respiratory, allergic, gastrointestinal and ophthalmic conditions.

Chronic Spontaneous Urticaria (CSU) Summary of Phase 1 and Phase 2 Data Presented to Date

CSU presents as itchy hives, angioedema or both for at least six weeks without a specific trigger; multiple episodes can play out over years or even decades. It is one of the most frequent dermatologic diseases with a prevalence of 0.5-1.0% of the total population or up to approximately 1 to 3 million patients in the United States (Weller et al. 2010. Hautarzt. 61(8), Bartlett et al. 2018. DermNet.Org). Approximately 50% of patients with CSU achieve symptomatic control with antihistamines. Omalizumab, an IgE inhibitor, provides relief for roughly half of the remaining antihistamine refractory patients. Consequently, there is a need for additional therapies.

We have completed a Phase 1b randomized, double-blind, placebo-controlled multi-center study of barzolvolimab in CSU. The study was designed to assess the safety of multiple ascending doses of barzolvolimab in patients with CSU who remain symptomatic despite treatment with antihistamines. Secondary and exploratory objectives included pharmacokinetic and pharmacodynamic assessments, clinical activity outcomes and quality of life assessments. Barzolvolimab was administered intravenously as add on treatment to H1-antihistamines, either alone or in combination with H2-antihistamines and/or leukotriene receptor agonists. 45 patients with moderate to severe CSU refractory to antihistamines were enrolled and treated [35 barzolvolimab (n=9 in 0.5 mg/kg; n=8 in 1.5 mg/kg; n=9 in 3.0 mg/kg; n=9 in 4.5 mg/kg) and 10 placebo].

At saturating doses (1.5 mg/kg and higher), barzolvolimab resulted in rapid, marked and durable responses in patients with moderate to severe CSU refractory to antihistamines. The 1.5 mg/kg, 3.0 mg/kg and 4.5 mg/kg dose groups showed similar markedly improved urticaria symptoms, including rapid onset of responses (as early as 1 week after the first dose) and prolonged disease control with sustained durability up to 24 weeks. Patients with prior omalizumab therapy also had similar symptom improvement as all patients.

Phase 1 CSU: Summary of Clinical Activity Assessments at Week 12 & 24

During post-treatment follow up, 71% (10 of 14) of patients who had been treated with doses greater than or equal to 1.5 mg/kg and had a complete response (UAS7=0) at Week 12, remained urticaria free at Week 24 (patients received last dose of barzolvolimab at Week 8). Profound and durable improvement in angioedema symptoms as measured through the weekly angioedema activity score (AAS7) was achieved across all dose levels evaluated with sustained activity observed with the 1.5 mg/kg and greater dose levels. Patients also reported improvements in quality of life outcomes as assessed by the Dermatology Life Quality Index (DLQI) which surveys patients’ perceptions of symptoms and feelings, daily activities, leisure, work and school performance, personal relationships and treatment.

Tryptase suppression, indicative of mast cell depletion, paralleled symptom improvement, demonstrating the impact of mast cell depletion on CSU disease activity.

Barzolvolimab was well tolerated. Most adverse events were mild or moderate in severity and resolved while on study. The most common treatment emergent adverse events were hair color changes, COVID-19, headache, neutropenia and urinary tract infections (UTIs). UTIs and COVID-19 were reported as unrelated to treatment. Generally transient, asymptomatic and mild changes in hematologic parameters were observed, consistent with observations from prior studies. No pattern of further decrease was observed with multiple dose administration.

Data from this study were reported across multiple medical meetings, including the American Academy of Allergy, Asthma & Immunology (AAAAI) Annual Meeting in February 2023, the European Academy of Allergy and Clinical Immunology (EAACI) Annual Congress in June 2023 and the European Academy of Dermatology & Venereology (EADV) Congress in October 2023.

We have completed a Phase 2 study in patients with CSU who remained symptomatic despite antihistamine therapy. The study was conducted at approximately 75 sites across 9 countries. The study was a randomized, double-blind, placebo-controlled, parallel group Phase 2 study that evaluated the efficacy and safety profile of multiple dose regimens of barzolvolimab to determine the optimal dosing strategy. 208 patients were randomly assigned on a 1:1:1:1 ratio to receive subcutaneous injections of barzolvolimab at 75 mg every 4 weeks, 150 mg every 4 weeks, 300 mg every 8 weeks or placebo during a 16-week placebo-controlled treatment phase. After 16 weeks, patients then entered a 36-week active treatment period, in which patients receiving placebo or the 75 mg dose were randomized to receive barzolvolimab 150 mg every 4 weeks or 300 mg every 8 weeks; patients already randomized to the 150 mg and 300 mg treatment arms remained on the same regimen as during the placebo-controlled treatment period. After 52 weeks, patients then entered a follow-up period for an additional 24 weeks. The primary endpoint of the study was mean change in baseline to Week 12 in UAS7 (weekly urticaria activity score). Secondary endpoints included safety and other assessments of clinical activity including ISS7 (weekly itch severity score), HSS7 (weekly hive severity score) and AAS7 (weekly angioedema activity score).

Topline data from this study were presented in November of 2023 and 12 week treatment results were presented at the AAAAI Annual Meeting in February 2024. Data from the 208 patients randomized in the study showed that barzolvolimab achieved the primary efficacy endpoint, with a statistically significant mean change from baseline to Week 12 in UAS7 compared to placebo at all dose levels. Secondary and exploratory endpoints in the study were also achieved at Week 12 and strongly support the primary endpoint results, including changes in ISS7 and HSS7 and responder analyses. Importantly, barzolvolimab demonstrated rapid, durable and clinically meaningful responses in patients with moderate to severe CSU refractory to antihistamines, including patients with prior omalizumab treatment. Demographics and baseline disease characteristics were well balanced across treatment groups. The majority of patients on study had severe disease (UAS7≥28).

Phase 2 CSU: Summary of Clinical Activity Assessments at Week 12

UAS7 Changes

UAS7, HSS7 and ISS7 data were analyzed using ANCOVA model and multiple imputation.

Barzolvolimab demonstrated strong improvement in UAS7 independent of omalizumab status at Week 12. Approximately 20% (n=41) of enrolled patients received prior treatment with omalizumab and more than half of these patients had omalizumab-refractory disease. These patients experienced a similar clinical benefit as the overall treated population within their individual dosing groups consistent with the barzolvolimab mechanism of action.

Barzolvolimab was well tolerated with a favorable safety profile. Most adverse events were mild to moderate in severity; through 12 weeks, the most common treatment emergent adverse events in barzolvolimab treated patients were urticaria/CSU (10%), hair color changes (9%), and neutropenia/ANC decrease (8%). The rate of infections was similar between barzolvolimab treated patients and placebo with no association between neutropenia and infections.

In June 2024, 12 week data on a secondary endpoint from the study, angioedema activity, and additional measures of angioedema control, were presented at the EAACI 2024 Congress. Approximately 72% of patients on study had angioedema at baseline. Barzolvolimab demonstrated significant improvements in AAS7 in patients with angioedema across all doses at Week 12. This improvement was rapid (within 2 weeks) and durable (continued through 12 weeks). Barzolvolimab demonstrated strong improvement in AAS7 independent of omalizumab status at Week 12. Patients on barzolvolimab experienced a > 8 point improvement in AAS7 (considered a clinically meaningful result) across all doses compared to placebo (p<0.05). Barzolvolimab increased angioedema free days compared to placebo through 12 weeks. Patients in the 300 mg cohort were angioedema free 77% of the time over the 12 week period.

Patients on study continued to receive barzolvolimab for up to 52 weeks. Long term treatment data were presented in September at the European Academy of Dermatology & Venereology (EADV) Congress 2024 and quality of life data were presented in March at the AAAAI Annual Meeting 2025. The data demonstrated a sustained and deepening disease efficacy, a well tolerated safety profile, greatly improved urticaria control and reduced disease impact on quality of life over a 52 week treatment period. Key highlights included:

• Improvements in UAS7 (weekly urticaria activity score), previously shown to be statistically significantly vs placebo at Week 12, were noted as early as Week 1 and were sustained or deepened at Week 52.
• At Week 16, patients receiving low dose barzolvolimab (75 mg) or placebo were transitioned to barzolvolimab 150 mg or 300 mg; after crossover, these patients experienced similar clinically meaningful disease response as the rest of the study population.
• 71% of patients treated with barzolvolimab 150 mg Q4W and 52% of patients treated with 300 mg Q8W had a complete response (no itch/hives; UAS7=0) at Week 52. These responses were observed early and sustained through 52 weeks.
• 74% of patients treated with barzolvolimab 150 mg Q4W and 68% of patients treated with 300 mg Q8W had well controlled (UAS7<6) disease at Week 52.
• These robust responses were observed regardless of prior omalizumab experience.
• Barzolvolimab was well tolerated with a favorable safety profile through 52 weeks of treatment. Most adverse events were grade 1 (mild), mechanism related (KIT) and expected to be reversible. The most common treatment emergent adverse events occurring in greater than 10% of barzolvolimab treated patients were hair color changes, neutropenia, urticaria, skin hypopigmentation (areas of skin lightening) and nasopharyngitis (common cold). Neutrophil counts did not decline further with continued dosing and there was no association between infections and neutropenia. The hypopigmentation was observed with longer term exposure and did not lead to treatment discontinuation. Adverse events were not dose dependent.
• Rapid and sustained improvement in urticaria control (UCT) and quality of life (DLQI) were observed in patients with CSU refractory to antihistamines. Up to 82% of patients reported that CSU symptoms no longer had an impact on their quality of life at Week 52 and up to 95% of patients reported meaningful improvement in quality of life based on DLQI at Week 52. Up to 82% of patients reported well-controlled urticaria based on UCT, and approximately half of patients reported complete control at Week 52.

In June of 2025, 52 week data on angioedema activity and additional measures of angioedema control were presented at the EAACI 2025 Congress. Barzolvolimab continued to demonstrate robust, durable and deepening improvements in angioedema symptoms over the treatment period. At Week 52, an 86% mean reduction from baseline was reported for 150 mg Q4W arm and an 82% reduction was reported for the 300 mg Q8W. Up to 77% of patients treated with barzolvolimab who had angioedema at baseline were angioedema free (AAS7=0) at Week 52. Patients treated with barzolvolimab were angioedema free up to 72% of the time over the 52 week treatment period. Up to 87% of patients reported clinically meaningful improvement (>8 point) in AAS7 at Week 52.

In June of 2025, long term follow up data from the Phase 2 CSU study were presented at the EAACI 2025 Congress. At Week 76, seven months after completion of dosing, patients continue to experience profound clinical benefit on study. Key highlights included:

• UAS7 mean change from baseline at Week 76 was -20.42 for patients treated with 150 mg Q4W and -21.10 for patients treated with 300 mg Q8W.
• 41% of patients treated with barzolvolimab 150 mg Q4W and 35% of patients treated with 300 mg Q8W had a complete response (no itch/hives; UAS7=0) at Week 76.
• 56% of patients treated with barzolvolimab 150 mg Q4W and 47% of patients treated with 300 mg Q8W had well controlled disease (UAS7≤6) at Week 76.
• 48% of patients treated with barzolvolimab 150 mg Q4W and 40% of patients treated with 300 mg Q8W reported that CSU had no impact on their quality of life at 76 weeks as measured by the Dermatology Life Quality Index (DLQI). Current clinical guidelines recommend complete response (UAS7=0) as the goal of treatment1 and achieving complete response is directly correlated to the greatest improvements in quality of life for patients2.
• These robust responses and improvements in quality of life were observed regardless of prior omalizumab experience.
• Barzolvolimab was well tolerated with a favorable safety profile through 76 weeks. No new safety signals were identified during the follow-up period. As expected, neutrophil counts returned to baseline following the completion of barzolvolimab treatment and the mild hair color changes and skin hypopigmentation observed on study were demonstrated to be reversible following discontinuation of treatment.

In September at EADV 2025, data were presented demonstrating rapid and strong efficacy regardless of baseline immunoglobulin E (IgE) levels and in November 2025 at the American College of Allergy, Asthma & Immunology’s Annual Scientific (ACAAI) Meeting, data were presented demonstrating that barzolvolimab leads to rapid and profound improvements in UCT7 scores with sustained disease control off treatment.

We believe these results strongly support the further development of barzolvolimab in CSU. In July 2024, we initiated two Phase 3 studies of barzolvolimab in CSU. The studies, EMBARQ-CSU1 and EMBARQ-CSU2, are designed to establish the efficacy and safety of barzolvolimab in adult patients with CSU who remain symptomatic despite H1 antihistamine treatment. Both Phase 3 trials are randomized, double-blind, placebo-controlled, parallel group, global studies (approximately 40 countries; 250 sites per study) where approximately 915 patients per trial will be randomized evenly to barzolvolimab 150 mg every 4 weeks (following 300 mg loading dose), barzolvolimab 300 mg every 8 weeks (following 450 mg loading dose) or placebo for 52 weeks. At 24 weeks, patients on placebo will be re-randomized to active treatment across both dosing groups. After completion of the 52 week treatment period, patients on study will continue to be followed for 16 weeks. The primary endpoint of the studies will evaluate the clinical effect of barzolvolimab in reducing urticaria activity (weekly urticaria activity score; UAS7) at Week 12. The studies are designed to detect a clinically meaningful difference between each of the active arms versus placebo in the overall population as well as in the subpopulation of omalizumab refractory participants. Enrollment continues as planned and is expected to be completed in the summer of 2026.

In addition, a global Phase 3b long term extension (LTE) study has been established for patient entry after completion of the EMBARQ - CSU Phase 3 trials. The study will consist of 2 Groups: Group 1 (Observation Group), containing patients whose disease remains well controlled (UAS7<16) and Group 2 (Barzolvolimab Retreatment Group) containing patients whose disease is currently moderate to severe (UAS7≥16). Patients in Group 2 will receive up to an additional year of treatment with barzolvolimab. Patients in the observation group (Group 1) whose CSU flares to a UAS7>/=16 in the first 6 months of the LTE will also be able to receive treatment.

Chronic Inducible Urticaria (CIndU) Summary of Phase 1 and Phase 2 Data Presented to Date

CIndUs are forms of urticaria that have an attributable cause or trigger associated with them, typically resulting in hives or wheals. The prevalence of CIndU is estimated at 0.5% of the total population and is reported to overlap in up to 36% of CSU patients (Weller et al. 2010. Hautarzt. 61(8), Bartlett et al. 2018. DermNet.Org). There are currently no approved therapies for chronic inducible urticarias other than antihistamines and patients attempt to manage symptoms associated with their disease through avoidance of triggers.

We completed a Phase 1b open label clinical trial in patients with CIndU refractory to antihistamines, conducted in Germany. This study was designed to evaluate the safety of a single intravenous dose (3 mg/kg) of barzolvolimab in patients with cold urticaria (ColdU) or symptomatic dermographism (SD). The study was expanded to include a cohort (single dose, 3 mg/kg) in patients with cholinergic urticaria (“CholU”) and a cohort at a lower dose (single dose, 1.5 mg/kg) in ColdU. Patient’s symptoms were induced via provocation testing that resembles real life triggering situations. Secondary and exploratory objectives included pharmacokinetic and pharmacodynamic assessments, including changes from baseline provocation thresholds, measurement of tryptase and stem cell factor levels, clinical activity outcomes, quality of life assessments and measurement of tissue mast cells through skin biopsies.

Generally patients on study had high disease activity at baseline that was poorly controlled and marked impairment in quality of life. At 3 mg/kg in the ColdU and SD cohorts, safety results were reported for 21 patients and activity results were reported for the 20 patients who received a full dose of barzolvolimab. At 1.5 mg/kg in the ColdU cohort, safety results were reported for 10 patients and activity results were reported for the 9 patients who received a full dose of barzolvolimab. At 3 mg/kg in the cholinergic cohort, safety results were reported for 21 patients and activity results were reported for the 20 patients who received a full dose of barzolvolimab.

Rapid (as early as 1 week) and durable responses were observed in patients as assessed by provocation testing.

• A complete response was achieved in 95% (n=19/20) of patients with ColdU and SD treated with a single dose at 3 mg/kg (n=10/10 ColdU; n=9/10 SD), including 3 patients who experienced insufficient response to prior omalizumab treatment. The median duration (range) of complete response through the 12-week observation period was 77+ days (29–86; n=10) for patients with ColdU and 57+ days (16–70; n=9) for patients with SD. A UCT score of ≥12 (well controlled) was achieved by 80% (n=16/20) of the patients within Week 4 post-treatment. By Week 8, all patients (100%; n=20/20) achieved well-controlled urticaria, which was sustained to Week 12 post-dose by 80% (n=16/20) of patients. Complete urticaria control (UCT=16) was achieved by 35% (n=7/20), 65% (n=13/20), and 40% (n=8/20) at Weeks 4, 8, and 12, respectively.
• A complete response was achieved in 100% (n=9 of 9) patients with ColdU treated with a single dose at 1.5 mg/kg, including 4 patients with disease refractory to omalizumab. The median duration of complete response through the 12-week observation period was 51+ days (7+ weeks). Following barzolvolimab administration, all patients achieved well controlled disease (UCT>12) with 7 of 9 achieving complete control (UCT=16).
• A complete response was achieved in 56% (n=5 of 9) patients with cholinergic urticaria treated with a single dose at 3 mg/kg. Most responses remained durable through to Week 12. 63% (5/8) patients reported well controlled disease (UCT ≥12) at Week 8 and 50% (4/8) at Week 12, respectively.
• Patients also reported improvements in quality of life outcomes as assessed by the Dermatology Life Quality Index (DLQI) which surveys patients’ perceptions of symptoms and feelings, daily activities, leisure, work and school performance, personal relationships and treatment.
• A single dose of barzolvolimab led to marked decreases in tryptase and in skin mast cells. The kinetics correlated with improvements in provocation testing and clinical activity, consistent with a central role for mast cells in the pathogenesis of ColdU and SD. This confirmed that serum tryptase level is a robust pharmacodynamic biomarker for assessing mast cell burden and clinical activity in inducible urticaria and potentially in other diseases with mast cell driven involvement.
• Barzolvolimab was well tolerated across all cohorts. In the 3 mg/kg ColdU and SD cohorts, most adverse events were mild, and the most common (≥3 patients) were hair color changes (76%; n=16/21), infusion reactions (43%; n=9/21), taste changes (38%; n=8/21), nasopharyngitis (24%; n=5/21), malaise (24%; n=5/21), and headache (19%; n=4/21). Hair color changes (generally small areas of hair color lightening) and taste disorders (generally partial changes of ability to taste salt or umami) are consistent with inhibiting KIT signaling in other cell types and completely resolved over time during follow-up. One patient with a history of fainting experienced loss of consciousness during infusion. The patient rapidly recovered. Importantly, no evidence of mast cell activation as measured by serum tryptase monitoring was observed in this patient. Barzolvolimab was also generally well tolerated by patients in the 1.5 mg/kg ColdU cohort and the 3.0 mg/kg cholinergic cohort with a similar safety profile to that reported previously. Across the Phase 1b inducible urticaria study, mean hematology parameters generally remained within the normal ranges—an important finding for a KIT inhibitor. Mild, transient, and asymptomatic decreases in hemoglobin and white blood cell parameters occurred for some patients.
• Long term follow up data was collected from the 3.0 mg/kg cohorts in cold urticaria and symptomatic dermographism. 14 patients consented to the optional evaluation (6 cold, 8 symptomatic dermographism); 10 of the 14 still had complete control of their disease as assessed by provocation testing at Week 12. Data were collected at one or more timepoints beyond Week 12 through Week 36. Most patients had return of symptoms and/or loss of urticaria control between 12 and 36 weeks. Remarkably, two patients remained provocation negative at 36 weeks, and four had well controlled disease (UCT ≥12) 36 weeks post dosing. Serum tryptase exhibits a similar rate of recovery as clinical symptoms, while skin mast cells return at a slower rate. Tissue KIT signaling, as approximated by SCF levels, was rapidly inhibited after dose administration and fully reactivated approximately 18 weeks after dosing. Tryptase levels return to pretreatment levels during follow up, while mast cells continue to recover. Drug related adverse events noted during the study all resolved.

Data from this study were reported in Allergy (Nov 2022) and across multiple medical meetings, including the GA²LEN Global Urticaria Forum (GUF) in December and the European Academy of Allergy and Clinical Immunology (EAACI) Annual Congress in June 2022.

We recently completed a Phase 2 study in patients with CIndU who remain symptomatic despite antihistamine therapy. The study was conducted at approximately 85 sites across approximately 12 countries. The randomized, double-blind, placebo-controlled, parallel group Phase 2 study evaluated the efficacy and safety profile of multiple dose regimens of barzolvolimab in patients with CIndU to determine the optimal dosing strategy. 196 patients in 2 cohorts (differentiated by CIndU subtype) including 97 patients with cold urticaria and 99 patients with symptomatic dermographism were randomly assigned on a 1:1:1 ratio to receive subcutaneous injections of barzolvolimab at 150 mg every 4 weeks, 300 mg every 8 weeks or placebo during a 20-week treatment phase. Patients then entered a follow-up phase for an additional 24 weeks. In addition, the study included the option for patients who had symptoms following the treatment phase, including patients who were on placebo, to enroll in an open label extension where all patients received 300 mg of barzolvolimab every 8 weeks. The primary endpoint of the study was the percentage of patients with a negative provocation test at Week 12. Secondary endpoints included safety and other assessments of clinical activity including CTT (Critical Temperature Threshold), CFT (Critical Friction Threshold) and WI-NRS (Worst itch numeric rating scale).

Topline primary endpoint data from this study were reported in July 2024 and 12 week treatment results were presented at the American College of Allergy, Asthma & Immunology’s Annual Scientific Meeting. Data from the 193 patients randomized and treated in the study showed that barzolvolimab achieved the primary efficacy endpoint, a statistically significant difference between the percent of patients with a negative provocation test compared to placebo at Week 12 as assessed by the TempTest® in ColdU and the FricTest® in SD. Secondary and exploratory endpoints in the study were also achieved at Week 12 and strongly support the primary endpoint results, including responder analyses, improvements in Critical Temperature and Critical Friction Thresholds (CFT and CFT), changes in WI-NRSprovo (itch associated with provocation test) and Urticaria Control Test. Demographics and baseline disease characteristics were well balanced across treatment groups. Patients on study had poorly controlled disease on initial provocation testing. In cold urticaria, patients presented with a mean baseline critical temperature threshold of approximately 19°C or 66°F on the TempTest on initial provocation testing. In patients with symptomatic dermographism baseline FricTest thresholds were an average of 3.6 out of 4 pins. UCT scores at baseline also reflected poorly controlled disease.

Summary of Clinical Assessments at Week 12

Patients experienced rapid disease improvement as early as two weeks (the first assessment) after receiving the initial dose of barzolvolimab as demonstrated by reductions in critical temperature and friction thresholds resulting in hives and rapid reduction in itch at the time of provocation testing (WI-NRSprovo).

Barzolvolimab was well tolerated with a favorable safety profile consistent with prior studies. Most adverse events were grade 1 (mild). Through 12 weeks, the most common treatment emergent adverse events in barzolvolimab treated patients were hair color changes (13%; Grade 1, n=15 / Grade 2, n=2) and neutropenia (10%; Grade 1, n=7 / Grade 2, n=6), which are mechanism related (KIT) and expected to be reversible. The rate of infections was similar between barzolvolimab-treated patients and placebo with no association between neutropenia and infections.

In March 2025, quality of life data were presented at the AAAAI Annual Meeting 2025. A marked and rapid improvement in urticaria control (UCT) and quality of life (DLQI) was observed and sustained through the 12-week period in patients with ColdU and SD. Up to 60% of patients reported that CIndU symptoms no longer had an impact on their quality of life at Week 12 and up to 69% of patients reported well-controlled urticaria based on UCT at Week 12.

Patients on study continued to receive barzolvolimab for up to 20 weeks. Data from this longer term treatment period were presented in November 2025 at the ACAAI Annual Scientific Meeting. The data demonstrated sustained efficacy and a favorable safety profile over the 20 week placebo controlled treatment period. Key highlights at 20 weeks included:

• Up to 66% of patients with ColdU and 49% of patients with SD obtained a complete response compared to 16% and 10% of patients on placebo, respectively.
• Up to 78% of patients with ColdU and 58% of patients with SD obtained a partial or complete response compared to 25% and 16% of patients on placebo, respectively.
• Marked improvement in critical temperature threshold (from baseline values of 18.7°C and 20.7°C to Week 20 values of 10.7°C and 9.2°C for barzolvolimab 150 mg Q4W and 300 mg Q8W, respectively compared to baseline values of 18.6°C to Week 20 values of 18.2°C for placebo ) and friction thresholds (from baseline values of 3.6 and 3.6 pins to 1.5 and 1.4 pins for barzolvolimab 150 mg Q4W and 300 mg Q8W, respectively compared to baseline values of 3.6 pins to 2.9 pins for placebo) were observed over the course of the 20 week treatment period. Sustained improvement in itch reduction at the time of provocation testing (WI-NRSprovo) was also observed at Week 20.
• After completing the treatment period, patients were eligible to enter a 24 week open label extension (OLE) upon resumption/continuation of symptoms. Consistent with the clinical endpoint results at Week 20, placebo-treated patients entered the OLE at a faster rate compared to barzolvolimab-treated patients.
• Barzolvolimab was well tolerated with a favorable safety profile over the 20 week treatment period consistent with previous studies. There was no difference between active treatment (2%) and placebo groups (3%) in rate of discontinuations due to adverse events. Most adverse events for patients on study drug were grade 1 (mild), mechanism related (KIT) and, as demonstrated in previous studies, expected to be reversible. The most common adverse events occurring in greater than 10% of patients in any treatment group through Week 20 were hair color changes (18%; Grade 1, n=22 / Grade 2, n=2) and neutropenia (12%; Grade 1, n=9 / Grade 2, n=6). Neutropenia was transient and there was no association with infections.

We believe these results strongly support the further development of barzolvolimab in CIndU and Celldex plans to initiate a global Phase 3 study in ColdU and SD in December 2025.

Prurigo Nodularis (PN)

We have expanded clinical development of barzolvolimab into prurigo nodularis (PN). PN is a chronic skin disease characterized by the development of hard, intensely itchy (pruritic) nodules on the skin. Mast cells through their interactions with sensory neurons and other immune cells are believed to play an important role in amplifying chronic itch and neuroinflammation, both of which are a hallmark of PN. There is currently only one FDA approved therapy for PN, representing an area of significant unmet need. Industry sources estimate there are approximately 154,000 patients in the United States with PN who have undergone treatment within the last 12 months and, of these, approximately 75,000 would be biologic-eligible.

We have completed a Phase 1b multi-center, randomized, double-blind, placebo-controlled intravenous study in PN. Data from the study, including 24 weeks of follow-up, were presented at the 12th World Congress on Itch (WCI) held in November 2023. 24 adults (evaluable: n=23 safety; n=22 efficacy) with moderate to severe PN were randomized across three arms: (1) barzolvolimab 3.0 mg/kg (n=9), barzolvolimab 1.5 mg/kg (n=7) and placebo (n=8). The primary endpoint of the study was safety; key secondary endpoints include changes from baseline in Worst Itch-Numerical Rating Scale (WI-NRS) & Investigator Global Assessment (IGA). The primary timepoint for evaluation of clinical activity was 8 weeks; patients were followed for safety and efficacy endpoints to 24 weeks. Patients on study generally had moderate to severe disease with mean baselines scores across all arms of 8.6 for WI-NRS and 3.3 for IGA.

A single IV dose of 3.0 mg/kg barzolvolimab resulted in rapid and durable reductions in itch and healing of skin lesions in patients with moderate to severe PN and that barzolvolimab was generally well tolerated.

• At Week 8, the percentage of patients with ≥4-point decrease in WI-NRS was 57% and 43% for the single dose 3.0 or 1.5 mg/kg barzolvolimab arms, respectively, and 25% for the placebo arm; this level of response generally persisted out

to Week 16. In the 3.0 mg/kg arm, a ≥4-point decrease in WI-NRS reduction was seen as early as the first week and reached a high of 71% of patients at Week 6 which was distinct from both the 1.5 mg/kg barzolvolimab and placebo arms.

% of Subjects with ≥4-point decrease in WI-NRS

• At Week 8, 29% of patients achieved clear or almost clear skin according to IGA following a single dose of barzolvolimab 3.0 mg/kg. This effect was noted as early as Week 2 (the first clinic visit) and was maintained out to week 12/16. No patients treated at 1.5 mg/kg barzolvolimab or placebo achieved clear or almost clear skin according to IGA through Week 8. 2 additional patients in the 1.5 mg/kg arm, 2 additional patients in the 3.0 mg/kg arm and 1 patient on placebo had IGA 0/1 at timepoints between Weeks 8 and 24.

% of Subjects with IGA 0/1

• Clinical activity was associated with profound serum tryptase reduction. At the 3.0 mg/kg dose, tryptase was profoundly reduced to, or below, the level of quantification and this level of reduction was maintained at least through 8 weeks. Tryptase reduction was observed in the 1.5 mg/kg arm but to a lesser extent.
• Adverse Events were generally mild to moderate in intensity and considered unrelated to treatment. During the initial 8 week observation period in the 3.0 mg/kg dosing arm, an anaphylactic reaction occurred in a complicated patient with multiple comorbidities; the event fully resolved without sequelae. Generally, adverse events seen during the 24-week follow-up period were consistent with comorbidities commonly observed in the PN population.

In April 2024, we initiated a Phase 2 subcutaneous study in PN. This randomized, double-blind, placebo-controlled, parallel group study is evaluating the efficacy and safety profile of 2 dose levels of barzolvolimab compared to placebo in approximately 120 patients with moderate to severe PN who had inadequate response to prescription topical medications, or for whom topical medications are medically inadvisable (such as concerns for safety). Patients are randomly assigned on a 1:1:1 ratio to receive barzolvolimab injections of 150 mg Q4W after an initial loading dose of 450 mg, 300 mg Q4W after an initial loading dose of 450 mg, or placebo during a 24‑week Treatment Phase. Participants then enter a follow-up phase with no study treatment for an additional 16 weeks through Week 40. The primary objective of this study is to evaluate the clinical effect of barzolvolimab, compared to placebo, on itch response as measured by the proportion of participants with ≥ 4-point improvement in the worst intensity itch per a numeric rating scale (WI-NRS). Secondary objectives include but are not limited to additional measures of itch response from baseline compared to different timepoints, the assessment of skin lesions as measured by the Investigator Global Assessment (IGA), QoL outcomes and safety. The study includes approximately 75 clinical trial centers worldwide, including the United States. Enrollment is ongoing. Initial data from this study are expected to be presented in the second half of 2026.

Atopic Dermatitis (AD)

In December of 2024, we announced the initiation of a Phase 2 study in atopic dermatitis (AD). AD is one of the most common chronic inflammatory skin diseases, with a lifetime prevalence of up to 20% of the US population and a substantial impact on quality of life (Kawakami, et al. 2009). Mast cells are strongly implicated in all facets of AD pathophysiology and the fundamental processes that characterize AD, including epithelial barrier dysfunction, immune cell recruitment, neuroinflammation (Keith, et al. 2023) and multiple other mast cell-associated factors that correlate with disease severity. Activated mast cells are also found in increased numbers in lesional biopsies. Two-thirds of patients treated with first line systemic therapy (1.7 million patients in the US) do not achieve complete control of their atopic dermatitis (Simpson, Bieber, Guttman-Yassky, et al. 2016) and new therapies that offer rapid, meaningful relief from the severe itching and breakdown of the skin associated with AD are needed. Given barzolvolimab’s potential as a mast cell depleting agent, we believe AD is an important indication for future study.

The randomized, double-blind, placebo-controlled, parallel group Phase 2 study is evaluating the efficacy and safety profile of subcutaneous barzolvolimab in patients with moderate to severe AD. Approximately 120 patients will be randomly assigned on a 1:1:1 ratio to receive subcutaneous injections of barzolvolimab at either 150 or 300 mg or placebo every 4 weeks after an initial loading dose of 450 mg or placebo during a 16-week placebo-controlled treatment phase. Participants randomized into the placebo arm will be re-randomized at Week 16 into 1 of the 2 active treatment arms. Patients then enter a 16-week active treatment phase, in which all patients will receive barzolvolimab every 4 weeks. The primary endpoint of the study is to evaluate the clinical efficacy of the two dose levels compared to placebo using the Peak Pruritus Numerical Rating Scale (PP-NRS) at Week 16, a well‐defined, reliable, sensitive and valid scale for evaluating worst itch intensity in adults with moderate‐to‐severe AD. Secondary endpoints include the evaluation of the clinical efficacy of barzolvolimab, compared to placebo across multiple patient-reported outcomes, including assessing impressions of disease change and severity and improvements in quality of life. When all clinical trial sites are open, the study includes approximately 40 clinical trial centers in the United States. Enrollment is ongoing. Initial data from this study are expected to be presented in the second half of 2026.

Eosinophilic Esophagitis (EoE)

In August 2025, we announced the discontinuation of development in eosinophilic esophagitis (EoE), a chronic inflammatory disease of the esophagus, based on interim results from a Phase 2 study. Identifying the key drivers of EoE has challenged the field and research has suggested that mast cells could play an important role in the disease pathogenesis. We designed this study to determine if barzolvolimab could deplete mucosal (intraepithelial) mast cells and, in turn, improve clinical outcomes in EoE. The primary endpoint of the study, absolute change from baseline to Week 12 in peak esophageal intraepithelial mast cell count was met, but the profound mast cell depletion observed did not result in improvement in EoE symptoms or endoscopic assessment of disease activity compared to placebo. Consistent with previously reported studies, barzolvolimab demonstrated a favorable safety and tolerability profile. Based on these results, further development in EoE was discontinued. The results do support future development with KIT- or SCF-targeted therapies in other GI indications where mucosal mast cells are believed to play an important role.

Additional Barzolvolimab Development Activities

In 2023, we completed the transfer of our current barzolvolimab manufacturing process to a CDMO and successfully scaled up the drug substance manufacturing process to produce larger cGMP batches in support of late-stage trials and to prepare for potential commercialization. Drug product manufacturing into 1 mL pre-filled syringes has been completed and are actively being used in the ongoing Phase 3 CSU trials. In the third quarter of 2025, we initiated the Process Performance Qualification (PPQ) manufacturing runs for drug substance and are currently planning for the drug product PPQ activities in 2026.

In February 2022, we reported interim data after completing the in-life dosing portion of our six-month chronic toxicology study in non-human primates. The only clinically adverse finding at the completion of dosing was a profound impact on spermatogenesis, an expected and well understood effect of KIT inhibition. As a standard part of toxicology studies, some animals from each group continued to be observed through a recovery period to understand the reversibility of any adverse findings. Due to the very high concentrations of barzolvolimab at the end of dosing, the recovery period was approximately one year. As we expected, and consistent with previous findings with KIT blocking antibodies, we were pleased to report in December 2022, that during this recovery period spermatogenesis fully recovered in all male animals as measured by both sperm count and motility. The final histologic analysis and study report were completed in early 2023 and were consistent with previously reported results. We are encouraged with these findings and believe these data strongly support continued development of barzolvolimab.

Bispecific Platform

Our next generation bispecific antibody platform is supporting the expansion of our pipeline with additional candidates for inflammatory diseases. Targets are being selected based on new science as well as their compatibility to be used in bispecific antibody formats with our existing antibody programs. Development is focused on emerging, important pathways controlling inflammatory diseases.

CDX-622

CDX-622 is a bispecific antibody that targets two complementary pathways that drive chronic inflammation, potently neutralizing the alarmin thymic stromal lymphopoietin (TSLP) and depleting mast cells via stem cell factor (SCF) starvation. TSLP has been directly implicated in several respiratory and dermatological disorders, such as asthma, chronic obstructive pulmonary disease (COPD), eosinophilic esophagitis, atopic dermatitis and chronic spontaneous urticaria, and in fibrotic diseases such as systemic sclerosis and idiopathic pulmonary fibrosis. In these disorders, TSLP is often upregulated and associated with disease severity. Similarly, mast cells drive or contribute to the pathophysiology of allergic, inflammatory, autoimmune and fibrotic disorders and CDX-622 contains a unique SCF neutralizing function that is expected to inhibit and deplete mast cells. Combined neutralization of SCF and TSLP with CDX-622 is expected to simultaneously reduce tissue mast cells and inhibit Type 2 inflammatory responses to potentially offer enhanced therapeutic benefit in inflammatory and fibrotic disorders. CDX-622 has been engineered to disable effector function (AQQ) and reduce clearance (YTE). In preclinical studies, CDX-622 inhibits TSLP and SCF with similar potency to both its respective parental mAbs and comparator mAbs in vitro and preferentially inhibits the soluble over the membrane form of SCF, which may lead to differential impact on KIT-dependent processes. CDX-622 was well tolerated in a multi-dose 8 week toxicology study in non-human primates and led to a profound mast cell depletion in several tissues. The No Adverse Event Level (NOAEL) was established to be 75 mg/kg, the highest dose level tested.

In November 2024, we initiated a Phase 1 study of CDX-622 in healthy volunteers. The Phase 1a clinical trial is a three-part, randomized, double-blind, placebo-controlled, dose escalation study designed to assess the safety, pharmacokinetics, and pharmacodynamics of single ascending doses (Part 1), multiple ascending doses (Part 2) and single ascending doses administered subcutaneously (Part 3) of CDX-622 in up to 80 healthy participants. A single dose of CDX-622 or placebo was administered intravenously once during Part 1. In Part 2, CDX-622 or placebo is administered every 2 weeks (Q2W) for up to 6 weeks following the first dose, for a total of 3 doses. A single dose of CDX-622 or placebo will be administered subcutaneously once during Part 3. Participants will be followed for 12 weeks in all Parts following the last dose of study drug. The pharmacodynamic biomarkers from blood and skin will be highly informative on the ability of CDX-622 to engage and neutralize SCF and TSLP. A subcutaneous formulation is currently being manufactured and will be added to this study in 2025.

We presented positive data from the single ascending dose portion of the study (Part 1) at the CIA (Collegium Internationale Allergologicum) Biennial Symposium in October 2025. CDX-622 was well tolerated with no dose limiting toxicities and no emergent events related to systemic KIT inhibition. CDX-622 exhibited a good pharmacokinetic profile and induced rapid and sustained dose dependent reductions in serum tryptase, indicative of mast cell inhibition and depletion. Enrollment is ongoing to the multiple ascending doses portion of the study (Part 2).

CRITICAL ACCOUNTING POLICIES AND ESTIMATES

See Note 2 to the unaudited condensed consolidated financial statements included elsewhere in this Quarterly Report on Form 10-Q for information regarding newly adopted and recent accounting pronouncements. See also Note 2 to our financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2024 for a discussion of our critical accounting policies and estimates. There have been no material changes to such critical accounting policies or estimates. We believe our most critical accounting policies include accounting for contingent consideration, revenue recognition, intangible and long-lived assets, research and development expenses and stock-based compensation expense.

RESULTS OF OPERATIONS

Three Months Ended September 30, 2025 Compared with Three Months Ended September 30, 2024

(In thousands)

Net Loss

The $24.9 million increase in net loss for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to an increase in research and development expenses related to barzolvolimab and decreases in revenue and investment and other income, net.

Revenue

Revenue from product development and licensing agreements for the three months ended September 30, 2025 was relatively consistent with the three months ended September 30, 2024. The $3.2 million decrease in contracts and grants revenue for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to a decrease in revenue from our contract manufacturing and research and development agreements with Rockefeller University. We expect revenue to remain relatively consistent over the next twelve months, although there may be fluctuations on a quarterly basis.

Research and Development Expense

Research and development expenses consist primarily of (i) personnel expenses, (ii) laboratory supply expenses relating to the development of our technology, (iii) facility expenses and (iv) product development expenses associated with our drug candidates as follows:

(In thousands)

Personnel expenses primarily include salary, benefits, stock-based compensation and payroll taxes. The $0.6 million increase in personnel expenses for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to an increase in employee headcount. We expect personnel expenses to increase over the next twelve months as a result of additional headcount to support the expanded development of barzolvolimab.

Laboratory supplies expenses include laboratory materials and supplies, services, and other related expenses incurred in the development of our technology. Laboratory supply expenses for the three months ended September 30, 2025 were relatively consistent with the three months ended September 30, 2024. We expect laboratory supplies expenses to remain relatively consistent over the next twelve months, although there may be fluctuations on a quarterly basis.

Facility expenses include depreciation, amortization, utilities, rent, maintenance and other related expenses incurred at our facilities. Facility expenses for the three months ended September 30, 2025 were relatively consistent with the three months ended September 30, 2024. In September 2025, we signed a new lease in New Haven, CT that we will relocate our existing New Haven operations to in 2026. We expect facility expenses to increase over the next twelve months, although there may be fluctuations on a quarterly basis.

Product development expenses include clinical investigator site fees, external trial monitoring costs, data accumulation costs, contracted research and outside clinical drug product manufacturing. The $15.8 million increase in product development expenses for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to an increase in barzolvolimab clinical trial and contract manufacturing expenses. We expect product development expenses to increase over the next twelve months as a result of the expanded development of barzolvolimab, including manufacturing PPQ activities planned for the fourth quarter of 2025 and throughout 2026, although there may be fluctuations on a quarterly basis.

General and Administrative Expense

The $0.6 million increase in general and administrative expenses for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to higher commercial planning expenses. We expect general and administrative expenses to increase over the next twelve months as a result of the expanded development of barzolvolimab and an increase in commercial planning efforts, although there may be fluctuations on a quarterly basis.

Investment and Other Income, Net

The $3.4 million decrease in investment and other income, net for the three months ended September 30, 2025, as compared to the three months ended September 30, 2024, was primarily due to lower levels of cash and investment balances. We expect investment and other income to decrease over the next twelve months due to lower levels of cash and investment balances, although there may be fluctuations on a quarterly basis.

Nine Months Ended September 30, 2025 Compared with Nine Months Ended September 30, 2024

(In thousands)

Net Loss

The $66.7 million increase in net loss for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to an increase in research and development expenses related to barzolvolimab and decreases in revenue and investment and other income, net.

Revenue

Revenue from product development and licensing agreements for the nine months ended September 30, 2025 was relatively consistent with the nine months ended September 30, 2024. The $4.5 million decrease in contracts and grants revenue for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to a decrease in revenue from our contract manufacturing and research and development agreements with Rockefeller University.

Research and Development Expense

Research and development expenses consist primarily of (i) personnel expenses, (ii) laboratory supply expenses relating to the development of our technology, (iii) facility expenses and (iv) product development expenses associated with our drug candidates as follows:

(In thousands)

Personnel expenses primarily include salary, benefits, stock-based compensation and payroll taxes. The $5.0 million increase in personnel expenses for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to higher stock-based compensation expense and an increase in employee headcount.

Laboratory supplies expenses include laboratory materials and supplies, services, and other related expenses incurred in the development of our technology. The $0.8 million increase in laboratory supply expenses for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to higher laboratory materials and supplies purchases.

Facility expenses include depreciation, amortization, utilities, rent, maintenance and other related expenses incurred at our facilities. The $0.4 million increase in facility expenses for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to higher repairs and depreciation expense.

Product development expenses include clinical investigator site fees, external trial monitoring costs, data accumulation costs, contracted research and outside clinical drug product manufacturing. The $43.3 million increase in product development expenses for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to an increase in barzolvolimab clinical trial and contract manufacturing expenses.

General and Administrative Expense

The $3.6 million increase in general and administrative expenses for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to higher stock-based compensation and an increase in employee headcount.

Investment and Other Income, Net

The $5.5 million decrease in investment and other income, net for the nine months ended September 30, 2025, as compared to the nine months ended September 30, 2024, was primarily due to lower levels of cash and investment balances.

LIQUIDITY AND CAPITAL RESOURCES

Our cash equivalents are highly liquid investments with a maturity of three months or less at the date of purchase and consist primarily of investments in money market mutual funds with commercial banks and financial institutions. We maintain cash balances with financial institutions in excess of insured limits. We do not anticipate any losses with respect to such cash balances. We invest our excess cash balances in marketable securities, including municipal bond securities, U.S. government agency securities and high-grade corporate bonds that meet high credit quality standards, as specified in our investment policy. Our investment policy seeks to manage these assets to achieve our goals of preserving principal and maintaining adequate liquidity.

The use of our cash flows for operations has primarily consisted of salaries and wages for our employees; facility and facility-related costs for our offices, laboratories and manufacturing facility; fees paid in connection with preclinical studies, clinical studies, contract manufacturing, laboratory supplies and services; and consulting, legal and other professional fees. We anticipate that our cash flows from operations will continue to be focused in these areas as we progress our current drug candidates through the clinical trial process and develop additional drug candidates. To date, the primary sources of cash flows from operations have been payments received from our collaborative partners and from government entities and payments received for contract manufacturing and research and development services provided by us. The timing of any new contract manufacturing and research and development agreements, collaboration agreements, government contracts or grants and any payments under these agreements, contracts or grants cannot be easily predicted and may vary significantly from quarter to quarter.

At September 30, 2025, our principal sources of liquidity consisted of cash, cash equivalents and marketable securities of $583.2 million. We have had recurring losses and incurred a loss of $177.4 million for the nine months ended September 30, 2025. Net cash used in operations for the nine months ended September 30, 2025 was $147.0 million. We believe that the cash, cash equivalents and marketable securities at September 30, 2025 are sufficient to meet estimated working capital requirements and fund current planned operations through 2027. This could be impacted if we elect to pay the future milestone under the Settlement Agreement with SRS in cash, in the event that we achieve the milestone related to that payment.

During the next twelve months, we may take further steps to raise additional capital to meet our long-term liquidity needs including, but not limited to, one or more of the following: the licensing of drug candidates with existing or new collaborative partners, possible business combinations, issuance of debt, or the issuance of common stock or other securities via private placements or public offerings. Although we have been successful in raising capital in the past, there can be no assurance that additional financing will be available on acceptable terms, if at all, and our negotiating position in capital raising efforts may worsen as existing resources are used. There is also no assurance that we will be able to enter into further collaborative relationships. Additional equity financings may be dilutive to our stockholders; debt financings, if available, may involve significant cash payment obligations and covenants that restrict our ability to operate as a business; and licensing or strategic collaborations may result in royalties or other terms which reduce our economic potential from products under development. Our ability to continue funding our planned operations into and beyond twelve months from the issuance date is also dependent on the timing and manner of payment of the future milestone under the Settlement Agreement with SRS, in the event that we achieve the milestone related to that payment. We may decide to pay that milestone payment in cash, shares of our common stock or a combination thereof. If we are unable to raise the funds necessary to meet our long-term liquidity needs, we may have to delay or discontinue the development of one or more programs, discontinue or delay ongoing or anticipated clinical trials, license out programs earlier than expected, raise funds at a significant discount or on other unfavorable terms, if at all, or sell all or a part of our business.

Operating Activities

Net cash used in operating activities was $147.0 million for the nine months ended September 30, 2025 as compared to $125.3 million for the nine months ended September 30, 2024. The increase in net cash used in operating activities was primarily due to increases in research and development and general and administrative expenses, partially offset by a decrease in advance payments to clinical research and contract manufacturing organizations. We expect that cash used in operating activities will increase over the next twelve months as a result of the expanded development of barzolvolimab.

We have incurred and will continue to incur significant costs in the area of research and development, including preclinical and clinical trials and clinical drug product manufacturing as our drug candidates are developed. We plan to spend significant amounts to progress our current drug candidates through the clinical trial process as well as to develop additional drug candidates. As our drug candidates progress through the clinical trial process, we may be obligated to make significant milestone payments, pursuant to our existing arrangements and arrangements we may enter in the future.

Investing Activities

Net cash provided by investing activities was $153.6 million for the nine months ended September 30, 2025 compared to net cash used in investing activities of $314.2 million for the nine months ended September 30, 2024. The increase in net cash provided by investing activities was primarily due to net sales and maturities of marketable securities of $155.1 million for the nine months ended September 30, 2025 as compared to net purchases of marketable securities of $313.0 million for the nine months ended September 30, 2024.

Financing Activities

Net cash provided by financing activities was $1.0 million for the nine months ended September 30, 2025 as compared to $441.1 million for the nine months ended September 30, 2024. The decrease in net cash provided by financing activities was primarily due to a decrease in net proceeds from stock issuances.

In March 2024, we issued 9,798,000 shares of common stock in an underwritten public offering, resulting in net proceeds of $432.3 million, after deducting underwriting fees and offering expenses.

We own financial instruments that are sensitive to market risk as part of our investment portfolio. Our investment portfolio is used to preserve our capital until it is used to fund operations, including our research and development activities. None of these market-risk sensitive instruments are held for trading purposes. We invest our cash primarily in money market mutual funds. These investments are evaluated quarterly to determine the fair value of the portfolio. From time to time, we invest our excess cash balances in marketable securities including municipal bond securities, U.S. government agency securities and high-grade corporate bonds that meet high credit quality standards, as specified in our investment policy. Our investment policy seeks to manage these assets to achieve our goals of preserving principal and maintaining adequate liquidity. Because of the short-term nature of these investments, we do not believe we have material exposure due to market risk. The impact to our financial position and results of operations from likely changes in interest rates is not material.

We do not utilize derivative financial instruments. The carrying amounts reflected in the consolidated balance sheet of cash and cash equivalents, accounts receivables and accounts payable approximate fair value at September 30, 2025 due to the short-term maturities of these instruments.

Evaluation of Disclosure Controls and Procedures.

As of September 30, 2025, we evaluated, with the participation of our Chief Executive Officer and Chief Financial Officer, the effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)). Based on that evaluation, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of September 30, 2025. Our disclosure controls and procedures are designed to provide reasonable assurance that information required to be disclosed in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within time periods specified by the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

Changes in Internal Control Over Financial Reporting.

There were no changes in our internal control over financial reporting during the quarter ended September 30, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

In addition to the other information set forth in this report, you should carefully consider the factors discussed in Part I, “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2024, which could materially affect our business, financial condition or future results. The risks described in our Annual Report on Form 10-K may not be the only risks facing us. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition and/or operating results.

There were no material changes to the risk factors previously disclosed in our Annual Report on Form 10-K filed with the SEC on February 27, 2025.