Celldex Completes Enrollment in Global Phase 3 Studies (EMBARQ-CSU1 and EMBARQ-CSU2) of Barzolvolimab in Chronic Spontaneous Urticaria

Rhea-AI Summary

Celldex (NASDAQ:CLDX) completed enrollment in its global Phase 3 EMBARQ-CSU1 and EMBARQ-CSU2 studies of barzolvolimab, randomizing 1,939 patients across 43 countries and >500 sites, six months ahead of guidance. Topline data are expected in Q4 2026 with a BLA planned for 2027. The trials test two dosing regimens versus placebo with the primary endpoint of UAS7 at Week 12 and primary analysis when the placebo-controlled portion completes at Week 24.

Positive

• Enrollment of 1,939 patients completed, the largest antihistamine-refractory CSU program
• Enrollment finished 6 months ahead of company guidance
• 43 countries and >500 sites indicate broad global participation
• Topline results expected in Q4 2026, enabling near-term readout
• BLA submission planned for 2027, providing a clear regulatory timeline
• Phase 2 showed up to 51% complete response at 12 weeks and up to 71% at 52 weeks

Negative

• Topline data not available until Q4 2026, delaying potential commercialization
• Primary endpoint analysis occurs after the 24-week placebo-controlled period, extending confirmation timeline
• Placebo patients are re-randomized at Week 24, shortening longer-term blinded comparisons

News Market Reaction – CLDX

+24.07% 4.5x vol

56 alerts

+24.07% News Effect

+18.7% Peak in 6 hr 11 min

+$399M Valuation Impact

$2.06B Market Cap

4.5x Rel. Volume

On the day this news was published, CLDX gained 24.07%, reflecting a significant positive market reaction. Argus tracked a peak move of +18.7% during that session. Our momentum scanner triggered 56 alerts that day, indicating high trading interest and price volatility. This price movement added approximately $399M to the company's valuation, bringing the market cap to $2.06B at that time. Trading volume was very high at 4.5x the daily average, suggesting strong buying interest.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Phase 3 CSU enrollment: 1,939 patients Countries and sites: 43 countries; >500 sites Complete response at 12 weeks: Up to 51% of patients +5 more

8 metrics

Phase 3 CSU enrollment 1,939 patients Global Phase 3 barzolvolimab CSU program (EMBARQ-CSU1/2)

Countries and sites 43 countries; >500 sites Global Phase 3 CSU program footprint

Complete response at 12 weeks Up to 51% of patients Phase 2 CSU barzolvolimab study (UAS7=0)

Complete response at 52 weeks Up to 71% of patients Phase 2 CSU active therapy duration

Sustained complete response off therapy Up to 41% of patients Seven months after last barzolvolimab dose in Phase 2 CSU

Angioedema-free at 12 weeks Up to 65% of patients Phase 2 CSU barzolvolimab treated (AAS7=0)

QoL no impact at 52 weeks Up to 82% of patients Phase 2 CSU DLQI 0/1 at Week 52

Treatment duration in Phase 3 52 weeks, with 24-week placebo control EMBARQ-CSU1/2 Phase 3 study design

Market Reality Check

Price: $30.63 Vol: Volume 815,732 vs 20-day ...

normal vol

$30.63 Last Close

Volume Volume 815,732 vs 20-day average 649,129, about 1.26x typical activity ahead of this update. normal

Technical Price 24.84 is trading above the 200-day MA at 24.01, showing strength into the Phase 3 milestone.

Peers on Argus

Biotech peers showed mixed moves, with one momentum name (VRDN) up 1.87% and oth...

1 Up

Biotech peers showed mixed moves, with one momentum name (VRDN) up 1.87% and others varying, suggesting today’s CLDX action is more company-specific than a broad sector rotation.

Previous Clinical trial Reports

5 past events · Latest: Dec 09 (Positive)

Same Type Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Dec 09	Phase 3 initiation	Positive	-5.7%	Started global Phase 3 program of barzolvolimab in ColdU and SD.
Nov 06	Phase 2 data update	Positive	-2.0%	Additional Phase 2 CSU data showing rapid, durable complete disease control.
Nov 06	Phase 2 results	Positive	-2.0%	Phase 2 ColdU and SD data with high complete and partial response rates.
Oct 30	Phase 1 results	Positive	+2.8%	Initial Phase 1 CDX‑622 data showing favorable safety and mast cell inhibition.
Sep 17	Phase 2 data	Positive	-0.5%	CSU Phase 2 data showing strong complete response rates independent of IgE.

Pattern Detected

Clinical trial updates have generally been positive scientifically but often met with muted or negative next-day price reactions, with only one of five events showing a positive move.

Recent Company History

Over the past six months, Celldex has steadily advanced its mast‑cell–targeted pipeline. Multiple barzolvolimab Phase 2 readouts in CSU, ColdU and SD showed high complete response rates and durable control, while a Phase 1 study of CDX‑622 demonstrated favorable safety and sustained mast cell inhibition. Despite these clinically positive data, four of five tagged clinical‑trial headlines triggered negative 24‑hour moves, underscoring a history of cautious market reactions to development milestones.

Historical Comparison

-1.5% avg move · Across five prior clinical‑trial headlines, average next‑day move was -1.48%. Today’s +2.14% reactio...

clinical trial

-1.5%

Average Historical Move clinical trial

Across five prior clinical‑trial headlines, average next‑day move was -1.48%. Today’s +2.14% reaction to early Phase 3 CSU enrollment completion is stronger and directionally more positive than that history.

Clinical news shows a clear progression: early Phase 2 CSU efficacy, broader ColdU/SD data, initiation of registrational Phase 3 trials, and now early completion of enrollment in the global CSU Phase 3 program.

Market Pulse Summary

The stock surged +24.1% in the session following this news. A strong positive reaction aligns with t...

Analysis

The stock surged +24.1% in the session following this news. A strong positive reaction aligns with the company’s rapid advancement of barzolvolimab, including early completion of enrollment in large global Phase 3 CSU studies and robust Phase 2 durability data. Historically, clinical‑trial headlines averaged a -1.48% next‑day move, so outsized gains could reflect shifting sentiment. Investors should weigh the high short‑term enthusiasm against prior instances where optimism faded after initial spikes.

Key Terms

phase 3, bla submission, randomized, double-blind, +3 more

7 terms

phase 3 medical

"completion of enrollment in the Company’s global Phase 3 program of barzolvolimab"

Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.

bla submission regulatory

"Topline data expected Q4 2026BLA submission planned for 2027"

A BLA submission is a company’s formal application to the U.S. Food and Drug Administration asking for permission to market a biologic drug or therapy. Think of it like applying for a permit to sell a complex medical product: the agency reviews safety, effectiveness, and manufacturing quality before deciding. For investors, a BLA filing signals a late-stage regulatory milestone that can reduce uncertainty and, if approved, unlock revenue and change a company’s valuation, while also carrying regulatory and timing risk.

randomized medical

"Both Phase 3 trials are randomized, double-blind, placebo-controlled, parallel group"

Randomized means participants or units in a study are assigned to different groups by chance rather than by choice, like flipping a coin to decide who gets a new treatment and who gets a comparison. For investors, randomized designs matter because they reduce bias and make results more trustworthy, so outcomes from randomized studies carry more weight when assessing regulatory approval, commercial prospects, and the risk that trial results will change a company’s valuation.

double-blind medical

"Both Phase 3 trials are randomized, double-blind, placebo-controlled, parallel group"

A double-blind process means that neither the people conducting an activity nor the people involved know certain key details, such as who is receiving a treatment or a placebo. This approach helps prevent bias from influencing the results, making the outcome more trustworthy. For investors, it ensures that decisions or judgments are based on unbiased information rather than preconceived opinions or expectations.

placebo-controlled medical

"Both Phase 3 trials are randomized, double-blind, placebo-controlled, parallel group"

"Placebo-controlled" describes a testing method where one group receives the actual treatment or intervention, while another group receives a harmless, inactive version called a placebo. This approach helps determine whether the real treatment has genuine effects beyond psychological expectations. For investors, understanding this ensures confidence that reported benefits are real and not influenced by bias or false perceptions.

uas7 medical

"reducing urticaria activity (weekly urticaria activity score; UAS7) at Week 12"

UAS7 is a standardized clinical score that sums a patient’s daily ratings of hive number and itch severity over seven days to quantify how active chronic hives are. Investors care because it’s a widely accepted measure used in clinical trials to show whether a treatment meaningfully reduces symptoms; like a thermometer for patient improvement, stronger UAS7 results can influence regulatory approval chances and commercial prospects.

omalizumab refractory medical

"as well as in the subpopulation of omalizumab refractory participants"

Omalizumab refractory describes a condition in which a patient's disease does not improve after treatment with omalizumab, a targeted antibody drug that blocks allergy-related immune signals. For investors, this signals an unmet medical need and a defined patient population that may require alternative therapies, affecting the potential market size, clinical trial design, and commercial opportunity for drugs aimed at those who do not respond to omalizumab.

AI-generated analysis. Not financial advice.

• Enrollment completed six months ahead of guidance, driven by significant unmet need for better treatments in CSU
• Topline data expected Q4 2026
• BLA submission planned for 2027
  

HAMPTON, N.J., Feb. 25, 2026 (GLOBE NEWSWIRE) -- Celldex (NASDAQ:CLDX) announced today the completion of enrollment in the Company’s global Phase 3 program of barzolvolimab in chronic spontaneous urticaria (CSU), which consists of two Phase 3 trials—EMBARQ-CSU1 and EMBARQ-CSU2. 1,939 patients were enrolled—the largest program conducted in antihistamine refractory CSU, including patients with advanced therapy experienced/refractory CSU. The studies included 43 countries and over 500 sites.

“Completing enrollment in these large Phase 3 CSU studies 6 months ahead of guidance highlights the significant unmet need in CSU and speaks to the excitement from patients and physicians about barzolvolimab and its potential as a best-in-disease treatment,” said Anthony S. Marucci, Co-founder, President and Chief Executive Officer of Celldex. “We are extremely grateful to these patients, their families and their treating physicians for their enthusiasm and participation in the EMBARQ-CSU1 and EMBARQ-CSU2 studies. We look forward to reporting topline results later this year and remain focused on completing preparations to support bringing this much needed treatment to more than 1.8 million patients in the United States suffering from CSU.”

Barzolvolimab uniquely targets the root cause of CSU—the mast cell—and has the potential to transform the CSU treatment landscape by providing rapid, profound and durable efficacy that is unparalleled in CSU, offering new hope for the patients suffering from this often severe and debilitating disease. Based on results from the completed Phase 2 study of barzolvolimab in CSU, barzolvolimab has the potential to deliver a best-in-class and best-in-disease clinical profile—symptom free complete control and dramatic improvements in quality of life and angioedema. Up to 51% of patients on study had a complete response and were symptom free (UAS7=0; no itch/no hives) at 12 weeks, which continued to deepen over 52 weeks of active therapy to up to 71% of patients. This profound clinical benefit continued even after patients were off therapy with up to 41% of patients reporting complete response seven months after receiving their last dose. Patients also reported dramatic improvements in angioedema control and quality of life. At 12 weeks, up to 65% of barzolvolimab treated patients were angioedema free (AAS7=0), which increased to up to 77% at Week 52 and remained at up to 64% seven months after last dose. At 12 weeks, up to 67% of patients treated with barzolvolimab reported their CSU had no impact on their quality of life (DLQI 0/1), which increased to up to 82% at Week 52 and remained at up to 48% seven months after last dose.

The Phase 3 Program is 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. 1,939 patients were randomized (n=963 EMBARQ-CSU1; n=976 EMBARQ-CSU2) 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 are re-randomized to active treatment across both dosing groups. The primary endpoint of the study will evaluate the clinical effect of barzolvolimab in reducing urticaria activity (weekly urticaria activity score; UAS7) at Week 12. The study is designed to detect a clinically meaningful difference between each of the active arms vs placebo in the overall population as well as in the subpopulation of omalizumab refractory participants. The primary endpoint analysis will be performed when all patients have completed the placebo controlled portion of the study at 24 weeks. A global Phase 3b long term extension study (LTE) has been established and is ongoing, which patients can enter following completion of the EMBARQ-CSU Phase 3 trials.

Please visit clinicaltrials.gov for additional information on EMBARQ-CSU1; NCT06445023 and EMBARQ-CSU2; NCT06455202).

About Barzolvolimab
Barzolvolimab is a humanized monoclonal antibody with a novel mechanism of action that targets mast cells by binding with high specificity to a unique part of the KIT receptor and potently inhibiting its activity. The KIT receptor is abundantly expressed by mast cells and critical for their function and survival. Mast cells are drivers of inflammatory responses such as hypersensitivity and allergic reactions and, in certain inflammatory diseases, such as chronic urticarias, mast cell activation plays a central role in the onset and progression of the disease. Based on data from robust, randomized, placebo controlled Phase 2 studies, barzolvolimab has significant potential as a first-in-class and best-in-disease treatment option for patients with chronic spontaneous urticaria (CSU), cold urticaria (ColdU) and symptomatic dermographism (SD). Barzolvolimab is currently being studied in Phase 3 studies in CSU and ColdU/SD and Phase 2 studies in prurigo nodularis (PN) and atopic dermatitis (AD), with additional indications planned for the future.

About Chronic Spontaneous Urticaria (CSU)
CSU is an underdiagnosed disease of misery marked by spontaneous hives, unbearable itch, and unpredictable episodes of disfiguring swelling (angioedema) that causes substantial mental health burden, profound impact on quality of life and is associated with a 1.7-fold increase in all cause mortality at 5 years. Mast cell activation plays a central role in the onset and progression of CSU. While the goal of CSU treatment is the complete absence of symptoms, the vast majority of patients today, even those receiving the most advanced approved and available therapies, continue to suffer from itch, hives, swelling, sleep disruption, and unrelenting anxiety about when the next flare up will occur.

About Celldex
Celldex is pioneering new horizons in immunology to deliver life-changing therapies. We are relentless in our pursuit of novel antibody-based treatments that engage the human immune system and directly affect critical pathways to improve the lives of patients with allergic, inflammatory and autoimmune disorders.
Visit www.celldex.com.

Forward Looking Statement
This release contains "forward-looking statements" made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements are typically preceded by words such as "believes," "expects," "anticipates," "intends," "will," "may," "should," or similar expressions. These forward-looking statements reflect management's current knowledge, assumptions, judgment and expectations regarding future performance or events. Although management believes that the expectations reflected in such statements are reasonable, they give no assurance that such expectations will prove to be correct or that those goals will be achieved, and you should be aware that actual results could differ materially from those contained in the forward-looking statements. Forward-looking statements are subject to a number of risks and uncertainties, including, but not limited to, our ability to successfully complete research and further development and commercialization of Company drug candidates, including barzolvolimab (also referred to as CDX-0159) and CDX-622, in current or future indications; the uncertainties inherent in clinical testing and accruing patients for clinical trials; our limited experience in bringing programs through Phase 3 clinical trials; our ability to manage and successfully complete multiple clinical trials and the research and development efforts for our multiple products at varying stages of development; the availability, cost, delivery and quality of clinical materials produced by our own manufacturing facility or supplied by contract manufacturers, who may be our sole source of supply; the timing, cost and uncertainty of obtaining regulatory approvals; the failure of the market for the Company's programs to continue to develop; our ability to protect the Company's intellectual property; the loss of any executive officers or key personnel or consultants; competition; changes in the regulatory landscape or the imposition of regulations that affect the Company's products; our ability to continue to obtain capital to meet our long-term liquidity needs on acceptable terms, or at all, including the additional capital which will be necessary to complete the clinical trials that we have initiated or plan to initiate; and other factors listed under "Risk Factors" in our annual report on Form 10-K and quarterly reports on Form 10-Q.

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 release. 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.

Company Contact
Sarah Cavanaugh
Senior Vice President, Corporate Affairs & Administration
(508) 864-8337
scavanaugh@celldex.com

Patrick Till
Meru Advisors
(484) 788-8560
ptill@meruadvisors.com

FAQ

How many patients were enrolled in Celldex's EMBARQ-CSU1 and EMBARQ-CSU2 trials (CLDX)?

Celldex enrolled 1,939 patients across both Phase 3 trials. According to the company, enrollment covered 43 countries and more than 500 sites, and finished six months ahead of the originally guided timeline.

When does Celldex expect topline results for barzolvolimab in CSU (CLDX)?

Topline results are expected in Q4 2026. According to the company, the primary endpoint (UAS7 at Week 12) will be analyzed after completion of the placebo-controlled portion at Week 24.

What regulatory timeline did Celldex give for barzolvolimab (CLDX)?

Celldex plans a BLA submission in 2027. According to the company, meeting this timeline depends on Phase 3 topline results expected in Q4 2026 and subsequent regulatory preparations.

What dosing regimens are being tested in Celldex's EMBARQ-CSU Phase 3 studies (CLDX)?

The trials test barzolvolimab 150 mg every 4 weeks (after 300 mg loading) and 300 mg every 8 weeks (after 450 mg loading). According to the company, both active arms are randomized versus placebo for 52 weeks.

What primary endpoint will Celldex use in the EMBARQ-CSU trials (CLDX)?

The primary endpoint measures reduction in urticaria activity using UAS7 at Week 12. According to the company, the primary analysis will occur after all patients complete the 24-week placebo-controlled portion.

What efficacy did barzolvolimab show in Phase 2 CSU data cited by Celldex (CLDX)?

Phase 2 showed up to 51% complete response at 12 weeks and up to 71% at 52 weeks. According to the company, responses persisted off therapy, with up to 41% symptom-free seven months after last dose.