Celldex Presents Positive Data Demonstrating Barzolvolimab Retreatment Achieves Similar Profound Efficacy to First Exposure in Patients with Cold Urticaria (ColdU) and Symptomatic Dermographism (SD) Further Demonstrating First-in-Class and Best-in-Disease Barzolvolimab Profile at AAAAI 2026

Rhea-AI Summary

Celldex (NASDAQ:CLDX) presented Phase 2 open‑label extension data at AAAAI 2026 showing that barzolvolimab retreatment produces rapid, profound efficacy similar to initial exposure in Cold urticaria (ColdU) and symptomatic dermographism (SD). In the OLE, complete response rates at Week 20 were 62% (ColdU) and 60% (SD), consistent with initial study results. Among prior complete responders, repeat complete response reached 82% (ColdU) and 86% (SD). Retreatment improved control (up to 68–69% well controlled) and was well tolerated. A global Phase 3 EMBARQ trial (NCT07266402) is enrolling.

Positive

• Complete response rates at Week 20: 62% ColdU
• Complete response rates at Week 20: 60% SD
• Repeat complete response in prior responders: 82% ColdU
• Repeat complete response in prior responders: 86% SD
• High disease control with retreatment: 68–69% well controlled
• Safety consistent with prior studies; retreatment tolerated

Negative

• Placebo patients entered OLE faster: median 56 days vs 105 days for barzolvolimab-treated
• Initial SD complete response in main study was lower (49%) than ColdU (66%)

Key Figures

Phase 2 total patients: 193 patients ColdU cohort size: 96 patients SD cohort size: 97 patients +5 more

8 metrics

Phase 2 total patients 193 patients Main portion of Phase 2 ColdU and SD study

ColdU cohort size 96 patients Phase 2 main study ColdU arm

SD cohort size 97 patients Phase 2 main study SD arm

Barzolvolimab dosing 150 mg Q4W, 300 mg Q8W Phase 2 main study dosing regimens

OLE enrollment 121 patients Phase 2 Open Label Extension, ColdU and SD

ColdU complete response 62% Week 20 in OLE after barzolvolimab retreatment

SD complete response 60% Week 20 in OLE after barzolvolimab retreatment

ColdU initial response 66% Week 20 complete response in main Phase 2 study

Market Reality Check

Price: $30.09 Vol: Volume 1,117,147 is modes...

normal vol

$30.09 Last Close

Volume Volume 1,117,147 is modestly elevated versus 20-day average of 935,232 shares. normal

Technical Shares at $30.09 are trading above the 200-day MA of $24.17 and sit 3.9% below the 52-week high of $31.31.

Peers on Argus

While CLDX was down 1.8%, close peers like AUPH and VERA showed small gains and ...

While CLDX was down 1.8%, close peers like AUPH and VERA showed small gains and others were flat to slightly positive, suggesting today’s move was stock-specific rather than a broad biotech or urticaria-sector reaction.

Historical Context

5 past events · Latest: Feb 25 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Feb 25	Earnings and update	Positive	+24.1%	Year-end 2025 results, strong cash and accelerated barzolvolimab Phase 3 progress.
Feb 25	Phase 3 enrollment	Positive	+24.1%	Completed enrollment of 1,939-patient global Phase 3 CSU program six months early.
Feb 23	Conference presentations	Positive	+5.7%	Announcement of multiple AAAAI 2026 barzolvolimab presentations, including OLE retreatment data.
Feb 09	Investor conferences	Neutral	+4.4%	Planned appearances at several healthcare investor conferences with webcast access.
Dec 09	Phase 3 initiation	Positive	-5.7%	Start of global EMBARQ-ColdU and SD Phase 3 after successful Phase 2 results.

Pattern Detected

Recent barzolvolimab and corporate updates have often coincided with strong positive moves, though there is at least one example of negative reaction to otherwise constructive clinical progress.

Recent Company History

Over the last several months, Celldex has consistently advanced barzolvolimab across chronic urticarias. On Dec 9, 2025, it initiated the EMBARQ-ColdU and SD Phase 3 program, though shares fell despite positive Phase 2 data. In February 2026, completion of enrollment in two large EMBARQ-CSU Phase 3 trials with 1,939 patients and a strong Q4 2025 update each coincided with a 24.07% gain. Announcements about upcoming AAAAI presentations on Feb 23, 2026 also saw a positive reaction, underscoring investor focus on barzolvolimab’s clinical trajectory.

Market Pulse Summary

This announcement details Phase 2 Open Label Extension results showing that barzolvolimab retreatmen...

Analysis

This announcement details Phase 2 Open Label Extension results showing that barzolvolimab retreatment in ColdU and SD can recapture high complete response rates, similar to first exposure, over a 20-week period. It reinforces the drug’s mast cell–targeting mechanism and supports the rationale for the ongoing global Phase 3 EMBARQ-ColdU and SD trial. In the context of earlier news on accelerated Phase 3 enrollment, investors may focus on future readouts and safety consistency across studies.

Key Terms

open label extension, monoclonal antibody, phase 2, phase 3, +3 more

7 terms

open label extension medical

"new positive data from the Phase 2 ColdU and SD Open Label Extension (OLE)"

An open-label extension is a follow-on phase of a clinical trial where participants keep receiving the experimental drug and both doctors and patients know what treatment is being given. It matters to investors because it produces longer-term safety and effectiveness information, helps regulators and companies assess ongoing benefits or risks, and can indicate whether a therapy has staying commercial value — like an extended test drive revealing durability and real-world performance.

monoclonal antibody medical

"Barzolvolimab is a humanized monoclonal antibody with a completely novel mechanism"

A monoclonal antibody is a laboratory-made protein designed to recognize and attach to a specific target in the body, such as a disease-causing substance or cell. It functions like a highly precise lock-and-key tool, helping to treat or detect illnesses. For investors, companies developing monoclonal antibodies can represent promising opportunities in the healthcare sector, especially as these treatments often address unmet medical needs.

phase 2 medical

"new positive data from the Phase 2 ColdU and SD Open Label Extension"

Phase 2 is the mid-stage clinical trial where a new drug or treatment is tested in a larger group of patients to see if it works and to keep checking safety after initial human testing. Think of it as a field test that proves whether a product actually delivers its promised benefit. Investors watch Phase 2 closely because its results strongly influence a medicine’s chances of reaching the market, the size of its potential sales, and the company’s valuation.

phase 3 medical

"A global Phase 3 trial (EMBARQ-ColdU and SD) (NCT07266402) designed to establish"

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.

complete response medical

"up to 41% of patients continued to experience a complete response seven months"

A complete response is a positive outcome in which a company’s efforts to address issues or questions fully resolve the problem, often meaning that no further action or investigation is needed. For investors, it signals that concerns have been thoroughly addressed, which can boost confidence in the company's stability or decision-making. Think of it like a doctor fully treating an illness, leaving no remaining symptoms.

mast cell medical

"targets the root cause of ColdU and SD—the mast cell."

A mast cell is a type of immune cell that sits in tissues like skin and the lining of the lungs and gut and releases chemical signals—such as histamine—when it detects danger. Think of it as a neighborhood alarm that calls in inflammation or allergy responses; its actions can drive allergic reactions, chronic inflammation, or disease. Investors pay attention because mast cells are common targets for new drugs, diagnostics, and safety issues that can affect a therapy’s market potential and regulatory path.

randomized medical

"a global randomized Phase 3 program testing barzolvolimab in adults with cold urticaria"

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.

AI-generated analysis. Not financial advice.

- Late breaking Poster Presentation at AAAAI -
- Ability to retreat facilitates a real-world paradigm in which treatment for ColdU and SD may be intermittent with barzolvolimab -

HAMPTON, N.J., March 01, 2026 (GLOBE NEWSWIRE) -- Celldex (NASDAQ:CLDX) presented new positive data from the Phase 2 ColdU and SD Open Label Extension (OLE), highlighting that retreatment with barzolvolimab leads to rapid improvement in urticaria control after symptom recurrence. Barzolvolimab is a humanized monoclonal antibody with a completely novel mechanism of action that uniquely targets the root cause of ColdU and SD—the mast cell. The data were shared today in a late breaking poster presentation at the 2026 American Academy of Allergy, Asthma & Immunology's (AAAAI) Annual Meeting being held in Philadelphia, PA. The data were presented by Jonathan A. Bernstein, MD, trial investigator and Professor of Clinical Medicine in the Department of Internal Medicine at the University of Cincinnati College of Medicine.

“Patients and physicians need treatment options that provide durable, symptom-free complete response and the potential for flexibility that reflects real world treatment paradigms,” said Diane Young, MD, Senior Vice President and Chief Medical Officer of Celldex. “We previously presented data in chronic spontaneous urticaria showing that up to 41% of patients continued to experience a complete response seven months after receiving their final dose on study. The data presented today from our inducible urticaria study demonstrate that when disease symptoms do recur, patients can be retreated and, importantly, achieve the same high levels of complete response they experienced on initial treatment. We believe barzolvolimab’s unique mechanism of action, which targets the root cause of these forms of chronic urticaria—the mast cell, drives this effect and supports barzolvolimab’s profile as a best-in-class, best-in-disease potential treatment option for patients with chronic urticarias.”

In the main portion of the Phase 2 study, 193 patients with ColdU (n=96) or SD (n=97) received 150 mg Q4W, 300 mg Q8W barzolvolimab, or placebo for 20 weeks. Patients with disease recurrence during the main study follow-up period qualified for the OLE. 121 patients entered the OLE, 61 patients with ColdU and 60 patients with SD, and 116 patients completed treatment in the OLE. Patients treated with placebo in the main study entered the OLE faster than patients treated with barzolvolimab (median time of 56 days versus 105 days from last dose in main study).

Barzolvolimab re-treatment achieved similar profound efficacy to first exposure in patients with ColdU and SD.

• With barzolvolimab re-treatment, 62% of patients with ColdU and 60% of patients with SD had a complete response at Week 20 in the OLE. These findings are consistent with the complete response rates in these patients to their initial treatment of 66% for ColdU and 49% for SD at Week 20 in the main study.
• Among patients with ColdU who achieved a complete response in the main study (n = 22), in the OLE, 82% of these patients achieved a complete response again and 95% achieved complete or partial response at Week 20.
• Among patients with SD who achieved a complete response in main study (n = 21), in the OLE, 86% of these patients achieved a complete response again and 100% achieved either a complete or partial response at Week 20.
• Marked, rapid reduction in critical temperature and friction thresholds were observed upon re-treatment,
• Barzolvolimab re-treatment resulted in clinically meaningful improvements in urticaria control, achieving a high rate of well controlled disease: up to 68% of patients with ColdU and 69% of patients with SD. 
• Barzolvolimab was well tolerated with a safety profile consistent with prior studies,
• The ability to re-treat facilitates a real-world paradigm in which treatment for CIndU may be intermittent.
• A global Phase 3 trial (EMBARQ-ColdU and SD) (NCT07266402) designed to establish the efficacy and safety of barzolvolimab in adult patients with ColdU and SD who remain symptomatic despite H1 antihistamine treatment initiated in late 2025 and is enrolling patients.

About Chronic Inducible Urticaria (CIndU), Cold Urticaria (ColdU), Symptomatic Dermographism (SD)
CIndU is characterized by the occurrence of hives or wheals that have an attributable trigger associated with them. ColdU symptoms include itching, burning wheals/hives and angioedema when skin is exposed to cold temperatures. SD symptoms include the development of wheals in response to stroking, scratching or rubbing of the skin. For these diseases, mast cell activation leading to release of soluble mediators is thought to be the driving mechanism leading to the wheals and other symptoms. 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.

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 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

What did Celldex (CLDX) report about barzolvolimab retreatment at AAAAI 2026?

Retreatment with barzolvolimab produced rapid, profound efficacy similar to initial treatment at Week 20. According to Celldex, OLE complete response rates were 62% for ColdU and 60% for SD, with strong repeat responses among prior complete responders.

How effective was barzolvolimab retreatment for patients who were prior complete responders in the Phase 2 OLE?

Most prior complete responders regained complete responses upon retreatment by Week 20. According to Celldex, 82% of ColdU and 86% of SD prior complete responders achieved complete response again in the OLE.

What safety and disease control outcomes did Celldex (CLDX) present for barzolvolimab retreatment?

Barzolvolimab retreatment was well tolerated with disease control improvements. According to Celldex, up to 68% of ColdU and 69% of SD patients achieved well controlled disease with a safety profile consistent with prior studies.

What were the enrollment and study size details for the Phase 2 ColdU and SD study (CLDX)?

The Phase 2 main study randomized 193 patients and 121 entered the OLE. According to Celldex, 96 ColdU and 97 SD were in the main study; 61 ColdU and 60 SD entered the OLE, with 116 completing.

Is there a Phase 3 trial for barzolvolimab in ColdU and SD and when did it start enrolling?

Yes. A global Phase 3 EMBARQ trial for ColdU and SD is enrolling patients. According to Celldex, EMBARQ (NCT07266402) initiated enrollment in late 2025 to establish efficacy and safety.