Celldex Presents Additional Positive Data from Phase 2 Chronic Spontaneous Urticaria (CSU) and Phase 2 Cold Urticaria (ColdU) and Symptomatic Dermographism (SD) Studies Further Demonstrating First-in-Class and Best-in-Disease Barzolvolimab Profile at AAAAI 2026

Rhea-AI Summary

Celldex (NASDAQ:CLDX) presented Phase 2 data at AAAAI (Feb 27, 2026) showing durable clinical benefit with barzolvolimab in CSU, ColdU and symptomatic dermographism. Key results: up to 71% complete response at 52 weeks in CSU, sustained off-treatment responses (up to 41% at 7 months), and enrollment of 1,939 patients in global Phase 3 CSU.

ColdU/SD data showed up to 66% (ColdU) and 49% (SD) complete response at Week 20 with marked QoL gains.

Positive

• 71% complete response at 52 weeks in CSU
• Sustained off-treatment response: 41% complete at 7 months
• Phase 3 CSU enrollment 1,939 patients, six months ahead of guidance
• 66% ColdU complete response at Week 20; 49% in SD

Negative

• 31%–50% of previously well-controlled CSU patients lost complete response by Week 76
• Some patients experienced symptom recurrence after treatment completion
• Phase 3 ColdU/SD enrollment is ongoing, timing and results remain uncertain

Key Figures

CSU complete response at 12 weeks: 51% of patients CSU complete response at 52 weeks: 71% of patients Off-treatment CSU complete response: 41% of patients +5 more

8 metrics

CSU complete response at 12 weeks 51% of patients Phase 2 CSU study; UAS7=0 symptom free at Week 12

CSU complete response at 52 weeks 71% of patients Phase 2 CSU study; UAS7=0 after 52 weeks of therapy

Off-treatment CSU complete response 41% of patients Complete response 7 months after last barzolvolimab dose

Severe CSU at baseline 67% of patients Subset receiving 52 weeks of barzolvolimab therapy

Phase 3 CSU enrollment 1,939 patients Global EMBARQ-CSU1 and EMBARQ-CSU2 program

ColdU complete response Week 20 66% of patients Phase 2 ColdU study; complete response at Week 20

SD complete response Week 20 49% of patients Phase 2 SD study; complete response at Week 20

ColdU/SD QoL no impact Up to 60% of patients DLQI 0–1 at Week 20 in ColdU/SD study

Market Reality Check

Price: $30.09 Vol: Volume 1,190,002 is 1.34x...

normal vol

$30.09 Last Close

Volume Volume 1,190,002 is 1.34x the 20-day average of 888,030, indicating elevated interest ahead of/around the AAAAI data. normal

Technical Shares at $30.63 are trading above the 200-day MA of $24.12 and sit 2.17% below the 52-week high of $31.31.

Peers on Argus

CLDX slipped 0.58% while peers were mixed: COGT -0.74%, AUPH -5.93%, CDTX roughl...

CLDX slipped 0.58% while peers were mixed: COGT -0.74%, AUPH -5.93%, CDTX roughly flat (+0.03%), VERA +2.69%, ARDX +0.68%. With no peers in the momentum scanner and divergent moves, trading appears more company-specific than sector-driven.

Previous Clinical trial Reports

5 past events · Latest: Feb 25 (Positive)

Same Type Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Feb 25	Phase 3 enrollment	Positive	+24.1%	Completed CSU Phase 3 enrollment early with 1,939 patients and clear timelines.
Dec 09	Phase 3 initiation	Positive	-5.7%	Initiated Phase 3 program in ColdU and SD after successful Phase 2 results.
Nov 06	CSU Phase 2 data	Positive	-2.0%	Reported additional Phase 2 CSU data with rapid, durable complete urticaria control.
Nov 06	ColdU/SD Phase 2	Positive	-2.0%	Presented ColdU/SD Phase 2 results showing high complete response rates and safety.
Oct 30	CDX-622 Phase 1	Positive	+2.8%	Positive Phase 1 CDX‑622 safety, PK and sustained mast cell inhibition data.

Pattern Detected

Clinical trial updates have produced mixed reactions: some major gains on key milestones but several modest declines despite positive data, suggesting uneven trading responses to R&D progress.

Recent Company History

Over the past year, Celldex has steadily advanced its mast cell–focused pipeline. Barzolvolimab moved from strong Phase 2 CSU and ColdU/SD data into large global Phase 3 programs, including 1,939 CSU patients and an initiated Phase 3 in ColdU/SD. Additional CSU efficacy and CIndU durability data presented at meetings in late 2025 reinforced the drug’s profile. CDX‑622 also delivered favorable Phase 1 safety and mast cell inhibition data. Today’s AAAAI update extends this clinical narrative with longer-term and quality-of-life outcomes.

Historical Comparison

+3.4% avg move · Past clinical trial updates in CLDX have averaged a 3.44% move with mixed direction. Today’s additio...

clinical trial

+3.4%

Average Historical Move clinical trial

Past clinical trial updates in CLDX have averaged a 3.44% move with mixed direction. Today’s additional AAAAI efficacy and durability data extend the same barzolvolimab storyline rather than marking a new trial phase shift.

Clinical-trial news shows a clear progression: initial positive Phase 2 CSU and ColdU/SD data, followed by initiation and completion of large Phase 3 programs, while CDX‑622 advanced from first-in-human safety to broader Phase 1 development.

Market Pulse Summary

This announcement details additional Phase 2 data for barzolvolimab in CSU and ColdU/SD, showing hig...

Analysis

This announcement details additional Phase 2 data for barzolvolimab in CSU and ColdU/SD, showing high complete response rates and sustained off‑treatment control, along with substantial improvements in quality of life and angioedema. It reinforces Celldex’s strategy of targeting mast cells across chronic urticarias and follows the fully enrolled 1,939‑patient CSU Phase 3 program. Investors may watch upcoming Phase 3 readouts, durability of benefit, and safety as key future inflection points.

Key Terms

chronic spontaneous urticaria, cold urticaria, symptomatic dermographism, mast cell, +2 more

6 terms

chronic spontaneous urticaria medical

"Phase 2 chronic spontaneous urticaria (CSU) and cold urticaria..."

A long-term condition that causes recurring, itchy hives and sometimes swelling that appear without a clear trigger, like an alarm that goes off unpredictably on its own. It matters to investors because its chronic nature creates ongoing demand for treatments, diagnostics and follow-on care, influencing pharmaceutical research priorities, drug market size, regulatory review timelines and healthcare cost projections.

cold urticaria medical

"Phase 2 ColdU and SD study, up to 53% of patients with ColdU..."

An allergic reaction in which exposure to cold — from air, water, or a cold object — causes red, itchy welts, swelling, or in severe cases whole-body symptoms. It matters to investors because its prevalence, treatment options, and safety profile can affect demand for therapies, the design and outcome of clinical trials, regulatory decisions, and potential workplace or product-liability costs; think of it like a sensitive smoke alarm that trips whenever the room gets cold.

symptomatic dermographism medical

"cold urticaria (ColdU) and symptomatic dermographism (SD)."

A form of physical urticaria where light pressure or stroking of the skin produces red, raised, itchy lines or welts—like someone “writing” on your skin with a finger. It matters to investors because it can influence clinical trial outcomes, product labeling, safety signals and market demand for dermatology or allergy treatments: a common, visible side effect can affect regulatory reviews, prescribing patterns and commercial uptake of therapies.

mast cell medical

"targets the root cause of CSU, 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.

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.

dermatology life quality index medical

"Dermatology Life Quality Index (DLQI2) consists of ten questions..."

A Dermatology Life Quality Index (DLQI) is a short, patient-completed questionnaire that measures how much a skin condition affects a person’s daily life, similar to a customer satisfaction score for health. Investors watch DLQI results because they show whether a treatment meaningfully improves patients’ day-to-day well-being, which can influence regulatory decisions, market demand, pricing, and insurance coverage — all drivers of a therapy’s commercial value.

AI-generated analysis. Not financial advice.

- Sustained off-treatment efficacy despite barzolvolimab clearance and normalization of tryptase, suggesting disease modification in patients with CSU treated for full 52 weeks -
- Greatly improved quality of life and reduced disease impact for patients with ColdU/SD at Week 20 -

HAMPTON, N.J., Feb. 27, 2026 (GLOBE NEWSWIRE) -- Celldex (NASDAQ:CLDX) presented additional positive data from the completed Phase 2 clinical trials of barzolvolimab in chronic spontaneous urticaria (CSU) and cold urticaria (ColdU) and symptomatic dermographism (SD). Barzolvolimab is a humanized monoclonal antibody with a completely novel mechanism of action that uniquely targets the root cause of CSU, ColdU and SD—the mast cell. The data were presented today at the 2026 Allergy, Asthma & Immunology's (AAAAI) Annual Meeting being held in Philadelphia, PA.

“Barzolvolimab’s novel mechanism of action uniquely targets the root cause of chronic urticarias—the mast cell—and is driving the unparalleled efficacy we are seeing across our studies in chronic spontaneous urticaria, cold urticaria and symptomatic dermographism,” said Diane Young, MD, Senior Vice President and Chief Medical Officer of Celldex. “The data presented at AAAAI continue to demonstrate that barzolvolimab has the potential to transform the treatment landscape by providing rapid, profound and durable efficacy, including symptom free complete control and dramatic improvements in quality of life and angioedema—offering new hope for the patients suffering from these often severe and debilitating diseases.”

Summary of Friday, February 27^rd Presentations:

Prolonged Off-Treatment Efficacy of Barzolvolimab in Chronic Spontaneous Urticaria; presented by Martin Metz, M.D., Professor, Department of Dermatology and Allergy, Head of Translational Research and Deputy Head of Clinical Trials at Charité – Universitätsmedizin in Berlin

Data from the abstract associated with this presentation were also highlighted by AAAAI in a press release issued in early February.

• As previously reported in the Phase 2 CSU study, up to 51% of patients on study experienced symptom free complete response (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—up to 41% of patients reported complete response seven months after receiving their last dose of barzolvolimab.
• In the analysis presented at AAAAI, the experience for the subset of patients who received 52 weeks of barzolvolimab therapy with 150 mg Q4W or 300 mg Q8W and completed treatment with at least well controlled disease (UAS7<6) at Week 76 was explored. The vast majority of patients included in this analysis had substantial disease burden at baseline, including severe disease (67%), angioedema (69%), very large impact on quality of life, and long disease duration (mean of 6 years).
  • At the end of the treatment period (52 weeks) 71% of patients had at least well controlled disease and, of these patients, 88% reported complete response (UAS7=0).
  • 69% of patients who achieved well controlled disease after 52 weeks of treatment also had well controlled disease at week 76, 7 months after their final dose of barzolvolimab.
  • 50% of patients who achieved well controlled disease after 52 weeks of treatment also had complete response at week 76, 7 months after their final dose of barzolvolimab.
  • Findings correlated with profound improvements in quality of life and angioedema in this subset of patients. 83% reported no impact of disease on QoL (DLQI 0/1) at Week 76 and 74% of patients with angioedema at baseline were angioedema free (AAS7=0)³ at Week 76.
  • For patients who did experience recurrence of disease symptoms after treatment completion, their disease was much milder than what it was at baseline.
• This sustained off-treatment efficacy was observed despite barzolvolimab clearance and normalization of tryptase (a measure of mast cell burden), suggesting disease modification and supports barzolvolimab’s significant potential to become a transformative treatment option for patients suffering from CSU.
• Celldex recently announced the completion of enrollment in the Company’s global Phase 3 program in CSU. The Program, which fully accrued six months ahead of guidance, consists of two 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.
  
  

Treatment with Barzolvolimab Improves Urticaria Control and Quality of Life in Patients with Chronic Inducible Urticaria (20 week analysis) presented by Martin Metz, M.D., Professor, Department of Dermatology and Allergy, Head of Translational Research and Deputy Head of Clinical Trials at Charité – Universitätsmedizin in Berlin

• As previously reported in the Phase 2 ColdU and SD study, up to 53% of patients with ColdU and 58% with SD achieved complete response (negative provocation test) at Week 12 (primary endpoint analysis).
• As previously reported, at Week 20, up to 66% of patients with ColdU and 49% with SD achieved complete response.
• Marked and rapid improvement in urticaria control (UCT¹) and quality of life (DLQI²) in patients with ColdU and SD were observed and sustained through the 20-week period.
  • Up to 60% of patients reported that disease symptoms no longer impacted QOL at Week 20.
  • Up to 69% of patients reported at least well-controlled urticaria based on UCT at Week 20.
• This Phase 2 study is the first large randomized, placebo-controlled study to demonstrate clinical benefit in patients with CIndU.
• In December 2025, Celldex initiated a global Phase 3 study in cold urticaria (ColdU) and symptomatic dermographism (SD), EMBARQ-ColdU and -SD, and enrollment is ongoing.
  
  

References:
¹Urticaria Control Test (UCT) consists of four questions (on a scale of 0-4; total 0-16) used to assesses symptoms, quality of life, treatment effectiveness and overall disease control in patients with chronic urticaria (spontaneous and inducible). UCT≥12 is well controlled and UCT=16 is complete control.
²Dermatology Life Quality Index (DLQI) consists of ten questions (on a scale of 0–3, total 0–30) used to measure the impact of skin disease on patient quality of life related to symptoms and feelings, daily activities, leisure, work and school, personal relationships, and treatment. DLQI 0–1 indicates no effect on a patient’s life.
³Angioedema Activity Score for 7 days (AAS7) assesses the severity of disease activity in patients with recurrent angioedema or urticaria. It sums daily scores (0-15) over one week (total: 0 -105), evaluating frequency, duration, severity, disfigurement, and impact on daily life.

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 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 completely 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 were the key CSU results Celldex (CLDX) presented at AAAAI on Feb 27, 2026?

Barzolvolimab produced up to 71% complete response at 52 weeks and sustained 41% complete response seven months off treatment. According to company, these data showed normalization of tryptase and off-treatment benefit suggesting potential disease modification in CSU.

How many patients were enrolled in Celldex's Phase 3 CSU program (CLDX) and when was enrollment completed?

Celldex enrolled 1,939 patients in the global Phase 3 CSU program, completing accrual six months ahead of guidance. According to company, the studies span 43 countries and over 500 sites, representing the largest antihistamine-refractory CSU program.

What efficacy did barzolvolimab show in ColdU and symptomatic dermographism in the Phase 2 program?

At Week 20, barzolvolimab achieved up to 66% complete response in ColdU and 49% in symptomatic dermographism. According to company, trials also showed rapid, sustained improvements in urticaria control and quality of life through Week 20.

What evidence did Celldex present that barzolvolimab may modify disease in CSU (CLDX)?

Sustained symptom control despite drug clearance and tryptase normalization supported disease modification. According to company, patients treated 52 weeks had persistent well-controlled or complete responses up to seven months after last dose.

What quality-of-life benefits did barzolvolimab show in the Phase 2 CSU and ColdU/SD studies?

The studies reported marked QoL gains: up to 83% of CSU patients reported no QoL impact at Week 76 and up to 60% of ColdU/SD reported no QoL impact at Week 20. According to company, improvements paralleled clinical response rates.