Celldex Announces Multiple Upcoming Presentations at AAAAI 2026 Supporting Barzolvolimab’s First-in-Class and Best-in-Disease Profile

Celldex (NASDAQ:CLDX) announced today that multiple presentations from the Company’s Phase 2 clinical trials of barzolvolimab in chronic spontaneous urticaria (CSU) and cold urticaria (ColdU) and symptomatic dermographism (SD) have been accepted for presentation at the 2026 American Academy of Allergy, Asthma & Immunology's (AAAAI) Annual Meeting being held in Philadelphia, February 27 – March 2.

New data from the Phase 2 ColdU and SD Open Label Extension (OLE) will be presented as a late breaker, highlighting that retreatment with barzolvolimab leads to rapid improvement in urticaria control after symptom recurrence.

All presentations will be posted on the Celldex website at the dates/times listed below. Presentation details are as follows:

Trial: Phase 2 ColdU and SD Study Presentation: Treatment with Barzolvolimab Improves Urticaria Control and Quality of Life in Patients with Chronic Inducible Urticaria Session Date / Time: 2/27/2026, 2:45 pm - 3:45 pm Title: Allergic Skin Diseases Type: Poster Session Poster Number: 072 Location: Convention Center, Level 2, Hall E

Trial: Phase 2 CSU Study Presentation: Prolonged Off-Treatment Efficacy of Barzolvolimab in Chronic Spontaneous Urticaria Session Date / Time: 2/27/2026, 2:45 pm - 3:45 pm Title: Allergic Skin Diseases Type: Poster Session Poster Number: 075 Location: Convention Center, Level 2, Hall E

Trial: Phase 2 ColdU and SD Study Presentation: Retreatment with Barzolvolimab Leads to Rapid Improvement in Urticaria Control After Symptom Recurrence in Chronic Inducible Urticaria Session Date / Time: 3/1/2026, 9:45 am - 10:45 am Title: Late Breaking Poster Session II Type: Poster Session LB Poster Number: L41 Location: Convention Center, Level 2, Hall E

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 [email protected]

Patrick Till Meru Advisors (484) 788-8560 [email protected]