Barzolvolimab

Investors sent Celldex’s share price down by 18% to $19.72 in premarket trading.\n Celldex has stopped development of barzolvolimab in eosinophilic esophagitis (EoE) despite meeting its primary endpoint in a phase 2 trial. The biotech showed the candidate depletes mast cells in the gastrointestinal tract, but that positive finding was overshadowed by the antibody\'s failure to improve clinical outcomes.EoE is a chronic inflammatory condition of the esophagus characterized by the infiltration of eosinophils and mast cells, two types of white blood cells. Yet, efforts to treat the condition by targeting white blood cells have floundered. Allakos’ lirentelimab reduced eosinophils in a phase 2/3 trial but showed no significant effect on a dysphagia scale that assessed patients’ ability to swallow food, a key symptom of EoE.Now, Celldex has suffered a similar setback. The biotech randomized 65 patients to receive the anti-KIT antibody barzolvolimab or placebo. After 12 weeks, mucosal mast cell levels in the gastrointestinal tract had fallen significantly in the barzolvolimab cohort compared to placebo, achieving the trial’s primary endpoint. Previously, Celldex had shown the antibody can deplete cutaneous mast cells.Yet, the mucosal mast cell primary endpoint was just one of two key areas of focus for Celldex. The biotech also wanted to show that depleting mast cells improves symptoms, as Celldex CEO Anthony Marucci explained on a Tuesday call with investors to discuss the data.“We have repeatedly said that we needed to not only see profound impact of cell depletion, but we also [needed] a reduction of dysphagia scores that would be clinically meaningful and compare favorably to the current standard of care,” Marucci said. “These results did not meet our internal hurdle rate, and we will not advance development in this indication.” Scores on the Dysphagia Symptom Questionnaire were no better for patients on barzolvolimab than placebo, the biotech reported. Equally, Celldex saw no significant improvement in endoscopic scoring of EoE-related inflammation and fibrosis in the treatment group. After Celldex reported the trial findings and program discontinuation, investors sent the biotech’s share price down by 18% to $19.72 in premarket trading.Celldex is continuing to test barzolvolimab in two phase 3 trials in chronic spontaneous urticaria as well as in phase 2 studies in atopic dermatitis and prurigo nodularis. The biotech advanced in those settings on the strength of evidence that barzolvolimab depletes cutaneous mast cells. The discovery in the EoE trial that barzolvolimab also depletes mucosal mast cells could open up other indications for KIT inhibitors.  The EoE trial suggests Celldex could expand beyond skin conditions to target gastrointestinal conditions where mast cells play a role. One possibility is that Celldex will apply its bispecific approach, rather than barzolvolimab, to gastrointestinal indications. Engaging two targets may unlock diseases where depleting mast cells is beneficial but insufficient to significantly improve clinical outcomes.  The failures of Allakos and Celldex in EoE have thinned the field of late-stage programs in this indication. Amgen and AstraZeneca are still in the running, with a phase 3 trial of the partners’ anti-TSLP antibody Tezspire now fully enrolled. Tezspire reduces blood eosinophil counts but works in severe asthma patients irrespective of their starting levels of the white blood cells. 

HAMPTON, NJ, USA I August 19, 2025 I Celldex Therapeutics, Inc. (NASDAQ:CLDX) today reported topline results from the Company’s ongoing Phase 2 study of barzolvolimab in eosinophilic esophagitis (EoE), a chronic inflammatory disease of the esophagus. 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. Celldex 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, Celldex will not advance development in EoE. 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. “As we explore barzolvolimab’s full potential as a mast cell depleting agent, we are ultimately defining which diseases are mast cell driven,” said Anthony Marucci, President and Chief Executive Officer of Celldex Therapeutics. “While we are disappointed in the clinical outcome in EoE, we are proud of our role in advancing the science for patients who need more effective treatment options.” “We remain focused on advancing the deep pipeline for barzolvolimab, with enrollment ongoing across four studies, including two Phase 3 studies in chronic spontaneous urticaria and Phase 2 studies in atopic dermatitis and prurigo nodularis, while we also finalize plans to initiate a Phase 3 program in inducible urticaria that will include both cold urticaria and symptomatic dermographism,” continued Marucci. “We are deeply committed to driving innovation in mast cell science and delivering life-changing therapies for patients and look forward to advancing barzolvolimab and our growing pipeline of KIT- and SCF-targeting candidates into additional indications in the future.” Summary of Key Findings Phase 2 Study Design This randomized, double-blind, placebo-controlled, parallel group Phase 2 study is evaluating the efficacy and safety profile of subcutaneous barzolvolimab in patients with active EoE. Patients on study were highly symptomatic and had moderate to severe EoE. Demographics and baseline disease characteristics were generally well balanced across treatment groups. 65 patients were randomly assigned on a 1:1 ratio to receive subcutaneous injections of barzolvolimab at 300 mg every 4 weeks or placebo during a 16-week placebo-controlled treatment phase. Following completion of the placebo-controlled treatment phase, all patients entered a 12-week active treatment phase and received barzolvolimab 300 mg every 4 weeks. Patients then entered a follow-up phase for an additional 16 weeks. The primary endpoint of the study is the reduction of esophageal intraepithelial infiltration of mast cells as assessed by peak esophageal intraepithelial mast cell count at 12 weeks. Secondary endpoints include the reduction of symptoms of dysphagia and esophageal intraepithelial infiltration of eosinophils and safety. For additional information on this trial (NCT05774184), please visit www.clinicaltrials.gov Webcast and Conference Call The Company will host a conference call/webcast today to discuss the results at 4:30 p.m. ET. To access the live and archived webcast, please visit the Events section on the Investor Relations page of Celldex’s website . Parties interested in participating via telephone may register here to receive the dial-in numbers and unique PIN to seamlessly access the call. Otherwise please access the listen-only webcast link. The archived webcast will be available for a limited time on the Company’s website. About Barzolvolimab Barzolvolimab is a humanized monoclonal antibody that binds the receptor tyrosine kinase KIT with high specificity and potently inhibits its activity. KIT is expressed in a variety of cells, including mast cells, which mediate inflammatory responses such as hypersensitivity and allergic reactions. KIT signaling controls the differentiation, tissue recruitment, survival and activity of mast cells. In certain inflammatory diseases, such as chronic urticaria, mast cell activation plays a central role in the onset and progression of the disease. Barzolvolimab is currently being studied in chronic spontaneous urticaria (CSU), two forms of chronic inducible urticaria (CIndU) – cold urticaria (ColdU) and symptomatic dermographism (SD), 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 . SOURCE: Celldex Therapeutics