Celldex Shares Plunge After Prurigo Nodularis Drug Fails Phase 2 Trial

Shares of Celldex Therapeutics (NASDAQ:CLDX) plunged 13% in after-hours trading Tuesday after the company announced that its Phase 2 clinical trial of barzolvolimab for prurigo nodularis did not meet its primary or key secondary endpoints. As a result of the data, the company is discontinuing the study for this indication.

Trial Fails to Meet Endpoints

The randomized, double-blind, placebo-controlled study evaluated the drug in 140 patients with moderate to severe prurigo nodularis, a chronic skin condition characterized by intensely itchy nodules. According to Celldex, the trial's primary endpoint—the proportion of patients achieving a significant reduction in itch by Week 12—was not met.

The company also reported that key secondary endpoints were not achieved at either of the two dose levels tested. The drug did, however, demonstrate a favorable safety and tolerability profile consistent with previous studies.

Implications of the Results

Barzolvolimab is a monoclonal antibody designed to deplete mast cells, a type of immune cell. The trial confirmed that the drug successfully reduced mast cells, as evidenced by a significant drop in serum tryptase, a biomarker. However, this biological effect did not translate into a clinical benefit for patients' itch or skin lesions compared to a placebo.

Ad

Celldex stated that these results indicate mast cells may not be a primary pathogenic driver of symptoms in prurigo nodularis. This finding is significant for understanding the disease's biology but represents a major setback for this specific development program.

Focus Shifts to Other Indications

Despite the failure in prurigo nodularis, Celldex is continuing to develop barzolvolimab for several other conditions where mast cells are believed to play a more central role. The company highlighted its ongoing pipeline for the drug, which provides key upcoming catalysts for investors:

• Chronic Spontaneous Urticaria: Topline data from a Phase 3 study is expected in September or October 2026.
• Symptomatic Dermographism & Cold Urticaria: Enrollment for Phase 3 trials is ongoing.
• Atopic Dermatitis: Topline data from a Phase 2 study is anticipated in late 2026.