Celldex shares drop as Phase 3 data for barzolvolimab show efficacy but raise anaphylaxis safety concerns

Celldex reported Phase 3 results for barzolvolimab in chronic spontaneous urticaria, showing strong efficacy against hives and itching.

Two cases of life-threatening anaphylaxis were observed among patients receiving the drug, raising safety concerns.

CEO Anthony Marucci said the incidence was extremely low, noting about 2,400 patients have been treated and the drug was generally well tolerated.

The news sent the stock down roughly 13% in early trading as investors focused on the safety signal.