Celldex Therapeutics’ Phase 3 program for barzolvolimab in chronic spontaneous urticaria advanced with efficacy, but safety questions emerged after the company reported two life-threatening anaphylaxis cases. The report landed after Celldex said barzolvolimab delivered the best efficacy results to date against chronic skin hives. Investors and clinicians will focus on how the safety findings alter risk-benefit calculations, including whether the events changed study conduct or triggered additional monitoring. For chronic indications, immunogenicity and acute hypersensitivity are central considerations because patients may remain on treatment for extended periods. The update sets up the next discussions around trial interpretation, potential protocol modifications, and whether mitigation strategies can address the anaphylaxis risk in a confirmatory development path.