Celldex Therapeutics (CLDX) Study result summary

Study background and rationale

• Phase II study evaluated barzolvolimab in moderate-to-severe prurigo nodularis (PN), a chronic, itch-driven skin disease with significant comorbidities, across six countries and 48 sites, enrolling 140 adults.

• Mast cell depletion was hypothesized to provide clinical relief based on prior phase I-B results and increased mast cell numbers in PN lesions.

Study design and patient population

• Randomized, double-blind, placebo-controlled trial with three arms: barzolvolimab 150mg Q4W, 300mg Q4W (after 450mg loading dose), and placebo, for 24 weeks plus 16-week follow-up.

• Patients had ≥20 PN nodules, WI-NRS ≥7, and IGA-CNPG-S ≥3 at baseline; mean age 57–60 years, disease duration 6–8 years.

• Study included an open-label extension for persistent symptoms post-treatment.

Efficacy results

• The trial did not meet primary or secondary endpoints; no significant difference in itch reduction or skin lesion improvement versus placebo at any dose or time point.

• Profound systemic mast cell depletion was confirmed by serum tryptase reduction, but this did not translate to clinical benefit.

• Discrepancy noted between positive phase I-B (IV administration) and negative phase II (subQ) results; possible impact of administration route and sample size.