Celldex shares slip as safety concerns cloud skin drug trial win
PUBLISHED Sep 22, 2026, 4:07 PM ET
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Celldex Therapeutics announced that its experimental drug, barzolvolimab, successfully met primary endpoints in two late-stage clinical trials for chronic spontaneous urticaria, significantly reducing disease activity at week 12. Complete response rates, defined as the absence of itching and hives, ranged from 42.1 percent to 45.7 percent for treated patients compared to up to 12.6 percent for placebos, with efficacy further improving at week 24. However, company shares fell nearly 15 percent following disclosures of two confirmed cases of probable anaphylaxis during the studies, including one patient requiring hospitalization. Management expects future drug labels to carry explicit warnings regarding hypersensitivity risks. Celldex plans to submit its formal marketing application to the United States Food and Drug Administration in 2027. The setback follows the discontinuation of a separate mid-stage trial for prurigo nodularis earlier this year, focusing investor attention heavily on the safety profile of barzolvolimab.
By Haya | JQJO News
Timeline of Events
- On July 2025 Celldex discontinued barzolvolimab for prurigo nodularis after trial failure.
- On September 22 2026 Celldex reported positive late-stage trials for barzolvolimab in CSU.
- On September 22 2026 Celldex disclosed two probable anaphylaxis cases during clinical studies.
- On September 22 2026 Celldex shares fell nearly fifteen percent on safety concerns.
- On September 22 2026 Analyst Kristen Kluska noted market hyper-focus on safety signals.
- On September 22 2026 Chief Medical Officer Diane Young reported sixteen percent dropout rate.
- On September 22 2026 Reuters published initial reporting on trial results and shares.
- On September 2027 Celldex plans regulatory submission to the United States Food.
News Intelligence
- Immediate US impact: Investors reevaluate biotechnology valuations based on drug safety profiles.
- Possible long-term US impact: Stricter regulatory scrutiny on biologics with hypersensitivity risks expected.
- Most affected groups: Biotechnology investors, pharmaceutical companies, patients with chronic spontaneous urticaria.
- Reader priority: Monitor verified regulatory filings and official clinical trial disclosures.
Left: Evidence was insufficient. Center: Reporting focused strictly on clinical trial results and share movement. Right: Evidence was insufficient.
Celldex announced late-stage trial results and safety data on Tuesday. https://www.reuters.com/business/healthcare-pharmaceuticals/celldex-shares-slip-safety-concerns-cloud-skin-drug-trial-win-2026-09-22/
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