GSK Shares Slide Over 6% After FDA Panel Rejects Blenrep Myeloma Combo
GSK (LON:GSK) shares fell by more than 6% on Friday following a setback from the U.S. Food and Drug Administration (FDA), as an advisory panel voted against the benefit-risk profile of Blenrep (belantamab mafodotin-blmf) in combination therapies for treating relapsed or refractory multiple myeloma.
The Oncologic Drugs Advisory Committee reviewed the therapy for adult patients who had undergone at least one prior treatment. The panel concluded that the potential benefits of the proposed Blenrep dosing regimen did not sufficiently outweigh the associated risks.
While the panel’s recommendation is non-binding, the FDA will take it into account as it finalizes its review. A decision is expected by July 23, the drug’s PDUFA (Prescription Drug User Fee Act) deadline.
GSK stated it remains engaged with the FDA throughout the review and emphasized that Blenrep combinations have already secured approval in several countries, including the UK, Japan, and Switzerland. These approvals are supported by data from the DREAMM-8 trial, while additional regulatory filings are underway in regions such as the European Union and China, based on results from the DREAMM-7 trial.
The FDA has granted Breakthrough Therapy Designation to the Blenrep combination and is conducting a priority review of the application.
Multiple myeloma ranks as the third most common blood cancer globally, with over 180,000 new cases annually. In the U.S. alone, more than 35,000 diagnoses were reported in 2024. Although treatable, the disease remains incurable and often develops resistance to existing treatment regimens.
GSK highlighted that many multiple myeloma patients receive care outside of academic hospitals, reinforcing the need for new treatment options suitable for community-based settings.
Blenrep is an antibody-drug conjugate that delivers a targeted chemotherapy payload directly to cancer cells. It binds to the BCMA protein found on myeloma cells and is linked to the cytotoxic agent auristatin F. The linker technology is licensed from Seagen Inc., while the monoclonal antibody is developed using POTELLIGENT Technology from BioWa Inc., a subsidiary of Kyowa Kirin Group.
In the UK, Blenrep is authorized in two combinations: with bortezomib and dexamethasone for patients who have had at least one prior treatment, and with pomalidomide and dexamethasone for those previously treated with lenalidomide.
The FDA’s final decision on the U.S. application is anticipated by month’s end.
