In a surprise setback for GSK, advisers to the Food and Drug Administration voted Thursday that the risks tied to the company's blood cancer drug Blenrep outweighed the benefits it had demonstrated in trials. The decision was driven by concerns about sometimes serious eye-related side effects and questions about the dose the company selected for treating multiple myeloma.
The FDA is set to decide whether to approve Blenrep by as soon as next week. While the agency often follows its advisers' recommendations, it is not required to do so.
Safety Concerns Drive Advisory Panel Decision
FDA staff reviewers had raised significant safety concerns about Blenrep when used in combination with other treatments, warning that the drug may cause eye damage in patients. In briefing documents released on the health regulator's website, staff reviewers stated that the benefit-risk profile of Blenrep remains unclear, citing concerns about safety, tolerability and appropriate dosages.
The drug causes ocular toxicity that represents "unique toxicity not seen with any currently available treatments for multiple myeloma," staff reviewers noted in their assessment.
Dosing Questions Complicate Approval Path
Beyond the eye safety issues, FDA staff suggested that lower dosages of Blenrep could offer patients similar efficacy in treating multiple myeloma while lowering the risk of side effects. This raised questions about whether GSK had selected the appropriate dose for the drug.
The advisory committee meeting on Thursday provided a forum for independent experts to weigh these concerns against the potential benefits of the treatment for multiple myeloma patients.
Regulatory Timeline and Next Steps
The FDA's final decision on Blenrep approval is expected by next week, following the advisory panel's recommendation. The agency's staff assessment and the advisory committee's vote represent significant hurdles for GSK's efforts to bring the blood cancer treatment to market.
The regulatory review process has highlighted the challenge of balancing potential therapeutic benefits against unique safety risks, particularly the ocular toxicity profile that distinguishes Blenrep from existing multiple myeloma treatments.
