FDA advisers say risks of GSK blood cancer drug outweigh benefits in surprise setback

Advisers to the Food and Drug Administration unexpectedly voted against GSK's blood cancer drug, Blenrep, citing that its risks, particularly serious eye-related side effects and concerns over the selected dosage, outweighed its demonstrated benefits. This negative recommendation significantly jeopardizes Blenrep's potential FDA approval, expected as soon as next week, despite the agency not being strictly bound by its advisers' recommendations. The vote follows earlier FDA staff concerns suggesting lower dosages could offer similar efficacy with reduced ocular risks, posing a notable setback for GSK's drug pipeline.

Analysis

An FDA advisory committee has unexpectedly voted against the approval of GSK's blood cancer drug, Blenrep, citing a negative risk-benefit profile. The recommendation was driven by significant concerns over serious eye-related side effects and questions regarding the appropriateness of the dosage selected by the company in its trials. This outcome aligns with prior concerns highlighted by FDA staff, who suggested a lower dose might offer a better balance of efficacy and safety. This vote introduces a material risk to the drug's final approval, with the FDA's decision expected as soon as next week. While the agency is not bound by this recommendation, it often aligns with its advisors, making a rejection or request for more data a high-probability outcome. The event represents a considerable setback for GSK's oncology pipeline and is reflected in the strongly negative sentiment score (-0.8 for GSK), indicating a heightened regulatory hurdle for Blenrep's path to market for treating multiple myeloma.

Key Decisions for Investors

• Investors should anticipate near-term negative pressure on GSK's stock price, as the advisory vote significantly increases the probability of a regulatory rejection for Blenrep by the FDA next week.
• A cautious or bearish stance is warranted in the short term given the high likelihood of a negative catalyst for the stock upon the final FDA ruling.
• Long-term investors should monitor GSK's subsequent commentary for any plans to pursue a revised clinical strategy with a lower dosage, which could offer a future, albeit delayed, path to market for Blenrep.