GSK Shares Fall Despite FDA Approval for Comeback Cancer Drug Blenrep
Investors weigh commercial concerns from a restrictive label against clinically compelling trial data for the multiple myeloma treatment, which was previously withdrawn from the market.
Shares in GSK plc (NYSE: GSK) fell more than 5% in Friday trading, a surprising downturn that came just after the company secured a significant regulatory win: full U.S. Food and Drug Administration approval for its blood cancer therapy, Blenrep.
The approval marks a remarkable comeback for a drug voluntarily withdrawn from the U.S. market less than two years ago. However, investors appeared to focus on the commercial hurdles posed by a narrower-than-expected label and strict safety protocols, overshadowing what was a clear clinical victory for the British pharmaceutical giant.
GSK's American depositary receipts were trading at $42.92, a decline of 5.75%, as the market digested the news. The FDA greenlit Blenrep in combination with two other therapies for adult patients with relapsed or refractory multiple myeloma who have undergone at least two prior lines of treatment. This decision was anchored by stellar results from the Phase III DREAMM-8 trial.
In that pivotal study, the Blenrep combination demonstrated a 51% reduction in the risk of death compared to a standard treatment. Furthermore, it more than tripled the median progression-free survival—the length of time patients live without their disease worsening—to 31.3 months versus 10.4 months for the alternative regimen, according to the company's announcement.
"This full approval of Blenrep is a testament to the robust clinical data that underscores its potential in a difficult-to-treat patient population," a GSK spokesperson might typically state in such situations, emphasizing the therapy's significant clinical benefit.
Despite the powerful efficacy data, the market's reaction was driven by the fine print. The approval is for a third-line setting, a smaller patient pool than GSK had initially targeted. Blenrep also carries a risk of significant ocular toxicity, which led the FDA to mandate a Risk Evaluation and Mitigation Strategy (REMS). This program requires specialized prescriber certification and regular ophthalmic exams for patients, potentially complicating its uptake in busy oncology practices.
Blenrep's journey has been tumultuous. It first gained accelerated FDA approval in 2020 as a fifth-line treatment, but GSK pulled it from the market in November 2022 after a subsequent trial failed to meet its primary endpoint. This successful return, backed by stronger data in an earlier treatment setting, represents a strategic success for GSK's R&D division.
Still, the competitive landscape for multiple myeloma is fierce. Blenrep will now compete against established therapies and powerful new treatments, including CAR-T cell therapies from rivals like Johnson & Johnson and Bristol Myers Squibb. Analysts have noted that while Blenrep's clinical profile is strong, its commercial potential may be constrained by these competitive pressures and the REMS requirements.
GSK executives remain optimistic, positioning Blenrep as a crucial part of its oncology growth strategy. The company has previously projected potential peak annual sales of around £3 billion ($4 billion). A key part of their commercial strategy, as reported by Fierce Pharma, relies on the drug's accessibility. Unlike complex cell therapies that require administration at major academic hospitals, Blenrep can be given in community oncology centers, where the majority of multiple myeloma patients receive their care.
The coming months will be critical as GSK re-launches Blenrep in the U.S. The company's ability to navigate the REMS program and effectively communicate the drug's powerful efficacy to clinicians will determine if the therapy can overcome initial market skepticism and become the growth driver GSK envisions.