GSK Shares Weigh on Footsie as FDA Panel Rejects Blenrep

GlaxoSmithKline share price (LON:GSK) is down 4% today, weighing on the Footsie as the FSA's advisory panel voted against approving Blenrep (belantamab mafodotin-blmf) in combination therapies for relapsed or refractory multiple myeloma.

The negative recommendation from the Oncologic Drugs Advisory Committee (ODAC) has sent ripples through the market, raising concerns about the drug's future prospects in the crucial U.S. market and impacting GSK's broader oncology ambitions.

The ODAC's decision entered on two proposed Blenrep combinations. The first, Blenrep with bortezomib (Velcade) and dexamethasone, was rejected by a vote of 5-3. The second, Blenrep with pomalidomide (Pomalyst) and dexamethasone, faced even stronger opposition, with a 7-1 vote against approval. The committee's primary concerns revolved around the drug's benefit-risk profile, specifically highlighting the high incidence of ocular toxicity, uncertainties surrounding the optimal dosing regimen, and the limited representation of U.S. patients in pivotal clinical trials.

Eye-related side effects, including blurred vision, photophobia, and dry eyes, were prevalent in the DREAMM-7 and DREAMM-8 studies, raising questions about patient tolerability and adherence. Furthermore, the committee questioned the appropriateness of the proposed dosages and the high rates of dose modifications observed during the trials. The lack of sufficient U.S. patient representation in the pivotal studies, with less than 5% enrolment in each, further fuelled the panel's reservations.

The FDA's final decision on Blenrep's approval is expected next week (by July 23). While the agency is not obligated to follow the advisory committee's recommendation, it typically aligns with such guidance.

Blenrep was initially approved in the U.S. in 2020 as a monotherapy for patients with relapsed or refractory multiple myeloma who had received at least four prior therapies. However, GSK voluntarily withdrew the drug in 2022 after it failed to demonstrate superiority over existing treatments in a confirmatory trial.

Despite the U.S. setback, Blenrep combinations have secured approvals in other key markets, including the United Kingdom, Japan, and potentially the European Union. The Medicines and Healthcare products Regulatory Agency (MHRA) in the UK approved the combinations in April 2025, followed by approval from the Ministry of Health, Labour and Welfare in Japan earlier this month. The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency recommended approval in May 2025, with a final decision expected in the third quarter of 2025. These approvals provide some solace for GSK, but the U.S. market remains a critical component of the drug's commercial potential.

Analysts are now weighing the potential impact of the FDA panel's decision on GSK's financial outlook. JPMorgan reaffirmed an “underweight” rating for GSK today, while Shore Capital maintains a “buy” rating. Deutsche Bank holds a “hold” rating with a price target of 1,450p.

The consensus price target of 1,667p offers a healthy perceived upside from here, although adjustments could be looming as circumstances shift.