GSK shares slide 6% after US panel rejects key cancer drug combination

GSK shares dropped 6%, erasing over £3 billion in market value, after a US FDA advisory panel rejected its Blenrep drug combination for advanced multiple myeloma, citing an unfavorable risk-benefit profile. This decision, ahead of a key FDA ruling in the critical US market, puts up to £1 billion in potential annual sales at risk and complicates GSK's broader ambition to achieve its £40 billion revenue target by 2031. While Blenrep is approved elsewhere, the US rejection reinforces market concerns about GSK's pipeline and strategic execution.

Analysis

GSK experienced a significant market repricing, with its shares falling 6% and erasing over £3 billion in market value, following a US FDA advisory panel's recommendation against its cancer drug, Blenrep. The panel's conclusion that the drug's benefits do not outweigh its risks at the proposed dosage introduces substantial uncertainty ahead of the final FDA decision due by July 23. This setback directly threatens GSK's oncology ambitions and its financial projections, as analysts at Shore Capital estimate up to £1 billion in potential annual sales are now at risk from the US market alone, a key component of the drug's forecasted £3-5 billion peak global sales. The development exacerbates concerns regarding GSK's ability to achieve its long-term revenue target of over £40 billion by 2031, a goal which market forecasts already indicated was challenging. Shore Capital's commentary highlights a persistent market sentiment, noting that such events reinforce the negative "accident-prone" perception that has historically suppressed GSK's valuation multiple, even as they maintain a buy recommendation at current levels.

Key Decisions for Investors

• Investors should anticipate continued share price volatility and potential further downside leading up to the final FDA ruling on Blenrep by July 23, as the negative panel vote signals a high probability of a formal rejection in the critical US market.
• The potential failure of Blenrep in the US necessitates a re-evaluation of GSK's long-term growth trajectory and its ability to meet the ambitious 2031 revenue target of £40 billion, potentially justifying a lower valuation multiple.
• For risk-tolerant, value-oriented investors, the significant share price drop may present an entry point, aligning with the view that the market has priced in the setback and that the company's valuation is attractive despite the pipeline risk.
• Monitor regulatory updates for Blenrep in the EU and China, as approvals in these large markets could partially mitigate the financial impact of a US rejection and provide some support for the stock.