GSK’s Blood‑Cancer Rebound: FDA Nod, Narrow Label, Market Uncertainty

GSK PLC has once again thrust itself into the spotlight, this time with the FDA’s reluctant approval of its once‑withdrawn antibody‑drug conjugate, Blenrep (belantamab mafodotin‑blmf). The decision, announced on 24 October 2025, grants the drug a single‑line indication in combination with bortezomib and dexamethasone for adults with relapsed or refractory multiple myeloma who have received at least two prior therapies. While the approval signals a potential blockbuster for the British drugmaker, the label’s strict constraints and the mixed market reaction expose the fragile nature of GSK’s therapeutic ambitions.

The FDA’s Split Decision

The U.S. Food and Drug Administration delivered a split verdict: Blenrep is now authorized as a combination therapy (BVd) but remains rejected for the broader single‑agent use that GSK had previously envisioned. An advisory committee had voted against the broader approval in July, a decision that the FDA ultimately respected. Consequently, GSK’s comeback is far narrower than the company had marketed to investors, a fact that has already rattled the London Stock Exchange.

Market Reaction: A Sharp Fall in Share Price

On Friday, GSK’s shares plunged, falling to a 52‑week low of £12.42 (1242.5 GBX) – a stark contrast to the 52‑week high of £16.84 (1684.5 GBX) earlier this year. The stock’s price‑earnings ratio of 20.03, once a marker of healthy valuation, now appears precarious amid the drug’s restricted approval. Investors, who had been banking on a broad market entry for Blenrep, were forced to confront the reality that the FDA’s decision limits the drug’s commercial potential.

Strategic Implications for GSK

GSK’s withdrawal from the U.S. market in 2022 after a failed confirmatory study had already cast doubt on the company’s ability to navigate regulatory hurdles. The 2025 FDA approval, while a technical triumph, does not erase the strategic missteps that led to the drug’s prior failure. The company must now confront several critical questions:

  1. Pricing and Reimbursement – With a narrow indication, can GSK secure favorable reimbursement terms that justify the drug’s development costs?
  2. Competitive Landscape – The myeloma market is crowded with biologics and small molecules. Will Blenrep’s limited label provide a competitive edge?
  3. Future R&D Focus – Should GSK double down on this therapy, or redirect resources toward more promising candidates that have not yet faced the same regulatory scrutiny?

Investor Outlook

For shareholders, the FDA approval offers a glimmer of hope but also a stark reminder of GSK’s volatility. The company’s current trading performance (as of 22 October) shows a close price of £16.57 (1657.5 GBX), yet the recent plunge underscores the risk inherent in biotech ventures that hinge on regulatory approval. Analysts will likely keep a close eye on GSK’s subsequent clinical data releases, pricing strategy, and potential partnership agreements that could offset the drug’s limited label.

Conclusion

GSK’s return of Blenrep to the U.S. market is a double‑edged sword. On one hand, the FDA’s approval restores a drug that was once a flagship candidate; on the other, the restricted label and adverse market reaction reveal the fragility of GSK’s strategic execution. Investors and industry observers alike must now assess whether the company can translate this narrow FDA nod into sustainable revenue growth or whether it will become another cautionary tale of pharmaceutical overreach.