Blenrep's Regulatory Crossroads: EU Triumph and US Hurdles Shape GSK's Oncology Ambitions

GlaxoSmithKline's (GSK) Blenrep (belantamab mafodotin) has navigated a dramatic regulatory arc in 2025, marked by a triumphant EU approval and a contentious U.S. review. For investors, the drug's divergent regulatory trajectories highlight the complex interplay of clinical innovation, market dynamics, and risk tolerance across geographies. This article dissects Blenrep's commercial potential, the implications of global regulatory divergence, and how investors might navigate the uncertainties ahead.

EU Approval: A Strategic Win for GSK

In July 2025, the European Commission granted Blenrep marketing authorization for relapsed or refractory multiple myeloma, following the European Medicines Agency's (EMA) positive opinion in May. This approval, based on robust phase III trial data showing improved progression-free and overall survival, positions Blenrep as a critical asset in GSK's oncology portfolio. The EU's willingness to embrace Blenrep reflects its recognition of the unmet need in a patient population with limited treatment options. Analysts project peak annual sales of $1.5 billion globally, with the EU contributing a significant share.

The EU's centralized reimbursement systems and strong healthcare infrastructure further enhance Blenrep's commercial viability. With market exclusivity through its orphan drug designation and a competitive edge in outpatient administration, GSK is well-positioned to capture a growing slice of the multiple myeloma treatment market, which is projected to reach $43.07 billion by 2037.

U.S. Regulatory Uncertainty: A High-Stakes Gambit

In stark contrast, the U.S. Food and Drug Administration (FDA) has taken a cautious stance. In July 2025, an FDA advisory panel voted against Blenrep's approval in combination therapies, citing severe ocular toxicity risks—keratopathy, visual acuity changes, and dry eye—as outweighing its benefits. This decision, while not binding, signals a high likelihood of regulatory rejection. The FDA's final decision, expected by July 23, 2025, will be pivotal for GSK's oncology ambitions.

The U.S. market, where oncology therapies command premium pricing, was critical to Blenrep's revenue projections. A rejection would not only cap its commercial potential but also force GSK to reevaluate its $1.4 billion investment in the drug. The FDA's scrutiny underscores a broader shift in regulatory priorities, with agencies increasingly emphasizing risk-benefit profiles and real-world tolerability.

Risk-Rebalance for Investors: Navigating Divergence

The regulatory divergence between the EU and U.S. presents both opportunities and challenges for investors. The EU approval offers a stable revenue runway, but the U.S. outcome remains a wildcard. For GSK, this duality underscores the importance of diversification. The company's recent $1 billion acquisition of IDRx and a $1.7 billion ADC partnership with Hansoh Pharma provide strategic buffers against Blenrep's potential U.S. shortfall.

Investors should also consider the competitive landscape. In the EU, Blenrep's outpatient administration and combination therapy flexibility give it an edge over therapies like J&J's Carvykti and Bristol Myers Squibb's Abecma. However, the U.S. market's dominance by CAR-T therapies and the FDA's safety concerns could limit Blenrep's penetration.

Strategic Recommendations for Investors

1. Short-Term Caution: The FDA's July 23 decision will likely drive near-term volatility. Investors with a risk-averse profile may consider trimming exposure or hedging with sector-wide plays like Merck or Roche.
2. Long-Term Focus: GSK's broader oncology pipeline, including ADC partnerships and IDRx, offers a safety net. If the FDA rejects Blenrep, the company's 2031 sales target of £40 billion may still be achievable through these assets.
3. Diversification: Pair GSK with less speculative pharma stocks to balance regulatory risk.
4. Monitor Post-Market Data: If approved in the U.S. with restrictions, track real-world outcomes from DREAMM-7 and DREAMM-8 trials to assess long-term potential.

Conclusion: A Tale of Two Markets

Blenrep's regulatory journey exemplifies the challenges of global drug commercialization. While the EU's approval validates its clinical value, the U.S. remains a high-stakes battleground. For GSK, the drug's success hinges on navigating these divergent regulatory environments while leveraging its broader oncology portfolio. Investors, in turn, must balance optimism about Blenrep's EU potential with caution regarding U.S. uncertainties. As the FDA's decision looms, the coming weeks will test both GSK's resilience and the market's appetite for risk.