GSK's Blenrep Rebounds: A New Lease on Life for Multiple Myeloma Patients—and Investors?

The UK Medicines and Healthcare products Regulatory Agency (MHRA) has handed GlaxoSmithKline (GSK) a second chance with its beleaguered blood cancer drug Blenrep, approving it in combination therapies for relapsed or refractory multiple myeloma. This marks a pivotal comeback for the drug, which was withdrawn globally in 2022 after failing as a monotherapy in late-stage trials. Now, paired with existing treatments like bortezomib and pomalidomide, Blenrep has demonstrated transformative results in phase III trials—data so compelling that GSK is racing to secure approvals in 14 countries, including the U.S. by July 2025. For investors, this could be a turning point for GSK’s oncology portfolio and its stock, which has struggled to find momentum in recent years.

The Science Behind the Comeback

Blenrep’s revival hinges on its role as an antibody-drug conjugate (ADC) targeting BCMA (B-cell maturation antigen), a protein abundant in multiple myeloma cells. In two pivotal trials—DREAMM-7 and DREAMM-8—the drug, when combined with standard therapies, delivered dramatic improvements in progression-free survival (PFS) and overall survival (OS). In DREAMM-7, the median PFS nearly tripled to 36.6 months versus 13.4 months for the control group, while the risk of death dropped by 42%. The three-year OS rate soared to 74%, compared to 60% for the comparator. In DREAMM-8, the median PFS for the Blenrep combination remained undefined at 24 months, far outperforming the bortezomib-based regimen’s 12.7 months.

Safety concerns, notably ocular events like keratopathy, were mitigated by adjusting infusion intervals and dosing—resulting in treatment discontinuation rates of ≤9%. This balance of efficacy and tolerability positions Blenrep as a practical option for patients, avoiding the complexities of CAR-T therapies that often require hospitalization.

Market Opportunity and Regulatory Momentum

Multiple myeloma, a blood cancer with a five-year survival rate of just 45% in the UK, affects roughly 170,000 people globally. With relapse rates exceeding 90% in first-line treatments, there is a pressing need for therapies that extend remission. Blenrep’s combination regimens target this gap, particularly for patients with high-risk cytogenetics or resistance to lenalidomide.

GSK’s regulatory push is aggressive: the drug has secured priority review in Japan and China, where it also received Breakthrough Therapy Designation. In the U.S., the FDA’s decision is pending by mid-2025, with a PDUFA date of July 23. If approved, Blenrep could command a price tag upwards of $150,000 annually, potentially generating hundreds of millions in sales.

Investment Implications

For GSK, Blenrep’s revival is a lifeline for its oncology division, which has lagged behind peers like Roche and Bristol-Myers Squibb. The drug’s mechanism—combining BCMA targeting with established therapies—aligns with GSK’s shift toward immuno-oncology and targeted treatments. However, success hinges on execution: the company must navigate a crowded market, including competitors like AbbVie’s venetoclax and Johnson & Johnson’s CAR-T therapy, while managing manufacturing and distribution for a complex ADC.

Investors should also consider risks: Blenrep’s prior withdrawal underscores the high stakes of drug development, and competition could cap pricing power. Yet the data from DREAMM-7 and DREAMM-8—published in the New England Journal of Medicine—suggests Blenrep could redefine earlier lines of treatment, moving beyond salvage therapy to first-line use.

Conclusion: A New Era for GSK’s Oncology Pipeline?

GSK’s Blenrep approval is a testament to the power of perseverance in pharmaceutical innovation. With combination therapies now showing transformative results, the drug could generate annual sales exceeding £500 million by 2030, according to analysts at Jefferies. For investors, the upside lies in GSK’s ability to leverage this win to strengthen its oncology franchise, which currently contributes only 10% of its revenue.

Yet the road ahead is fraught with competition and regulatory scrutiny. If GSK can secure U.S. approval and demonstrate Blenrep’s cost-effectiveness in real-world settings, the drug could become a cornerstone of multiple myeloma treatment—and a catalyst for renewed investor confidence. As the clock ticks toward July’s FDA decision, this approval isn’t just about a single drug; it’s a referendum on GSK’s future in oncology.

For now, the data is clear: Blenrep’s comeback is a win for patients, and investors would be remiss not to take note.