GSK's Blenrep Secures Second Phase III Victory, Signaling Possible U.S. Market Return

GlaxoSmithKline (GSK) has announced a significant milestone for its cancer drug, Blenrep, with a second successful Phase III trial, which may pave the way for its return to the U.S. market. Blenrep, an antibody-drug conjugate, had previously received accelerated approval from the FDA as a treatment for fourth-line multiple myeloma in 2020. However, due to the failure of a confirmatory Phase III trial in November 2022, the FDA requested its withdrawal from the U.S. market. Despite this setback, GSK has been conducting further studies with the aim of reviving the drug.

The recent success is attributed to a trial known as DREAMM-8, which compared Blenrep-based treatment against the standard care for patients with second-line and later multiple myeloma. In this trial, all 302 participants were given pomalidomide plus dexamethasone, and were then randomly assigned to receive either Blenrep or bortezomib, marketed as Velcade. The Blenrep group demonstrated a notably longer progression-free survival rate than the control group, leading to an early unblinding of the trial data. Although GSK has not yet disclosed specific data, it has indicated that the Blenrep regimen significantly improved the time to disease progression or death compared to the standard treatment.

Additionally, GSK reported a positive trend in overall survival for the Blenrep group, suggesting that while the endpoint was not statistically significant at the interim analysis, the situation could evolve as more data becomes available. The company is continuing to monitor overall survival outcomes.

With the success of the two Phase III trials, GSK is poised to discuss the results with regulatory authorities, potentially leading to a resubmission for Blenrep's market availability in the U.S. Hesham Abdullah, GSK's global head of oncology R&D, has expressed optimism about Blenrep's potential to transform the treatment landscape for relapsed or refractory multiple myeloma.

However, if Blenrep does enter the market, it will encounter fierce competition from other BCMA-directed therapies such as CAR-T cell treatments and T-cell engagers, which are already vying for market share in the multiple myeloma space. Despite the challenges, the successful trials could bolster GSK's performance beyond its current mid-term forecasts. The company had previously raised its 2031 sales target but did not include Blenrep in its projections. Since its withdrawal from the U.S., Blenrep's sales have significantly dropped.

The positive developments for Blenrep come at a crucial time for GSK, as it seeks to regain its footing in the oncology market and enhance its product portfolio. The drug's potential reintroduction to the U.S. market could mark a significant step forward for both the company and patients in need of innovative treatment options for multiple myeloma.