GSK Reignites Blenrep Blockbuster Aspirations With Data from Phase III Studies

GSK in Dresden/iStock, 13threephotography

Pictured: GSK's office in Dresden, Germany/iStock, 13threephotography

After a brief market exit in November 2022, GSK appears to be giving its multiple myeloma treatment Blenrep (belantamab mafodotin) a second chance, with company executives touting its “multi-blockbuster” potential in a virtual oncology-focused investor event on Monday.

Much of GSK’s renewed enthusiasm for the antibody-drug conjugate (ADC) comes from promising data from two Phase III studies—DREAMM-7 and DREAMM-8—which saw strong signals of efficacy in Blenrep-based treatment regimens when used in multiple myeloma patients who had undergone at least one prior line of treatment.

In DREAMM-7, which compared Blenrep against Johnson & Johnson’s Darzalex (daratumumab), GSK reported a “significant increase” in progression-free survival (PFS) in patients treated with the ADC. The Blenrep regimen resulted in a nearly 60% drop in the risk of disease progression or death versus Darzalex. The PFS benefit was statistically significant, with a p-value of less than 0.00001.

In addition, median PFS in the Blenrep arm was 36.6 months, compared to those patients treated with Darzalex who only saw a median PFS of 13.4 months. The difference of approximately 23 months was “statistically significant and clinically meaningful,” according to GSK.

At the time of analysis, Blenrep also showed an “early, strong, and clinically meaningful trend” toward better overall survival (OS) versus Darzalex. DREAMM-7 will continue its follow-up for OS.

The Blenrep regimen also had superior depth of response than the Darzalex treatment, resulting in more than double the percentage of patients achieving at least complete response.

Results from DREAMM-8—which compared a Blenrep-based regimen versus a corresponding treatment schedule that used Takeda’s Velcade (bortezomib)—were similarly promising.

Patients treated with GSK’s ADC saw a “statistically significant and clinically meaningful” decrease in the risk of disease progression or death, which was almost 50% lower than in the Velcade group. Median PFS for Velcade treatment was 12.7 months, while it had not yet been reached at the time of analysis in the Blenrep patients.

The Blenrep regimen also elicited deeper treatment responses than the Velcade schedule. More than twice the percentage of patients in the Blenrep arm achieved complete response or better than those treated with Velcade.

Given these promising data, GSK Chief Commercial Officer Luke Miels estimated during Monday’s investor event that Blenrep could reach peak sales of more than $3 billion, driven mostly by the second-line opportunity in multiple myeloma. Blenrep could eventually dislodge Darzalex as the standard of care in this setting, Miels said.

Blenrep, an ADC that targets the BCMA protein, was originally approved under the FDA’s accelerated pathway in August 2020. At the time, it was authorized as a monotherapy for relapsed or refractory multiple myeloma patients who had progressed after prior treatment with a proteasome inhibitor, anti-CD38 antibody and immunomodulatory agent.

In November 2022, after falling short of its primary efficacy endpoint in its confirmatory Phase III trial DREAMM-3, GSK decided to pull Blenrep from the U.S. market.

Tristan Manalac is an independent science writer based in Metro Manila, Philippines. Reach out to him on LinkedIn or email him at or

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