GSK's anti-BCMA drug hits goal in pivotal multiple myeloma test

GSK CSO Hal Barron
GSK Chief Scientific Officer Hal Barron (GSK)

A phase 2 trial of GlaxoSmithKline’s BCMA drug has hit its primary endpoint, keeping Chief Scientific Officer Hal Barron’s group on track to file for approval in multiple myeloma by the end of the year. The data mark a milestone in Barron’s attempt to establish GSK as a major player in the oncology market.

GSK is yet to share data from the trial, limiting its initial disclosure of the news to the fact the study hit its primary goal and demonstrated a “clinically meaningful overall response rate.” But whatever GSK has seen is good enough to support its plan to use data from the trial as the bedrock of a filing for approval later this year.

The drug, an anti-BCMA antibody-drug conjugate that uses Seattle Genetics’ technology, moved into phase 2 on the back of the 60% response rate achieved in an earlier trial. In the most recent analysis of the earlier trial, the complete response rate was 15% and progression-free survival stood at 12 months.

GSK achieved those results in a potentially hard-to-treat population. Fourteen of the 35 patients enrolled in the second part of the previous study had received five or more prior lines of therapy, although only 13 of the participants had taken Johnson & Johnson’s anti-CD38 antibody Darzalex. 

The top-line findings shared today come from an even harder to treat patient population, with GSK limiting enrollment to people who had already tried an anti-CD38 antibody, as well as a proteasome inhibitor and immunomodulatory drug. In the earlier trial, the response rate fell to 38.5% in people previously treated with Darzalex, as compared to 71.4% among patients who had taken J&J’s drug.

Positive results in the population targeted by the latest trial could equip GSK to establish belantamab mafodotin as a go-to drug for patients whose disease advances following treatment with therapies such as Darzalex. In the longer term, GSK wants to use its drug in earlier lines of therapy.

In a statement about the data, GSK CSO Hal Barron said the company is continuing “to investigate how [belantamab mafodotin] could help even more patients with this disease.” Those investigations include trials that are testing belantamab mafodotin in combination with Merck’s Keytruda and in addition to dexamethasone and Celgene’s Pomalyst. Through combinations, GSK hopes to move its therapy into first and second-line settings.