FDA AdCom recommends GSK’s anti-BCMA drug for approval 12-0 despite searing in-house review — does it matter?

The FDA may have ripped GlaxoSmithKline for the safety of its anti-BCMA drug, but that didn’t stop an advisory committee from voting 12-0 to recommend approval for the multiple myeloma treatment.

The decision is in line with the committee’s long-running preference to approve cancer drugs that show enough efficacy and not overwhelming safety concerns, with the goal of giving oncologists as many tools to work with as possible as they treat individual patients. Yet while it signaled a strong likelihood of FDA approval — and boosted GSK’s stock by a nifty 1.6% — the vote still leaves open the question of how useful the drug will ultimately be and, accordingly, how well it will sell for a company trying to claw back into the cancer therapeutics business.

The case for the therapy, an antibody drug conjugate called belantamab, is simple: It had a 31% response rate in multiple myeloma patients who had failed multiple other lines of therapies, including the J&J blockbuster Darzalex.

The case against the drug is also simple: The FDA concluded that GSK, running single-arm trials, failed to prove it helps patients live longer.  And the downsides were significant: Nearly a fifth of patients in one trial saw their vision decline to levels at which they would not legally be allowed to drive in one state. One patient on the application dose and two patients on the higher dose became legally blind. “[I]t is not clear that the benefits outweigh the risk of ocular toxicity,” the FDA concluded in its review last week.

All that may not be enough to dramatically curtail the drug’s commercial potential if it weren’t for the deep well of experimental therapies that have shown far better results in the clinic and are now nearing approval.

GSK will likely have to compete with the anti-BCMA CAR-T therapy from J&J-partnered Legend Biotech that recently showed a 100% response rate and a 69% complete response rate in patients who had undergone a median of five lines of therapy. Bluebird and Bristol Myers Squibb have faced embarrassing delays in bringing their so-called “ide-cel” CAR-T therapy to market, but their data are pretty clear: a 71% response rate and a 31% complete response rate in Phase II.

Then there’s the bispecifics from Regeneron, Amgen and Bristol Myers, which are further behind but have been greeted with promise. In a dose-escalation study unveiled at ASH in December, Regeneron’s REGN5458 induced responses in 4 of 7 patients who had already received 7 lines of therapy.

Belantamab was meant to be a central part of GSK’s return to cancer under CEO Emma Walmsley, and it may soon get an approval. How much it will mean for patients or for a drug company looking to re-cement its name remains unclear.