A blood cancer drug from GSK failed to outperform standard treatment in a Phase 3 clinical trial, disrupting the British drugmaker’s plans to confirm its medicine’s conditional approval with follow-up evidence of its benefit.
In a study of 325 adults with relapsed or refractory multiple myeloma, GSK’s drug, called Blenrep, did not extend progression-free survival by significantly more than a treatment regimen consisting of Bristol Myers Squibb’s Pomalyst and the steroid dexamethasone.
Patients treated with Blenrep went a median of 11.2 months without their disease worsening or death, compared to a median of 7 months for those given Pomalyst and dexamethasone, GSK said Monday. The difference wasn’t enough to meet the study’s threshold for success, however, and a statistical measure for comparing relative risk showed roughly no difference between the two groups.
GSK is also measuring how long patients live in the study, but noted in its statement that the data is not yet mature.
A type of medicine known as an antibody-drug conjugate, Blenrep was granted accelerated approval by the Food and Drug Administration in 2020 based on its ability to shrink tumors. As a condition of that OK, GSK is required to further prove Blenrep’s benefit with data showing treatment can help delay disease progression or extend survival. The study that read out results Monday was meant to do so, meaning the negative results will set back GSK’s confirmatory plans.
Two other studies testing Blenrep earlier in the course of multiple myeloma treatment are ongoing, with results expected in the first half of 2023.
While Blenrep was the first drug of its kind to win U.S. approval, sales have remained slow since its 2020 launch. Over the first nine months of this year, GSK recorded sales of 91 million pounds, or about $104 million.
Other drugs targeting the same cancer protein as Blenrep does have since been approved, too, presenting GSK with new competition. Two cell therapies from Bristol Myers Squibb and Johnson & Johnson are now available, and J&J recently won FDA approval of a bispecific antibody drug that also targets the protein, known as BCMA.