GSK’s anti-BCMA multiple myeloma drug shows durability in updated data

GlaxoSmithKline GSK House in Brentford, UK
The data show an identical ORR after a year of follow-up, showing “not only the potential efficacy of the medicine but the durability and depth of response,” the company said. (GlaxoSmithKline)

GlaxoSmithKline's anti-BCMA treatment staved off cancer progression for one year in patients with recurrent or treatment-resistant multiple myeloma, new phase 1 data show. The data also confirmed the response rate—the ratio of patients whose tumors shrank in response to the treatment—of 60% reported in an interim analysis presented at the American Society of Hematology Congress in December 2017.

The study, DREAMM-1, is an open-label study of GSK’s anti-BCMA (B-cell maturation antigen) antibody-drug conjugate, GSK2857916. The data are from part 2 of the study, which enrolled 35 patients with relapsed or refractory multiple myeloma, who received the recommended dose of the drug identified in part 1. Fourteen of the patients had previously undergone more than five lines of therapy and 21 patients had received Janssen’s Darzalex (daratumumab), an anti-CD38 drug approved for patients who had previously undergone multiple treatments and for whom proteasome inhibitors and immunomodulators do not work.

The data show an identical overall response rate after a year of follow-up, displaying “not only the potential efficacy of the medicine but the durability and depth of response,” the company said in a statement Thursday. Additionally, the new data show that patients went 12 months without their disease getting worse, compared to their previously reported median progression-free survival of 7.9 months. And over the course of the one-year follow-up, the number of patients whose cancer was eliminated by the treatment increased to 15%.

RELATED: AbbVie, Teneobio ink $90M deal to develop BCMA bispecific for multiple myeloma

The response rate and median progression-free survival were higher in the 21 patients who had not been treated with Darzalex—they were 71% and 15.7 months respectively. As for the 13 patients who had previously received Darzalex, these figures were lower—38.5% and 7.9 months. The findings appear in the Blood Cancer Journal. 

“These data are very encouraging and I am excited by what they could mean for people living with multiple myeloma. We are aggressively advancing this potential new medicine and plan to have pivotal data to support its filing by the end of this year,” said Dr. Hal Barron, Glaxo’s chief scientific officer and R&D chief, in the statement. 

All of the patients experienced at least one side effect, most commonly thrombocytopenia, blurred vision and cough, but “no new safety signals were identified during this treatment period,” according to GlaxoSmithKline. About half of the patients suffered a serious side effect, most commonly pneumonia, lung infection and infusion-related reactions. Four patients died during the study due to disease progression. 

“GSK2857916 demonstrated a rapid, deep, and durable clinical response with a significant progression-free survival in a heavily pre-treated population,” the study authors concluded.

And even though patients who had previously received Darzalex didn't do as well as patients who had not, they could still benefit from treatment with GSK2857916.

"While the response rate is lower in the latter population [patients who had received Darzalex], it is still an encouraging response for a population of patients who typically respond poorly with any treatments following daratumumab failure," the authors wrote. They called for further research to understand the difference in response between Darzalex and non-Darzalex patients and suggested that the reason may well be that "the patients in the study who had received daratumumab had MM for longer and had more refractory disease."

The authors suggested that GSK2857916 could be tested in combination with other therapies and in patients with different forms of multiple myeloma. 

“Overall, our results suggest that GSK2857916 is a promising therapy for patients with relapsed and refractory MM, including those in whom all other standard and available therapies have failed,” they wrote. 

The BCMA field has been heating up. GSK's news comes shortly after AbbVie and Teneobio inked a $90 million pact to develop a BCMA- and CD3-targeting bispecific antibody for multiple myeloma. And at ASH 2018, Amgen presented early clinical data on its anti-BCMA T cell engager AMG 420 showing a 70% ORR. But it hasn’t been smooth sailing for all parties, as just last month, Gilead quietly abandoned an anti-BCMA cell therapy for multiple myeloma that it picked up in its $12 billion acquisition of Kite Pharma.