GlaxoSmithKline PLC, one of the U.K.'s largest drugmakers, said patients with advanced multiple myeloma had a 31% overall response rate when treated with its experimental anti-BCMA agent, offering a potential new treatment option should U.S. regulators give it the go-ahead.
Known as belantamab mafodotin, or GSK2857916, the anti-BCMA agent was given to patients in the Dreamm-2 trial who had received an average of seven previous lines of treatment that had failed, in doses of either 2.5 milligrams or 3.4 milligrams per kilogram, every three weeks. Thirty of the 97 patients, or 31%, of those in the 2.5-milligram cohort achieved an overall response. Eighteen of these achieved a very good partial response or better, including three patients with complete responses, GSK said.
Side effects were consistent with the previous Dreamm-1 trial, with changes in the outer layers of the cornea, known as keratopathy, affecting some 27% of participants, causing 1% of the lower dose patients to drop out. Furthermore, overall survival in patients achieving a response was not reached in the six month follow-up period.
"Patients with multiple myeloma whose disease has progressed despite currently available therapy have limited options and poor outcomes," said Hal Barron, GSK's chief scientific officer and president of research and development. "Data from the Dreamm-2 study show that, if approved, belantamab mafodotin could offer an important new treatment option for these patients."
Patients in Dreamm-2 had more advanced disease and poorer prognosis than those in Dreamm-1, the first-in-human study. But the data was consistent with observations of a similar subset of patients in the initial study, and GSK is now applying for U.S. regulatory approval of the lower dose.
Belantamab mafodotin, which was granted breakthrough therapy status by the FDA in 2017, would be the first anti-BCMA agent available anywhere if approved.
Its success would be a validation of GSK's move back into oncology, orchestrated by Axel Hoos, GSK's head of oncology, and Hal Barron in the last year. Hoos told S&P Global that belantamab mafodotin could become a $5 billion product and is expected to launch in 2020.
Full results from the Dreamm-2 trial, published Dec. 16 in The Lancet Oncology, have been eagerly awaited by analysts. Steve Scala of Cowen had forecast an overall response rate of 30% for the anti-BCMA agent and believes that ocular toxicity is manageable.
"In recent years, BCMA has become one of the most promising targets in multiple myeloma research," said Sagar Lonial, Chief Medical Officer, Winship Cancer Institute of Emory University and Principal Investigator for Dreamm-2. "The data published today from Dreamm-2 not only reinforce the significance of BCMA as a potentially viable target, but also underscore the potential of belantamab mafodotin, if approved, as a practical treatment option in this patient population."
Further studies are continuing on the effect of belantamab mafodotin as third-line monotherapy in relapsed multiple myeloma, as well as in combination with other treatments in the first- and second-line setting as part of the broader Dreamm clinical development program.