Responses to Regeneron's bispecific linvoseltamab have risen but so have adverse events and deaths associated with the multiple myeloma drug.
All patients reported at least one adverse event and 14 deaths occurred "due to treatment-emergent" adverse events in the early-stage trial. Regeneron posted the results Thursday ahead of this weekend's American Society of Hematology's annual meeting.
In a phase 1/2 dose-escalation trial dubbed LINKER-MM1, Regeneron's drug was associated with a 71% objective response rate in patients with heavily pre-treated multiple myeloma, the company said. Researchers also tracked a 46% rate of complete responses or better.
The ongoing trial has enrolled 282 patients who have tried at least three lines of prior therapy or who are triple refractory. So far, investigators have 11 months of study follow-up. Before enrollment, patients in the study had tried a median five lines of therapy.
This data drop follows a prior release from last year's ASH conference when Regeneron touted a 64% response rate and a 45% rate of partial responses or better.
Safety remains an important consideration for this medicine. During the ASH update last year, Regeneron said that 95% of patients experienced some type of adverse event. During Thursday's update, the figure grew to 100%, with 85% of patients experiencing a grade 3 or worse event. The most common adverse event in the study was cytokine release syndrome (CRS), with most of those cases being grade 1, the company said.
In addition, there were 14 patient deaths "due to treatment-emergent" adverse events, with 11 being due to infections, Regeneron said.
Trial investigators administered Regeneron's drug, an investigational BCMAxCD3 bispecific antibody, under a "step-up dosing regimen" intended to help mitigate instances of CRS, according to the company.
The CRS rate is in the “lower range” among comparable medicines, Karen Rodriguez-Lorenc, Regeneron's linvoseltamab global program head, said in an interview. Because this is an intravenous drug, the CRS cases occur earlier after treatment, allowing for easier monitoring and care, she explained.
Meanwhile, the LINKER-MM1 response rate is in the “higher range” among medicines in the class, so linvoseltamab could be "potentially the best-in-class BCMAxCD3," she said.
Regeneron plans to share the results with regulatory authorities and remains on track to submit an FDA biologics license application this year, Rodriguez-Lorenc said.
“All in all, we think that because of the high efficacy, the manageable safety profile and this regimen that is more convenient, we think that we can have the best-in-class BCMA," Rodriguez-Lorenc said.
The phase 1 dose-escalation part of the trial is complete, having assessed safety, tolerability and toxicities spanning nine doses.
As for the phase 2 portion of the trial, investigators are tracking the primary objective of the overall response rate. Secondary measures include duration of response, progression-free survival and overall survival.