A Phase I Study to Assess the Safety and Pharmacokinetics of Single-agent Lorvotuzumab Mertansine (IMGN901) in Patients with Relapsed and/or Refractory CD-56-positive Multiple Myeloma.

BackgroundDespite therapeutic advancements that have significantly improved outcomes in multiple myeloma (MM), it remains an incurable disease. Patients with relapsed and/or refractory MM have an aggressive disease course, with inferior outcomes, necessitating the need for agents with novel therapeutic mechanisms. We present the results of a completed phase I trial of single-agent lorvotuzumab mertansine, a unique antibody-drug conjugate targeting CD56, which is frequently expressed in MM.Patients and methodsThirty-seven patients with relapsed MM were enrolled in a dose-escalation phase I clinical trial to determine the maximum tolerated dose of lorvotuzumab mertansine (112 mg/m2), followed by an expansion phase at the maximum tolerated dose.ResultsDespite a high proportion of patients with relapsed and/or refractory MM (56.8%), stable disease or better was noted in 42.9% of patients, and these patients had a long duration of response (median, 15.5 months). The adverse event profile was favorable, with a low incidence of grade 3/4 adverse events and no infusion-related reactions. No humoral responses were detected against the study drug.ConclusionThis completed phase I trial of single-agent lorvotuzumab mertansine provides ample evidence of safety and signals of clinical activity for this agent, warranting its further clinical development as part of combination regimens for the management of MM.