Indatuximab Ravtansine (BT062) Monotherapy in Patients With Relapsed and/or Refractory Multiple Myeloma

Background: Indatuximab ravtansine (BT062) is an antibody-drug conjugate that binds to CD138, which is overexpressed on multiple myeloma (MM) cells. Patients and Methods: We report from 2 clinical studies of patients with relapsed and/or refractory MM previously treated with an immunomodulatory drug and a proteasome inhibitor. Single- and multi-dosing schedules were investigated to define dose-limiting toxicities, maximum tolerated dose (MTD), recommended phase II dose, and to describe safety, efficacy, and pharmacokinetics. Results: In the first-in-human study, indatuximab ravtansine was administered to 32 patients on day 1 of each 21-day cycle. The MTD was 160 mg/m². In the phase I/IIa study, indatuximab ravtansine was administered to 35 patients on days 1, 8, and 15 of each 28-day cycle, and the MTD/recommended phase II dose was 140 mg/m². Most (88%) adverse events were grade 1 or 2, the most common being diarrhea and fatigue. There was rapid clearance of indatuximab ravtansine and no relevant accumulation. Over 75% of heavily pretreated patients achieved stable disease or better. With the multi-dose schedule, minor and partial responses occurred in 14.7% of patients, the median time to progression was 3 months, and the median overall survival was 26.7 months. Conclusion: Our data support further investigation of indatuximab ravtansine as part of a combination regimen for relapsed and/or refractory MM.