Phase 1 first-in-human study of MEDI2228, a BCMA-targeted ADC, in patients with relapsed refractory multiple myeloma.

MEDI2228 is an antibody drug conjugate (ADC) comprised of a fully human B-cell maturation antigen (BCMA) antibody conjugated to a pyrrolobenzodiazepine (PBD) dimer. This phase 1 trial evaluated MEDI2228 in patients with relapsed/refractory (R/R) multiple myeloma (MM), who received prior treatment with approved agents from 3 classes of antimyeloma drugs (proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies). Primary endpoint was safety and tolerability; secondary endpoints included efficacy, pharmacokinetics, and immunogenicity. A total of 107 patients were treated and the maximum tolerated dose (MTD) was 0.14 mg/kg Q3W. Two patients had dose-limiting toxicities (DLTs; thrombocytopenia; 0.20 mg/kg Q3W). The most frequent treatment-related adverse events were photophobia (43.9%), rash (29.0%), and thrombocytopenia (19.6%). In MTD cohort A ( MEDI2228 is an ADC comprised of a fully human anti-BCMA antibody conjugated to the cytotoxic PBD payload, tesirine.MEDI2228 monotherapy demonstrated efficacy across all dose levels; and responses were observed in patients with triple refractory MM.This study further validates BCMA as a target for ADC-based therapy in MM; ocular toxicity precluded further clinical development.