LMB-75

LMB-75 is a recombinant immunotoxin (RIT) designed to target B-cell maturation antigen (BCMA), a protein highly expressed on multiple myeloma cells. It consists of a disulfide-stabilized variable fragment (dsFv) derived from the anti-BCMA monoclonal antibody BM306, fused to domain III of Pseudomonas Exotoxin A (PE). The mechanism of action involves the antibody fragment binding to BCMA on the cell surface, followed by internalization of the complex. Once inside the cell, the toxin fragment inhibits protein synthesis by ADP-ribosylating elongation factor 2 (EF-2), ultimately leading to apoptosis. Developed by researchers at the National Cancer Institute, LMB-75 has demonstrated potent anti-tumor activity and complete responses in bone marrow mouse models of multiple myeloma, supporting its potential as a therapeutic agent for BCMA-positive malignancies.