Monoclonal and Bispecific Anti-BCMA Antibodies in Multiple Myeloma

B-cell maturation antigen (BCMA), a member of the tumor necrosis factor receptor superfamily, is universally expressed by normal and neoplastic plasma cells and plays a critical role in the proliferation, survival and tumor progression in multiple myeloma (MM). B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) have been recognized as proliferation ligands for BCMA in the bone marrow microenvironment. Soluble BCMA levels in the serum correlates with disease phase and tumor burden and is a predictor of progression-free survival (PFS) and overall survival (OS). Recently, the introduction of new monoclonal antibodies against CD38 (Daratumumab and Isatuximab) and SLAM7 (Elotuzumab) has changed the therapeutic approach to MM, improving the response rate and the time to progression, both in newly diagnosed and refractory/relapsed patients. Among the surface antigens on MM cells, BCMA is a suitable target for the design of new antibody-based strategies. Experimental approaches targeting BCMA are currently being investigated and include antibody-drug conjugates (ADCs), bispecific antibodies (bsAbs) and genetically engineered T-cells with chimeric antigen receptors (CAR). In this review we summarize the more recent findings about BCMA biologic rationale as a therapeutic target and report the updated results of preclinical and clinical studies focused on ADCs and bsAbs targeting BCMA.