Comprehensive Review of Bispecific Antibody Constructs In Multiple Myeloma: Affinities, Dosing Strategies and Future Perspectives.

Despite significant advancements, multiple myeloma (MM) remains incurable, and there is still a pressing need for new therapeutic strategies with highly selective mechanisms of action and balanced off-target toxicity. In recent years, the development of "off-the-shelf" bispecific antibodies (bsAbs) has significantly enhanced our ability to treat relapsed or refractory MM. Teclistamab, elranatamab (both BCMA × CD3), and talquetamab (GPRC5D × CD3) are approved for treating MM patients who have received at least 3 prior lines of therapy, including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 monoclonal antibody. Meanwhile, the range of available bsAbs is rapidly expanding, offering patients and healthcare providers a broad selection of options that vary in target antigens, binding domains, construct designs, dosing regimens, and side effects. As linvoseltamab, alnuctamab, and ABBV-383 (all BCMA × CD3), as well as forimtamig (GPRC5D × CD3) and cevostamab (FcRH5 × CD3) progress through late-stage clinical development, emerging trispecific antibodies are now available that target either 2 different MM-associated antigens or provide additional co-stimulatory signals to prevent T-cell exhaustion. Despite this plethora of therapeutic options, resistance to bsAbs is an inevitability, and the optimal positioning of these drugs within the current MM treatment landscape remains to be determined. In this review, we examine the available data on all clinically accessible bsAbs, evaluating their potential, current limitations, and implications for efficacy and safety, with the aim of achieving deeper responses and longer overall survival for MM patients.