Integrating Immune Therapies for the Treatment of Multiple Myeloma

Patients with relapsed or refractory multiple myeloma (RRMM) that is refractory to a proteasome inhibitor, an immunomodulatory drug (IMiD), and an anti-CD38 antibody (triple-class refractory MM) have poor outcomes. Recently, 2 classes of T-cell engaging therapies-CAR T-cell therapy and bispecific T-cell engaging antibodies (BsAbs)-have resulted in unprecedented response rates and survival outcomes in these heavily pretreated patients. The most common targets are BCMA and GPRC5D, with other targets in development. The main classes of adverse effects include cytokine release syndrome, neurotoxicity, infections, and cytopenias, as well as adverse effects unique to specific products. As of September 2023, 2 BCMA-targeting CAR-T cell products, 2 BCMA-targeting BsAbs, and 1 GPRC5D-targeting BsAb, are FDA-approved for standard-of-care use in patients with RRMM who received at least 4 prior lines of therapy, including prior treatment with a proteasome inhibitor, an IMiD, and an anti-CD38 antibody. Earlier-line use is under investigation and has shown promising results. Several other investigational CAR-T constructs and bispecific antibodies are in clinical development. As these therapies become more widely used, including in earlier-line setting, efforts to understand optimal sequencing and mitigate toxicities remain critical.