Immunotherapy and Treatments in Multiple Myeloma: Response, Durability, and Challenges

Multiple myeloma (MM) is a blood cancer wherein abnormal plasma cells accumulate in the bone marrow and overproduce monoclonal proteins, resulting in anemia, bone damage, kidney disorders, and increased infection risk. This narrative review compares newer immunotherapies, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies, with established MM treatments in terms of effectiveness, durability of response, limitations, and their potential role in future treatment strategies. This narrative review of clinical studies and scientific literature focuses on treatment response, measurable residual disease (MRD) negativity, progression-free survival, treatment-related toxicities, resistance, and accessibility of treatment options. Based on the findings, immunotherapies can provide substantial responses and MRD negativity, especially in patients with relapsed or refractory MM. CAR T-cell therapy provides durable disease control after a single infusion, whereas bispecific antibodies can be used without individualized cell collection and manufacturing. However, these approaches have certain limitations, including infections, cytopenias, cytokine release syndrome, neurotoxicity, treatment resistance, high cost, and limited access. These findings suggest that immunotherapy should complement, rather than replace, established treatments. Future research should focus on personalized treatment selection, combination therapies, and sequencing strategies to improve response durability, reduce toxicity, overcome resistance, and expand equitable access to MM treatments.