Role of Radiotherapy in the Era of Novel Immune-Based Treatment Strategies for Multiple Myeloma.

Radiotherapy (RT) constitutes an important treatment modality in multiple myeloma (MM), traditionally used for the management of symptomatic osteolytic and extramedullary lesions. Objectives of RT are symptom alleviation and prevention of complications such as neurological deficits and pathological fractures. Over the past decade, systemic therapy (ST) for MM has undergone substantial advancements, notably with the incorporation of monoclonal antibodies in frontline regimens, as well as the emergence of bispecific antibodies and chimeric antigen receptor T-cells (CAR-T) for relapsed and refractory disease. These therapeutic innovations have introduced new clinical challenges and expanded the indications for RT, including its role as bridging therapy prior to CAR-T therapy, salvage therapy following CAR-T failure, and in the management of oligoprogressive and/or extramedullary disease. The integration of novel systemic agents prompts critical questions regarding synergistic interactions, feasibility, efficacy, and tolerability of combined RT and ST approaches. Herein, we present a literature review summarizing current evidence stratified by systemic treatment modalities, and discuss the clinical implications within the contemporary therapeutic landscape of MM.