Immune Fitness in Older Patients With Relapsed and Refractory Multiple Myeloma

Relapsed/refractory multiple myeloma (RRMM) predominantly affects older adults, who exhibit marked heterogeneity in treatment outcomes despite receiving the same therapies. Clinical frailty scores, such as the International Myeloma Working Group (IMWG) Frailty Index, predict survival and treatment tolerance but provide limited information on immune competence, a key determinant of response to T-cell-based immunotherapies. The PRIME study is a prospective, multicenter, non-interventional exploratory study designed to evaluate the relationship between immune fitness and clinical outcomes in patients aged 65 years or older with RRMM treated with standard-of-care chimeric antigen receptor T-cell (CAR-T) therapy or bispecific antibodies. Peripheral blood samples collected before treatment initiation will be analyzed to characterize T-cell differentiation, activation, senescence, exhaustion, and T-helper cell subsets using multiparametric immunophenotyping. Serum biomarkers, including soluble B-cell maturation antigen (sBCMA) and senescence-associated soluble markers, will also be assessed. * The primary objective is to determine whether baseline immune profiles are associated with quality of response at 3 months after treatment initiation. * Secondary objectives include evaluating the association between immune profiles and treatment-related toxicities, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), other neurological toxicities, and infectious complications. Exploratory analyses will integrate immune, geriatric, sarcopenia, and clinical variables using statistical approaches to identify novel predictors of efficacy, survival, and toxicity. By combining immune phenotyping with frailty assessment, the PRIME study aims to improve biological risk stratification and support the development of more personalized treatment strategies for older patients with multiple myeloma.