A T-cell–based metric of immune age predicts outcomes in older patients with myeloma receiving daratumumab-based therapy

Immunotherapy has transformed the treatment landscape of multiple myeloma (MM), a hematological cancer predominantly affecting older individuals. Yet, whether immune aging, shaped by intrinsic aging processes, genetics, and external factors, affects treatment efficacy remains unclear. To address this, we investigated the influence of age on the immune system in patients with MM and explored whether immune aging associates with clinical outcomes in older patients. Using flow cytometry, we conducted high-dimensional profiling of T cells and natural killer cells in peripheral blood and bone marrow samples of 124 older (>65 years) and 145 younger (≤65 years) patients with newly diagnosed MM (ages 34-92 years) enrolled in the HOVON-143 and CASSIOPEIA/HOVON-131 trials. On average, older patients exhibited a more activated, differentiated, and senescent T-cell compartment than younger patients. Nonetheless, substantial interindividual variation in T-cell subset frequencies within both age groups indicated that calendar age inadequately reflects an individual's immune status. We therefore developed an immune clock on high-dimensional phenotypic T-cell data to quantify each patient's "immune age," revealing substantial variation in immune ages among patients of similar calendar age. Importantly, immune age appeared a stronger predictor of clinical outcomes than calendar age in older, nonfit patients with newly diagnosed MM receiving daratumumab-ixazomib-dexamethasone, even after adjusting for frailty and other established risk factors. Overall, these findings highlight immune age as a clinically relevant composite metric that better reflects a patient's immune status than their calendar age. Validating this methodology in other immunotherapy settings may improve our ability to predict immunotherapy efficacy in older patients with MM or other hematological cancers.