Complex association of body mass index and outcomes in patients with relapsed and refractory multiple myeloma treated with CAR-T cell immunotherapy

Background aims Chimeric antigen receptor-T (CAR-T) cells have exhibited remarkable efficacy in treating refractory or relapsed multiple myeloma (R/R MM). Although obesity has a favorable value in enhancing the response to immunotherapy, less is known about its predictive value regarding the efficacy and prognosis of CAR-T cell immunotherapy. Methods We conducted a retrospective study of 111 patients with R/R MM who underwent CAR-T cell treatment. Using the body mass index (BMI) classification, the patients were divided into a normal-weight group (73/111) and an overweight group (38/111). We investigated the effect of BMI on CAR-T cell therapy outcomes in patients with R/R MM. Results The objective remission rates (ORRs) after CAR-T cell infusion were 94.7% and 89.0% in the overweight and normal-weight groups, respectively. The duration of response (DOR) and overall survival (OS) were not significant difference between BMI groups. Compared to normal-weight patients, overweight patients had an improved median progression-free survival (PFS). There was no significant difference in cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) between the subgroups. In terms of hematological toxicity, the erythrocyte, hemoglobin, platelet, leukocyte and neutrophil recovery was accelerated in the overweight group. Fewer patients in the overweight group displayed moderate per cent CD4 and CD4/CD8 ratios compared to the normal-weight group. Furthermore, the per cent CD4 ratios were positively correlated with the levels of cytokines [interleukin-2 (IL-2) (day 14), interferon gamma (IFN-γ) (day 7), and tumor necrosis factor alpha (TNF-α) (days 14 and 21)] after cells infusion. On the other hand, BMI was positively associated with the levels of IFN-γ (day 7) and TNF-α (days 14 and 21) after CAR-T cells infusion. Conclusions Overall, this study highlights the potential beneficial effect of a higher BMI on CAR-T cell therapy outcomes.