• 40% bacterial, 53% viral and 6% fungal infections in 29 out of 55 multiple myeloma patients were observed post BCMA CART
• Majority of infections post BCMA CAR-T were mild-moderate and involved upper or lower respiratory system
B-cell maturation antigen-targeted chimeric antigen receptor T cell therapy (BCMA CAR-T) is an effective treatment for relapsed refractory multiple myeloma (RRMM). However the pattern of infectious complications is not well-elucidated. We performed a single-center retrospective analysis of infection outcomes up to 1-year post BCMA CAR-T for MM from 2018-2020. Fifty-five MM patients were treated with BCMA CAR-T. Prior to lymphodepletion (LD), 35% of patients had severe hypogammaglobulinemia and 18% had severe lymphopenia. Most patients (68%) received bridging chemotherapy (BC) prior to LD. In the first month post CAR-T, 98% patients had grade 3-4 neutropenia. At 1-year post infusion, 76% patients had hypogammaglobulinemia. With a median follow-up of 6.0 months (95% CI: 4.7 to 7.4), there were a total of 47 infection events in 29 (53%) patients, 40% bacterial, 53% viral and 6% fungal. Most (92%) were mild-moderate and of the lower/upper respiratory tract system (68%). Half of infections (53%) occurred in the first 100 days post CAR-T infusion. Though no statistically significant risk factors for infection were identified, prior lines of therapy, use of BC, recent infections, and post CAR-T lymphopenia were identified as possible risk factors that need to be further explored. This is the largest study to date to assess the infectious complications post BCMA CAR-T. Despite multiple risk factors for severe immunosuppression in this cohort, relatively few life-threatening or severe infections occurred. Further larger studies are needed to better characterize the risk factors for and occurrence of infections post BCMA CAR-T.