Comprehensive characterization of cytopenia after chimeric antigen receptor-T cell infusion in patients with relapsed or refractory multiple myeloma.

Background: Many studies have demonstrated the effectiveness of chimeric antigen receptor-T (CAR-T) cell therapy for relapsed or refractory multiple myeloma (RRMM), but the hematologic toxicity has not been well characterized.

Methods: A total of 111 adults with RRMM who received BCMA CAR-T cells, BCMA + CD19 CAR-T cells or tandem BCMA/CD19 dual-target (BC19) CAR-T cells infusion were enrolled. We characterized cytopenia and hematologic recovery at different time points after CAR-T-cell therapy, analyzed the effect of cytopenia on prognosis and identified the risk factors.

Results: Patients had a high probability of cytopenia, with anemia, neutropenia and thrombocytopenia occurring in 92%, 95% and 73%, respectively. There were 60 (54%) patients had prolonged hematologic toxicity (PHT) after D28. The median hemoglobin and platelet count were significantly lower at D28 post-CAR-T cell therapy than at baseline. Hemoglobin increased to above baseline at D90. The median absolute neutrophil count was lower than baseline at D0 and D28, and it recovered to baseline at D180. The baseline level of lactate dehydrogenase was associated with thrombocytopenia. Extramedullary involvement was associated with hemoglobin recovery, while the baseline level of albumin and types of CAR-T were related to platelet recovery. Patients with anemia at baseline and at D0, D180 and D360 had shorter progression-free survival (PFS), while anemia at D0, D60, D180 and D360 was associated with shorter overall survival (OS). Neutropenia at D0 was associated with shorter PFS and patients with neutropenia at D90 or D180 had shorter OS. Patients with thrombocytopenia at any time had shorter PFS and OS. Compared to patients without PHT, patients with PHT had shorter PFS and OS.

Conclusions: The majority of RRMM patients treated with CAR-T cells experienced cytopenia. Cytopenia occurred at specific time points was associated with a poorer prognosis.