Recovery-Model: a model for CAR T-cell-related thrombocytopenia in relapsed/refractory Multiple myeloma

Abstract Background: Multiple myeloma (MM) patients treated with anti-BCMA chimeric antigen receptor (CAR) T-cell therapy tend to have delayed platelet recovery Patients and methods: This was a single-center retrospective observational study, which included a cohort of MM patients treated with anti-BCMA CAR-T in ChiCTR-OPC-16009113, ChiCTR1800018137, and ChiCTR1900021153. Results: 58 MM patients treated with anti-BCMA CAR-T were included, and delayed platelet recovery (platelet not recovered to 50×109 /L within 28 days) could be observed in 36% of patients. The regression analysis identified factors influencing platelet recovery such as baseline platelet counts (p < 0.0001, r = -0.59) and the Recovery-Model was created. High Recovery- Model score indicated a greater risk of delayed platelet recovery after CAR-T infusion and reflected the risk of hematologic toxicity. Predictive biomarkers of the model included baseline platelet count, baseline hemoglobin, logarithm of baseline ferritin, and cytokine release syndrome grade. Finally, survival analysis showed the significant relationship between overall survival, delayed platelet recovery (p = 0.0457) and a high Recovery-Model score (P = 0.0011). Conclusions: Inflammation-related factors and hematopoietic reserve were associated with delayed platelet recovery. We developed a model to predict the risk of platelet recovery and hematological toxicity in R/R MM patients after anti-BCMA CAR-T treatment.