Management of hematological toxicities after BCMA-directed CAR-T cell therapy

The CAR-HEMATOTOX (CAR-HT) score can assess hematotoxicity risk, but its utility in guiding supportive care remains underexplored. We analyzed 224 multiple myeloma patients treated with BCMA-directed CAR-T therapy (2016-2024), stratified by CAR-HT score (low <2 vs high ≥2). We evaluated the incidence and timing of early immune effector cell-associated hematotoxicity (ICAHT), other cytopenias, transfusion burden, cytopenia-directed interventions (growth factors and stem cell boosts), infections, and survival outcomes. High CAR-HT scores (58%) were associated with more grade 3 ICAHT (45.4% vs 23.3%) and grade 4 ICAHT (5.4% vs 1.2%; p = 0.0069), higher rates of grade ≥3 anemia (43.1% vs 24.4%, p < 0.0001) and thrombocytopenia (50.8% vs 27.9%, p < 0.0001). These patients were 7 times more likely to require red cell and platelet transfusions (p < 0.0001). G-CSF and TPO agonists were variably effective. Stem cell boosts (4%) led to rapid trilineage recovery. Infections occurred more frequently among high CAR-HT patients and those receiving intensive cytopenia-directed interventions. There were no significant differences in progression-free or overall survival between CAR-HT groups. Cytopenia-directed interventions did not affect survival. The CAR-HT score is a practical clinical risk tool that predicts transfusion burden and helps guide supportive care after BCMA CAR-T therapy.