What drives CAR-T emergent cytopaenia?

Prolonged cytopaenia after CAR-T cell therapy is an acknowledged problem. At present, the causes and implications of prolonged cytopaenia are unclear. The paper by Kitamura et al identified that prolonged cytopaenia is associated with alterations in the bone marrow niche identified before CAR-T therapy, indicating a potential predictor of this serious side-effect of treatment. Commentary on: Kitamura et al. Bone marrow microenvironment disruption and sustained inflammation with prolonged haematologic toxicity after CAR T-cell therapy? Br J Haematol 2022 (Online ahead of print). doi: 10.1111/bjh.18747.