[Hematologic side effects of cell and immunotherapy]

Cellular and immunological cancer therapies have substantially changed the treatment landscape of malignant diseases. In particular, chimeric antigen receptor (CAR) T-cell therapy and immune checkpoint inhibitors (CPI) have enabled durable responses in previously refractory malignancies. However, these treatment strategies are associated with distinct immune-mediated toxicities that differ considerably from the toxicity profiles observed with conventional cytotoxic chemotherapy. Hematologic complications represent an important subgroup of these adverse events. Hematologic immune-related adverse events (irAEs) under CPI therapy are rare but may be associated with considerable morbidity and mortality. In contrast, hematologic toxicities are common after CAR T-cell therapy and are summarized under the term ICAHT (immune effector cell-associated hematotoxicity). These cytopenias may present early after therapy due to lymphodepleting conditioning or later as prolonged or biphasic cytopenias associated with inflammatory bone marrow suppression. In addition, severe hyperinflammatory syndromes such as immune effector cell-associated hemophagocytic syndrome (IEC-HS) may occur and require rapid recognition and treatment. A structured diagnostic approach is essential to differentiate therapy-related cytopenias from disease progression, bone marrow infiltration, or secondary hematologic malignancies. Management strategies depend on the severity of the cytopenia and include supportive measures, immunomodulatory therapies, and in selected cases targeted anti-cytokine treatments. Early recognition and interdisciplinary management are crucial to reduce morbidity and improve patient outcomes.