Thrombotic Events Are Unusual Toxicities of Chimeric Antigen Receptor T-Cell Therapies

Coagulation abnormalities associated with CAR-T-cell therapy in haematological malignancies: A review

Chimeric antigen receptor (CAR)-T-cell therapy has demonstrated considerable efficacy and safety in the treatment of patients with relapsed/refractory haematological malignancies. Owing to significant advances, CAR-T-cell therapeutic modality has undergone substantial shifts in its clinical application. Coagulation abnormalities, which are prevalent complications in CAR-T-cell therapy, can range in severity from simple abnormalities in coagulation parameters to serious haemorrhage or disseminated intravascular coagulation associated with life-threatening multiorgan dysfunction. Nonetheless, there is a lack of a comprehensive overview concerning the coagulation abnormalities associated with CAR-T-cell therapy. With an aim to attract heightened clinical focus and to enhance the safety of CAR-T-cell therapy, this review presents the characteristics of the coagulation abnormalities associated with CAR-T-cell therapy, including clinical manifestations, coagulation parameters, pathogenesis, risk factors and their influence on treatment efficacy in patients receiving CAR-T-cell infusion. Due to limited data, these conclusions may undergo changes as more experience accumulates.

Recognizing, defining, and managing CAR-T hematologic toxicities

Autologous CAR-T cell therapy (CAR-T) has improved outcomes for patients with B-cell malignancies. It is associated with the well-described canonical toxicities cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), which may be abrogated by corticosteroids and the anti-IL6 receptor antagonist tocilizumab. Practitioners and researchers should be aware of additional toxicities. Here we review current understanding and management of hematologic toxicities after CAR-T, including cytopenias, coagulopathies, bleeding and clotting events, hemophagocytic-lymphohistiocytosis, and tumor lysis syndrome. We pay particular attention to cytopenias, recently termed immune effector cell-associated hematological toxicity (ICAHT). While the "H" is silent, hematotoxicity is not: ICAHT has the highest cumulative incidence of all immune adverse events following CAR-T. Early cytopenia (day 0-30) is closely linked to lymphodepleting chemotherapy and CRS-related inflammatory stressors. Late ICAHT (after day 30) can present either with or without antecedent count recovery (e.g., "intermittent" vs "aplastic" phenotype), and requires careful evaluation and management strategies. Growth factor support is the mainstay of treatment, with recent evidence demonstrating safety and feasibility of early granulocyte colony-stimulating factor (G-CSF) (e.g., within week 1). In G-CSF refractory cases, autologous stem cell boosts represent a promising treatment avenue, if available. The CAR-HEMATOTOX scoring system, validated for use across lymphoid malignancies (B-NHL, multiple myeloma), enables pretherapeutic risk assessment and presents the potential for risk-adapted management. Recent expert panels have led to diagnostic scoring criteria, severity grading systems, and management strategies for both ICAHT and the recently termed immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS), now clarified and defined as a distinct entity from CRS.

CAR T-Cell Therapy for Multiple Myeloma: A Clinical Practice-Oriented Review

The emergence of chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of hematologic malignancies, including multiple myeloma (MM). Two BCMA-directed CAR T-cell products - idecabtagene vicleucel (ide-cel) and ciltacabtagene autoleucel (cilta-cel) - have received US Food and Drug Administration (FDA) approval for patients with relapsed/refractory MM who underwent four or more prior lines of therapy (including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody). Despite producing unprecedented response rates in an otherwise difficult to treat patient population, CAR T-cell therapies are commonly associated with immune-related adverse events (e.g., cytokine release syndrome and neurotoxicity), cytopenias, and infections. Moreover, many patients continue to exhibit relapse post-treatment, with resistance mechanisms yet to be fully understood. Ongoing basic, translational, and clinical research efforts are poised to generate deeper insights into the optimal utilization of these therapies, improve their efficacy, minimize associated toxicity, and identify new target antigens in patients with MM.