Safety and efficacy of eltrombopag in patients with post‐CAR T cytopenias

Background While chimeric antigen receptor (CAR) T‐cell therapy has revolutionized the treatment outcomes of relapsed/refractory hematological malignancies, this therapy is associated with post‐treatment cytopenias, which can pose a challenge to its safe administration. This study describes the management of post‐CAR T cytopenias using the thrombopoietin mimetic eltrombopag. Methods This retrospective analysis included adult patients with lymphoma or myeloma who received CAR T‐cell therapy at two academic medical centers. Eltrombopag was initiated for patients who had persistent high‐grade leukopenia and/or thrombocytopenia beyond 21 days post‐CAR T infusion. Risk factors and outcomes were assessed and compared for patients who did or did not receive eltrombopag. Results Among the 185 patients analyzed, a majority (88%) experienced thrombocytopenia or leukopenia at day +30 post‐CAR T infusion. A total of 42 patients met the criteria for eltrombopag treatment and initiated therapy. Patients who received eltrombopag were more likely to have pre‐existing cytopenias at lymphodepletion, receive bridging therapy, experience an infection, or require intensive care. Recovery from cytopenias occurred within 180 days for a majority (94%) of patients. Conclusions The use of eltrombopag for post‐CAR T leukopenia and thrombocytopenia was considered safe without any significant toxicities. The use of eltrombopag for post‐CAR T cytopenias might be effective in a high‐risk patient population but requires further study.