Thrombopoietin receptor agonist for treating bone marrow aplasia following anti-CD19 CAR-T cells—single-center experience

Anti CD-19 chimeric antigen receptor T (CAR-T) cells demonstrate effective early anti-tumor response; however, impaired hematopoietic recovery is observed in about 30% of patients with prolonged cytopenia appearing as an unmet need for optimal treatment. All adult patients given commercially available anti CD-19 CAR-T for diffuse large B cell lymphoma (DLBCL) were screened at 21-28 days after CAR-T infusion for cytopenia. In case of severe persistent cytopenia, patients were given TPO receptor agonists. Initial dose of eltrombopag was 50 mg/day and gradually increased to a maximal dose of 150 mg/day. Romiplostim was given as subcutaneous injection once a week for 2 doses (125 mcg). Response was defined as transfusion independency along with resolution of severe neutropenia (ANC 500 /microL) and/or platelets 20,000/microL for three consecutive values on different days. TPO receptor agonists were tapered down when response was met. From May 2019 to December 2021, 93 patients were eligible (74%, tisagenlecleucel and 26%, axicabtagene ciloleucel). The median age was 69 (range, 19-85) years. Six patients (6.5%) (tisagenlecleucel, n = 4 or axicabtagene ciloleucel, n = 2) demonstrated prolonged severe cytopenia and were treated with TPO receptor agonists (eltrombopag, n = 4; romiplastim, n = 1, both drugs, n = 1). Median time from CAR-T infusion to initiation of TPO receptor agonist was 43 (range, 21-55) days. All patients were transfusion-dependent and were given daily GCSF prior to TPO receptor agonist administration. Response to TPO receptor agonists was seen in all 6 patients. Median time from TPO receptor agonist initiation to resolution of cytopenia was 22 (range, 8-124) days for Hb, 27 (range, 6-38) days for platelets, and 29 (range, 7-61) days for neutrophils. A complete resolution of all blood counts (ANC 500 /microL and platelets 20,000/microL and hemoglobin 8 gr/dL) was seen in 5/6 patients. No toxicity was observed during the therapy course. This paper supports further investigation of TPO receptor agonists in the treatment of persistent cytopenia following CAR-T cell therapy.