Pb1729: retrospective study of maintenance therapy with chidamide after transplantation for patients with high risk t-cell acute lymphoblastic leukemia/lymphoma

Topic: 2. Acute lymphoblastic leukemia - Clinical Background: T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is a highly aggressive type of hematological cancer with poor prognosis. Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is currently one of the most effective treatment strategies, however, post-transplantation relapse is still the most important factor influencing prognosis. Here we explore the effect of Chidamide, a novel antineoplastic drug, in maintenance therapy after Allo-HSCT in T-ALL/LBL. Aims: To investigate the efficacy and safety of Chidamide in maintenance therapy after Allo-HSCT for patients with T-ALL/LBL. Methods: The clinical data of six patients with high-risk T-ALL/LBL who received allo-HSCT and post-transplant maintenance therapy with Chidamide from November 2019 to February 2023 was collected. The efficacy and safety were retrospectively analyzed. The minimal residual disease (MRD), acute and chronic graft versus host disease (GVHD), progression-free survival (PFS) rate, overall survival (OS) rate and side effect of Chidamide were analyzed. Results: All of the six patients achieved complete remission and MRD negativity within 30 days after transplantation, including 1 case who previously have central nervous system leukemia (CNSL). 2/6 patients developed grade I-II acute GVHD, and no grade III-IV acute GVHD or any grade chronic GVHD was observed. The median follow-up period was 21 (12-37) months, 2/6 patients relapsed in 5 and 6 months after transplantation respectively. They obtained salvage therapy and still alive with sustain remission. The median survival time was 21 (12-37) months, the 1-year OS rate was 100%, and the 1-year PFS rate was 66.7%. The main adverse effects of Chidamide after transplantation were hematologic adverse effects, mainly manifested as thrombocytopenia (grade 2-3), neutropenia (grade 1-4) and anemia (grade 3), which were improved by extending the interval of Chidamide. One patient developed fatigue (grade 1), 2 patients developed nausea and vomiting (grade 1), 2 patients developed abnormal liver function (grade 2). The symptoms were easily relieved by symptomatic treatment. Summary/Conclusion: This study demonstrates that maintenance therapy with Chidamide after transplantation is safe and effective for high-risk T-ALL/LBL patients and need further investigation. Keywords: T cell lymphoma, Allogeneic hematopoietic stem cell transplant, HDAC inhibitor, T cell acute lymphoblastic leukemia