[Efficacy and safety of venetoclax combined with decitabine, modified HA regimen and DLI in the treatment of relapsed pediatric AML/MDS after allogeneic hematopoietic stem cell transplantation].

Objective: To investigate the efficacy and safety of venetoclax combined with the decitabine, cytarabine, and homoharringtonine (HHT) regimen and donor lymphocyte infusion (DLI) for the preventive and salvage therapy of pediatric acute myeloid leukemia (AML) /myelodysplastic syndrome (MDS) after allogeneic hematopoietic stem cell transplantation (HSCT) . Methods: A total of 29 relapsed pediatric/minimal residual disease-positive AML after HSCT were recruited at the Peking University Institute of Hematology from January 1, 2021, to June 1, 2023. They were treated with the above combination regimen and administered with DLI after 24-48 hours at the end of chemotherapy, and the treatment response and adverse reactions were regularly assessed. Results: The overall response rate (ORR) was 75.8%, CR rate was 88.9% (8/9) in the hematologic relapse group, and MRD negativity rate was 61.1% (11/18) in the MRD-positive group. The incidence of agranulocytosis, anemia, and thrombocytopenia with a classification above grade 3 were 100%, 82.7%, and 100%, respectively. The median time of the granulocyte deficiency period was 15 days. Acute graft-versus-host diseases (aGVHD) with a classification of grades Ⅲ-Ⅳ occurred in 11.1% of the patients after DLI, while moderate or severe cGVHD occurred in 7.4% of the patients. The single risk factor for ORR was MNC counts of less than 10×10(8)/kg, and the relapse occurred within 100 days. At a median follow-up of 406 days, the 1-year OS was 65%, and the 1-year OS was 57% in the group with no reaction (P=0.164) compared with 71% in the group who had an overall reaction. Conclusion: The combined regimen based on the DAC, VEN, and modified HA regimen showed a high response rate in the salvage therapy for pediatric AML after the relapse of HSCT. However, bridging to transplantation should be performed immediately after remission to result in a long survival rate.