Efficacy of haploidentical allogeneic hematopoietic cell transplantation following two courses of venetoclax and azacytidine therapy in patients over 55 years old with acute myelogenous leukemia

Introduction: The combination of venetoclax (VEN) and azacytidine (AZA) has demonstrated potential in achieving rapid and effective remissions in elderly patients with acute myeloid leukemia (AML). Allogeneic hematopoietic stem cell transplantation is a promising potential cure for high-risk AML, as VEN-based therapies have a worse prognosis in elderly patients. This study aimed to assess the efficacy of sequential haploidentical HSCT following two courses of VEN and AZA therapy in patients with AML aged 55 years and older. Methods: We conducted a retrospective study on AML patients aged 55 to 70 years who received intensive chemotherapy or two courses of VEN/AZA therapy, followed by haplo-HSCT based on disease risk degree, measurable residual disease status and patient’s preference. Results: Between January 2019 and December 2023, 141 newly diagnosed AML patients received initial treatment with intensive chemotherapy or VEN/AZA therapy. Among them, 64 patients received haplo-HSCT, while 77 did not. The 1-year over survival (OS) and relapse-free survival (RFS) of patients who received haplo-HSCT were significantly higher than those who did not receive haplo-HSCT (P<0.05). Among patients who received transplantation, there was no significant difference in 1-year OS and RFS between the VEN/AZA and intensive chemotherapy groups: 76.3% vs 69.3% (P = 0.367) for OS, and 74.5% vs 69.7% (P = 0.473) for RFS. High-risk ELN stratification and the presence of ≥4 gene mutations were associated with lower OS and RFS in both univariate and multivariate analysis. Conclusions: AML patients over 55 years of age who received haplo-HSCT after two courses of VEN/AZA therapy had outcomes similar to those who received haplo-HSCT after intensive chemotherapy, suggesting that two courses of VEN/AZA therapy as a bridge to halpo-HSCT are feasible for patients over 55 years old.