Gilteritinib maintenance after allogeneic hematopoietic stem cell transplantation for relapsed/refractory acute myeloid leukemia with FLT3-internal tandem duplication mutation

<b>Background:</b> Patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) with FLT3-Internal Tandem Duplication (ITD) mutation have a poor prognosis and high risk of relapse, even after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Prevention of disease relapse remains a challenge.<b>Objective:</b> To investigate the efficacy and tolerability of gilteritinib maintenance therapy in R/R AML patients with FLT3-ITD mutation.<b>Methods:</b> We retrospectively analyzed 96 AML patients who received allo-HSCT between 2017 and 2022. Patients were divided into two groups based on whether they received gilteritinib maintenance therapy or not. To minimize selection bias, we implemented propensity score matching and selected 80 propensity score-matched patients for comparison, 40 in each group. The therapeutic process and clinical outcomes were retrospectively analyzed.<b>Results:</b> All patient baseline and transplant characteristics were similar between the gilteritinib and the control group. Gilteritinib therapy conferred significant survival advantages (<i>P</i> = 0.013 for OS and <i>P</i> = 0.026 for RFS). Relapse remained the main reason of treatment failure with 3-year incidence of 25.0% (95%CI 12.8-39.2%) and 55.0% (95%CI 38.1-69.0%) for the gilteritinib group and the control group(<i>P</i> = 0.010). In multivariate Cox regression analysis, gilteritinib maintenance was the only factor associated with improved OS (HR = 0.395, <i>P</i> = 0.040) and RFS (HR = 0.447, <i>P</i> = 0.030).<b>Conclusions:</b> Our results indicated that gilteritinib maintenance therapy reduced the risk of relapse for FLT3-ITD mutated R/R AML. Compared with patients without maintenance therapy, gilteritinib treatment showed a similar incidence of NRM and GVHD, leading to significant survival advantages in this high-risk cohort of patients.