Impact of FLT3 inhibitors on the outcomes of FLT3-ITD-positive acute myeloid leukemia following allogeneic hematopoietic stem cell transplant: A systematic review and meta-analysis.

Abstract

e18503 Background: Acute Myeloid Leukemia (AML) with FLT3-ITD mutations has poor prognosis and high relapse rates after allogeneic hematopoietic stem cell transplantation (allo-HCT). Post-transplant FLT3 inhibitor (FLT3i) maintenance therapy aims to prevent relapse and improve survival. However, randomized trials vary in FLT3i potency, its use during induction, maintenance duration, and measurable residual disease (MRD) assessment, which contribute to conflicting impacts on relapse-free survival (RFS) and overall survival (OS). This systematic review and meta-analysis assessed the efficacy and safety of FLT3i maintenance versus standard-of-care (SOC) in FLT3-ITD-positive AML post-allo-HCT. Methods: A systematic review was conducted following PRISMA guidelines, focusing on randomized controlled trials (RCTs) assessing FLT3i maintenance after allo-HCT. Comprehensive searches in PUBMED, EMBASE, CENTRAL, and ClinicalTrials.gov identified eligible studies. Statistical analyses were performed in R software (version 4.4.0) using the “meta” package. Results: Four RCTs involving 701 patients were included, with 351 patients in the intervention group and 350 in the control group. Patients’ ages ranged from 18 to 78 years, with 51.4% male and 48.6% female. Cytogenetic risk in the intervention group was 4.7% favorable, 74.4% intermediate, and 4.7% adverse; in the control group, these rates were 2.5%, 65.9%, and 4.7%, respectively. FLT3i maintenance significantly reduced pooled relapse risk (HR 0.50, 95% CI: 0.34–0.74) and pooled mortality (HR 0.63, 95% CI: 0.44–0.91) at a median follow up of 24 months from allo-HCT. Hematologic toxicity was higher in the FLT3i group (RR 2.12, 95% CI: 1.67–2.70), as was chronic GVHD (RR 1.18, 95% CI: 1.00–1.41). Acute GVHD (RR 1.05, 95% CI: 0.78–1.41) and hepatotoxicity (RR 1.09, 95% CI: 0.72–1.66) rates were similar, while skin toxicity was less frequent in the FLT3i group (RR 0.36, 95% CI: 0.16–0.84). Conclusions: Our analysis suggests that FLT3i maintenance post-allo-HCT improves RFS and OS in FLT3-ITD-mutated AML patients compared to SOC but is associated with increased hematologic toxicity and chronic GVHD. Future clinical trials should evaluate the benefit of FLT3i maintenance post alloHCT based on MRD status assessed by next generation sequencing (NGS) based assays. Outcomes reported by the included studies. Type of FLT3-i Relapse free survival at 24 months Overall Survival at 24 months HR (95% CI) P-value HR (95% CI) P-value Levis et al. Giltetrinib 0.679(0.459-1.005) 0.52 0.846(0.554-1.293) 0.44 Burchert et al. Sorafenib 0.39(0.18-0.85) 0.01 0.516(0.239-1.112) 0.85 Maziarz et al. Midostaurin 0.60(0.17-2.14) 0.42 0.58(0.19-1.79) 0.34 Xuan et al. Sorafenib 0.37(0.22-0.63) <0.0001 0.48(0.27-0.86) 0.01 Pooled Hazard Ratio (95% CI) 0.50 (0.34-0.74) 0.63 (0.44-0.91)