Outcomes for patients with IDH-mutated acute myeloid leukemia undergoing allogeneic hematopoietic cell transplantation: Post-transplant outcomes of IDH-mutated acute myeloid leukemia

Abstract Background : Disease relapse after hematopoietic cell transplantation (HCT) is a major cause of treatment failure for patients with acute myeloid leukemia (AML). Maintenance therapy following HCT for patients with targetable mutations such as mutated IDH1 or IDH2 may improve outcomes, and clinical trials evaluating this strategy are ongoing. However, clinical outcomes of IDH1- and IDH2-mutated AML patients following HCT have not been well-described. Objective : The primary objective of this study was to describe the clinical characteristics and post-HCT outcomes of IDH-mutated AML patients. Survival outcomes included progression-free survival (PFS), overall survival (OS), and cumulative incidences of relapse and non-relapse mortality (NRM). Study Design : In this multicenter retrospective analysis, 112 adult patients with IDH1- or IDH2-mutated AML who underwent HCT and did not receive an IDH inhibitor as maintenance therapy post-HCT were identified at Massachusetts General Hospital, Dana Farber Cancer Institute, and Ohio State University. Mutation testing was performed using next-generation sequencing panels. Patient characteristics were collected retrospectively and their survival outcomes were analyzed. Univariate and multivariate analyses were performed. Results : The median patient age was 64.1 years. The median follow-up was 27.5 months. 78.5% of patients had intermediate- or adverse-risk disease by European LeukemiaNET criteria. 58% of patients received intensive induction chemotherapy, 82% of patients underwent HCT during first complete remission (CR) or CR with incomplete hematologic recovery (CRi), and 34% of patients received myeloablative conditioning (MAC). Frequently detected co-mutations were DNMT3A (35.7%), NPM1 (33.1%), and FLT3-ITD (13.4%); TP53 mutations were detected in 3.6% of patients. For IDH1-mutated patients transplanted during first CR/CRi, the 1- and 2-year PFS was 75% and 58%, respectively. For IDH2-mutated patients transplanted in first CR/CRi, the 1- and 2-year PFS was 64% and 58%, respectively. The 2-year cumulative incidence of relapse was 31% and 25% for IDH1- and IDH2-mutated cohorts, respectively. Multivariable analysis suggested first CR/CRi and age ≤60 was associated with improved outcomes for IDH2-mutated patients. Conclusions : To date, this is the largest multicenter study of outcomes of IDH-mutated AML patients following HCT. Our analysis provides important benchmarks for analysis and interpretation of results emerging from clinical trials evaluating maintenance IDH1 and IDH2 inhibitor therapy for AML patients after HCT.