Measurable residual disease monitoring in AML with FLT3-ITD treated with intensive chemotherapy plus midostaurin

Measurable residual disease (MRD) monitoring in acute myeloid leukemia (AML) with an FLT3 internal tandem duplication (FLT3-ITD^pos) has been hampered by the broad heterogeneity of ITD mutations. Using our recently developed FLT3-ITD paired-end next-generation sequencing (NGS)–based MRD assay (limit of detection 10⁻⁴ to 10⁻⁵), we evaluated the prognostic impact of MRD at different time points in 157 patients with FLT3-ITD^pos AML who were enrolled in the German-Austrian Acute Myeloid Leukemia Study Group 16-10 trial and who were treated with a combination of intensive chemotherapy and midostaurin, followed by midostaurin maintenance. MRD negativity (MRD^neg) after 2 cycles of chemotherapy (Cy2), which was observed in 111 of 142 (78%) patients, was predictive of superior 4-year rates of cumulative incidence of relapse (CIR) (4y-CIR; 26% vs 46%; P = .001) and overall survival (OS) (4y-OS; 70% vs 44%; P = .012). This survival advantage was also seen among patients who underwent allogeneic hematopoietic-cell transplantation during first complete remission (4y-CIR, 14% vs 39%; P = .001; 4y-OS, 71% vs 49%; P = .029). Multivariate models for CIR and OS after Cy2 revealed FLT3-ITD MRD^neg as the only consistent favorable variable for CIR (hazard ratio [HR], 0.29; P = .006) and OS (HR, 0.39; P = .018). During follow-up, conversion from MRD^neg to MRD positivity (MRD^pos) was a strong, independent factor for inferior CIR (HR, 16.64; P < .001) and OS (HR, 4.05; P < .001). NGS-based FLT3-ITD MRD monitoring identifies patients at high risk for relapse and death following treatment with intensive chemotherapy and midostaurin. Using NGS-based technology.