FLT3-ITD Measurable Residual Disease Monitoring in Acute Myeloid Leukemia Using Next-Generation Sequencing

Abstract

The in-frame internal tandem duplication (ITD) of the FMS-like tyrosine kinase 3 (<i>FLT3</i>) gene is an important negative prognostic marker in acute myeloid leukemia (AML). <i>FLT3</i>-ITD monitoring is essential for patients at relapse or those receiving <i>FLT3</i>-targeted therapies. Fragment analysis (FA) is commonly used to detect and quantify <i>FLT3</i>-ITDs; however, detecting low-burden <i>FLT3</i>-ITDs after a treatment is challenging. We, therefore, developed a customized, next-generation sequencing (NGS)-based <i>FLT3</i>-ITD assay that includes a new ITD-tracing algorithm, "SEED", optimized for measurable residual disease (MRD) monitoring. NGS-SEED showed an enhanced sensitivity (0.001%) and has a superior performance over conventional fragment analysis. We further investigated the prognostic impact of MRD analyzed by NGS-SEED in AML patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT). Our assay showed that the MRD assessed before and after HSCT were significantly associated with a risk of relapse and a poor overall survival, respectively, in a time-dependent analysis. Thus, this report highlighted the prognostic value of serial MRD monitoring using a sensitive method in a clinical setting of AML patients with <i>FLT3</i>-ITD.