Plasma ctDNA Monitoring in Pediatric Acute Leukemia

Overview

This retrospective-prospective observational cohort study aims to evaluate peripheral blood plasma circulating tumor DNA (ctDNA) dynamics in pediatric acute leukemia and compare ctDNA results with concurrent bone marrow multiparameter flow cytometry minimal residual disease (MFC-MRD), droplet digital PCR (ddPCR), and RNA sequencing findings. The study includes a retrospective cohort with available clinical and molecular data and a prospective cohort with serially collected peripheral blood and bone marrow samples at predefined treatment time points. The study will assess consistence between plasma ctDNA and conventional bone marrow-based assays, characterize longitudinal ctDNA dynamics, and explore the association between ctDNA patterns and relapse or survival outcomes.

Minimal residual disease assessment is essential for treatment response evaluation and risk stratification in pediatric acute leukemia. Conventional MRD monitoring mainly relies on bone marrow-based assays, including multiparameter flow cytometry, molecular assays, and sequencing-based methods. However, repeated bone marrow sampling is invasive, and peripheral blood plasma ctDNA may provide a minimally invasive approach for dynamic disease monitoring. This study will include pediatric patients with acute leukemia who have available peripheral blood plasma ctDNA testing data and corresponding clinical or molecular information. Existing clinical records, laboratory results, leukemia-related genetic findings, bone marrow MFC-MRD results, ddPCR results, RNA sequencing results, treatment information, and follow-up outcomes will be retrospectively collected. After study registration, follow-up outcomes and additional serial molecular monitoring data will be prospectively collected when available. Peripheral blood plasma cfDNA/ctDNA results will be compared with matched or corresponding bone marrow-based assessments, including MFC-MRD, ddPCR, and RNA sequencing. The study will evaluate the concordance between plasma ctDNA and conventional bone marrow-based assays at different treatment time points, including diagnosis, pre-transplantation, post-transplantation, follow-up, and suspected relapse when available. The study will further assess ctDNA clearance, persistence, or re-emergence during treatment and follow-up. Exploratory analyses will evaluate whether ctDNA dynamics are associated with treatment response, relapse, event-free survival, relapse-free survival, and overall survival.