Plasma ctDNA Monitoring in Pediatric Acute Leukemia

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.

Inclusion criteria

• Patients diagnosed with pediatric acute leukemia, including acute lymphoblastic leukemia, acute myeloid leukemia, or mixed phenotype acute leukemia.
• Age younger than 18 years at diagnosis.
• Availability of peripheral blood plasma cfDNA/ctDNA testing data.
• Availability of clinical data and at least one corresponding bone marrow-based assessment, including MFC-MRD, ddPCR, RNA sequencing.
• For prospectively collected follow-up data or samples, written informed consent will be obtained from parents or legal guardians.
• For retrospectively collected data, consent procedures will follow the approval of the institutional ethics committee.

Exclusion criteria

• Patients without available peripheral blood plasma cfDNA/ctDNA data.
• Patients with insufficient clinical or laboratory data for analysis.
• Samples failing cfDNA/ctDNA quality control.
• Withdrawal of consent for prospective follow-up or additional sample collection.
• Patients judged by the investigator to be unsuitable for inclusion.