Post-Transplant Relapse in Acute Leukemia: Comparative Value of MRD and Chimerism

Area of Science:

• Hematology
• Oncology
• Transplantation Medicine

Background:

• Relapse is a primary cause of treatment failure following allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia.
• Current post-transplant surveillance relies on measurable residual disease (MRD) and donor chimerism, but their predictive value and optimal timing are unclear.

Purpose of the Study:

• To compare the prognostic performance of MRD and donor chimerism in predicting relapse after AHSCT in adult patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL).

Main Methods:

• Retrospective cohort study of 264 adult patients (186 AML, 78 ALL) undergoing AHSCT.
• MRD assessed by multiparametric flow cytometry at day 28, and months 3 and 12.
• Chimerism assessed by short tandem repeat PCR.
• Cox regression analysis to identify independent relapse predictors.

Main Results:

• In AML, MRD positivity at month 3 (HR 3.69) and mixed total chimerism at month 3 (HR 2.47) independently predicted relapse and were associated with inferior survival.
• MRD detected relapse earlier and more sensitively than chimerism in AML.
• In ALL, mixed chimerism at month 3 predicted relapse in univariate analysis; MRD had limited power due to small sample size.

Conclusions:

• Post-transplant MRD monitoring at month 3 offers superior risk stratification for relapse in AML compared to chimerism.
• In ALL, MRD and chimerism may be complementary, but further research with larger cohorts is needed.
• Disease-specific, risk-adapted surveillance strategies post-AHSCT are warranted.