Comparative Analysis of T‐Cell and Bone Marrow Chimerism for Relapse Prediction in Acute Leukaemia Post‐Transplantation

Allogeneic haematopoietic stem cell transplantation is a critical treatment for acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL), yet the risk of treatment failure still persists. Chimerism analysis serves as a potential tool for predicting disease recurrence and survival rates, but its specific role has not yet been clearly defined. This study aimed to explore the role of decreased T-cell and bone marrow (BM) chimerism in predicting post-transplant relapse and survival in patients with acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). The study subjects were 305 AML and ALL patients who underwent allogeneic haematopoietic stem cell transplantation at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, from January 1, 2018, to September 1, 2023. We monitored the chimerism rate at monthly intervals after transplantation until either patient relapse or the end of follow-up. T-cell and BM chimerism were tested at the same time points. Relapse probabilities were estimated by the Kaplan-Meier method and compared with the log-rank test. Gehan-Breslow-Wilcoxon test was used to assess the impact of T-cell and BM chimerism levels on survival probabilities. In AML patients, our analysis revealed no significant correlation between the presence of initial mixed chimerism (at Day +30 post-transplantation) and the relapse rate. Among patients with ALL, the number with initial mixed chimerism was insufficient for statistical analysis. In AML patients whose bone marrow chimerism rate decreased first (n = 13) had a higher relapse rate and a lower survival rate than those whose T-cell chimerism rate decreased first (n = 11) (p < 0.01). In patients with ALL, there was no significant difference in the relapse or survival rates between patients whose bone marrow chimerism rate decreased first (n = 12) and those whose T-cell chimerism rate decreased first (n = 15) (p > 0.05). While a decrease in bone marrow chimerism effectively predicts AML relapse, T-cell chimerism demonstrates lower predictive efficacy. Further research is necessary to identify reliable predictors for relapse in ALL patients. The integration of chimerism analysis with other prognostic indicators, along with early monitoring and preemptive intervention, may enhance patient survival and quality of life.