The application value of dynamically observing the chimerism rate in whole blood in the treatment of myelodysplastic syndrome (MDS) with haploidentical hematopoietic stem cell transplantation (haplo-HSCT).

A retrospective case analysis was conducted on 43 patients who received haplo-HSCT treatment in the Hematology Department of North China University of Science and Technology Affiliated Hospital from January 2012 to January 2024. These patients were divided into a complete chimerism group of 33 patients (14 in the high-risk group and 19 in the low-risk group) and a mixed chimerism group of 10 patients (4 in the high-risk group and 6 in the low-risk group). The differences in overall survival (OS) rate, event-free survival (EFS) rate, cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) rate were compared between the groups.

Follow-up was conducted until December 2024, with a median follow-up time of 34 (6-78) months after haplo-HSCT. The OS rate and EFS rate in the complete chimerism group [69.7% (95%CI: 52.2%-82.8%) and 57.6% (95%CI: 40.9%-72.6%), respectively] were higher than those in the mixed chimerism group [40.0% (95%CI: 16.8%-61.7%) and 30.0% (95%CI: 10.8%-50.3%), respectively], with statistically significant differences (χ²=4.258, 4.058, both P<0.05).There were no statistically significant differences in CIR and NRM rates between the two groups (both P>0.05). The OS and EFS rates in the high-risk complete chimerism group [64.3% (95%CI: 38.8%-83.7%) and 50.0% (95%CI: 26.8%-73.2%)] were higher than those in the high-risk mixed chimerism group [0 (95%CI: 0-49%) and 0 (95%CI: 0-38.7%)], with statistically significant differences (χ²=6.187, 6.187, both P<0.05). However, there were no significant differences in OS rate, EFS rate, CIR, and NRM rate between the low-risk complete chimerism group and the mixed chimerism group (both P>0.05). Multivariate Cox analysis revealed that post-transplantation relapse (HR=5.85, 95%CI: 1.98-17.20), high-risk MDS (HR=4.71, 95%CI: 1.45-15.30), and mixed chimerism status (HR=3.32, 95%CI: 1.12-11.15) were independent risk factors affecting overall survival in MDS patients.

The dynamic detection of chimerism rate, combined with risk stratification, aids in the early identification of high-risk relapsed populations, and provides certain guidance for stratified individualized treatment in MDS patients after haplo-HSCT.