Comparison of Therapeutic Effects between Young Haploidentical Donors and Elderly HLA-Matched Relative Donors for AML Patients Who Undergoing Allogeneic Hematopoietic Stem Cell Transplantation with Conditioning Regime Including ATG

Objective: Donor selection is one of the issues faced in allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aims to compare the impact of young haploidentical donors and elderly matched relative donors on the outcomes of AML patients undergoing allo-HSCT with conditioning regime including ATG, providing reference for donor selection.

Methods: A retrospective analysis was conducted on 708 AML patients who underwent allo-HSCT at our hospital from 2014 to 2021. Among them, 354 patients were included in this study, with 289 patients receiving haploidentical transplantation from donors under the age of 50 (haplo group) and 65 patients receiving fully matched sibling transplantation from donors over the age of 50 (MSD group). Clinical characteristics and transplantation outcomes of both groups of patients and donors were compared.

Results: Among the 354 AML-MRC patients, there were 178 males and 176 females, with a median age of 41 (18~56) years. The median follow-up time was 35 (95% CI 30~49) months, and the median overall survival (OS) was 78 (95% CI 23~) months. The 3-year OS rate was 63.1% (95% CI 45.6%~81.4%), the 3-year event-free survival (EFS) rate was 59.0% (95% CI 40.8%~66.1%), the cumulative incidence of relapse (CIR) was 26.8% (95% CI 16.6%~30.0%), and the transplantation-related mortality (TRM) was 22.7% (95% CI 13.2%~33.8%). There were no statistically significant baseline differences between the haplo group and MSD group. The 3-year OS rates for haplo group vs. MSD group were 0.660 (95% CI 0.597-0.731) vs. 0.670 (95% CI 0.558-0.806) (p=0.7), the 3-year EFS rates were 0.620 (95% CI 0.543-0.720) vs. 0.570 (95% CI 0.458-0.656) (p=0.6), and the TRM rates were 0.165 (95% CI 0.121-0.282) vs. 0.134 (95% CI 0.062-0.234) (p=0.6). The CIR rates were 0.199 (95% CI 0.147-0.250) vs. 0.275 (95% CI 0.165-0.397) (p=0.196), and the cumulative incidence of grade II-IV aGVHD was 0.288 (0.237-0.342) vs. 0.309 (95% 0.200-0.424) (P=0.891). The incidence of cGVHD was 0.140 (0.099-0.188) vs. 0.250 (95% 0.147-0.367) (p=0.032).

Conclusion: For AML patients undergoing allo-HSCT with conditioning regime including ATG, compared to elderly fully matched donors, young haploidentical donors may reduce the occurrence of post-transplant cGHVD.