P738: allogeneic hematopoietic stem cell transplantation in therapy-related myelodysplastic syndrome: a retrospective cohort matched study

Topic: 10. Myelodysplastic syndromes - Clinical Background: Therapy-related myelodysplastic syndrome (t-MDS) has poor prognosis and requires allogeneic hematopoietic stem cell transplantation (HSCT) Aims: In this study, we evaluated key HSCT outcomes in t-MDS patients compared to de novo MDS (d-MDS) Methods: We conducted a retrospective matched cohort study with 111 MDS patients who underwent HSCT. We excluded patients with any missing data. Fourteen t-MDS patients were matched to d-MDS patients in different allocation ratios with the nearest-neighbor propensity score matching, caliper 0.2. The matching factors included sex, age at the time of HSCT, IPSS-R, ECOG, armand risk, and the donor type. We hypothesized that t-MDS and d-MDS patients may have similar 5-year overall survival (OS) when treated with HSCT. To compare OS and acute myeloid leukemia (AML) transformation rate, we used log-rank test. Additionally, we performed competing-risk regression on cumulative incidences of relapse (CIR). Frequencies of neutrophil engraftment, platelet recovery, and incidences of graft-versus-host disease (GVHD) were compared with chi-square test. Also, we compared median times to neutrophil engraftment and platelet recovery with wilcoxon test. Matching was performed in RStudio (v2022.07.2). Further analysis was conducted with Stata/BE (v17.0), level of significance 0.05. Results: In total, 14 t-MDS and 42 d-MDS were matched in a 1:3 allocation ratio. Patients shared similar baseline characteristics between groups. The median follow-up was 37 months (4-134 months). There was no difference in 5-year OS between the two groups with 35% survival rate in t-MDS and 57% rate d-MDS (p=0.24). Event-free survival for AML transformation was 71% and 76% for t-MDS and d-MDS, respectively (p=0.55). The 5-year CIR rate was 21% and 19% in t-MDS and d-MDS groups, respectively (HR=1,79, 95% CI 0,68 to 4,69). The frequencies of engraftment for neutrophil were 86% and 88%, for platelets were 79% and 81% for t-MDS and d-MDS, respectively (p>0.05 for both). Also, the median time to neutrophil engraftment and platelet recovery was similar between the two groups: 20 and 21 days for neutrophil, 15 and 16 days for platelets for t-MDS and d-MDS, respectively (p>0.05 for both).The incidence of acute GVHD was 36% (n=5) and 38% (n=16) in t-MDS and d-MDS groups, respectively (p = 0.87). The incidence of chronic GVHD was 36% (n=5) for the former and 36% (n=15) for the letter. Summary/Conclusion: Among MDS patients treated with HSCT we observed no difference in 5-year OS between therapy-related and de novo disease when appropriately matched by propensity score. Thus, HSCT can provide patients with t-MDS with a prognosis comparable to d-MDS group. However, further studies with larger sample size are required.Keywords: Myelodysplastic syndrome, Allogeneic hematopoietic stem cell transplant, MDS