Survival after Hematopoietic Stem Cell Transplantation in an Older, Fit Cohort of Patients with Advanced Myelodysplastic Syndromes: The MDS-TAO Study

Background: The utility of reduced-intensity conditioning hematopoietic stem cell transplantation (RIC HSCT) for fit elderly patients with advanced myelodysplastic syndromes (MDS) is unclear.

Methods: The MDS Transplant-Associated Outcomes Study, or "MDS-TAO," was a prospective longitudinal observational study at the Dana-Farber/Harvard Cancer Center designed to examine survival, quality of life, and other outcomes for RIC HSCT versus non-HSCT approaches for HSCT-eligible patients with advanced MDS ages 60 to 75. All patients who met eligibility criteria were approached in the leukemia or HSCT clinics; 96% agreed to enroll. Inclusion criteria included histologically-confirmed diagnosis of MDS or CMML, and (1) therapy-related disease or (2) Int-2/high IPSS (Greenberg, Blood, 1997), or (3) non-IPSS poor-risk cytogenetics (Haase, Blood, 2007), or (4) severe cytopenia/platelet or red cell transfusion-dependence. Exclusions were (1) comorbidities that in the judgment of the treating physician precluded HSCT eligibility (2) prior donor search and (3) patient unwillingness to consider HSCT. Considering time to transplant as a time-dependent variable, hazard ratio for ultimate HSCT was estimated using Cox regression analysis controlling for age, gender, ECOG performance status, IPSS, IPSS cytogenetic risk group, and year of consent. Landmark analyses at 5 months were conducted to present estimates of overall survival for patients who were alive for at least 5 months and received HSCT versus patients who did not (landmark cohort). Subgroup analyses (e.g., molecular characteristics) are also ongoing.

Results: 290 patients were enrolled between May 2011 and May 2018; 24 had less than 1.5 months of follow up after consent and were excluded from this analysis. Of the remaining 266 patients, 143 were deceased at last follow up. Baseline characteristics are presented in the table. The median follow-up time among survivors was 31 months (range 1.9, 84). 102 patients received HSCT, of whom 45 subsequently died; of the 164 patients who have not undergone HSCT, 98 have died. The median time to HSCT among those transplanted (n=102) was 4.6 months. The median follow-up for patients alive and not yet transplanted (n=66) was 24 months (range 1.9, 82). Considering time to HSCT as a time-dependent variable (n=266), the hazard ratio for death in multivariable analysis was 0.63 (95% CI 0.42-0.96, p=0.03). Poor risk IPSS cytogenetic group was the only other factor associated with mortality, HR=1.86 (95% CI 1.15-3.00, p=0.006); age, gender, ECOG performance status, IPSS, and consent year were not. Five months was chosen for the landmark analysis given it was closest to the median time to HSCT. In the landmark cohort (N=229), HSCT patients were more likely to have Int-2/high IPSS at baseline (65% vs 35% for none, p=0.0003). No other baseline characteristics were different. Figure A shows Kaplan-Meier plots for the landmark cohort, comparing 54 who received HSCT ≤ 5 months versus 175 patients who did not receive a transplant within 5 months (log rank p=0.04). Figure B shows Kaplan-Meier plots for HSCT comparing 99 patients who received HSCT at any time during follow-up versus 130 patients who did not (log rank p=0.005).

Conclusion: In this large cohort of fit elderly patients with advanced MDS, a treatment strategy that included HSCT was associated with better overall survival.

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