Risk Factors Analyses for Outcomes after Unrelated Cord Blood Transplantation for Children with Myelodysplastic Syndromes. An Analysis on Behalf of EWOG-MDS and Eurocord Groups.

Myelodysplastic syndromes (MDS) are very rare diseases in children and hematopoietic stem cell transplantation remains the only curative treatment. This is a retrospective registry-based study of 42 children with MDS (refractory cytopenia n=21, refractory anemia with excess of blasts n=15, and refractory anemia with excess of blasts in transformation n=6), who underwent unrelated cord blood transplantation (UCBT). Both databases from Eurocord and EWOG-MDS group were used. Diagnosis of MDS was established by each reporting center based on the WHO classification modified for pediatric patients. Median age was 7.4 years, median cell dose infused was 4.2 × 10⁷/Kg and median follow-up was 39 months. All patients received one cord blood unit, with 0 or 1 HLA disparity in 22, and 2 or more in 20. Twenty-five children received a Busulfan-based conditioning regimen. The association of Cyclosporine A and prednisone was used in 69% of patients. The 60-day cumulative incidence (CI) of engraftment was 69±7%, in a median time of 25 days. In multivariable analysis, ABO match (Hazard Ratio=2.94, 95% Confidence Interval=1.23–6.66, p=0.01) and refractory cytopenia (HR=2.38, 95% Confidence interval=1.01–5.55, p=0.05) were favorable factors associated with neutrophil recovery. Thirteen patients developed acute GVHD grades II–IV. Moreover, 16 children had skin, 5 liver, 6 gastrointestinal involvements (stages 2–4). The 100-day CI of aGVHD was 29±7%. Of 20 evaluable patients, 10 developed chronic GVHD and the 1-year CI of cGVHD was 24±7%. The 2-y CI for treatment-related mortality was 56±8%. In univariable analysis, recipient’s weight was the only statistical significant factor associated with TRM (47% for children weighting less than < 38Kg versus 80% for remainders, p=0.05). In addition, there was a trend of higher TRM for patients who received CBU with 2 or more HLA disparities (p=0.09). The 2-y overall survival and disease-free survival were 37±8% and 32±8% respectively. In multivariable analysis, OS improved when recipient’s weight at UCBT was lower than 38kg (HR= 2.53, 95% confidence interval=1.16–5.55; p=0.02). In conclusion, since hematopoietic stem cell transplantation is the only treatment with curative potential, UCBT is a reasonable option for children without an identical sibling donor. Moreover, outcomes might be improved with better donor and patient’s selection.