224: Outcomes of Unrelated Umbilical Cord Blood Transplantation in Pediatric Patients with Myelodysplastic Syndrome

Myelodysplastic syndromes (MDS) in children are associated with significant morbidity and risk of leukemic transformation. Allogeneic hematopoietic stem cell transplantation is the only curative therapy. Many patients do not have a suitable donor. Between 1995 – 2006, 25 pediatric patients lacking matched living stem cell donors were transplanted with unrelated umbilical cord blood (UCB). M:F ratio of the study group was 1.8; Eight (32%) patients belonged to ethnic minorities; the median age was 9.77 years (range 1.11-19.73) and median weight was 32.8 kg (range 8.3-62.6). Five patients had therapy-related MDS (3 ALL, 1 NHL, 1 Neuroblastoma). MDS stage was RA/RC 10 pts, RAEB 7 pts, RAEB-T 3pts, and AML 5 pts. Monosomy 7 was present in 17 (68%) pts. Median time from diagnosis to transplant was 7.17 months (range 2-61). Preparative regimen was TBI based in 17 pts (68%). Cyclosporine was used for GVHD prophylaxis with Solu-medrol in 24 pts and CellCept in 1 pt. Grafts were matched at HLA Class I (A and B) at low resolution and HLA Class II (DRB1) at the allelic level. 6 pts were 5/6, 18 pts were 4/6, and 1 pt was 3/6 HLA matched. The grafts contained a median of 4.39 × 10e7 (range 1.68-29.16) nucleated cells/kg pre-cryopreservation and 3.58 × 10e7/kg (range 1.01-21.25) infused. The median CD 34+ cell dose infused was 1.5 × 10e5/kg (range 0.17-28.46). Cumulative incidence of neutrophil engraftment (ANC > 500/ μL) at day 100, platelet engraftment (>50K untransfused) at day 180, acute GVHD grades 2-4 at day 100, chronic GVHD, relapse and non relapse mortality at 1 yr were 72%, 56%, 20%, 32%, 8% and 36.5% respectively. 5 yr probabilities of OS and EFS were 46% and 41%. Thirteen patients died, 5 of infectious complications (1 toxoplasmosis, 1 aspergillosis, 2 EBV including 1 LPD, 1 adenovirus), 4 of relapse, 1 of graft failure, and 3 of multi system organ failure. EFS of pts < 10 yrs of age (p = 0.05) , weighing < 33kg (p = 0.03), and those with monosomy 7 (p = 0.05) was superior. These results, especially in younger patients with Monosomy 7 and early stage MDS are equivalent to matched allogeneic bone marrow transplant data. We conclude that unrelated UCB donors should be actively considered for pediatric patients with MDS who lack a living related or unrelated stem cell donor to enable transplantation when the disease is in early stage.Tabled 1Event Free Survival by CovariatesNEvents1 yr estimate %(95% CI)3 yr estimate (95% CI)p-valueKARYOTYPE0.05Monosomy 7 present17864.7 (42-87.4)58.8 (35.4-82.2)Monosomy 7 absent8637.5 (4-71)18.8 (0-49.7)RECIPIENT AGE0.05> 10 years11945.5 (16-74.9)27.3 (1.0-53.6)<= 10 years14564.3 (39.2-89.4)64.3 (39.2-89.4)RECIPIENT WT.0.03> 33 kg121041.7 (13.8-69.6)25 (0.5-49.5)<= 33 kg13469.2 (44.1-94.3)69.2 (44.1-94.3) Open table in a new tab