Unrelated Cord Blood Transplantation (UCBT) in Adults with MDS or Secondary Acute Myeloblastic Leukemia (sAML): a Survey On Behalf of Eurocord and CLWP of EBMT.

Unrelated cord blood transplantation is an alternative option to treat patients with high risk hematologic malignancies in the absence of an HLA identical donor. Results of UCBT in patients with MDS or secondary leukaemia (sAML) have been scarcely published.

We performed a survey to identify predictors of outcomes in a large cohort of 108 adults with MDS or sAML reported to Eurocord-Promise data bases (62 centres in 17 countries in Europe) and transplanted with an UCBT from 1998 to 2007. Sixty-seven patients were transplanted for sAML (secondary to MDS in 42 cases) and 41 for MDS. Worst status before UCBT for MDS was RA in 4, RAEB1 in 10, RAEB2 in 14, CMML or RAEBt in 9, unclassified in 4 patients. IPSS classification at transplantation was low, intermediate 1, intermediate 2, high or missing in 8, 12, 7, 6 and 8 patients, respectively. For patients with sAML, 48% were transplanted in CR1 at UCBT. Median age at UCBT was 43 years (from 18 to 72 years). Median time from diagnosis to UCBT was 10 months.

77 patients received a single and 31 a double UCBT. UCB grafts had ≥ 2/6 HLA mismatched in 60 % of cases. Myeloablative conditioning regimen (MAC) was given to 57 patients whereas 51 patients received a reduced intensity conditioning regimen (RIC). GVHD prophylaxis consisted in CSA+MMF in 52, CSA+steroids in 43 and other combinations in 13 patients. Median number of collected nucleated cells was 3.4 for single and 4.6 × 10⁷/kg for double UCBT. Median follow-up was 25 months.

cumulative incidence (CI) of neutrophil recovery at day 60 was 82±4% with a median time to achieve more than 500 ANC/mm3 of 23 days. Neutrophil recovery was independently associated with number of CD34+ cells/kg (> 1.1 × 10⁵, Hazard Ratio (HR), 1.79; P= .02) and advanced disease status (intermediate 2 or high MDS and sAML not in CR; HR, 1.92; P= .007). CI of grade II-IV acute GVHD at day 100 and chronic GVHD at 2 years were 26±4% (II n=18, III n=6, IV n =6) and 42%±8, respectively. Two-year non-relapse mortality was significantly higher after MAC (62% vs. 34%, p=0.009). In counterpart, 2-year relapse rate was higher after RIC (14% vs 29%, p=0.02). Two-year DFS and OS were 30 and 34%, respectively. In univariate analysis, among patient-, disease- and transplant- factors studied only patients with high risk disease at maximal pre-transplant stage or transplanted > 18 months after diagnosis had significant poorer DFS (disease risk: 49% vs. 22%; time: 35% vs. 15%). However, in multivariate analysis, the only factor associated with decreased DFS was advanced disease (HR: 2.05; p= .01).

These data indicate that UCBT is an acceptable alternative option to treat adults with high risk MDS or sAML without a HLA-matched related or unrelated bone marrow donor. Controlled disease at time of transplantation improves outcome. More investigations are needed to compare these results with outcomes after other stem cell sources from unrelated HSCT donor.

No relevant conflicts of interest to declare.