122-P

Abstract

Aim Current practice for identifying a suitable 4/6 matched CBU is antigen level matching at HLA-A and B and allele level matching at HLA-DRB1, while matching at HLA-C is not typically considered. Recent studies have suggested that matching at HLA-C may improve transplant related mortality (Eapen et al., 2011). Determining the availability of a suitably matched (x/8) CBU is important for potentially improving transplant related outcomes for patients. Methods We examined a cohort of single CBU transplants from December to February 2012 to determine if a better matched (antigen level at HLA-A, B, C and allele level at HLA-DRB1, x/8) unit was available in the Be The Match Registry®. The better matched unit had to retain the traditional 4/6 or better match category (MC) and a minimum cell dose of 2.5 × 107 TNC/kg or no lower than the selected unit TNC. CBU without HLA-C typing were considered matched if algorithm predictions were ⩾50%. Results 119 single CBU transplant cases were assessed. 79 (66%) of these cases selected the best matched unit. 40 (34%) had a better matched x/8 unit available, where 36 (90%) improved one MC (x/8) and four cases (10%) improved two MCs. The cell dose of the better matched unit was lower in 57.5% of cases, with the median change in cell dose of −9.3%. Conclusions The benefit of HLA-C matching for CBU transplant has not been fully elucidated. This analysis highlights that although current practice may not always consider HLA-C matching, often a similar or better matched unit is available including HLA-C. This study cannot account for the myriad of factors considered in CBU selection such as cell dose, mismatching at a particular locus (e.g. HLA-DRB1), previous confirmatory typing, patient antibodies, CBU protocols or physician preference. These data indicate that when solely considering HLA matching in CBU selection, units that also matched at the C locus while maintaining similar unit cell dose were available.