Abstract
Aim Studies have indicated improved clinical outcomes for CBT recipients with NIMA+ at HLA-A, B antigens, or -DRB1 alleles (standard matching for CBT). The frequencies of the HLA types for NIMA+ are associated with more common HLA and haplotypes. Therefore, NIMA+ may lead to better HR matching at HLA-A, B, and C. We have previously shown that HR matching at HLA- A, B, C, and DRB1 (X/8) decreased TRM in single CBT for acute leukemia. We evaluated CBT HR match association with NIMA +/- cases. Methods The cohort consisted of 705 CBTs from NMDP or Eurocord performed between 2000 and 2010. HR was available or imputed retrospectively using the NMDP’s HLA imputation algorithm, based on population haplotype frequencies, to infer the most likely phased genotype. 70% of recipients (HLA- A, B, C, DRB1 imputed alleles: N = 1052, 1024, 1170, 34, respectively) and 95% of CB units (HLA- A, B, C, DRB1 imputed alleles: N = 921, 908, 925, 20, respectively) had at least one allele imputed. HR match grades were determined at X/8. The distribution of NIMA+/- and HR match grades were then evaluated in the following groups based on the probability of TRM observed previously at 6-7/8, 4-5/8, and ⩽ 3/8. Results In the 5/6 cohort (N = 344) there were 17 NIMA+ (5%) and 327 NIMA- (95%). In the 4/6 (N = 361) cohort there were 39 NIMA + (11%) and 322 NIMA- (89%). The overall HR match counts were as follows: 322, 359, and 24 for 6-7/8, 4-5/8, and ⩽ 3/8, respectively. The table below shows the X/8 HR match grades stratified by NIMA+/-. The overall frequency of the 5/6 and 4/6 CBT cases having better HR match grades with NIMA+ vs. NIMA- was 100% vs. 79% (p = 0.04) and 10% vs. 13% (p = 0.86), respectively. Conclusion There was significant skewing in the 5/6 NIMA+ group to better HR matching. There was no significant difference in the 4/6 subset between the NIMA+/- groups. In this small population NIMA+ 5/6 had a better HR level matching. It remains to be seen whether the skewed HR matching is a driver of the previously observed NIMA effect.
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