BACKGROUND: Double-cord-blood transplantation (DCBT) offers an option for patients receiving reduced-intensity transplants. These unique transplants have two donors, both of whom are usually HLA mismatched at one to two loci.

STUDY DESIGN AND METHODS: Fifty-three patients were recipients of a reduced-intensity DCBT. Cords were at least 4/6 allele-level HLA-A, -B, and -DR match with the patient and each other with a minimum combined cell dose of more than 3.7 × 107 total nucleated cells per kg. Twenty-one patients received cyclosporine/mycophenolate mofetil and 32 patients received sirolimus/tacrolimus (SIR/TAC) for graft-versus-host disease prophylaxis. The effect of allele level HLA typing on clinical endpoints of overall survival (OS), disease-free survival (DFS), engraftment, and acute graft-versus-host disease (aGVHD) were assessed.

RESULTS: Neutrophil (p = 0.001) engraftment and platelet engraftment (p = 0.027) were significantly faster in patients who have closer Class I (HLA-A, -B, -C) matching. Neutrophil engraftment was faster in patients who had closer HLA-B matching to their combined cords (p = 0.007). There was a low incidence of aGVHD overall, especially in the SIR/TAC group. Class I HLA matching had no effect on aGVHD. HLA-DR and -DQ had no effect on engraftment or aGVHD.

CONCLUSION: Class I allele matching, and HLA-B matching specifically, were associated with faster neutrophil engraftment. High-resolution HLA matching did not affect OS or DFS.