- Availability of a human leukocyte antigen (HLA) matched (6/6) sibling donor or 8/8 matched unrelated donor; Donors with mismatch at HLA-A, HLA-B, HLA-C, and HLA-DR will be reviewed by matched unrelated donor (MUD) committee and allowed if their mismatch with the recipient does not require additional GVHD prophylaxis (other than tacrolimus and sirolimus), donors with mismatch at HLA-DQ or HLA-DPB are eligible; donor evaluation according to City of Hope (COH) standard operating procedure (SOP)