Donor type and HLA match

Survival rates after matched unrelated donor and umbilical cord blood transplant have improved significantly over the past decade and offer an outcome similar to that obtained with matched sibling donor transplants.[60,115-118]; [119,120][Level of evidence B4]; [121][Level of evidence C1]; [122][Level of evidence C2] Rates of clinically extensive GVHD and treatment-related mortality remain higher after unrelated donor transplant compared with matched sibling donor transplants.[61,78,115] However, there is some evidence that matched unrelated donor transplant may yield a lower relapse rate. National Marrow Donor Program and CIBMTR analyses have demonstrated that rates of GVHD, treatment-related mortality, and OS have improved over time.[123-125]; [126,127][Level of evidence C1]

Another CIBMTR study suggested that outcome after one- or two-antigen mismatched cord blood transplants may be equivalent to that for a matched family donor or a matched unrelated donor.[128] In certain cases in which no suitable donor is found or an immediate transplant is considered crucial, a haploidentical transplant using large doses of stem cells may be considered.[129,130] Improved approaches to haploidentical HSCT using alpha-beta T-cell receptor (TCR)/CD19 depletion or posttransplant cyclophosphamide have shown survival rates that are similar to those in studies using other stem cell sources.[131] A large multicenter trial from Italy showed similar outcomes using alpha-beta TCR/CD19–depleted haploidentical donors compared with matched unrelated donors, with lower rates of GVHD.[132] A second multicenter trial using alpha-beta TCR/CD19–depleted killer immunoglobulin-like receptor (KIR)–favorable haploidentical donors showed survival outcomes comparable to all other stem cell sources, with lower rates of GVHD and transplant-related mortality.[133]