When would you consider an umbilical cord blood transplant over a haploidentical transplant with post-transplant cyclophosphamide, or using a desensitization protocol for high donor-specific antibodies?  

High DSA are a real problem. We generally use an MFI of 1000 as a threshold - below that there is less concern. Confusingly, even with high DSA, the rejection rate is not 100% so it is often tough to make a decision. UCB transplantation is somewhat inferior to haplotransplant in terms of overall out...