Posttransplant cyclophosphamide‐based anti–graft‐vs‐host disease prophylaxis in patients with acute lymphoblastic leukemia treated in complete remission with allogeneic hematopoietic cell transplantation from human leukocyte antigen‐mismatched unrelated donors versus haploidentical donors: A study on behalf of the ALWP of the EBMT | Publicación