Haploidentical hematopoietic stem cell transplantation for patients with myeloid sarcoma: a single center retrospective study

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been regarded as a potential strategy for myeloid sarcoma (MS). The previous reports focused mainly on matched sibling donor (MSD) or matched unrelated donor (MUD) transplantation. There are no reports on haploidentical HSCT (haplo-HSCT) in MS. We retrospectively reviewed 14 MS patients who underwent haplo-HSCT. All patients achieved complete donor engraftment. The median time for neutrophil engraftment and platelet engraftment were 10 (12-21) days and 18 (8-31) days. The 100-day cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) and 3-year cumulative incidence of chronic GVHD were 37.7% (95%CI, 23.2-52.1%) and 35.7% (95%CI, 22.2-49.2%). Cytomegalovirus (CMV) reactivation was documented in 86% patients, and only one patient developed CMV pneumonia. Treatment-related mortality occurred in one (7%) patient. The 1- and 3-year cumulative incidence of relapse was 21.4% (95%CI, 11.8-31.1%) and 35.7% (95%CI, 22.4-49.0%). The probability of overall survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 64.3% (95%CI, 43.5-95.0%), respectively. The probability of disease-free survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 57.1% (95%CI, 36.3-89.9%), respectively. In conclusion, haplo-HSCT is a feasible method for patients with MS who have no MSD or MUD.