Prognostic factors in haploidentical transplantation with post-transplant cyclophosphamide for acute myeloid leukemia

Background aims: Haploidentical hematopoietic stem cell transplantation (haplo‐HCT) is an appropriate option when an HLA-matched related or unrelated donor is not available. Haplo-HCT using post-transplant cyclophosphamide (PTCy) is being increasingly performed worldwide due to its effective suppression of GVHD and its safety. Methods: We conducted a large nationwide cohort study to retrospectively analyze 366 patients with acute myeloid leukemia undergoing haplo‐HCT with PTCy between 2010 and 2019 and to identify prognostic factors. Results: A multivariate Cox analysis revealed that an older recipient age (≥60 years), a male donor to a male recipient, a cytomegalovirus IgG-negative donor to a cytomegalovirus IgG-positive recipient, a poor cytogenetic risk, a noncomplete remission status at the time of transplantation, and a history of HCT were independently associated with worse overall survival (OS). Based on each hazard ratio, these factors were scored (1–2 points) and stratified by their total score into three groups: favorable (0–1 points), intermediate (2–3 points), and poor (4 points or more) groups, and 2-year OS rates were 79.9%, 49.2%, and 25.1%, respectively (P < 0.001). Conclusions: The present study revealed significant prognostic factors in haplo‐HCT with PTCy, and a scoring system based on these factors may be used to predict outcomes.