Comparison of outcomes for patients with acute myeloid leukemia undergoing haploidentical stem cell transplantation in first and second complete remission

There was no consensus on whether prognostic advantages existed when transplant conducted at first complete remission (CR1) stage than at second complete remission (CR2) stage for patients with AML who received haploidentical hematological stem cell transplantation (haplo-HSCT). In 768 consecutive AML patients who received haplo-HSCT from January 2014 to December 2017, a 1:2 ratio matched-pair analysis was performed, 69 patients who in CR2 group and 138 CR1 patients were enrolled. Hematopoietic recovery, graft versus host disease (GVHD), relapse, transplant related mortality (TRM), disease-free survival (DFS) and overall survival (OS) were compared in two groups, and further evaluated in low-, intermediate-, and high-risk subgroups. The cumulative incidences of 30-day myeloid recovery and 90-day platelet recovery were comparable in CR1 and CR2 groups. The cumulative incidences of grade II-IV and grade III-IV aGVHD were not significantly different. The cumulative incidences of relapse at 3-year and 5-year in these two groups were 12.4% versus 11.6% (P = 0.880) and 12.4% versus 17.5% (P = 0.322). The cumulative incidences of TRM at 3-year and 5-year were both 10.9% versus 23.2% (P = 0.019). The probability of DFS at 3-year and 5-year were 76.7% versus 65.2% (P = 0.029) and 76.7% versus 59.3% (P = 0.009). The probability of OS at 3-year and 5-year were 81.8% versus 68.1% (P = 0.026) and 76.7% versus 59.3% (P = 0.026). In the intermediate-risk group, TRM was lower in CR1 group, DFS and OS of CR1 group were superior to CR2 group. In conclusion, haplo-HSCT at CR1 stage was of better prognosis for intermediate-risk AML patients than at CR2 stage.