T-cell-depleted haploidentical stem cell transplantation results improve with time in adults with acute leukemia: A study from the Acute Leukemia Working Party of the European Society of Blood and Marrow Transplantation (EBMT).

BACKGROUND: T-cell-depleted, haploidentical transplantations (haplos) are commonly offered to patients who have high-risk, acute leukemia in the absence of a human leukocyte antigen (HLA) full-matched donor.

METHODS: To determine the effect of transplantation period, the authors divided 308 adults with de novo, acute leukemia who underwent T-cell-depleted haplo from 2005 to 2015 into 2 groups, according the year in which they underwent transplantation (2005-2011 [n = 191] and 2012-2015 [n = 117]).

RESULTS: The median age was 41 years in patients who underwent transplantation before 2012 and 46 years in those who underwent transplantation after 2012 (P = .04). Most patients had acute myeloid leukemia (75% vs 69%; P = .26) and were in first complete remission (CR1) (55% vs 64%; P = .12) at the time of transplantation. The cumulative incidence of grade 2, 3, and 4 acute graft-versus-host disease (GvHD) and chronic GvHD were not different between the 2 groups (acute GvHD: 20% vs 22% cumulative incidence in patients who underwent haplo before and after 2012, respectively [P = .67]; chronic GvHD: 19% vs 11% cumulative incidence, respectively; P = .12]. The 2-year relapse incidence was 20%, the nonrelapse mortality (NRM) rate was 48%, and no difference was observed over time (21% vs 19% [P = .72] and 54% vs 38% [P = .11] for patients who underwent haplo before and after 2012, respectively). The main cause of NRM was infection. Haplo after 2012 (hazard ratio [HR], 0.57; P = .01), younger age (HR, 0.82; P = .02), and receipt of a reduced-intensity conditioning (RIC) regimen (HR, 0.53; P = .01) were independently associated with lower NRM. The 2-year overall survival rate was 36% and improved after 2012 (29% vs 47% before 2012; P = .02); and it was higher for patients who underwent transplantation in CR1 (41% vs 29%; P = .01). In multivariate analysis, haplo after 2012 (HR, 0.54; P = .003) and receipt of a RIC regimen (HR, 0.54; P = .005) were independently associated with better overall survival. Similarly, leukemia-free survival and GvHD-free/relapse-free survival (GRFS) improved over time: the leukemia-free survival rate was 31% (25% vs 43% in the groups who underwent transplantation before and after 2012, respectively; P = .05), and the GRFS rate was 24% (19% vs 34%, respectively; P = .09). In addition, leukemia-free survival and GRFS improved among patients who received a RIC regimen.

CONCLUSIONS: The outcome of patients with acute leukemia who underwent T-cell-depleted haplo has improved over time. Cancer 2018;124:2142-50. © 2018 American Cancer Society.