Allogeneic Stem-Cell Transplantation for Patients with AML in Second Complete Remission Transplanted from Unrelated Donors with Post-Transplant Cyclophosphamide

This study was conducted by the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation to assess outcomes in patients with acute myeloid leukemia (AML) in second complete remission (CR2) transplanted from unrelated donors and who received post-transplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis.

The study enrolled patients with AML, aged ≥18 years in CR2 who underwent unrelated donor allogeneic stem-cell transplant (allo-SCT) with PTCy between 2010 and 2019. A total of 127 patients were included in the study. Median age was 45.5 years; 54.3% were male, 55.9% had intermediate cytogenetic risk by UK Medical Research Council classification, and 5.5% had adverse cytogenetic risk. Time from diagnosis to transplantation was 20.4 months. The majority of donors (60.6%) were 10/10 unrelated donors; 50.4% received myeloablative conditioning, and 49.6% received reduced intensity, most frequently with busulfan and fludarabine. All patients received PTCy as anti-GVHD prophylaxis in combination with immunosuppression (cyclosporine A/mycophenolate mofetil [MMF] or MMF/tacrolimus or in vivo T-cell depletion). Karnofsky performance score was >90 in 71.2%, and the hematopoietic cell transplantation─specific comorbidity index was zero in 61.5% of the patients. Engraftment was achieved by 97.6%.

At median follow-up of 19.2 months, the 2-year total GVHD rate was 34.3% and the extensive chronic GVHD rate was 13.8%. The 2-year nonrelapse mortality (NRM) was 17.2%; 2-year relapse incidence (RI) was 21.1%. The 2-year leukemia-free survival (LFS), overall survival (OS), and GVHD-free relapse-free survival (GRFS) were 61.7%, 65.2%, and 49.3%, respectively. Among the deaths reported, cause attribution was as follows: RI, 41%; infections, 23.1%; and GVHD, 20.5%.

Multivariate analysis revealed that time from diagnosis to transplant was a significant prognostic factor for RI (hazard ratio [HR], 0.19; P <.001), LFS (HR, 0.3; P <10-3), OS (HR, 0.31; P <.001), and GRFS (HR, 0.40; P <.001). Age was a prognostic factor for NRM (HR, 1.83; P = .002), favorable risk cytogenetics for OS (HR, 0.21; P = .036), and female-to-male combination (HR, 0.15; P = .011) and reduced intensity conditioning (HR, 3.74; P = .004) for chronic GVHD.

Based on these results, it was concluded that outcomes of AML patients who underwent allo-SCT from unrelated donors while in CR2 with PTCy as GVHD prophylaxis were similar to those achieved using conventional GVHD prophylaxis, as well as to those achieved in patients who underwent allo-SCT from unrelated donors with PTCy while in CR1.

Source: Nagler A, et al. ASH 2021; abstr 3916.

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