Antilymphocyte globulin (ATG) added to the myeloablative conditioning regimen of patients undergoing allogeneic stem cell transplantation resulted in a lower incidence of chronic graft-versus-host disease (GVHD) compared with conditioning regimens without ATG.
At two years, the cumulative incidence of chronic GVHD was 32.2% (95% CI, 22.1–46.7) for the ATG group vs 68.7% (58.4-80.7) for the non-ATG group (P < .001). At one year, 91% of the ATG group had discontinued cyclosporine, compared with 39% in the non-ATG group. The difference between groups was most pronounced in rates of the clinical extensive form of chronic GVHD: 7.6% (3.0-19.6) with ATG compared with 52.4% (39.3-69.9) without ATG.
Courtesy Wikimedia Commons/The Armed Forces Institute of Pathology/Public Domain
Bone marrow smear from a patient with acute myelomonocytic leukemia.
T-cell depletion may cause a loss of graft-versus-leukemia effects, which is cause for concern. This study showed similar rates of relapse-free and overall survival for the ATG and non-ATG groups. Two-year relapse-free survival was 59.4% (47.8-69.2) in the ATG group and 64.6% (50.9-75.3) in the non-ATG group. The composite 2-year survival, free from chronic GVHD and relapse, was 36.6% (25.2-48.0) for the ATG group vs 16.8% (9.2-26.4) for the non-ATG group, according to the study reported in the January 7 issue of the New England Journal of Medicine (2016;374:43-53).
Chronic GVHD is the leading cause of later illness and death after allogeneic hematopoietic stem-cell transplantation, according to the authors. “Even if a modest increase in the rate of relapse in the ATG group cannot be ruled out, the significantly lower incidence of chronic GVHD with ATG resulted in a significantly higher rate of 2-year survival free from chronic GVD among patients who received ATG than among those who did not receive ATG (50% vs. 23%),” wrote Dr. Nicolaus Kröger, Professor and Medical Director of the Department of Stem Cell Transplantation at the University Hospital Hamburg-Eppendorf, Germany, and colleagues.
The prospective, open-label, randomized phase 3 trial evaluated 155 patients at 27 centers from 2006 to 2012. Patients with acute leukemia undergoing allogeneic stem cell transplantation with peripheral blood stem cells were randomized 1:1 to receive myeloablative conditioning with or without ATG.
Post-transplantation lymphoproliferative disorder was not observed in either group. The ATG and non-ATG groups had similar rates of infectious complications (57.8% and 54.2%, respectively), and nonrelapse-related death at 2 years (14.0% and 12.0%, respectively).
The study was funded by the Neovii Biotech and the European Society for Blood and Marrow Transplantation; ClinicalTrials.gov number, NCT00678275. Dr. Kröger reported grant support from Neovii Biotech. Several of his coauthors reported ties to industry.