Low Risk of Chronic Graft-versus-Host Disease and Relapse Associated with T Cell–Depleted Peripheral Blood Stem Cell Transplantation for Acute Myelogenous Leukemia in First Remission: Results of the Blood and Marrow Transplant Clinical Trials Network Protocol 0303

Abstract

Graft-versus-host disease (GVHD) is most effectively prevented by ex vivo T cell depletion (TCD) of the allograft, but its role in the treatment of patients undergoing allogeneic hematopoietic cell transplantation (HCT) for acute myelogenous leukemia (AML) in complete remission (CR) remains unclear. We performed a phase 2 single-arm multicenter study to evaluate the role of TCD in AML patients in CR1 or CR2 up to age 65 years. The primary objective was to achieve a disease-free survival (DFS) rate of >75% at 6 months posttransplantation. A total of 44 patients with AML in CR1 (n = 37) or CR2 (n = 7) with a median age of 48.5 years (range, 21-59 years) received myeloablative chemotherapy and fractionated total body irradiation (1375 cGy) followed by immunomagnetically selected CD34-enriched, T cell‒depleted allografts from HLA-identical siblings. No pharmacologic GVHD prophylaxis was given. All patients engrafted. The incidence of acute GVHD grade II-IV was 22.7%, and the incidence of extensive chronic GVHD was 6.8% at 24 months. The relapse rate for patients in CR1 was 17.4% at 36 months. With a median follow-up of 34 months, DFS for all patients was 82% at 6 months, and DFS for patients in CR1 was 72.8% at 12 months and 58% at 36 months. HCT after myeloablative chemoradiotherapy can be performed in a multicenter setting using a uniform method of TCD, resulting in a low risk of extensive chronic GVHD and relapse for patients with AML in CR1.