Randomized Phase III BMT CTN Trial of Calcineurin Inhibitor-Free Chronic Graft-Versus-Host Disease Interventions in Myeloablative Hematopoietic Cell Transplantation for Hematologic Malignancies

Abstract

Purpose: Calcineurin inhibitors (CNI) are standard components of graft-versus-host disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT). Prior data suggested that CNI-free approaches using donor T-cell depletion, either by ex vivo CD34 selection or in vivo post-transplant cyclophosphamide (PTCy) as a single agent, are associated with lower rates of chronic GVHD (cGVHD).

Methods: This multicenter phase III trial randomly assigned patients with acute leukemia or myelodysplasia and an HLA-matched donor to receive CD34-selected peripheral blood stem cell, PTCy after a bone marrow (BM) graft, or tacrolimus and methotrexate after BM graft (control). The primary end point was cGVHD (moderate or severe) or relapse-free survival (CRFS).

Results: Among 346 patients enrolled, 327 received HCT, 300 per protocol. Intent-to-treat rates of 2-year CRFS were 50.6% for CD34 selection (hazard ratio [HR] compared with control, 0.80; 95% CI, 0.56 to 1.15; P = .24), 48.1% for PTCy (HR, 0.86; 0.61 to 1.23; P = .41), and 41.0% for control. Corresponding rates of overall survival were 60.1% (HR, 1.74; 1.09 to 2.80; P = .02), 76.2% (HR, 1.02; 0.60 to 1.72; P = .95), and 76.1%. CD34 selection was associated with lower moderate to severe cGVHD (HR, 0.25; 0.12 to 0.52; P = .02) but higher transplant-related mortality (HR, 2.76; 1.26 to 6.06; P = .01). PTCy was associated with comparable cGVHD and survival outcomes to control, and a trend toward lower disease relapse (HR, 0.52; 0.28 to 0.96; P = .037).

Conclusion: CNI-free interventions as performed herein did not result in superior CRFS compared with tacrolimus and methotrexate with BM. Lower rates of moderate and severe cGVHD did not translate into improved survival.

Trial registration: ClinicalTrials.gov NCT02345850.

FIG 1.

CONSORT diagram. Completed indicates participants has completed the 2-year follow-up per protocol or died during the study. Tac and MTX, tacrolimus and methotrexate.

FIG 2.

(A) Probabilities of CRFS by treatment arm. (B) Probabilities OS by treatment arm. (C) Cumulative incidences of moderate to severe chronic GVHD by treatment arm. (D) Cumulative incidences of TRM by treatment arm. (E) Cumulative incidence of disease relapse by treatment arm. (F) Probabilities of RFS by treatment arm. CRFS, chronic relapse-free survival; GVHD, graft-versus-host disease; OS, overall survival; PTCy, post-transplant cyclophosphamide; RFS, relapse-free survival; Tac and MTX, tacrolimus and methotrexate; TRM, transplant-related morality.

FIG 3.

(A) Cumulative incidences of neutrophil recovery by treatment arm. (B) Cumulative incidences of platelet recovery by treatment arm. (C) Summary of causes of death by treatment arm. EBV, Epstein-Barr virus; GVHD, graft-versus-host disease; PTCy, post-transplant cyclophosphamide; Tac and MTX, tacrolimus and methotrexate.