Phase I-II Trial of Early Azacitidine after Matched Unrelated Donor Hematopoietic Cell Transplantation

Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic cell transplantation (allo-HCT). The hypomethylating agent azacitidine (AZA) has been shown to be effective in preclinical and clinical studies for the prevention of acute GVHD (aGVHD). We sought to determine the maximum tolerated dose (MTD) of AZA when given on days 1 to 5 of a 28-day cycle for 4 cycles, starting on day +7 after allo-HCT, as well as its impact on aGVHD and chronic GVHD (cGVHD), relapse, and overall survival (OS) in patients undergoing matched unrelated donor allo-HCT. This study was a single-arm, single-center, open-label phase I-II study with a total of 15 and 38 patients enrolled in the phase I and II portions of the trial, respectively. A standard 3+3 study design was used in phase I, and all patients in phase II received AZA at the MTD determined in phase I. The MTD of AZA starting at day +7 post-transplantation was 45 mg/m². Phase II of the study was halted after enrolling 38 of the planned 46 patients following an interim analysis that suggested futility. Overall, AZA at 45 mg/m² exhibited a side effect profile consistent with prior reports and had a minimal impact on engraftment. The cumulative incidence of clinically significant aGVHD by day +180 was 39.9% (95% confidence interval [CI], 22% to 53.7%). The incidence of all-grade cGVHD was 61.4% (95% CI, 40.3% to 75%). At 1 year, OS was 73.7% (95% CI, 60.9% to 89.1%), and the disease relapse rate was 11.4% (95% CI,.2% to 21.3%). Our results suggest that early post-allo-HCT AZA has limited efficacy in preventing aGVHD and cGVHD but could have a beneficial effect in preventing disease relapse.