Impact of measurable residual disease on outcomes of unrelated donor haematopoietic cell transplantation with post‐transplant cyclophosphamide in AML in first complete remission

Abstract

SummaryPre‐transplant measurable residual disease (MRD) predicts relapse and outcome of allogeneic haematopoietic cell transplantation (allo‐HCT). The impact of MRD on the outcomes of post‐transplant cyclophosphamide (PTCy)‐based allo‐HCT from a matched unrelated donor (UD) is unknown. This study assessed the impact of MRD in acute myeloid leukaemia (AML) in the first complete remission (CR1). A total of 272 patients (MRD negative [MRD−], n = 165; MRD positive [MRD+], n = 107) with a median follow‐up of 19 (range: 16–24) months were studied. The incidence of grades II–IV and grades III–IV acute GVHD at day 180 was 25.2% and 25% (p = 0.99), and 10.6% and 6.8% (p = 0.29), respectively, and 2‐year chronic GVHD was 35% and 30.4% (p = 0.96) in MRD+ and MRD− cohorts, respectively. In multivariate analysis, MRD+ status was associated with a higher incidence of relapse (RI) (hazard ratio [HR] = 2.56, 95% CI: 1.39–4.72), lower leukaemia‐free survival (LFS) (HR = 2.04, 95% CI: 1.23–3.39), overall survival (OS) (HR = 1.83, 95% CI: 1.04–3.25) and GVHD‐free, relapse‐free survival (GRFS) (HR = 1.69, 95% CI: 1.10–2.58). MRD status did not have a significant impact on non‐relapse mortality (NRM), or acute or chronic GVHD risk. Among patients with AML undergoing UD allo‐HCT with PTCy, pre‐transplant MRD+ status predicted a higher relapse rate, lower LFS, OS and GRFS.