Next-generation sequencing–based MRD in adults with ALL undergoing hematopoietic cell transplantation

Measurable residual disease (MRD) is an adverse prognostic factor in adult patients with acute lymphoblastic leukemia (ALL) undergoing hematopoietic cell transplant (HCT). Next-generation sequencing (NGS) can detect MRD with a sensitivity of 10^–6, but the prognostic value of NGS-based MRD in adult patients with ALL undergoing HCT remains minimally studied. To evaluate the prognostic value of NGS-based MRD in adult patients with ALL undergoing HCT, patients aged ≥18 years with ALL who underwent allogeneic HCT at Stanford University or Oregon Health & Science University between January 2014 and April 2021 and were evaluated for MRD using the NGS-based clonoSEQ assay were included in this study. MRD was assessed before HCT (MRD_pre) and up to 1 year after HCT (MRD_post). Patients were followed up for leukemia relapse and survival for up to 2 years after HCT. In total, 158 patients had a trackable clonotype for MRD monitoring. The cumulative incidence of relapse was increased at all levels of MRD_pre, including in patients who had low MRD_pre of <10^–4 (hazard ratio [HR], 3.56; 95% confidence interval [95% CI], 1.39-9.15). In multivariable analysis, MRD_pre level remained significantly prognostic; however, detectable MRD_post was the strongest predictor of relapse (HR, 4.60; 95% CI, 3.01-7.02). In exploratory analyses limited to patients with B-cell ALL, the detection of post-HCT immunoglobulin H (IgH) MRD clonotypes, rather than non-IgH MRD clonotypes, was associated with relapse. In this analysis across 2 large transplant centers, we found that the detection of MRD by NGS at a level of 10^–6 offers significant prognostic value in adults with ALL undergoing HCT.