Clinical utility of next-generation sequencing-based minimal residual disease in paediatric B-cell acute lymphoblastic leukaemia

We assessed the clinical utility of next-generation sequencing (NGS)-based monitoring of minimal residual disease (MRD) in a uniformly treated cohort of 79 patients with paediatric B-cell acute lymphoblastic leukaemia. Bone marrow samples were collected at the time of diagnosis, days 33 and 80, pre- (4–5 months) and post- (24 months) maintenance therapy time points, and at relapse. We identified leukaemia-specific CDR3 sequences in 72 of 79 patients (91%) and detected MRD in 59 of 232 samples. Although MRD was detected in 28 of 55 samples (51%) on day 33, the frequencies of MRD detection decreased to 25% (16/65) at day 80, 19% (11/58) at 4–5 months and 7·4% (4/54) at 24 months. In a univariate analysis, positive MRD results on day 80 [relative risk (RR) 95% confidence interval (CI) = 7·438 (2·561–21·6), P < 0·001], at 4–5 months [RR (95% CI) = 10·24 (3·374–31·06), P < 0·001], and at 24 months [RR (95% CI) = 19·26 (4·974–74·59), P < 0·001] exhibited statistically significant associations with inferior leukaemia-free survival; this was confirmed using a Cox proportional hazard model. Our study suggests the promising potential of NGS-MRD for patients with B-cell ALL.