LAUSR

The effect of prolonged pulse therapy with vincristine and dexamethasone (VD) during maintenance therapy on the outcome of paediatric patients with TCF3‐PBX1 positive acute lymphoblastic leukaemia (ALL) remains uncertain. We conducted non‐inferiority analysis of 263 newly diagnosed TCF3‐PBX1 positive ALL children who were stratified and randomly assigned (1:1) to receive seven additional VD pulses (the control group) or not (the experimental group) in the CCCG‐ALL‐2015 clinical trial from January 2015 to December 2019 (ChiCTR‐IPR‐14005706). There was no significant difference in baseline characteristics between the two groups. With a median follow‐up of 4.2 years, the 5‐year event‐free survival (EFS) and 5‐year overall survival (OS) in the control group were 90.1% (95% confidence interval [CI] 85.1–95.4) and 94.7% (95% CI, 90.9–98.6) comparable to those in the experimental group 89.2% (95% CI 84.1–94.7) and 95.6% (95% CI 91.8–99.6), respectively. Non‐inferiority was established as a one‐sided 95% upper confidence bound for the difference in probability of 5‐year EFS was 0.003, and that for 5‐year OS was 0.01 by as‐treated analysis. Thus, omission of pulse therapy with VD beyond one year of treatment did not affect the outcome of children with TCF3‐PBX1 positive ALL.