CD20 expression has no prognostic role in Philadelphia-negativeB-precursor acute lymphoblastic leukemia: new insights from the molecularstudy of minimal residual disease.

The prognostic significance of CD20 expression in acute lymphoblastic leukemia has been investigated in children and adults and is still under debate. The aim of our study was to correlate CD20 expression with clinical-biological characteristics and outcome in 172 Philadelphia-negative patients prospectively treated in a multicenter trial introducing the molecular evaluation of minimal residual disease for therapeutic purposes. We considered 20% as the threshold for CD20 positivity. Complete remission rate, minimal residual disease negativity rate at weeks 10, 16 and 22, and disease-free and overall survival were similar among CD20 positive and negative patients, even considering minimal residual disease results and related therapeutic choices. Our study failed to demonstrate any prognostic significance for CD20 expression in Philadelphia-negative acute lymphoblastic leukemia. This conclusion is supported for the first time by a comparable minimal residual disease response rate among CD20 negative and positive patients