Estudo prospectivo de doença residual mínima em crianças com leucemia Linfoide Aguda

Abstract

MRD analysis of Ig and TCR genes rearrangements by conventional PCR can be an effective and low cost alternative for risk stratification in patients with ALL. The purpose of this study was to compare Ig/TCR gene rearrangements MRD assessment by qualitative PCR with the reference assay, RQ-PCR, at the end of induction period (day 28-35) in children from three leading institutions in Belo Horizonte, Minas Gerais, Brazil. Of the 74 patients diagnosed with ALL and treated from 2010 to 2012, MRD was performed by qualitative PCR in 57 and by both tests in 44. MRD was positive in 9/57 (15.8%) patients by the conventional method and in 11/44 (25%) by the quantitative test, considering the cutoff point of 1X10-3 for pB-ALL and 1X10-2 for T-ALL. The estimated 3.5-year probabilities of overall and leukemia-free survival (LFS) were 73.6% and 72.3%, respectively. The 3.5-year LFS was significantly higher in consensus primers MRD-negative children (p=0.032). There was no significant association between MRD held by RQ-PCR and LFS. In a multivariate analysis using Cox model, MRD qualitative assay was the only variable significantly related to LFS. In conclusion, given the difficulties in the implementation of MRD monitoring by RQ-PCR in most treatment centers in Brazil, we suggest the use of the conventional strategy as a cost-effective alternative in our context.