Comparison between qualitative and real-time polymerase chain reaction to evaluate minimal residual disease in children with acute lymphoblastic leukemia

• Main Authors: Francisco Danilo Ferreira Paula, Silvana Maria Elói-Santos, Sandra Guerra Xavier, Mônica Aparecida Ganazza, Patricia Yoshioka Jotta, José Andrés Yunes, Marcos Borato Viana, Juliana Godoy Assumpção
• Format: Article
• Language: English
• Published: Elsevier 2015-12-01
• Series: Revista Brasileira de Hematologia e Hemoterapia
• Subjects: Minimal residual disease; Polymerase chain reaction; Acute lymphoblastic leukemia; Leukemia free survival
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-84842015000600373&lng=en&tlng=en

ABSTRACT Introduction: Minimal residual disease is an important independent prognostic factor that can identify poor responders among patients with acute lymphoblastic leukemia. Objective: The aim of this study was to analyze minimal residual disease using immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements by conventional polymerase chain reaction followed by homo-heteroduplex analysis and to compare this with real-time polymerase chain reaction at the end of the induction period in children with acute lymphoblastic leukemia. Methods: Seventy-four patients diagnosed with acute lymphoblastic leukemia were enrolled. Minimal residual disease was evaluated by qualitative polymerase chain reaction in 57 and by both tests in 44. The Kaplan-Meier and multivariate Cox methods and the log-rank test were used for statistical analysis. Results: Nine patients (15.8%) were positive for minimal residual disease by qualitative polymerase chain reaction and 11 (25%) by real-time polymerase chain reaction considering a cut-off point of 1 × 10−3 for precursor B-cell acute lymphoblastic leukemia and 1 × 10−2 for T-cell acute lymphoblastic leukemia. Using the qualitative method, the 3.5-year leukemia- free survival was significantly higher in children negative for minimal residual disease compared to those with positive results (84.1% ± 5.6% versus 41.7% ± 17.3%, respectively; p-value = 0.004). There was no significant association between leukemia-free survival and minimal residual disease by real-time polymerase chain reaction. Minimal residual disease by qualitative polymerase chain reaction was the only variable significantly correlated to leukemia-free survival. Conclusion: Given the difficulties in the implementation of minimal residual disease monitoring by real-time polymerase chain reaction in most treatment centers in Brazil, the qualitative polymerase chain reaction strategy may be a cost-effective alternative.