Droplet Digital PCR Is a Robust Tool for Monitoring Minimal Residual Disease in Adult Philadelphia-Positive Acute Lymphoblastic Leukemia

• Published in: The Journal of molecular diagnostics : JMD Vol. 20; no. 4; pp. 474 - 482
• Main Authors: Coccaro, Nicoletta, Anelli, Luisa, Zagaria, Antonella, Casieri, Paola, Tota, Giuseppina, Orsini, Paola, Impera, Luciana, Minervini, Angela, Minervini, Crescenzio F., Cumbo, Cosimo, Parciante, Elisa, Carluccio, Paola, Brunetti, Claudia, Specchia, Giorgina, Albano, Francesco
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2018
• ISSN: 1525-1578; 1943-7811; 1943-7811
• DOI: 10.1016/j.jmoldx.2018.03.002

The breakpoint cluster region–abelson 1 p190 fusion transcript is the most frequent variant observed in Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL). Qualitative-PCR and real-time quantitative PCR are the currently used methods to monitor minimal residual disease (MRD) in Ph+ ALL patients; for the latter, full standardization and an international quality validation are lacking. Here, we developed a droplet digital PCR (ddPCR) assay for MRD monitoring in p190+ ALL cases. The analytical performance was assessed by the limit-of-detection determination, showing a reliability, sensitivity, and precision of the assay of up to 0.001%. Comparison of results obtained with qualitative PCR and ddPCR in 117 follow-up samples from 16 of 26 Ph+ ALL patients showed discordant results in 27% of cases (32 of 117). Real-time quantitative PCR analysis of 19 ddPCR-positive samples with a low tumor burden failed to provide quantitative results in 63% of cases (12 of 19). These results highlight that in p190+ ALL the ddPCR method has a sufficient analytical performance for very low MRD monitoring and for predicting molecular relapse several months before hematologic relapse. In conclusion, MRD monitoring by ddPCR may better stratify Ph+ ALL patients at risk of disease progression.