MRD Monitoring in Ph+ ALL: Digital Droplet PCR Outperforms Q-RT-PCR

Digital droplet PCR (ddPCR) – a third-generation MRD monitoring technology – significantly increased the proportion of quantifiable bone-marrow specimens from adult patients with Ph-positive acute lymphoblastic leukemia (ALL), showing good sensitivity and accuracy and a high rate of reproducibility when compared with quantitative real-time PCR (Q-RT-PCR), Italian researchers reported in a paper published online in August in Hematological Oncology

The researchers, led by Robin Foà and Sabina Chiaretti of Sapienza University of Rome, analyzed 98 samples (10 diagnostic and 88 follow-up samples) from 40 patients with Ph-positive ALL, all of which had been previously analyzed by Q-RT-PCR. Among the 10 diagnostic samples, they observed high concordance between the results obtained by ddPCR and Q-RT-PCR. Among the 88 follow-up samples, 29 of 54 samples (53.7%) deemed positive non-quantifiable (PNQ) by Q-RT-PCR were identified as positive and quantifiable by ddPCR; 13 (24.1%) were confirmed as PNQ and 12 (22.2%) as negative.  

Although ddPCR has been shown to be sensitive and accurate for monitoring MRD in several hematological malignancies, including Ph-negative ALL, this is only the second study to compare ddPCR with Q-RT-RCR in Ph-positive ALL; the prior study involved the analysis of 20 samples.

“The results showed that our ddPCR BCR/ABL1 assay had a sensitivity between 1x 10−5 and 5 x 10−6,” the researchers write, adding that advantages of ddPCR include no requirement for a reference curve, affordable cost, and ease of interpretation of results.

  • Ansuinelli M, Della Starza I, Lauretti A, et al. Applicability of droplet digital polymerase chain reaction for minimal residual disease monitoring in Philadelphia-positive acute lymphoblastic leukaemia [published online ahead of print, 2021 Aug 16]. Hematol Oncol. 2021;10.1002/hon.2913. doi:10.1002/hon.2913

Tags: MRD, ALL, september, news brief, Digital, outperforms, PCR, droplet, monitoring

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