LQCL2313 - CMLE - DIGITAL POLYMERASE CHAIN REACTION AND THE LIQUID BIOPSY, POTENTIAL ALLIES IN THE FIGHT AGAINST CANCER-DIGITAL POLYMERASE CHAIN REACTION AND THE LIQUID BIOPSY, POTENTIAL ALLIES IN THE FIGHT AGAINST CANCER

DIGITAL POLYMERASE CHAIN REACTION AND THE LIQUID BIOPSY, POTENTIAL ALLIES IN THE FIGHT AGAINST CANCER

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This document focuses on the advancements and applications of digital polymerase chain reaction (dPCR) in molecular diagnostics, especially in relation to liquid biopsies in clinical testing, with an emphasis on cancer detection and treatment. <br /><br />**Learning Objectives:**<br />Participants will understand how dPCR applies to liquid biopsies, tumor heterogeneity, methods to partition samples in dPCR, and how to interpret dPCR scatterplots. They will also assess applications of next-generation sequencing (NGS) versus PCR.<br /><br />**History & Case Study:**<br />A 55-year-old man presented with persistent coughing and blood traces. Initial tests showed elevated c-reactive protein, slight anemia, and neutrophilia, but no pathogens. Imaging revealed a mass in the lung, confirmed as cancer. Due to limited tissue from bronchoscopy, dPCR and liquid biopsy were used to identify targetable mutations for treatment.<br /><br />**Digital PCR (dPCR):**<br />Developed in 1992, dPCR partitions a sample into numerous microreactions for amplification, distinct from traditional PCR. It uses two methods: chip digital PCR (cdPCR) and droplet digital PCR (ddPCR). cdPCR utilizes microfluidic chips, while ddPCR uses water-oil emulsions creating single droplets. Both methods use fluorescent primers for target gene detection, creating scatterplots for analysis. dPCR excels in absolute quantification and is less sensitive to inhibitors, although still up to 1000 times more sensitive than traditional PCR. <br /><br />**Liquid Biopsy:**<br />Liquid biopsy allows non-invasive detection and monitoring of cancers by analyzing circulating tumor DNA (ctDNA) from blood samples. dPCR and NGS are tools used for mutation detection. While PCR is more specific and cost-effective, NGS offers a broader scope of mutation detection. Liquid biopsy is advantageous for tracking tumor evolution and treatment response, facilitating timely intervention for better outcomes. However, challenges like DNA heterogeneity and low concentration still exist.<br /><br />**Partnership of dPCR and Liquid Biopsy:**<br />dPCR and liquid biopsy are already used together effectively, as seen in non-small cell lung cancer and HER2 breast cancer cases, improving treatment selection and monitoring. Combining dPCR with NGS enhances mutation detection and monitoring capabilities.<br /><br />**Future Directions:**<br />Ongoing research aims to use liquid biopsies for general cancer screening, striving to improve assay sensitivities and multiplexing capabilities.<br /><br />**Case Conclusion:**<br />The patient's ctDNA was tested via dPCR, revealing an EGFR mutation, leading to targeted anti-EGFR therapy, demonstrating the efficacy of these technologies in clinical settings.<br /><br />**Summary:**<br />dPCR and liquid biopsies have greatly improved identifying mutations and monitoring cancer, although limitations and the need for further standardization remain. These technologies continue to make significant impacts on cancer diagnostics and patient care.

Keywords

digital polymerase chain reaction

dPCR

molecular diagnostics

liquid biopsy

cancer detection

next-generation sequencing

tumor heterogeneity

ctDNA

EGFR mutation

clinical testing