HERCULES, Calif. — April 14, 2018 — New research showcasing the importance of Bio-Rad's Droplet Digital PCR (ddPCR) technology in clinical applications will be featured in more than 60 presentations at the American Association for Cancer Research (AACR) Annual Meeting in Chicago, April 14–18.
One growing application area of ddPCR technology is guiding therapeutic decisions. Doctors need to know as quickly as possible whether their prescribed treatment is working or not so they can adjust the regimen. The key in making that determination is identifying and consistently measuring a biomarker that can indicate treatment outcome. Use of ddPCR technology in the clinic is increasing due to the technology's ability to reliably detect and quantify these biomarkers, as well as ddPCR's technical simplicity, speed, and cost-effectiveness.
Researchers continue to find novel ways to explore these biomarkers using ddPCR technology, whether they are epigenetic markers to determine cancer recurrence after surgery or cell-free DNA (cfDNA) derived from a tumor that reveals the effectiveness of immunotherapy. Below, we highlight a few of these studies that will be presented at this year's AACR meeting.
Using ddPCR Technology to Identify a Potential Epigenetic Biomarker of Lung Cancer
For patients with early-stage non-small cell lung cancer (NSCLC), the only recommended treatment option is surgery. Following surgery, approximately a third of these patients relapse after five years. Drs. Ana Robles, Delphine Lissa, Curtis Harris, and collaborators at the National Cancer Institute in Bethesda, Maryland, sought prognostic biomarkers that could predict relapse in patients with stage I lung adenocarcinoma, a major subtype of NSCLC.
With the knowledge that the HOXA9 promoter is methylated in stage I tumors, Robles, Lissa, and team used ddPCR technology to analyze HOXA9 promoter methylation in formalin-fixed, paraffin-embedded tumor specimens. They found an association between higher methylation levels and increased recurrence rates after five years. This indicated that HOXA9 methylation levels, as detected via ddPCR technology, could be used in combination with other biomarkers to identify high-risk stage IA and IB patients and potentially steer these patients for follow-up chemotherapy to prevent recurrence.
ddPCR Helps Detect Metastatic Cervical Cancer and Monitor Immunotherapy Response
Human papillomavirus (HPV) cfDNA in the blood is a unique tumor marker for metastatic cervical cancers. Dr. Liang Cao and his team at the National Cancer Institute investigated whether this biomarker could be used to identify patients with HPV16- or HPV18-positive metastatic cervical cancer and to assess the patient's response to tumor-infiltrating lymphocyte (TIL) immunotherapy.
Using ddPCR, Dr. Cao's team genotyped and quantified circulating HPV cfDNA in serum samples from patients with HPV-positive metastatic cervical cancer. They found HPV cfDNA in all samples from known cancer patients and none in samples from healthy blood donors. In patients who exhibited a positive response to TIL therapy, the researchers were able to use ddPCR technology to detect a transient peak in HPV cfDNA, a sign of tumor death.
Early Prediction of Treatment Response in HPV-associated Oropharyngeal Cancer with ddPCR Technology
HPV is also associated with most oropharyngeal squamous cell carcinomas (OPSCCs), a disease in which distant metastatic disease can occur in up to 10% of patients. Monitoring this condition with imaging can be challenging and slow, so Dr. Glenn Hanna and his colleagues at the Robert and Renée Belfer Center for Applied Cancer Research at the Dana-Farber Cancer Institute investigated the feasibility of using ddPCR technology in identifying signs of OPSCC and monitoring patients' response to treatment.
“While HPV-specific serum and salivary antibody testing has been evaluated, HPV cfDNA has not been well studied as a biomarker to characterize metastatic or advanced oropharyngeal cancer causally related to HPV,” said Dr. Hanna. “Some small studies have looked at HPV DNA via qPCR or antibodies in patients with newly diagnosed HPV oropharynx cancers to try and understand viral clearance after chemoradiation, but these efforts have been limited by the sensitivity of the assays.”
Using ddPCR, the team detected and quantified five strains of HPV cfDNA in blood samples from a small cohort of patients with recurrent metastatic HPV-positive OPSCC, who were undergoing either conventional treatment or immunotherapy. They found that HPV cfDNA levels strongly correlated with both disease burden and distant sites of metastasis. In three cases, Dr. Hanna and team detected a decline in cfDNA levels up to 14 days prior to imaging evidence that later confirmed treatment response.
“This study shows that ddPCR is a feasible alternative to imaging for measuring disease burden: it offers greater sensitivity for detecting HPV cfDNA with relatively low sample volumes,” Dr. Hanna said. “It also uses peripheral blood and therefore could potentially act as a liquid biopsy if it were validated for clinical use.”
Financial support for this study was provided by the Expect Miracles Foundation and the Robert A. and Renée E. Belfer Foundation.
Bio-Rad will also host an Exhibitor Spotlight Presentation in Theater A, McCormick Place South, entitled: “Droplet Digital PCR and the Power of Partitioning: Advanced Applications for Liquid Biopsy” on Tuesday, April 17, at 12:30 PM. The presentation will feature scientific talks by Dr. Marzia Del Re, PharmD, PhD, from the University Hospital of Pisa, Italy, and Dr. Ed Schuuring, PhD, from The University Medical Center Groningen, the Netherlands.
Bio-Rad's new, fully automated 4-color multiplexed digital PCR system, the QX ONE ddPCR System, will be on display at Bio-Rad's booth (#1031). The booth will also feature the company's award-winning QX200 Droplet Digital PCR System, the Illumina Bio-Rad Single-Cell Sequencing Solution, and several new ddPCR assays available on Bio-Rad's Digital Assay Site.
Please visit bio-rad.com/digitalPCR to learn more about Bio-Rad's Droplet Digital PCR technology at AACR.
The QX ONE and QX200 Droplet Digital PCR Systems are for research use only and are not intended for use in diagnostic procedures.
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