Texas researchers believe they now have a reliable non-invasive tool to detect early pancreatic cancer, potentially at a stage amenable to surgical treatment.
They are reporting that a protein encoded by the gene glypican-1 (GPC1) present on cancer exosomes may be used as part of a potential non-invasive diagnostic and screening tool.
Released by cancer cells, exosomes are lipid bilayer-enclosed extracellular vesicles (EVs) that contain DNA, RNA, and proteins. Circulating in the blood and secreted by all cells, they now appear to be novel particles for earlier detection of pancreatic cancer.
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The investigators isolated and monitored GPC1-enriched circulating exosomes from the blood of patients with pancreatic cancer (GPC1+ crExos).
They found that GPC1+ crExos were detected in small amounts of serum from about 250 patients with absolute specificity and sensitivity. In addition, the tool was able to distinguish patients with chronic pancreatitis from those with early-stage and late-stage pancreatic cancer.
“The test will be ready at some point in the near future,” said study investigator Raghu Kalluri, MD, PhD, who is the chair of Cancer Biology at The University of Texas MD Anderson Cancer Center, Houston, TX. Dr. Kalluri went on to explain that the teams research found levels of GPC1+ crExos were significantly lower in patients following surgical removal of the tumor.
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Researchers evaluated crExos from healthy donors as well as patients with breast cancer and pancreatic cancer and have recently published their findings.1 Elevated GPC1+ crExos were seen in both breast and pancreatic cancers.
Dr. Kalluri said GPC1+ crExos can be detected and isolated in blood samples that were stored in freezers almost 30 years ago, unlike circulating tumor cells (CTCs), which require large amounts of fresh blood. DNA, RNA, and proteins can be isolated from cancer exosomes from stored specimens for further genetic and biological analyses.
Subsequently, cancer exosomes are more than just a biomarker, they provide a trove of cancer-specific information.
“The test can be used on diagnosed patients to track treatment and surgical outcomes. But the value that does not escape anyone’s attention is early detection and tracking high-risk groups as more evidence is collected,” Dr. Kalluri told Cancer Therapy Advisor.
Dr. Kalluri and his colleagues believe that GPC1+ crExos appear to be a more reliable screening tool than the commonly used CA 19-9 biomarker.
The study found that GPC1+ crExos detected the possibility of pancreatic cancer in mouse models of pancreatic cancer at a time when the mice showed no signs of pancreatic disease by magnetic resonance imaging (MRI).
“One scenario for early detection is a combined approach with imaging. Today, if we screened a population with MRI and/or computed tomography (CT) studies, we could indeed find early pancreatic cancers in the adult population, but the cost would be unacceptably high and there would likely be a significant number of false–positive results, which would lead to additional costs and morbidity from unnecessary workups,” said study co-investigator David Piwnica-Worms, MD, PhD, who chairs the Cancer Systems Imaging at The University of Texas MD Anderson Cancer Center in Houston, TX.
