ANGLE announced that work by the Barts Cancer Institute on the Parsortix system, a blood test to both detect prostate cancer and evaluate its aggressiveness, has yielded positive results supporting its efficiency as a simple and non-invasive test with greater specificity than the current standard, the prostate-specific antigen (PSA) blood test.
Parsortix is based on a technology able to detect circulating tumor cells in blood, presenting a cheap and easy option for routine testing. ANGLE has been working with Barts, a cancer institute that is part of Queen Mary University of London, to evaluate its system.
A PSA blood analysis is now frequently a first step in prostate cancer detection, together with a rectal examination of the prostate. High levels of PSA, or an enlarged prostate, leads to tissue biopsy — a sequence of events that is far from optimal.
PSA is not sensitive in detecting prostate cancer, correctly identifying only a fraction of cases. It also often provides false negative results, indicating that cancer is present when it is not, so that final evaluation has mainly depended on tissue biopsies. In 75–80 percent of men going through biopsies no cancer is found, and only 10 percent of those detected need aggressive treatment.
Tissue biopsies are invasive, and can, in fact, also miss a present cancer. They also exposes men without cancer to unnecessary testing, increasing the risk for infection.
If the blood test could do what ANGLE hopes it can, many men who would otherwise undergo unnecessary surgery could be placed on active surveillance, while men with aggressive cancers could quickly receive proper care.
The data, presented at the 10th ISMRC International Symposium on Minimal Residual Cancer: Liquid Biopsy in Cancer Diagnostics and Treatment in Hamburg, showed that Parsortix could detect circulating tumor cells in all patients with metastasized prostate cancer.
In patients with early stage disease, where clinicians performed a tissue biopsy and decided to put them on ‘active surveillance’ rather than offering a medical intervention, the system identified circulating tumor cells in 75 percent of patients.
Aggressiveness of cancer is currently determined using the so-called Gleason score, which requires assessment of the appearance of cells from a tissue biopsy. The ANGLE study compared the number of tumor cells identified by the Parsortix system to the Gleason score, and noted that they matched for all patients investigated. This would suggest the system is at least as efficient in determining aggressiveness as the analysis of a solid biopsy.
Finally, the system might be as effective as the Gleason score to predict whether a cancer is localized or has metastasized.
Given the positive results, ANGLE plans to work with Barts and other cancer centers to develop clinical tests to validate the method for clinical application of routine cancer detection and assessment — studies that will likely take at least 18 months to complete.
“These are highly encouraging results for the use of the Parsortix system for a clinical application in prostate cancer. This opens the potential of another highly differentiated liquid biopsy application for Parsortix in a key area of medical need, which cannot be addressed by ctDNA or antibody-based circulating tumor cells systems, where there is the potential to improve patient care and at the same time reduce healthcare costs,” Andrew Newland, ANGLE’s founder and chief executive, said in a news release.
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