Liquid biopsy to optimise prostate cancer treatment

Cedars-Sinai Cancer investigators have developed a nanotechnology-based test that can detect and profile prostate cancers — even in microscopic amounts. Their research, published in the journal nanotoday, suggests that their liquid biopsy could spare many patients unnecessary treatment-related side effects, directing them instead to effective therapies that could prolong their lives.

Created by Dr Edwin Posadas and his team, the test isolates and characterises extracellular vesicles (EVs) — microscopic packets of protein and genetic material that are shed by cells — from blood samples. The EV Digital Scoring Assay can efficiently pull these EV packets from the blood and analyse them in a manner that is said to be faster than any currently available test.

“This research will revolutionise the liquid biopsy in prostate cancer,” said Posadas, Medical Director of the Urologic Oncology Program and Co-Director of the Experimental Therapeutics Program in Cedars-Sinai Cancer. “The test is fast, minimally invasive and cost-effective, and opens up a new suite of tools that will help us optimise treatment and quality of life for prostate cancer patients.”

Posadas envisions the test being used to help patients who have their prostate gland removed and later experience a rise in levels of prostate-specific antigen (PSA) in their blood, which can indicate cancer recurrence. If a remnant of the cancer has been left behind in the prostate bed, where the prostate gland once was, Posadas said focused radiation therapy can cure the disease or delay progression — but this treatment is not without risks.

“The bladder and rectum are near the prostate bed and can be damaged during the course of radiation therapy,” Posadas said. “The risk is only worth it if a man is going to benefit.”

If microscopic cancer deposits have spread outside the prostate area, focused radiation treatment will not prevent disease progression. These deposits, called micro-metastases, are not always detectable, even with the most advanced imaging, but investigators were able to detect them using the EV test.

“This would allow many patients to avoid the potential harms of radiation that isn’t targeting their disease and instead receive systemic therapy that could slow disease progression,” Posadas said.

The team tested blood samples from 40 patients with prostate cancer and found they were able to distinguish cancer localised to the prostate from cancer that had spread to other parts of the body. Then in retrospective case studies, investigators tested blood samples taken over time from three prostate cancer patients, including one patient who had undergone focused radiation treatments. Posadas was concerned that the patient was not benefiting, and the test confirmed that the treatments were not effective because he had micro-metastatic disease.

Posadas said the test could be adapted to guide treatment as prostate cancer therapies become more targeted at the molecular level, ultimately extending patients’ lives. The researchers are now working to further refine the test so that it can be studied in greater detail, with the aim of working with local and national partners and to bring the test into wide clinical practice in the near future.

“This type of liquid biopsy … is key to next-generation precision medicine that represents the newest frontier in cancer treatment,” said Dr Dan Theodorescu, Director of Cedars-Sinai Cancer.

Image credit: iStock.com/Bet_Noire