Researchers at the UK Institute of Cancer Research (ICR) and the Royal Marsden NHS Foundation Trust have developed a new three-in-one blood test for a precision prostate cancer therapy that targets mutations in the BRCA genes.
Designed for testing and analysing cancer DNA in the blood, the new test allowed the researchers to detect patients who are most likely to benefit from treatment with PARP inhibitor drugs and identify men who are not responding to the therapy.
The analysis was also used to monitor a patient’s blood throughout treatment for signs of resistance to the medication.
The capabilities of the new test are expected to specifically enable the future use of a PARP inhibitor, called olaparib, as a standard treatment for advanced prostate cancer.
Olaparib is being developed to kill cancer cells carrying errors in genes such as BRCA1 or BRCA2 that play a role in repairing damaged DNA.
According to ICR, the test has the potential to extend survival time by effective targeting of therapy, minimising medicine side effects and allowing treatment with precision drugs.
The research team collected blood samples from 49 subjects in the TOPARP-A Phase II clinical trial of olaparib at the Royal Marsden.
Analysis of the samples enabled the researchers to identify the genetic mutations that are used by prostate cancer to resist olaparib therapy.
The measure of cancer DNA levels circulating in the blood indicated that patients responding to olaparib demonstrated a drop of 49.6% in the levels, while the non-responding patients showed an increase in the levels by 2.1% at week eight.
Patients with reduced levels of blood DNA following the treatment were found to have survived an average of 17 months when compared to 10.1 months in the case of men with high cancer DNA levels.
Prostate Cancer UK Research deputy director Dr Matthew Hobbs said: "The results from this study and others like it are crucial as they give an important understanding of the factors that drive certain prostate cancers or make them vulnerable to specific treatments."
“However, there is still much more to understand before the potentially huge benefits of widespread precision treatment for prostate cancer will reach men in clinics across the UK. That is why Prostate Cancer UK is investing so heavily in this area, including supporting this research released today.”
Image: Blood samples ready for analysis. Photo: courtesy of The Institute of Cancer Research.