A blood test that could pick out which men with advanced prostate cancer would benefit from new drug treatment olaparib has been developed.
Prostate cancer is the most common cancer in men.
The new test detects cancer DNA in the blood, helping doctors check whether precision drugs are working.
However, larger studies involving more men needed to take place to confirm if doctors could rely on the test.
Blood samples from 49 men with advanced prostate cancer were collected by researchers, as part of the phase II clinical trial of olaparib.
This type of precision drug is seen as the future of cancer medicine but because it is a targeted treatment, the drug does not work for everyone.
Researchers from The Institute of Cancer Research and the Royal Marsden NHS Foundation Trust said the test could help target treatment better and also reduce its side effects.
They used the test to identify men who were not responding to the treatment in 4 to 8 weeks and also to pick up signs that the cancer was evolving and becoming resistant to the drugs.
Prof. Johann de Bono, consultant medical oncologist at the two organizations, said: “From these findings, we were able to develop a powerful, three-in-one test that could in future be used to help doctors select treatment, check whether it is working and monitor the cancer in the longer term.”
“Not only could the test have a major impact on treatment of prostate cancer, but it could also be adapted to open up the possibility of precision medicine to patients with other types of cancer,” he added.
British scientists have announced that Olaparib, the first drug that targets precise genetic mutations in prostate cancer, has been shown to be effective in a “milestone” trial.
The study, at the Institute of Cancer Research in London, took place on 49 men with untreatable cancer.
Olaparib had low overall success, but slowed tumor growth in 88% of patients with specific DNA mutations.
Cancer Research UK said the trial was exciting.
Olaparib, the first marketed drug to tackle inherited cancer mutations, was licensed in 2014 for women with ovarian cancer who have faulty BRCA genes.
The future of cancer medicine is treating cancers by their mutated DNA rather than what part of the body they are in.
The breast cancer drug Herceptin is already used only in patients with specific mutations. Olaparib targets mutations that change the way DNA is repaired.
The trial results, published in the New England Journal of Medicine, showed the drug worked in 14 out of 16 men with such mutations.
Levels of Prostate Specific Antigen (PSA), which is produced by tumors, was more than halved and there were also significant falls in the number of prostate cancer cells detected in the blood and in the size of secondary tumors.
Patients responded to the drug for between six months and nearly a year and a half.
Prostate cancer is the fifth most deadly type of cancer in men.
However, a larger clinical trial is needed before doctors can say if the drug extends life expectancy.