Copies of the androgen receptor gene could indicate response to standard prostate cancer drugs.
Biomarkers can be harnessed to predict treatment response and can even help providers choose the right treatment in certain cases. For advanced prostate cancer, a blood test may be able to predict whether a targeted treatment will be effective, according to a study published by the Annals of Oncology.
In the study, the authors detected tumor DNA in blood and were able to determine which cancers had multiple copies of the androgen receptor gene.
This gene is necessary for prostate cancer to proliferate. The androgen receptor is also known to play a vital role in developing resistance to the standard treatments, abiraterone and enzalutamide.
Included in the study were blood samples from 265 men with advanced prostate cancer who received targeted treatment with abiraterone or enzalutamide prior to treatment with docetaxel chemotherapy. Samples were taken from patients before treatment with abiraterone or enzalutamide and after disease progression.
"Abiraterone and enzalutamide are excellent treatments for advanced prostate cancer and some men can take these drugs for years without seeing a return of their cancer,” said researcher Gerhardt Attard, MD, PhD. “But in other men, these drugs do not work well and the disease rapidly returns. Currently there is no approved test to help doctors choose whether these are the best treatments for an individual.”
In the first trial, which included 171 patients, the authors discovered that patients whose blood carried multiple copies of the gene that codes for the androgen receptor were 4 times more likely to die during the study compared with patients without multiple copies, according to the study.
The results were confirmed in a study that included 94 patients. The authors found that men with multiple copies of the gene had an 8-fold shorter treatment response than men with 1 to 2 copies.
Patients with multiple copies of the androgen receptor gene were also observed to have a lesser response to targeted treatments compared with patients who do not have multiple copies of the gene, according to the study.
The authors believe that patients with multiple copies of the gene could avoid inadequate treatment and physicians could offer additional therapy.
While the test requires further clinical evaluation, the authors state that it would be inexpensive and easily implemented in a clinical setting to provide personalized treatment, according to the study.
"We have developed a robust test that can be used in the clinic to pick out which men with advanced prostate cancer are likely to respond to abiraterone and enzalutamide, and which men might need alternative treatments,” Dr Attard said. "Our method costs less than £50, is quick to provide results, and can be implemented in hospital laboratories across the NHS. We are now looking to assess our test in prospective clinical trials and would hope it can become part of standard patient care."