New research revealed the genetic clues that explained why tumours resist a particular drug used for treating advanced prostate cancer. The discovery could guide health care providers to individualized treatments for castration-resistant prostate cancer, did not respond to standard hormone therapy. The research was published in the edition of Annals of Oncology.

Even though approved therapies were available for castration-resistant prostate cancer, the treatments affected each patient differently.

The principal investigator Dr Manish Kohli and co-principal investigator Dr Liewei Wang found genetic markers which might predict resistance to the drug abiraterone acetate/prednisone (a treatment aimed at stopping the progression of advanced, metastasized prostate cancer).

The study provided insights into the genetic markers of tumours and their drug resistance that allowed health care providers to match a treatment that could succeed on the first attempt.

Dr Kohli said prostate cancer was dissimilar in each patient. The researchers discovered thousands of genetic characteristics in each a tumour and identified specific genes that enabled them to take an individualized approach to treatment with the drug. The study findings increased the development of predictive biomarker-based strategies for patients with advanced castration-resistant prostate cancer, he added.

Whole-exome DNA sequencing and RNA sequencing were performed on metastasized tumours of the participants (n=92) before therapy. After three months the tests were performed again. The scientists grew the patient's cancer in mice from a piece of the patient's cancer tissue. Experimental drugs were then tested on cancers that grew in mice.

"The discovery of these genetic signals after such an elaborate and extensive evaluation of the patients' genetic makeup has not been previously performed. Such knowledge can empower physicians to manage patients with advanced-stage, castration-resistant prostate cancer better," Dr Kohli said.

In the U.S., around 15% males affected with prostate cancer and 10-20% of whom developed castration-resistant prostate cancer. The average lifespan at that advanced stage was < one and half year.

Keith Stewart, M.B., Ch.B., Carlson and Nelson Endowed Director of the Mayo Clinic Center for Individualized Medicine, said, "This research is an example of how Mayo Clinic and the Center for Individualized Medicine are transforming patient care through advanced genetic tests to address the unmet needs of our patients with advanced prostate cancer. This discovery is an additional way to customize treatment plans based on a patient's unique genetic makeup."

The researchers concluded that they would study further to determine the drug combination which would overcome drug resistance in patients with these genetic markers.