Researchers in the U.S. and U.K. have, for the first time, created a map of genetic mutations related to the most deadly type of prostate cancer, when the disease has spread to other parts of the body. The study indicates that for as many as 90 percent of men with advanced prostate cancer, there are either already effective treatments or ones on the way.
“We have shown that in the majority of patients, we can find hijacked switches in their DNA, genomic changes that can be targeted by drugs already available today or drugs we are confident we'll have in the future,” says Johann de Bono, professor of experimental cancer medicine at the Institute of Cancer Research, London and one of the authors of the recent study. He calls the findings the Rosetta stone of prostate cancer research.
For their study, published Thursday in the journal Cell, de Bono and his team conducted gene sequencing on biopsies of bone, soft tissues, lymph nodes and liver tissue of 150 patients with advanced, metastatic prostate cancer. When prostate cancer begins to metastasize, it typically spreads to the bone, often in unpredictable patterns. An analysis of these metastases required the researchers to identify and remove a chunk of bone that contained tumor. This is the reason why progress has been slow in research on treatment for advanced prostate cancer, says de Bono.
Around 20 percent of tumor samples from men in the study were found to have mutations in the BRCA1 and BRCA2 genes, which are biomarkers linked to increased risk for certain types of breast and ovarian cancers. In women with BRCA-positive breast cancer, PARP inhibitors (a class of drug that blocks an enzyme used by cells to repair damage) effectively inhibit the malignant cells from repairing themselves, which halts the spread of the disease. The new findings suggest that cases of prostate cancer with these mutations are also likely to respond to PARP inhibitors.
The study also identified a number of new mutations that weren’t previously associated with metastatic prostate cancer. They include the PI3K and RAF gene families. The researchers say these genes could be targeted with drugs currently in trial.
The study’s findings echo a larger trend in cancer research: When it comes to identifying effective drug treatments, the site of the cancer is less significant than a particular cancer’s genetic blueprint.
Prostate cancer is the third most common cancer in men worldwide, after non-melanoma skin cancer and lung cancer. In the U.S., approximately 220,800 men are diagnosed with prostate cancer annually, and the disease is the cause of about 27,540 deaths each year, according to the National Cancer Institute.