Uncontrolled cancer cell growth results from misbehaving genes. An intriguing approach to cancer therapy is to specifically identify the mutated genes. After identification, in some cases a treatment to counteract the damaging effects of that gene may have been developed for the treatment of some other type of cancer besides prostate cancer.
There are still many challenges to overcome in our attempts to use genetically-guided approach. While we now have the ready ability to identify malfunctioning genes by name, we don’t always know the gene’s actual function. Also, in most cases, medicines to counteract the mutations we detect don’t yet exist. Another problem has been problems obtaining cancer tissue for analysis. Until recently, due to the bone-centric nature of prostate cancer metastases, bone biopsy was the only way to obtain access the tumor cells so genetic analysis could be performed. Fortunately, the ability to analyze cancer DNA released into the blood stream from dying cancer cells may now replace the need for bone biopsy. One assay, performed by Guardant Health called Guardant 360 tests for approximately 70 of the most commonly seen mutations seen in various cancers.
The fact that targeted therapy for specific mutations can be successful was most notably validated by the discovery that Olaparib, an FDA-approved drug for ovarian cancer, may also be beneficial in men with prostate cancer who have a specific mutation in the BRCA gene. It turns out that this BRCA mutation (or other related types of mutation related to DNA repair) occur fairly frequently in men with advanced metastatic prostate cancer. A study testing Olaparib for treatment of prostate cancer patients was published in the New England Journal of Medicine. It showed that Olaparib was very effective in 15 out of 16 men who had this type of mutation in their cancer cells. In men without this specific type of mutation the response rate to Olaparib was less than 10 percent. Hopefully, genetic testing will lead to further such discoveries.
ABOUT THE AUTHOR
Mark Scholz, MD is the Executive Director of the Prostate Cancer Research Institute. He is also the Medical Director of Prostate Oncology Specialists Inc. He received his medical degree from Creighton University in Omaha, NE. Dr. Scholz completed his Internal Medicine internship and Medical Oncology fellowship at University of Southern California Medical Center. He is co-author of Invasion of the Prostate Snatchers. He has authored over 20 scientific publications related to the treatment of prostate cancer.