Genomics Clinical Trials - July 2019

This issue is devoted to the genetics and genomics of prostate cancer, which is one of the most promising and exciting areas of prostate cancer research. Already, this line of investigation is having a major impact. For example, by better defining the genomics of patients entering clinical trials, there can be a marked reduction in the number of patients needed to reach statistical significance. This can potentially reduce the costs of drug development dramatically.

Research into the role of genetics and genomic alterations in the biology and treatment of prostate cancer are still at a much earlier stage than it is for breast cancer. While laboratory studies have discovered a wide range of genes that might act to determine prostate cancer behavior in the clinic, proof that these changes actually determine outcome in the clinic are rather limited. There are even fewer examples where drugs attacking these changes have been FDA-approved for the treatment of prostate cancer.

The PD-1 inhibitor, Keytruda (pembrolizumab) is at present the only example. In 2017, this drug

was approved to treat cancers that show mismatch repair or microsatellite instability.  These mutations are found in a small proportion of prostate cancer patients.

There are a number of mutations targeted by drugs that are in advanced testing, so this list may expand rapidly. One of the more promising targets is BRCA2. Mutations that alter the function of this gene are known to be involved in breast and ovarian cancer. Cancer cells with these BRCA2 mutations become dependent on the protein, PARP, for their survival and drugs that inhibit PARP can be effective therapy. Studies on patients with advanced prostate cancer show that altered BRCA2 is found in 10-30% of cases. PARP inhibitors have shown significant activity in early clinical trials. Randomized controlled trials needed for FDAapproval are in progress.

Genomic information can also be used to determine how likely prostate cancer is to behave aggressively. This can help identify patients who are likely to do well with active surveillance or to be at low risk for recurrence after an initial attempt at curative treatment.

While genomics promises to revolutionize the treatment of prostate cancer, this revolution requires support from the patient community. The key studies can only be done if patients elect to participate in these trials. For this reason, we made sure to provide you with information on how to become involved in this process.

Charles E. Myers, Jr., MD

July's Issue