Comprehensive genomic profiling for prostate cancer is gaining traction as a tool to inform treatment plans. A new study has identified targetable genomic alterations in 57% of advanced prostate cancers.1 Knowing the prevalence of these alterations in the population could help guide new clinical trials for targeted therapies for the disease.

In the study, published in JCO Precision Oncology, the researchers compiled data from routine clinical testing of prostate cancer samples from 3476 unique patients. About half the samples came from primary tumor tissue, and the other half from metastatic sites. They tested the samples using Foundation Medicine’s FoundationOne assay, which looks at more than 300 different biomarkers. On average, they found 3.5 genomic alterations per sample in primary tumor samples, and 5.5 in metastatic sites. Many of these alterations are targetable by drugs already approved by a regulatory agency or are in development.  

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“We’ve reached an exciting point in thinking about genomics in prostate cancer,” said Jon Chung, PhD, associate director of clinical development at Foundation Medicine, Cambridge, Massachusetts, and first author on the paper. Historically, prostate cancer hasn’t been considered to have a lot of targetable genomic alterations, he said. But in the last few years, targeted therapies for this cancer have begun to show promise. “What we wanted to do was take a fresh look as of today,” Dr Chung said. “We wanted to see what alterations we have and where they fit in this actionability scale.” The actionability scale is the European Society for Medical Oncology (ESMO) Magnitude of Clinical Benefit Scale (ESCAT),2 published in August 2018, to provide a standardized framework for ranking genomic alterations and how targetable they are. 

“This is the most exciting part of this,” said Neeraj Agarwal, MD, director of the genitourinary oncology program at the Huntsman Cancer Institute in Salt Lake City, Utah, who is also senior author of the study. “In more than half of the patients, there is a molecular target that is targetable by a drug either currently available in the clinic, or currently available under investigation in a clinical trial.” 

Not surprisingly, many of the genetic culprits identified in prostate cancer also drive other cancer types. In some cases, therapies have already been developed to target them. “If it has the same molecular defects as a breast cancer does, and the breast cancer responds to this treatment, because it targets that pathway, then it may be worth trying,” said Robert Pilarski, MS, MSW, associate professor of human genetics at the Ohio State University, Columbus, who was not involved in the study. “This is leading oncologists to treat with chemo they wouldn’t have used before.” Pilarski, a licensed genetic counselor, pointed out that the new data dovetail with trends in hereditary testing for prostate cancer.