The expanding role of biomarkers in prostate cancer
Experts examine the rapid rise of PSMA PET, genetic testing and novel biomarkers.
PSA, the first biomarker in prostate cancer, has been part of patient care for decades. Use of PSMA PET for staging has skyrocketed from single digits in 2021 to over 50% currently. Trials for biomarkers, biomarker-based imaging, germline mutation testing and tumor somatic testing are on the rise. Prostate cancer guidelines increasingly incorporate novel biomarkers for potential clinical consideration.
“Biomarkers are something that everyone who is taking care of prostate cancer patients needs to be aware of,” said Mohummad Minhaj Siddiqui, MD, professor of surgery and chief of urology at the University of Maryland School of Medicine and chief of urology at Maryland VA Healthcare System. He moderated a Focus On session Friday afternoon exploring the current state of biomarkers, MRI and PSMA PET imaging in prostate cancer.
Biomarkers are molecules in body fluids or tissues that can indicate a normal or abnormal biological process. They can be used alone or in combination with different imaging modalities and other clinical measures to help diagnose or guide management decisions.
“We have biomarkers that have been shown in multiple studies to improve the ability to detect high-grade cancer,” said Simpa S. Salami, MD, MPH, associate professor of urology at the University of Michigan School of Medicine.
There are few direct comparisons between biomarkers, and many need further validation, he added, but diagnostic performance seems to be similar. Current biomarkers can confirm diagnosis with up to 30% fewer biopsies.
But not all widely used biomarkers have been well validated. Black patients, for example, are known to have lower electroretinogram (ERG) expression, which limits the utility of ERG-based tests.
MRI improves the detection of high-grade prostate cancer but should not eliminate surveillance biopsy. PSMA PET can facilitate staging before treatment.
“I use MRI and PET every day when I’m designing radiation-targeted areas,” said Mack Roach III, MD, professor of radiation oncology and urology at the University of California, San Francisco. “It took us a long time to understand PSA, and it’s going to take us a long time to figure out what to do with all these biomarkers and a lot of validation.”
Multiple new agents have been approved for prostate cancer with multiple mechanisms and indications. Many are being moved into earlier, hormone-responsive settings without clear guidance. PSMA PET imaging is commonly used to diagnose, classify and track disease, also without clear guidelines.
Prostate Cancer Working Group 4 (PCWG4) is moving toward more evidence-based biomarker criteria and trial designs to optimize approaches for those who are most likely to benefit, said Michael A. Carducci, AEGON professor in prostate cancer research at the Hopkins Kimmel Cancer Center. PCWG4 is proposing a new indications model and new terminology, as well as specific approaches to the use of genetic testing and genomic evaluation to tailor treatment for PARP inhibitors and other agents.
