Prolaris Test Helps ID Higher-risk Patients Who May Safely Skip ADT

Prolaris Test Helps ID Higher-risk Patients Who May Safely Skip ADT

Prolaris — a genetic test that predicts the aggressiveness of prostate cancer — can accurately identify which men with intermediate- or high-risk disease will benefit from adding androgen deprivation therapy (ADT) to standard radiation therapy, a study shows.

This Myriad Genetics’ test was found to be superior to other methods at predicting cancer spread (metastasis) in these patients, and thereby at distinguishing those who could avoid ADT.

The findings, “Association of the clinical cell-cycle risk score with metastasis after radiation therapy and identification of men with prostate cancer who can forgo combined androgen deprivation therapy,” were shared in an oral presentation at the 2021 Genitourinary Cancer Symposium, held virtually Feb. 11–13.

“This new data helps distinguish the most appropriate personalized treatment path for each patient based on how their specific tumor is behaving,” Jonathan Tward, MD, PhD, the study’s first author and an associate professor in the department of radiation oncology at the University of Utah, said in a press release.

“For some men, this means being able to avoid overtreating patients with therapies including hormone treatment that can momentously impact their quality of life, while still appropriately treating their prostate cancer,” Tward added.

Todd Cohen, MD, the vice president of Myriad’s medical affairs for urology, said that the company was the first to offer “a test that directly measures the molecular biology of an individual patient’s prostate cancer.”

“This study by Dr. Tward and his team is another strong validation of the prognostic power of the Prolaris test and our ongoing commitment to providing healthcare professionals with the tools needed to determine the most effective treatments and monitoring strategies for each patient,” Cohen added.

Prolaris predicts cancer aggressiveness by analyzing the activity of 46 genes involved in cancer cell proliferation, using tissue collected during a biopsy to confirm a cancer diagnosis or during surgery to remove the prostate.

It then combines this information with the patient’s Gleason score — a measure of prostate cancer aggressiveness based on how cells look under a microscope — and levels of prostate cancer antigen, a biomarker of prostate cancer.

The result is a so-called combined clinical cell-cycle risk (CCR) score, which can be used to better predict the likelihood of prostate cancer progression over 10 years. A more accurate prediction allows for more precise treatment, avoiding excessive treatment that both raises the risk of side effects and care costs.

In previous research, Prolaris was shown to help identify those men with apparent low-risk disease who may safely opt for active surveillance only — meaning, no treatment until the detection of disease progression — and those who may need extensive treatment.

Other studies have highlighted the test’s potential in identifying men with intermediate or high-risk prostate cancer who could avoid additional and intensive therapy, such as ADT, when choosing radiation therapy, or radiation therapy when choosing surgery.

In 2020, a guideline update from the National Comprehensive Cancer Network included Prolaris as one of two tests recommended to guide treatment for men with unfavorable intermediate- and high-risk prostate cancer.

Now, Tward and colleagues evaluated if Prolaris also could predict the benefit of adding ADT to radiation therapy in men with unfavorable intermediate- or high-risk prostate cancer.

They retrospectively examined clinical data covering 718 of such patients, all given dose-escalated radiation therapy either alone or in combination with ADT, and who were followed for a median of 5.9 years.

The team evaluated the ability of the CCR score — with a high-risk threshold of 2.112 — to predict the development of metastasis in patients treated with single or combination therapy.

Results showed that men with CCR scores below the high-risk threshold had a 10-year risk of metastasis of 4.2%, while those with a score greater than the threshold had a risk of 25.3%.

Notably, among men with a CCR below threshold score, adding ADT to radiation therapy resulted in no significantly greater benefit relative to radiation therapy alone (4.2% vs. 3.9% 10-year risk of metastasis).

Data also highlighted that about 50% of men with unfavorable intermediate-risk prostate cancer and 20% of those with a high-risk disease may have CCR scores below the risk threshold, and could safely consider radiation therapy alone.

“Men with scores below the [high-risk] threshold may not significantly reduce their 10-year risk of metastasis with the addition of ADT,” the researchers wrote in the abstract.

In addition, the CCR score was found to be superior to other risk-stratifying approaches at predicting metastasis in these patients, and therefore guiding treatment.

These findings suggest that the Prolaris test can be used to identify which men with intermediate-risk or high-risk prostate cancer may benefit from additional hormonal treatment and those who may avoid it.

According to Myriad, about 60% of prostate cancer patients in the U.S. currently have insurance or Medicare with access to Prolaris.