Myriad Genetics’ Prolaris — a genetic test that predicts the aggressiveness of prostate cancer — can identify which men with intermediate or high-risk prostate cancer will benefit from combining androgen deprivation therapy (ADT) with standard therapy, a study shows.
The data, “Ability of the combined clinical cell-cycle risk score to identify patients that benefit from multi versus single modality therapy in NCCN intermediate and high-risk prostate cancer,” were presented in a poster session at the 2020 American Society of Clinical Oncology (ASCO) Genitourinary Cancer Symposium, held recently in San Francisco.
“While it has been demonstrated that multi-modality therapy [combination therapy] can improve overall survival in prostate cancer, it comes at the risk of increased morbidity and increased cost to the healthcare system,” Jonathan Tward, MD, PhD, the study’s first author and associate professor in the department of radiation oncology at the University of Utah, said in a press release.
“Prolaris provides a unique tool that can accurately predict which patients with high-risk prostate cancer will truly benefit from multi-modality therapy and conversely which patients with lower risk can safely avoid such treatments,” Tward said.
The test analyzes the activity of 46 genes involved in cancer cell proliferation and determines their aggressiveness, using tissue collected during a biopsy to confirm a cancer diagnosis.
Clinicians can use the test to better predict the prognosis of prostate cancer over 10 years. It works in combination with a person’s Gleason score — a measure of prostate cancer aggressiveness based on how cells look under a microscope — and levels of prostate cancer antigen (PSA), a biomarker of prostate cancer. The result is a so-called combined clinical cell-cycle risk (CCR) score.
Prolaris was shown in a previous study to help identify which patients with apparent low-risk disease may safely opt for active surveillance only — meaning, having no treatment until the detection of disease progression — and those who may require extensive treatment.
Using the test could thus prevent unnecessary treatment for a number of men, thus reducing their risk of side effects and care costs.
Now, a team of researchers evaluated whether Prolaris also could be used to predict the benefit of combination therapy over ADT alone in men with intermediate-risk or high-risk prostate cancer.
They retrospectively examined the clinical data of 718 prostate cancer patients deemed to have unfavorable intermediate risk and high risk according to the National Comprehensive Cancer Network guidelines and the Prolaris test.
The men, who were followed-up for a median of 5.1 years, had been treated either with ADT alone or with a combination of ADT with radiation therapy or surgery, or with radiation therapy following surgery.
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.
The results showed that among men with a CCR score greater than the high-risk threshold (44% of patients), those given combination therapy showed a significantly lower risk of developing metastasis than those treated with ADT alone.
On the other hand, combination therapy resulted in no significantly greater benefit than single therapy among men with a CCR score below the high-risk threshold.
The data also highlighted that about 73% of men with unfavorable intermediate-risk prostate cancer and 27% of those with a high-risk disease may have CCR scores below the risk threshold and consider ADT alone.
These findings suggest that the Prolaris test can be used to identify which men with intermediate-risk or high-risk prostate cancer will benefit most from combination therapy and those who may avoid additional treatment.