Studies Confirm Prognostic Value of Multigene Test for Prostate Cancer

Three new clinical studies, including a large validation study, confirm the prognostic value of a unique prostate cancer test that measures expression of multiple tumor-cell genes.

Myriad Genetics, Inc. (Salt Lake City, UT, USA) has presented, at the 2014 American Urological Association (AUA) Annual Meeting (Orlando, FL, USA), data from 3 studies on the Prolaris test for prostate cancer (PrCa), including a large clinical validation study of patients diagnosed by needle biopsy. A key finding of the validation study was that Prolaris accurately differentiated newly diagnosed patients who were likely to die of PrCa within 10 years from those with lower-risk disease.

Prolaris is a novel, quantitative, 46-gene RNA-expression test that directly measures PrCa tumor cell growth characteristics for stratifying the risk of disease progression. It accurately predicts cancer-specific death and metastases and is a much stronger indicator of clinical outcomes than Gleason score or PSA. Two patients with the same PSA and Gleason scores may have a very different estimate of mortality risk when their Prolaris Score is included.

"The aggressiveness of newly diagnosed PrCa is variable and difficult to predict. What clinicians really need is a well-validated prognostic test that accurately predicts disease-specific mortality and can improve patient care," said Jack Cuzick, PhD, study investigator and head of the Center for Cancer Prevention at Queen Mary University of London. "Currently, with standard clinical tools like Gleason Score or PSA, we can't adequately define prognosis. The Prolaris test provides useful new information and is highly prognostic for disease-specific death among men being conservatively treated."

The validation study included 761 conservatively-managed PrCa patients diagnosed by needle biopsy. The primary endpoint was PrCa death and the median follow-up time was 9.5 years. Results showed that for each 1 unit increase in the Prolaris score, patients had approximately double the risk of dying from PrCa. Data also showed that Prolaris is more predictive of mortality than Gleason score, PSA, age, clinical stage, or extent of disease individually and almost doubles the total predictive information when they are combined. In sum, Prolaris has now been validated from nine cohorts and over 6,000 patients.

In a second study presented at AUA, 230 men who had pathologic Gleason Scores of either 3+4 or 4+3 were examined. The Prolaris test was performed on the samples and the rates of biochemical recurrence (BCR) were compared in each group. Results showed that there was no difference in BCR based on an assessment using Gleason Score alone. However, Prolaris significantly outperformed the current practice of upgrading to Gleason 3+4 or 4+3 in predicting which patients would experience BCR after a radical prostatectomy. These results underscore that genomic tests must be correlated with meaningful oncologic endpoints, rather than endpoints, like upgrading.

"Prolaris has been extensively validated in thousands of patients and is the most studied molecular prognostic test for PrCa in history," said Michael Brawer, MD, vice president of Medical Affairs, Myriad Genetics; "Prolaris is rapidly becoming the leading test to assess the aggressiveness of PrCa and to help physicians select the most appropriate clinical management for patients newly diagnosed with PrCa."

The third study featured at AUA evaluated the prognostic utility of the Prolaris score generated from needle biopsy in men treated with prostatectomy. Importantly, the results of this study found that the Prolaris test was the strongest predictor of metastatic PrCa compared to other tested clinical variables. Patients with a high Prolaris score have more than a 6-fold higher risk of developing metastases compared to patients with a low score. These results further confirm that Prolaris may be used at the time of disease diagnosis to better determine which patients are at highest risk and thus help select more appropriate medical care based on personal risk profiles.

Related Links:
Myriad Genetics
Prolaris