Myriad this week announced results from a study showing that the company's Prolaris assay accurately predicted elevated risk of prostate cancer recurrence in a cohort of men who had received radical prostatectomies.
Myriad conducted the study with researchers at the University of California, San Francisco, who presented the results last week at the 2012 Genitourinary Cancers Symposium in San Francisco.
The researchers analyzed the Prolaris score, which is based on the expression levels of 46 cell cycle progression genes, in 413 men who had undergone radical prostatectomy. They found that the test effectively stratified men by their risk of biochemical recurrence and enhanced the clinical parameters currently used in risk assessment measures. The test offered independent prognostic information beyond PSA, Gleason grade, and pathologic staging, the company reported.
Myriad launched Prolaris in 2010. Earlier this month, the company said it was putting more marketing force behind the assay — doubling its sales force to 20 — following positive data from several studies showing that Prolaris can distinguish whether a patient has a less or more aggressive form of prostate cancer (PGx Reporter 2/2/2012).
The study is the second in which the company explored the use of Prolaris for patients who had undergone prostatectomies. Two others have evaluated the score as predictor of mortality risk in patients with clinically localized prostate cancer.
Investment bank Oppenheimer believes the results are promising. In a research note issued after the company announced the findings, analysts from the firm said that "with the release of this study, [Myriad] is closer to launching in the post-prostatectomy setting."
The Prolaris test has so far been assessed in approximately 3,000 prostate cancer patients, according in four different studies. According to Myriad, the Prolaris score has been the "strongest single predictor of prostate cancer aggressiveness" in all of these trials.
In the latest study, Myriad and the UCSF team analyzed 413 men who underwent a radical prostatectomy. The Prolaris score correctly stratified patients based on recurrence risk, the company reported.
After five years, 100 percent of the men who scored in the lowest risk group had no disease recurrence, while half of those with high risk scores did see their cancer recur, Myriad said.
"Importantly, the Prolaris score was found to enhance clinical parameters currently used in risk assessment and offered independent prognostic information beyond PSA, Gleason grade, and pathologic staging," the company said.
In a statement, Peter Carroll, chair of urology at UCSF, said that the study demonstrated “the ability of the Prolaris test either alone, or in conjunction with pathologic features, to predict which men may have an aggressive form of prostate cancer and are at an increased risk for recurrence.“
According to Carroll, the results show the test could “help men and healthcare providers make better-informed decisions regarding additional treatment after surgery.”
According to the Oppenheimer report, Myriad expects to publish the full study, PRO-004, in the British Journal of Cancer later this quarter.
The analysts wrote that Myriad is planning its initial launch of Prolaris in the pre-prostatectomy indication "with payor talks ongoing."
Myriad currently has at least one other study of Prolaris underway. PRO-006 is a prospective trial investigating how Prolaris scores impact physicians' treatment decisions. According to the company the findings will be useful for reimbursement discussions (PGx Reporter 2/2/2012).