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Myriad Presents Data at AACR on PTEN's Ability to Predict Prostate Cancer Outcomes


Originally published April 20.

Myriad Genetics this week presented data from a clinical trial that suggest that expression of the PTEN gene may be clinically useful in assessing a man's risk of prostate cancer recurrence after radical prostatectomy.

Researchers from Myriad and the Fondazione IRCCS Istituto Nazionale Tumori in Milan, Italy, presented the clinical trial data at the American Association for Cancer Research's annual meeting in Washington, DC, this week. PTEN is a tumor-suppressor gene that is mutated in a large number of cancers at a very high frequency.

In the study, the researchers examined prostate tumor tissue from 132 patients for which five-year follow-up data were available following prostatectomy surgery. After determining PTEN protein expression in tumor tissue samples by immunohistochemisty, researchers reported that PTEN was predictive of biochemical recurrence of prostate cancer in this patient group.

In the study, 24 percent of the tumors were PTEN negative. "In multivariate analyses, PTEN status was a significant predictor of outcome after adjusting for pathological stage (p-value = 0.009), neoadjuvant therapy (p-value = 0.014), or both (p-value = 0.04)," the researchers reported in the abstract. "These data support the hypothesis that PTEN status predicts outcome after radical prostatectomy, and suggest further, that PTEN may be a clinically important molecular marker for defining aggressive prostate cancer."

Additionally, the study found that the loss of PTEN function was predictive of patient survival at a statistically significant level after adjusting for tumor stage. This finding suggests that "PTEN status provides additional prognostic information not otherwise available to physicians," Myriad said in a statement.

Earlier this year, Myriad launched Prolaris, a 46-gene prognostic test that quantitatively determines the risk of prostate cancer recurrence in patients who have undergone a prostatectomy (PGx Reporter 03-03-10).

As many as 80,000 men undergo a radical prostatectomy in the US annually. Approximately 35 percent of these men will have a biochemical recurrence of their prostate cancer.

"Molecular markers designed to offer urologists an accurate and objective way of determining an individual's recurrence risk, beyond current clinical assessment techniques, should have significant clinical utility," Myriad said in a statement. "Patients at higher risk of recurrence are candidates for more intensive screening and therapeutic strategies given the aggressiveness of their cancers. Patients at lower risk of recurrence are good candidates for less frequent and intrusive observation."

Myriad's Prolaris test measures the expression levels of multiple genes related to cell cycle progression, and can identify patients at low risk of disease with 95 percent certainty according to the firm, which could help them avoid adverse reactions associated with unnecessary, aggressive treatments. Men with high Prolaris scores would be considered for more intensive screening and adjuvant therapy to address their more aggressive disease, the company said.

Before publication of this article, PGx Reporter did not receive an answer from Myriad as to whether the Prolaris test panel includes the PTEN gene.

In general, the findings presented at AACR "provide further evidence of the important role the PTEN gene plays in prostate cancer," Jerry Lanchbury, Myriad Genetics' chief scientific officer, said in a statement. "PTEN also shows promise in numerous other cancer types and we look forward to future studies that will further extend this gene's potential clinical utility."

Myriad also markets a test called Prezeon that measures the loss of PTEN function, which is associated with more aggressive forms of cancer and poorer survival, as well as response to cancer drugs such as EGFR inhibitors and mTOR inhibitors.

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