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With Publication of Study, GenomeDx Anticipating Broader Market Availability of Prostate Cancer Dx


Following the online publication of a validation study involving its Decipher multi-gene prostate cancer test, GenomeDx Biosciences announced that it plans to initiate broader marketing efforts for the test in the third quarter of this year.

The Journal of Urology on June 12 published a study, entitled "Validation of a Genomic Classifier that Predicts Metastasis Following Radical Prostatectomy in an At Risk Patient Population," which showed that Decipher could gauge which prostate cancer patients were at greater risk of metastatic disease based on measuring 22 genomic markers. Study investigators from the Mayo Clinic, GenomeDx, and other institutions further found that the prognostic ability of the genomic test was better than conventional measures by Gleason score and prostate-specific antigen testing.

GenomeDx has developed Decipher specifically as a tool that doctors can use to assess the extent to which prostate cancer patients are at risk for disease metastasis after a radical prostatectomy, so that they can aggressively treat those at high risk and conservatively manage those at low risk. The company told PGx Reporter that it is planning to market the test using its own sales team to urologic surgeons who perform prostatectomies.

The study published in JU identified more than 1,000 prostate cancer patients who underwent radical prostatectomy in Mayo Clinic's tumor registry between 2000 and 2006. These patients had PSA scores of greater than 20 ng/mL and had Gleason scores of eight of more. Within this cohort, researchers led by Mayo's Jeffrey Karnes randomly tested 219 patients with Decipher, 69 of whom eventually developed metastatic disease.

Using analytical models, researchers then gauged the ability of Decipher to predict disease metastasis five years after radical prostatectomy. The data showed that less than 3 percent of those patients that Decipher determined to be at low risk, 6 percent of those the test deemed to be at intermediate risk, and more than 22 percent of those classified as high risk experienced disease metastasis five years after surgery.

Although by standard clinical measures these more than 200 patients would be considered at high risk of metastasis, Decipher classified 60 percent of them to be at low risk, 21 percent as intermediate risk, and maintained only 19 percent as high risk. Those reclassified by Decipher into the low-risk category were 2.5 times less likely to have metastatic cancer, GenomeDx said in announcing the publication of this data.

"In this study, we found the test was able to re-classify from high risk to low risk 60 percent of patients, including high Gleason score patients that, upon clinical follow-up, had exceptionally good outcomes and never needed secondary therapy," Karnes, a urologist at Mayo, said in a statement.

Multivariate analysis showed that Decipher was the predominant predictor of metastasis compared to standard measures. According to GenomeDx, the Decipher test result is "completely independent" of PSA and other clinical variables.

"These results indicate that genomic information from the primary tumor can identify patients with adverse pathology who are most at risk for metastasis and potentially lethal prostate cancer," Karnes et al. concluded in the JU paper. The data further "suggest that genomic alterations in aggressive prostate cancer manifest early, many years before the metastatic disease is detected clinically."

The National Comprehensive Cancer Network and the American Urological Association recommend that men who have undergone radical prostatectomy and are at increased risk of metastasis receive treatment, such as radiation. But these secondary treatments have significant side effects.

Meanwhile, according to the study published in JU, within the overall cohort of more than 1,000 men in the Mayo database who had received radical prostatectomy, the incidence of metastasis was only 6 percent at five years and around 7 percent at 10 years. GenomeDx is hoping to market Deciper as a tool that urologists can use to gain insights into which patients really need aggressive treatment, and spare those at low risk of metastasis from having to take unnecessary toxic treatments.

"Currently men with advanced or high-risk prostate cancer have heterogeneous outcomes, and this test can help better risk-stratify these men after surgery," Karnes added in a statement.

In the paper, the authors noted that the current study could not determine whether Decipher can predict whether high-risk patients will benefit from radiation or hormone therapies. "Evaluation of [the] genomic classifier in randomized clinical trial datasets will help to better understand the relationship between [the] genomic classifier and benefit from specific therapies, and in turn can also lead to better selection of truly high-risk patients for [the] future," the study authors wrote.

In April, GenomeDx and Mayo expanded their research agreement, allowing GenomeDx to exclusively license certain IP, as well as access Mayo's clinical data and samples on prostate cancer patients. The deal, GenomeDx said, would enable researchers to follow patients for longer-term biomarker-based outcomes.

At the American Urological Association's annual meeting, researchers from Johns Hopkins University and GenomeDx presented data from a study in which they looked at a cohort of men who had radical prostatectomy and five-year follow up data. The analysis showed that while standard pathological and clinical factors could gauge which of the nearly 5,000 men were at risk of metastasis, these measures had limited ability to assess which at-risk patients – those with biochemical recurrence or adverse pathology at the time of surgery – were likely to develop rapid metastatic disease.

Additionally, this week, researchers from GenomeDx and elsewhere published in PLoS One the methodology by which they developed the multi-gene panel underlying Decipher. The 22 gene-expression classifier was developed by analyzing more than 500 samples from the Mayo database of patients who underwent radical prostatectomy from 1987 to 2001 and had a median follow-up of nearly 17 years. The cohort was enriched with patients who experienced disease metastasis and had rising PSA levels that progressed to metastatic disease.

GenomeDx is also conducting studies to garner data that will convince payors to reimburse for the test, and the company has said it plans to submit information to Medicare contractor Palmetto GBA for insurance coverage (PGx Reporter 2/20/2013). A company spokesperson added that GenomeDx has started reimbursement discussions with private payors, as well.

GenomeDx's test, focusing on the post-prostatectomy patient population, will enter a crowded prostate cancer molecular diagnostic market in which a number of tests are seeking to gauge patients' disease aggressiveness at various stages in the care continuum.

For example, Genomic Health has launched an Oncotype DX prostate cancer test that analyzes the expression of 17 genes within four biological pathways to gauge prostate cancer aggressiveness. Prostate cancer patients who are deemed to be at very low risk, low risk, or intermediate risk of progressing are eligible to be tested with the Oncotype Dx test. If, based on standard clinical measures, a person's prostate cancer is considered high risk, then he is not a candidate for Genomic Health's test.

Myriad Genetics also markets Prolaris, a test that gauges a panel of cell cycle progression genes. The test is indicated as a prognostic tool to gauge disease aggressiveness for men upon first cancer diagnosis and after they've had surgery to remove all or part of the prostate gland (PGx Reporter 6/12/2013).