Asuragen this month published details about its development of miRInform Pancreas, a microRNA-based test for differentiating pancreatitis from pancreatic ductal adenocarcinoma, and stressed the importance of the validation process during the development of these kinds of tests.
“Because this was the very first miRNA test that had been developed for diagnostics, there was interest as far as what our methods, procedures, and purpose were,” Rollie Carlson, Asuragen’s president, told Gene Silencing News this week.
Carlson also noted that the company is pushing forward a fine-needle aspirate version of the test that it expects to have ready for commercialization by year-end.
In the paper, which appeared in Expert Review of Molecular Diagnostics, the Asuragen team noted that “chronic pancreatitis can share many of the features of pancreatic cancer, both microscopically and during pre-operative imaging studies.”
Thus, an objective test to discriminate between the two is valuable for definitive diagnosis, they wrote.
First commercialized in 2008 (GSN 4/24/2008), miRInform Pancreas analyzes total RNA extracted from formalin-fixed, paraffin-embedded specimens for two miRNAs: miR-196a and miR-217. Over-expression of the former has been associated with poor patient survival in pancreatic ductal adenocarcinoma, and has been implicated in a variety of other cancers. Meanwhile, miR-217 has been shown to act as a tumor suppressor in PDAC.
According to the Asuragen researchers, PDAC is associated with an up-regulation of miR-196a and a down-regulation of miR-217, as compared to normal pancreas and chronic pancreatitis specimens. The test has both a specificity and sensitivity of around 95 percent.
In the study, the team also highlighted the importance of validation when it comes to developing a miRNA diagnostic, especially in light of the US Food and Drug Administration's plans to regulate such tests in the future.
“As FDA oversight is increased, we anticipate that laboratories will need to pay particularly close attention to the methods and design of their validation studies,” the study authors wrote.
”Analytical validation is really determining that your test … is sensitive enough,” Carlson said. “Once you’ve established that, then you have to do clinical validation on specimens that are representative. There you can set what would be the specific sensitivity and specificity and predict the power of the test for that purpose.”
The first miRNA diagnostic to reach the market, miRInform Pancreas has done well so far, but the company has found that “it has a limited application because it’s done on [formalin-fixed, paraffin-embedded] material,” he said.
As such, Asuragen has had an FNA version of test in the works for several years. At the University of Miami’s Winter Symposium focusing on regulatory RNA in 2008, Asuragen presented data showing that analysis of FNA material correlated well with data from frozen tissue samples.
Carlson said “there’s very strong interest in the FNA test,” and that the company plans for it to be available the second half of this year.
In addition, Carlson said the company is planning to launch kits later this year on based on other miRNAs covered by Asuragen's intellectual property, including miR-21, which has applications for breast, colon, and lung cancer, according to Carlson.
“We’re not going to have specific indications, but we’ll make the assays available for what would lead to clinical development in those areas,” he said.
According to Carlson, a colon cancer diagnostic, and more importantly, a colon cancer recurrence test “based on tissue,” are both also in the works. He said the company developed a classifier that it presented at the Association for Molecular Pathology annual meeting last November.
“We’re going through the validation of that signature with an outside major medical institution,” he said, but declined to disclose which one. “Assuming it’s validated, then we will look to have that available in early 2012.”
A blood-based test for lung cancer is at the same point in development, he added.
Carlson said the company is currently focused on cancer, but the next target might be lupus and other autoimmune diseases, “if not doing it directly ourselves, then with partnering.”
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