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With Large Study, Interleukin Hopes to Drive Adoption, Reimbursement of Dx for Personalized Dental Care


This article has been updated from an earlier version with additional comments from Eliot Lurier.

By Turna Ray

Interleukin Genetics is hoping to garner payor interest in its PST Genetic Test with a large study intended to show that genetic information in addition to clinical factors can inform how often patients at low risk of gum disease need to visit the dentist.

The University of Michigan School of Dentistry and Interleukin announced last month that they had finished enrolling patients in a 5,400-subject clinical trial. Based on results from Interleukin's genetic test as well as clinical and environmental factors, the subjects will be classified as being at low risk or high risk for periodontitis progression. The researchers hope to determine whether visiting a dentist twice a year impacts tooth loss in patients classified as being at low risk for severe or progressive periodontal disease (PGx Reporter 3/28/2012).

The study is being funded by Renaissance Health Service, a nationwide insurance firm that provides coverage for dental care. Renaissance insures 8.6 million people and last year paid out $2.2 billion in dental benefits.

If findings from this University of Michigan trial show that using genetic testing to risk stratify patients and guide dental care improves outcomes, Interleukin is hoping that this will spur reimbursement for genetic testing for patients who are covered under Renaissance dental plans. Furthermore, with the study, Interleukin is attempting to advance a new prevention focused, molecularly-guided treatment strategy in dental care.

"Our data from 19 previous studies suggested that low-risk individuals did not progress, but most periodontal disease was in a subpopulation with increased risk," Eliot Lurier, Interleukin's chief financial officer, told PGx Reporter this week. "We knew that if such results were true then we could save the system money. The logical choice was to approach payers with the concept and seek reimbursement."

Interleukin's PST Genetic Test identifies individuals at heightened risk for "severe and progressive periodontal disease and significant tooth loss." The diagnostic analyzes a proprietary panel of SNPs that have been associated in studies with the expression of inflammation-causing interleukin cytokines.

A systematic review and meta-analysis recently published in the Journal of Periodontology by researchers from Harvard University, the University of Sheffield, and Interleukin found that IL-1A and IL-1B gene variations are "significant contributors to chronic periodontitis in Caucasians."

For the University of Michigan study, researchers began enrolling patients in November 2010 by identifying potential study participants through a large dental claims database with more than 15 years of oral health history. Individuals who agreed to participate in the trial were asked to provide a DNA sample, which the researchers analyzed with Interleukin's PST Genetic test. Based on the test results and other clinical information, study investigators then classified participants as either low risk or high risk for periodontitis progression.

The study's primary endpoint is tooth loss at 15 years for low-risk individuals with one versus two dentist visits per year.

"The study will evaluate whether a second annual cleaning is necessary for the prevention of tooth loss and periodontal disease in low-risk individuals, defined as nonsmoking, PST negative, and without diabetes," Lurier said. "The study is also designed to determine if high-risk individuals need more prevention."

By investigating the genetic and environmental factors that underlie gum disease and tooth loss in individuals, Interleukin is hoping its diagnostic tool will help physicians personalize the level of care their patients need. Moreover, if patients at low risk of severe gum disease can do just as well with one annual visit to the dentist, as opposed to two visits, Interleukin's test could potentially help physicians deliver preventative dental care in a more cost-effective manner.

Currently, dentists recommend that individuals visit every six months for an examination and cleaning. However, according to William Giannobile, director of the Michigan Center for Oral Health Research and the leader of the study involving the PST Genetic Test, a recent systematic review provided "insufficient evidence" to either support or refute that adults need two preventative dental visits per year.

Given the high cost of dental care in the US, Interleukin is hoping to gain insurance coverage for the test if clinical trials demonstrate that the PST Genetic Test can drive savings in the healthcare system.

Approximately 8 percent to 15 percent of adult Americans have moderate to severe periodontitis, which can lead to tooth loss if gone untreated. According to the Centers for Disease Control and Prevention, 25 percent of adults in the country 60 and older have lost all of their teeth. In 2009, people in the US spent $102 billion in dental services.

With positive findings from this trial, "there should be no more one size fits all" treatment in dental care, such as the recommended "two [annual] cleanings for everyone," Lurier said. Also, with positive results from the University of Michigan study, the company is expecting "a dramatic increase in marketability of the test."

The PST Genetic Test has been on the market as a laboratory-developed test since 2003. Quest’s Oral DNA group holds a non-exclusive license to market the diagnostic.

Under current regulatory guidelines, Interleukin plans to continue to market the test as an LDT. "We are still evaluating our regulatory strategy, but at this time LDTs do not require US Food and Drug Administration preapproval," Lurier said.

Interleukin is expecting the study with the University of Michigan to be completed "in a few months." Although Renaissance Health Services is funding the trial, Interleukin wouldn't reveal the costs of the 5,400-patient study.

"We have sufficient funding to complete the study," Lurier said.

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