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Exagen Files Breast Cancer Recurrence Kit For FDA Clearance; Highlights 'Availability,' Low Cost

Exagen last week filed its breast cancer recurrence test for 510(k) clearance with the US Food and Drug Administration, hoping that the test’s ability to increase physician convenience and lower lab costs will give it an edge over competitors.
The test, eXagenBC, is in line to be the fourth genomic-based breast cancer-recurrence assay to hit the market after assays made by Genomic Health, Agendia, and Quest.
Exagen officials have previously touted the computational approach used to develop the test [see PGx Reporter 02-14-07]. This technology, which is designed to identify “the smallest combination of genes” predictive for a disease, will allow eXagenBC to be validated in “any qualified laboratory in the US.”
Unlike competing products which have to be performed at single, CLIA-certified laboratories, the eXagenBC test kit will give doctors greater leeway in choosing labs, which Exagen hopes will in turn lower testing services costs, and yield faster results.
Exagen “Not a Lab”
“It is our business strategy to not become a laboratory,” Exagen CEO James McClinitic said last week. “It is our business strategy to discover unique gene sets that we can build into kits and that we can prove with a blinded trial that they indeed do what we say they do, and then have them cleared through FDA.”
According to McClinitic, the advantage of eXagenBC is not that it is necessarily more accurate than its competitors, but rather that it is more convenient for physicians. Exagen’s assay, a fluorescent in situ hybridization test, can be validated in molecular pathology clinical laboratories with FISH capabilities, giving physicians more flexibility to use any lab of their choosing.
“It’s not a situation where our test is more accurate or more sensitive than Genomic Health’s. That’s not the point,” McClinitic explained. “We are not a CLIA lab. We will be selling this kit to other laboratories, hospitals, and reference laboratories around the US.”
EXagenBC “allows the doctor’s favorite laboratory – it could be in the local area or be one of the national laboratories – to do the test,” he said. “This kit is more available to a wider group of people. If it were Quest laboratories, or Genzyme, or LabCorp, they could all have it and run the test on a local basis. … So I think it’s more available.”
In touting eXagenBC’s “convenience,” Exagen appears to be positioning itself to compete most directly with Agendia’s MammaPrint test kit, the first FDA-cleared IVDMIA.
The FDA has expressed its intent to regulate certain algorithm-based laboratory-developed genetic tests called in vitro diagnostic multivariate index assays [see PGx Reporter 02-14-07].
According to McClintic, eXagenBC will likely not be considered an IVDMIA. However, rival Genomic Health’s OncotypeDX test may be considered an IVDMIA according to an FDA draft guidance on these types of tests. Genomic Health and the agency are currently under discussion regarding the status of the test.
At the time of its approval in February, Agendia suggested that a green light from the FDA could encourage physicians to adopt the product in the US and in Europe.
Meanwhile, the company doesn’t plan on performing the test analysis in the US, opting instead to use a single lab in the Netherlands [see PGx Reporter 02-07-07].  A single site may allow the company to control the quality of its testing services, but shuttling samples from the US to the Netherlands may increase the time doctors and their patients wait for results.
On the other hand, Genomic Health and Quest’s tests are not FDA-approved, and are performed in the companies’ US-based CLIA-certified labs.
Exagen’s test, which has been available to labs for investigational use, is designed to test women with Stage I breast cancer to determine a patient’s risk for breast cancer recurrence.
The test classifies patients’ risk of breast cancer recurrence based on a score. Patients are considered low risk if the test returns a score below 3, while high risk women score above 3. “If you score a 3.1 versus 7.4, there are orders of magnitude greater,” McClintic said. “Generally, physicians get very concerned when patients are above 10 percent of the risk of recurrence.”  
Genomic Health’s Oncotype Dx, which tests for breast cancer recurrence and chemotherapy response, is indicated for women with Stage I or Stage II estrogen receptor-positive, node-negative breast cancer who were taking tamoxifen.
Agendia’s MammaPrint, indicated for early-stage, node-negative breast cancer, gauges a patient’s risk of breast cancer recurrence at five and 10 years.
Quest’s breast cancer gene expression-ratio test, licensed from AviaraDx, gauges recurrence in patients with ER-positive, lymph-node negative breast cancer.
Inviting Liability?
Ultimately, eXagenBC’s advantage could become its greatest liability.
In marketing a kit that will be validated in laboratories not owned by Exagen, the company may end up absorbing the brunt of any liability that arises from defective tests.

“It’s not a situation where our test is more accurate or more sensitive than Genomic Health. That’s not the point. … This kit is more available to a wider group of people.”

By comparison, in conducting the tests in their own labs, Genomic Health, Agendia, and Quest are more insulated against lawsuits for bad tests since the companies can claim that they are simply providing test results and not marketing a product that happens to be faulty. 
The Department of Health and Human Services, in a recent draft report on pharmacogenomics, points out that “exposure to product liability for PGx testing may depend on whether a test is made available as a product, (i.e., as an IVD), or in-house by a clinical laboratory.”
In the latter case, “the clinical laboratory provides a service (i.e., the test results), rather than a product, and is therefore not subject to liability for product defects,” the report states.
However, the liability structure may change if regulatory oversight of lab-developed test are strengthened either by the FDA, or by CMS’ CLIA regs and the FTC.
“As demand for more rapid turnaround of PGx test results increases, and if regulatory oversight of laboratory-developed tests by CLIA and FTC is strengthened, more tests are likely to be offered as kit products,” HHS observes in the report. “These potential changes could expose companies that manufacture, distribute or interpret genetic tests to product defect liability.”
Selling Like Pharma
Exagen is already ramping up its sales force in anticipation of eXagenBC’s launch, and modeling its sales strategy after big pharma.
McClintic said Exagen is currently in the process of hiring its first 10 sales people, who will be trained to speak to medical professionals most likely to order eXagenBC — mainly oncologists and breast surgeons. The reps will train employees in laboratories that have signed on to offer eXagenBC.
“They will be able to speak to physicians in a highly technical way, very much like pharmaceutical companies’ [sales] detail [to] physicians,” McClintic said.
Larry Lesko, director of FDA’s Office of Clinical Pharmacology and Biopharmaceutics, recently suggested that diagnostics developers should emulate pharma’s model of reaching out directly to physicians in order to encourage physician adoption of genetic tests [see PGx Reporter 03-07-07].

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