By Turna Ray
Luminex this week launched its first pharmacogenetic test, the xTAG CYP2D6 kit, after gaining 510(k) clearance from the US Food and Drug Administration.
The company said that the xTAG CYP2D6 kit is the first assay in a line of CYP tests that it is developing. The test is available through Luminex Molecular Diagnostics and distribution partner Fisher HealthCare.
According to the firm, the xTAG CYP2D6 Kit "is not indicated for stand-alone diagnostic purposes and is not intended to be used to predict drug response or non-response." However, the company said that it can help physicians "manage patients for whom they may prescribe certain drugs that are metabolized by the enzyme cytochrome P450 2D6."
The company did not respond to questions about the CYP2D6 test ahead of press time.
According to information in the FDA's 510(k) database, the test was cleared in August and claimed Roche's Amplichip CYP450 test as a predicate device.
The FDA's decision summary notes that the xTAG CYP2D6 kit is "used to simultaneously detect and identify a panel of nucleotide variants found within the highly polymorphic CYP2D6 gene located on chromosome 22 from genomic DNA extracted from an EDTA or citrate anticoagulated whole blood sample" and can also identify "gene rearrangements associated with the deletion (*5) and duplication genotypes."
The summary adds that the kit "is a qualitative genotyping assay which can be used as an aid to clinicians in determining therapeutic strategy for therapeutics that are metabolized by the CYP2D6 gene product," but is "not indicated for stand-alone diagnostic purposes."
The approval is in line with a recent trend by the FDA to include language in a test's label that allows sponsors to sell their tests broadly as pharmacogenomic tools but does not let companies claim that such tests can predict response to specific drugs in marketing the diagnsotic. This labeling distinction, it seems, is dictated by the level of evidence and types of data submitted by the test sponsors.
For example, although AutoGenomics last month garnered clearance from the FDA for its Infinity CYP2C19 Assay — which gauges the *2, *3, and *17 SNPs in the gene — the test's label makes no mention of its use as a test to administer Plavix, a drug that is metabolized by the enzyme. An FDA spokesperson at the time told PGx Reporter that AutoGenomics submitted "sufficient data" to the agency to demonstrate the assay could detect enzyme activity in metabolizing drugs in the CYP2C19 pathway, but the firm did not submit data on the test that would allow for it to be cleared specifically as a Plavix PGx test (PGx Reporter 10/27/10).
Luminex does not mention any one drug by name in its announcement of the launch of the CYP2D6 test, indicating that it may have taken a similar regulatory route as the AutoGenomics assay.
The firm touted the launch of the kit as the "first innovation in CYP2D6 diagnostics in five years" because it combines multiplex testing and pharmacogenetics.
"The information it provides has significant potential to help doctors improve care by assisting them in determining the best therapeutic strategy for an individual patient," the company claims.
The enzyme CYP2D6 is linked to the metabolism of around 25 percent of prescription drugs, including beta-blockers, opiates, selective serotonin reuptake inhibitors, tricylic antidepressants, neuroleptics, and antiarrhythmics.
Studies have suggested that abnormal CYP2D6 metabolizers are more likely to experience side effects and see limited benefit from medications metabolized by the enzyme. By identifying these individuals through CYP2D6 testing, doctors would be able to guide patients to alternative treatments.
According to a statement from PGXL Laboratories, which utilizes the xTAG CYP2D6 assay, Luminex's test allows for higher throughput, shorter turnaround times, and lower per-sample cost than other CYP2D6 genotyping technologies.
Luminex said that the xTAG CYP2D6 Kit can identify individuals who possess both common and rare CYP2D6 poor-metabolizer variants. The test platform can gauge SNPs in the CYP2D6 gene, as well as identify gene rearrangements associated with deletion and duplication of genotypes. The company further highlighted the eight-hour turnaround time for the test, which operates on the firm's 200 system.
The CYP2D6 kit is Luminex's second xTAG test to be cleared by the FDA. In September 2009, the agency cleared the company's xTAG Cystic Fibrosis 39 Kit v2.
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