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New FDA Genotyping Guidance Opens Door to AmpliChip Rivals

NEW YORK, March 11 (GenomeWeb News) - A recently released guidance issued by the US Food and Drug Administration will make it easier for Roche and Affymetrix rivals to win FDA clearance for tests that resemble the AmpliChip drug-metabolism diagnostic, GenomeWeb News has learned.


The document, entitled Class II Special Controls Guidance Document: Drug Metabolizing Enzyme Genotyping System, may help molecular diagnostic companies and their microarray partners more efficiently develop and submit their own array-based tests that help predict drug metabolism.


The Guidance is standard procedure, according to an FDA official. For a device that has no "predicate" product against which the FDA can draw a comparison --- as was the case for the AmpliChip when it was being reviewed by the FDA --- manufacturers are required to undergo a laborious pre-market approval process. This process "takes a long time and requires clinical trials," the FDA official said.


In the case of the AmpliChip and the resulting Class II guidance, which was released on the Center for Devices Radiological Health's web site on March 9, the document serves as a kind of roadmap for diagnostic companies wishing to market a product similar to the AmpliChip. In order for these companies to win FDA clearance for their products and begin marketing them as in vitro diagnostics like the AmpliChip, they will be required to "go by the [less stringent] 510(k) process and not have to do the pre-market approval," the FDA official said.


The document also means that Roche can go back to the FDA with a product similar to the AmpliChip and not have to go through the same approval process as it had originally, the official noted.


The FDA issues these guidances "to give people an idea of how they can assure safety and effectiveness, and what types of things the FDA will need to review" for their own 510(k) clearance, she said.


The official asked not to be named because FDA policy requires their employees to maintain anonymity when talking to the press.


As GenomeWeb News reported in January, the FDA cleared the second of two genes in Roche's AmpliChip CYP450 test, clearing the way for the device to be sold as an in vitro diagnostic in the United States.


The approval came three weeks after the FDA cleared the first half of the product. The AmpliChip, based on Affymetrix's Gene Chip technology, comprises two genes in the CYP450 family: 2D6 and 2C19.


As GenomeWeb News reported in December 2004, the FDA on Dec. 23 approved the 2D6 portion, but made no statement about the 2C19 gene.


The final approval means that physicians in the United States will be able to prescribe the test, which could help them decide dosages for drug families such as anti-depressants, anti-psychotics, anti-arrhythmics, beta-blockers, analgesic, anti-emetics, cancer drugs, anti-convulsants, proton pump inhibitors, benzodiazepines, and anti-malarials. (Pharmacogenomics Reporter, a GenomeWeb News publication, published an article in January that mentioned Roche's marketing strategy for the AmpliChip.)


The AmpliChip was approved for sale in the European Union in September.


"The use of this test is an important step forward in making personalized medicine a reality and has the potential to help physicians improve patient outcomes," Heino von Prondzynski, CEO of Roche Diagnostics, said in a statement in January.

According to Roche, multiple variations in the CYP2D6 gene can "result in poor, intermediate, extensive ("normal"), or ultra- rapid metabolism of CYP2D6-dependent drugs from a variety of classes," including anti-depressants, anti-psychotics, anti-arrhythmics, beta-blockers, analgesics, anti-emetics, and "some" anti-cancer drugs.


Variations in the CYP2C19 gene, meantime, "result in either normal or poor metabolism of CYP2C19-dependent drugs from a variety of classes, including anti-convulsants, proton pump inhibitors, benzodiazepines, and anti-malarials," the Swiss diagnostics giant said.

"Physicians can use the genetic information from this test to prevent harmful drug interactions and to assure drugs are used optimally, which in some cases will enable patients to avoid less effective or potentially harmful treatment choices," Lester Crawford, acting FDA commissioner, said in an agency statement in January.

The FDA said that the AmpliChip "is the first DNA microarray test to be cleared by the FDA and its clearance paves the way for similar microarray-based diagnostic tests to be developed in the future."

Affy's GeneChip System 3000Dx instrument, on which the AmpliChip CYP450 test is run, was cleared by the FDA on Dec. 23.

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