As expected, Laboratory Corporation of America has begun a service that genotypes patient samples with Roche Diagnostics' CYP450 AmpliChip.
The move follows the reference laboratory giant's August announcement that it had begun validating the microarray, which is the only such device cleared by the US Food and Drug Administration for the indication.
As the first microarray genotyping service offered by LabCorp for patients, CYP450 testing with Roche's AmpliChip can reasonably be expected to illustrate how the Swiss diagnostic company's next microarray-based test will make its way to clinical testing.
But though the volume of CYP450 testing is generally expected to remain light, emerging competition might change the situation. Number-two reference lab Quest Diagnostics also offers testing using the chip, and large regional lab Specialty Diagnostics, which said in October that it had added the test to its diagnostics menu, expects to offer it soon.
The next microarray in line for Roche is a leukemia AmpliChip microarray, which is slated to roll out toward the end of this year and the beginning of 2006, Walter Koch, the head of the firm's pharmacogenomics department, told Pharmacogenomics Reporter in February. The microarray is designed to classify tumor cells into one of 20 subtypes, he said.
"For our clinical trials work, we've been looking at lots of different arrays, whether they be microarrays or bead-based arrays or whatever, but as yet, except for the [comparative genomic hybridization] chip, we've not launched anything else."
LabCorp said in July that it would assist Roche in evaluating the leukemia microarray. In the same statement, LabCorp also announced that it had begun validating the Roche CYP450 AmpliChip, a step widely — and correctly — viewed as a prelude to the reference lab deciding to offer the test as a service.
LabCorp's announcement that it would evaluate the leukemia array may not offer the same guarantee that it would pick up the test as would an announcement that it is validating the test. "We do a lot of evaluations, and we do a fair number of validations," Marcia Eisenberg, LabCorp's vice president overseeing research and development in molecular diagnostics, told Pharmacogenomics Reporter in August. "When you're committing the time and effort and resources to a validation, you're doing that with the hope that at the conclusion it will be something you can offer to physicians for their patients."
However, LabCorp's adoption of the AmpliChip CYP450 test could be fairly viewed as a trailblazing case for the company's use of microarray diagnostics in general, Paul Billings, LabCorp's LabCorp's senior geneticist and vice president for biotechnology and healthcare strategy, told Pharmacogenomics Reporter. "For our clinical trials work, we've been looking at lots of different arrays, whether they be microarrays or bead-based arrays or whatever, but as yet, except for the [comparative genomic hybridization] chip, we've not launched anything else," he said.
LabCorp began array based CGH testing in September.
Following the leukemia chip, Roche is also planning on releasing a p53-sequencing AmpliChip for research use. "We will need a diagnostic for resequencing p53 if [Roche's] MDM2-inhibitors make it through trials," Koch said of the company's AmpliChip p53 mutational-analysis test. The cancer drugs are currently "close to Phase I," he said. The p53 chip will likely be launched next year, he added.
Sizing Up Rivals
Rivals to the AmpliChip CYP450 are just beginning to emerge, though the microarray's novelty combined with its relatively high cost, the lack of competing FDA-cleared CYP450 chips, and the complexity of microarrays in general have conspired to ensure that competitors in the CYP450-testing market are limited for now to PCR-based SNP testing.
On the cost side, the differences are significant. A typical PCR diagnostic testing for CYP450 can cost approximately $300. A typical AmpliChip test ordered from LabCorp costs $1,360 per patient sample. Quest will test a patient sample with the AmpliChip CYP450 array for $1,570, while Michael Dugan, vice president and laboratory director at Specialty Laboratories, told Pharmacogenomics Reporter this week that his company only discusses prices with customers. Specialty Laboratories customer service representatives were unable to locate AmpliChip testing in the company's test menu.
Quest appears to have been the first to offer CYP450 AmpliChip testing, having begun the service about two months ago without an accompanying announcement, Gary Samuels, a company spokesperson said this week. Specialty Laboratories said in October that its AmpliChip test would probably be available for order by the end of that month, but the company has yet to offer it. "We will have the test active very shortly," and its launch will be announced in a special client letter, Dugan said this week.
"I don't think we are looking for this to grow to become a routine high-volume diagnostic test."
But demand for the CYP450 AmpliChip is generally expected to be light. The chip does not offer LabCorp customers results that they couldn't get through PCR testing, LabCorp's Eisenberg said in July, and added that poor physician education is one of the main factors affecting demand for CYP450 testing in general.
The company has been offering PCR-based CYP450 2D6 testing — one of the two gene interrogations performed simultaneously by the AmpliChip — as a diagnostic under Clinical Laboratory Improvement Amendments rules since the spring, and plans to begin offering PCR-based testing for the other gene, 2C19, as well.
"I don't think we are looking for this to grow to become a routine high-volume diagnostic test," Samuels said in July. "This is not cholesterol testing or cystic fibrosis testing."
"We're already seeing demand [supporting] psychiatric prescriptions, but 2D6 and 2C19 cut [across] a broad range of pharmaceuticals, so it's possible we'll see some interest from other areas as well," said LabCorp's Billings.
All of the AmpliChip arrays are designed to run on Affymetrix' FDA-cleared GeneChip reader. The CYP450 AmpliChip is designed to identify multiple genetic variants in two cytochrome P450 genes, CYP2D6 and CYP2C19, which metabolize 40 to 45 percent of all prescription drugs, including antidepressants, pain relievers, and cardiovascular agents.
— Chris Womack ([email protected])