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DxS, Roche Expand KRAS Dx Distribution; ASCO Studies Support mCRC KRAS Testing

UK-based personalized medicine company DxS expanded the marketing of its TheraScreen K-RAS Mutation test after European regulators narrowed the indication for the metastatic colorectal cancer drug Vectibix to include only patients whose tumor carries the wildtype KRAS gene.
The worldwide distribution deal, penned with Roche this week, also coincided with the American Society of Clinical Oncology’s annual meeting in Chicago, during which researchers reported results from a multinational, prospective study supporting KRAS testing for all colorectal cancer patients.
In the US, Amgen’s Vectibix (panitumumab) is indicated for the treatment of metastatic CRC following standard chemotherapy. The US Food and Drug Administration has indicated it is awaiting prospective clinical trial data before updating the drug’s label with genetic testing information.
“The US represents an important additional market opportunity for K-RAS testing,” Melinda Baker, director of global communications at Roche Molecular Diagnostics, told Pharmacogenomics Reporter this week.
According to Baker, DxS is currently collecting prospective clinical data to support a submission for FDA approval of the KRAS test. The test is CE-marked in Europe.
Additionally, under the terms of distribution deal, DxS granted Roche exclusive distribution rights to its TheraScreen EGFR 29-Mutation test for all global markets except North America and Hong Kong. This test is also CE-marked.
DxS’ EGFR test may help better define the patient population for tyrosine kinase inhibitors, such as AstraZeneca’s Iressa and Genentech’s Tarceva. In the US, Tarceva has supplanted the non-small cell lung cancer market for Iressa, which currently has limited distribution in the US due to low efficacy in the general non-small cell lung cancer population.
However, a study published last month in the Journal of Clinical Oncology by Sequist et al. concluded that Iressa has more than double the response rate in NSCLC patients with certain genetic mutations compared to the response rate in the general population [see PGx Reporter 05-28-2008].
Genzyme Genetics is currently the only US licensee of the EGFR patent. Baker indicated, however, that DxS has initiated discussions with the FDA regarding possible approval routes for its EGFR mutation test.
“There is a growing demand for tests to indicate disease prognosis and identify patient groups more likely to benefit from a particular drug,” Daniel O’Day, Roche Molecular Diagnostics CEO, said in a statement. “Through our partnership with DxS we can leverage our extensive global infrastructure and commercial reach to provide these tests, which have the potential to improve treatment outcome in some patients.”
Baker noted that Roche will market the DxS TheraScreen tests to a range of laboratories, including large reference labs and smaller regional and local pathology laboratories.
DxS did not state a price for these tests. According to the company, the tests “have been priced to meet the current reimbursement criteria, and may vary by market.”
ASCO Presentations
The distribution deal with Roche will enable DxS “to meet the growing demand for these tests,” DxS CEO Stephen Little said in a statement this week.
In particular, demand for DxS’ KRAS mutation test may be fueled by a study presented this week at ASCO’s annual meeting.
The large, multinational prospective clinical trial, presented by lead author Eric Van Cutsem, professor at the University Hospital Gasthuisberg in Leuven, Belgium, showed that mCRC patients who carry the wildtype version of the KRAS gene are much more likely than patients with the mutated form of the gene to benefit from the monoclonal antibody Erbitux.
“KRAS testing should be routinely conducted in all colorectal cancer patients immediately after diagnosis to ensure the best treatment strategies for the individual patient,” Van Cutsem said during a news conference last week.
In the study, Van Cutsem and colleagues used tumor samples from 587 study participants with mCRC to determine patients’ KRAS status and found that 59.3 percent of patients with the wildtype KRAS gene treated with Erbitux and chemotherapy saw their tumors shrink by more than half. Of patients treated with chemotherapy alone, 43.2 percent of patients responded.
While the Erbitux/chemo combination for all patients resulted in a 15-percent decrease in risk for cancer progression, in wildtype carriers the combination treatment showed a 32-percent decreased risk.
Meanwhile, patients whose tumor carried the mutated KRAS gene experienced the same clinical results whether their regimen included Erbitux or not. KRAS mutations were found in 35.6 percent of patients in the study.
Pharmacogenomics Reporter sister publication GenomeWeb Daily News, reporting from the ASCO meeting in Chicago, quoted Julie Gralow, news conference moderator and associate professor of medicine at the University of Washington, saying that Van Cutsem’s findings give oncologists “new tools to identify the most appropriate treatment for each patient while avoiding over-treatment with drugs that have potentially toxic side effects.
“We now know the two-thirds of patients who will respond to [Erbitux], and we don’t need to give the drug to the [remaining] third now,” Gralow said at the news conference announcing the results of Van Cutsem’s study.
Roche’s Baker cited Van Cutsem’s study to note “there is growing recognition with oncologists in many markets that KRAS testing can aid therapy selection.”
DxS’ KRAS mutation test detects seven mutations in codons 12 and 13 of the K-RAS oncogene, which are frequently found in several types of cancer, including colorectal, pancreatic, lung, gall bladder, bile duct, and thyroid.
The study by Van Cutsem and colleagues was sponsored by Merck KGaA of Germany, which sells Erbitux in markets outside the US.

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