By Turna Ray
Transgenomic this week launched its Surveyor Scan KRAS kit, claiming it can detect mutations not picked up by DxS' TheraScreen: KRAS Mutation Kit and standard sequencing methods.
The Surveyor KRAS test is the first mutation detection kit Transgenomic is launching on its Surveyor nuclease and Wave HS DHPLC platform, which uses PCR amplification and hybridization to form heteroduplex DNA molecules in samples with KRAS mutations. The Surveyor nuclease splices the DNA strands at mismatched base pairs, and the different-sized DNA segments then stand apart on a chromatogram as additional peaks when compared to non-mutant DNA.
“In addition to detecting the most common activating mutations, it also detects other mutations that current sequence-specific methods will not find," claimed Eric Kladjian, Transgenomic’s Chief Scientific Officer, in a statement.
In launching its Surveyor Scan KRAS mutation detection kit, Transgenomic will take on DxS' KRAS test, which is being globally marketed by Roche Diagnostics, and being developed as a companion test for two major colorectal cancer drugs, Bristol-Myers Squibb's Erbitux and Amgen's Vectibix [see PGx Reporter 09-02-2009].
Earlier this year, the US Food and Drug Administration updated the labeling for Erbitux and Vectibix to note that patients with certain KRAS mutations will not respond to these EGFR-inhibiting monoclonal antibodies. DxS, which was acquired by Qiagen in September, has submitted its test for approval by the FDA [see PGx Reporter 03-04-2009].
At the American Association of Cancer Research's annual meeting this year, OSI Pharmaceuticals presented data from a lung cancer study comparing Transgenomic's Surveyor Scan KRAS test with standard sequencing and DxS' Scorpions ARMS allele-specific KRAS test.
"The study demonstrated that the Surveyor method was more sensitive then sequencing and a better predictor of response to single-agent anti-EGFR therapy than Scorpions ARMS," Transgenomic said.
According to the company, its Surveyor Scan KRAS test detects mutations by enzymatic cleavage at mutation sites; identifies all known and unknown mutations in both KRAS coding exons; includes control templates for common mutation sites in codons 12, 13 and 61; and can be used with formalin-fixed paraffin-embedded tissues.
By comparison, DxS' KRAS test kit detects seven KRAS mutations in codons 12 and 13; detects mutations at 10 copies or below; is compatible with most real-time PCR machines; and can be used with DNA samples from fresh or frozen tumor samples and PET samples.
Both firms claim that their tests can detect mutations that are missed by sequencing and that they are able to detect 1 percent of KRAS mutant in a background of wild-type DNA.
According to Transgenomic CEO Craig Tuttle, the Surveyor Scan KRAS test will be the first of several detection kits the company is developing for diagnostic use with its Wave HS platform. "Additionally, we will be able to develop Surveyor Scan kits on other instrument platforms; we believe that this will enhance the adoption of our assay," Tuttle said.
Transgenomic said it plans to follow the launch of the KRAS test kit with tests for detecting BRAF, p53, and other mutations for cancer prognosis and treatment response.