Early detection of colorectal cancer in blood plasma: Clinical evidence supporting use of septin 9 DNA methylation in laboratory routine

Purpose: Colorectal cancer (CRC) screening has a low compliance rate, although the prognosis for colorectal cancer patients is more likely to be favorable when the disease is detected early. The Septin9 test is a potential new alternative as a CRC screening tool especially for patients not willing to accept a screening colonoscopy or perform FOB testing. A single blood sample can be taken at a local physician's office and then analyzed by a diagnostic laboratory. Epigenomics has developed an IVD assay for detection of methylated DNA within the Septin 9 gene (mSEPT9) in plasma, marketed under the brand name Epi proColon early detection test. Several independent case- control studies on more than 3,300 plasma samples demonstrated that the detection of methylated DNA within the Septin 9 gene (mSEPT9) in plasma is strongly associated with the presence of CRC. Description: To broaden test availability and further determine the characteristics of the Septin9 test in the clinical routine we have evaluated the performance of the test on 257 clinical specimens and performed a concordance study on technical material as well as 169 clinical specimens using assay versions optimized for use on two common real-time PCR systems. The Septin9 test detects CRC-derived, cell-free DNA in blood plasma. DNA is extracted from human plasma, bisulfite converted, and then purified using the Epi proColon workflow. Detection of DNA is accomplished via the Epi proColon real-time PCR assay combining a highly sensitive DNA methylation specific mSEPT9 DNA detection assay and ACTB DNA measurement as an internal control. The real-time PCR assay has been optimized for two common real-time PCR systems: the Roche LightCycler 480 and the Applied Biosystems 7500 Fast real-time PCR system. Results and Conclusion: The clinical performance of the Epi proColon real-time PCR assay has been established in a case - control study on 257 plasma specimen. We demonstrated that this assay detects around two thirds of CRCs even if disease is in an early, still localized state, while keeping the specificity at about 90% when plasma from colonoscopy verified CRC negatives are tested. These results are in concordance with previous studies using research grade workflows. The side-by-side testing of plasma specimens from 169 individuals including CRC of all stages as well as clinical controls study provided evidence for a high level concordance of results for the two assay versions. The tumormarker mSEPT9 has now been demonstrated in several independent studies to reliably detected themajority of CRCs cases using routine blood plasma samples. The IVD assay offered with the Epi proColon early detection kit provides diagnostic laboratories with a certified tool for detection of mSEPT9 in plasma. The studies to date have shown that Septin9 testing may be a viable alternative for individuals rejecting other methods for colorectal cancer screening. A prospective collection of approximately 8,000 individuals undergoing screening for CRC in 32 centers in U.S. and Germany, called PRESEPT, has identified more than 50 invasive CRC patients. The results of mSEPT9 testing in this intended use population will provide a high level of evidence for the usefulness of this new method as a CRC screening alternative.