Methylated Septin Research Articles

Cost-effectiveness of colorectal cancer screening in Germany: current endoscopic and fecal testing strategies versus plasma methylated Septin 9 DNA.

Background and study aims: Colorectal cancer (CRC) screening strategies in Germany include guaiac-based fecal occult blood testing (gFOBT) starting at age 50 and a switch to colonoscopy at age 55 or continued gFOBT testing, but screening utilization is limited. Blood-based biomarkers, such as methylated Septin 9 DNA (mSEPT9), may improve screening rates. We performed a cost-effectiveness analysis of current and emerging CRC screening strategies in Germany. Methods: Using a validated Markov model, we compared annual gFOBT for ages 50 through 54 followed by biennial testing until age 75 (FOBT) or by colonoscopy at ages 55 and 65 (FOBT/COLO 55,65), substitution of fecal immunochemical testing (FIT) for gFOBT (FIT, FIT/COLO 55,65), and annual or biennial plasma mSEPT9 testing. We also considered persons who utilize only colonoscopy and varied age at colonoscopy utilization. Results: The current strategies were more effective and less costly than no screening. FIT was more effective and less costly than mSEPT9 testing. FIT/COLO 55,65 cost €12 200 per quality-adjusted life-years gained in comparison with FIT. mSEPT9-based screening was cost-effective in comparison with no screening but was dominated by other cost-saving strategies. Differential screening utilization and adherence greatly affected incremental results between strategies. In probabilistic analyses, FIT was preferred in 49 % and FIT/COLO 55,65 in 47 % of iterations. Conclusion: Currently available CRC screening strategies in Germany, including hybrid fecal testing/colonoscopy, are likely to be cost-saving. Current strategies appear superior to mSEPT9-based screening. The impact of blood-based biomarkers is likely to depend on utilization and adherence as much as on test performance characteristics and cost.

Colorectal Cancer Screening with Blood-Based Biomarkers: Cost-Effectiveness of Methylated Septin 9 DNA versus Current Strategies

Screening reduces colorectal cancer mortality, but many persons remain unscreened. Screening with a blood test could improve screening rates. We estimated the comparative effectiveness and cost-effectiveness of colorectal cancer screening with emerging biomarkers, illustrated by a methylated Septin 9 DNA plasma assay ((m)SEPT9), versus established strategies. We conducted a cost-utility analysis using a validated decision analytic model comparing (m)SEPT9, fecal occult blood testing (FOBT), fecal immunochemical testing (FIT), sigmoidoscopy, and colonoscopy, projecting lifetime benefits and costs. In the base case, (m)SEPT9 decreased colorectal cancer incidence by 35% to 41% and colorectal cancer mortality by 53% to 61% at costs of $8,400 to $11,500/quality-adjusted life year gained versus no screening. All established screening strategies were more effective than (m)SEPT9. FIT was cost saving, dominated (m)SEPT9, and was preferred among all the alternatives. Screening uptake and longitudinal adherence rates over time strongly influenced the comparisons between strategies. At the population level, (m)SEPT9 yielded incremental benefit at acceptable costs when it increased the fraction of the population screened more than it was substituted for other strategies. (m)SEPT9 seems to be effective and cost-effective compared with no screening. To be cost-effective compared with established strategies, (m)SEPT9 or blood-based biomarkers with similar test performance characteristics would need to achieve substantially higher uptake and adherence rates than the alternatives. It remains to be proven whether colorectal cancer screening with a blood test can improve screening uptake or long-term adherence compared with established strategies. Our study offers insights into the potential role of colorectal cancer screening with blood-based biomarkers.

Weighty talks about wise choices

Weighty talks about wise choices

Sensitive and selective amplification of methylated DNA sequences using helper-dependent chain reaction in combination with a methylation-dependent restriction enzymes.

We have developed a novel technique for specific amplification of rare methylated DNA fragments in a high background of unmethylated sequences that avoids the need of bisulphite conversion. The methylation-dependent restriction enzyme GlaI is used to selectively cut methylated DNA. Then targeted fragments are tagged using specially designed ‘helper’ oligonucleotides that are also used to maintain selection in subsequent amplification cycles in a process called ‘helper-dependent chain reaction’. The process uses disabled primers called ‘drivers’ that can only prime on each cycle if the helpers recognize specific sequences within the target amplicon. In this way, selection for the sequence of interest is maintained throughout the amplification, preventing amplification of unwanted sequences. Here we show how the method can be applied to methylated Septin 9, a promising biomarker for early diagnosis of colorectal cancer. The GlaI digestion and subsequent amplification can all be done in a single tube. A detection sensitivity of 0.1% methylated DNA in a background of unmethylated DNA was achieved, which was similar to the well-established Heavy Methyl method that requires bisulphite-treated DNA.

The Stool DNA Test Is More Accurate Than the Plasma Septin 9 Test in Detecting Colorectal Neoplasia

Several noninvasive tests have been developed for colorectal cancer (CRC) screening. We compared the sensitivities of a multimarker test for stool DNA (sDNA) and a plasma test for methylated septin 9 (SEPT9) in identifying patients with large adenomas or CRC. We analyzed paired stool and plasma samples from 30 patients with CRC and 22 with large adenomas from Mayo Clinic archives. Stool (n = 46) and plasma (n = 49) samples from age- and sex-matched patients with normal colonoscopy results were used as controls. The sDNA test is an assay for methylated BMP3, NDRG4, vimentin, and TFPI2; mutant KRAS; the β-actin gene, and quantity of hemoglobin (by the porphyrin method). It was performed blindly at Exact Sciences (Madison, Wisconsin); the test for SEPT9 was performed at ARUP Laboratories (Salt Lake City, Utah). Results were considered positive based on the manufacturer's specificity cutoff values of 90% and 89%, respectively. The sDNA test detected adenomas (median, 2 cm; range, 1-5 cm) with 82% sensitivity (95% confidence interval [CI], 60%-95%); SEPT9 had 14% sensitivity (95% CI, 3%-35%; P = .0001). The sDNA test identified patients with CRC with 87% sensitivity (95% CI, 69%-96%); SEPT9 had 60% sensitivity (95% CI, 41%-77%; P = .046). The sDNA test identified patients with stage I-III CRC with 91% sensitivity (95% CI, 71%-99%); SEPT9 had 50% sensitivity (95% CI, 28%-72%; P = .013); for stage IV CRC, sensitivity values were 75% (95% CI, 35%-97%) and 88% (95% CI, 47%-100%), respectively (P = .56). False positive rates were 7% for the sDNA test and 27% for SEPT9. Based on analyses of paired samples, the sDNA test detects nonmetastatic CRC and large adenomas with significantly greater levels of sensitivity than the SEPT9 test. These findings might be used to modify approaches for CRC prevention and early detection.

Detecting colorectal cancer based on presence of methylated septin 9 DNA in plasma.

e14071 Background: The improved prognosis for early-detected colorectal cancer (CRC) has supported the value of CRC screening. However, compliance is very low, partly due to the inconvenience and unpleasant nature of colonoscopy and fecal sampling. The availability of a blood-based test for CRC detection might improve compliance and enable early detection of more cancers. Detection of methylated septin 9 DNA in plasma has been associated with CRC in prior studies. We report herein the development and validation of a clinical test for methylated septin 9 DNA in plasma. Methods: Total nucleic acids were extracted from plasma using the Chemagen MSM platform. Bisulfite conversion and purification of DNA was performed using the Zymo Research DNA Direct kit. Methylated septin 9 DNA was detected using methylation-specific real-time PCR. We evaluated sensitivity, specificity, and clinical performance using plasma samples from colonoscopy-negative individuals and CRC patients at varying stages. Results: The PCR was specific for methylated DNA in the range of 0.0005–50 ng DNA/reaction. No septin 9 PCR products were detected at the same concentrations of unmethylated DNA. Five of 46 (11%) colonoscopy-negative individuals tested positive for methylated septin 9 DNA. The detection rate among CRC patients was 12/18 (67%) stage I, 8/18 (44%) stage II, 7/10 (70%) stage III, and 5/5 (100%) stage IV cases. The overall clinical sensitivity was 63%, and the specificity was 89%. Conclusions: This methylated septin 9 DNA PCR test is highly sensitive and specific for detection of the analyte. In patient samples, the assay has a clinical sensitivity and specificity comparable to fecal occult blood (FOBT) and immunochemical tests. Thus, the assay may prove to be useful for identifying patients at risk of colorectal cancer. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Quest Diagnostics Quest Diagnostics

Free circulating DNA based colorectal cancer screening from peripheral blood: the possibility of the methylated septin 9 gene marker

DNA methylation acts in early tumorigenesis. Its detection is possible either from tissue, stool or peripheral blood. Septin 9 is a sensitive methylation marker, which has been studied in several cancers such as breast and ovarian tumors and in neurological or hematological diseases. Septin proteins have an important role from cytoskeleton organisation to development of embryonal pattern. Nowadays intensive researches are going on about the relation between the septin 9 gene hypermethylation and colorectal cancer development.