Genetic Testing for Helicobacter pylori Treatment
DESCRIPTION
Helicobacter pylori (H. pylori) is a bacterium associated with a range of gastrointestinal disorders such as peptic ulcer disease, chronic gastritis, and gastric malignancy. Eradication of H. pylori has been proven beneficial for a number of indications.
There are currently multiple regimens for treating H. pylori infection. These include proton pump inhibitors or PPIs (as well as similar medication) to suppress acid production, in combination with antibiotic treatment, consisting of one or more agents such as amoxicillin, clarithromycin, or metronidazole. Treatment failures are most often attributed to antibiotic resistance or poor compliance.
Genetic factors may influence the success of H. pylori treatment through effects on PPI metabolism. Individuals with polymorphisms in the CYP2C19 gene, a component of the cytochrome P450 (CYP450) system, metabolize PPIs more slowly than normal. Differences in PPI metabolism lead to variation in gastric acid suppression, with associated variability in gastric pH, and potential impact on the efficacy of H. pylori treatment. Observational research suggests that individuals who are extensive metabolizers of PPIs have lower eradication rates following standard treatment for H. pylori, compared with poor metabolizers.
The Roche AmpliChip Cytochrome p450® genotyping test has been approved by the Food and Drug Administration (FDA) as a class II medical device. The test examines the polymorphisms in CYP2D6 and CYP2C19 isoenzymes of the cytochrome P450 enzyme system. Approval for this device was originally granted in December 2004 as an aid in determining treatment choice and individualizing treatment dose for therapeutics that are metabolized primarily by the CYP2D6 enzyme. The use of information on the CYP2C19 polymorphisms was not addressed as part of the FDA approval process.
POLICY
Genetic testing for the treatment of Helicobacter pylori is considered investigational.
See also:
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ADDITIONAL INFORMATION
The scientific evidence does not permit conclusions on whether the use of a pharmacogenomics-based treatment regimen for H. pylori improves eradication rates.
In the single randomized, controlled trial comparing a pharmacogenomics-based treatment regime with a standard regime, eradication rates after first-line treatment were higher for the pharmacogenomics group compared with the standard treatment group. However, because of numerous variations in treatment protocol within the pharmacogenomics groups, it is not possible to determine whether the improvement resulted from the tailored PPI dosages according to CYP2C19 genetic status, or due to other variations in the treatment protocol unrelated to CYP2C19 status. It is possible that other clinical factors, such as clarithromycin resistance, or other treatment factors, such as length of antibiotic treatment, may have influenced eradication rates. Therefore, additional trials are needed to address the issues noted above, including alternative treatment regimens, before conclusions can be made on whether a pharmacogenomics-based treatment regimen improves H. pylori eradication rates compared to the standard treatment regimen. Since the impact of this testing on clinical outcomes (clinical utility) is not currently known, this testing is considered investigational.
SOURCES
BlueCross BlueShield Association. Medical Policy Manual. (7:2011). Genetic testing for Helicobacter pylori treatment (2.04.50). Retrieved November 8, 2011 from BlueWeb. (13 articles and/or guidelines)
Ishida, Y., Goto, Y., Kondo, T., Kurata, M., Nishio, K., Kawai, S., et al. (2006). Eradication of Helicobacter pylori accruing to genotypes of CYP2C19, IL-1B, and TNF-A. International Journal of Medical Sciences, 3 (4), 135-140.
Li-Wan-Po, A., Girard, T., Farndon, P., Cooley, C., & Lithgow, J. (2010). Pharmacogenetics of CYP2C19: Functional and clinical implications of a new variant CYP2C19*17. British Journal of Clinical Pharmacology, 69 (3), 222-230.
U. S. Food and Drug Administration. (2007, June). Center for Devices and Radiological Health. Medical devices. Guidance on pharmacogenetic tests and genetic tests for heritable markers. Retrieved November 8, 2011 from http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm077862.htm.
ORIGINAL EFFECTIVE DATE: 10/11/2008
MOST RECENT REVIEW DATE: 12/8/2011
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