Authors' objectives:

The aim of this report is to review the available information on the use of the AmpliChip CYP450 test (Roche Molecular Systems, Pleasanton CA), a drug metabolizing enzyme (DME) genotyping system that detects genetic variations (polymorphisms) in two CYP450 genes, CYP2D6 and CYP2C19, using deoxyribonucleic acid (DNA) extracted from patients' blood. It is used with the GeneChip System 3000Dx microarray platform developed by Affymetrix (Santa Clara CA). This test, intended to help physicians with drug selection and individualization of drug therapy, helps to identify the following CYP2D6 metabolizer phenotypes: poor metabolizer, intermediate metabolizer, extensive metabolizer, or ultrarapid metabolizer; and of the CYP2C19 phenotypes.

Authors' recommendations: No published studies show that patient outcomes can be predicted or altered by knowledge of DME status in the absence of other confounding variables. Prospective studies are needed to assess the benefits and potential risks of this technology in guiding drug selection and dose adjustment. Until such studies are available, DME test results can only supplement other tools for therapeutic decision making, with routine monitoring by a physician. To offer the Roche AmpliChip CYP450 test, a laboratory would be required to buy the Affymetrix GeneChip System 3000Dx. At this time, the AmpliChip CYP450 test is the only diagnostic test that requires this instrumentation. Pharmacogenomic testing carries many social and ethical issues. 'Personalized' drug therapy may improve patient outcomes, and facilitate the development of new drugs, but there is a potential for the inappropriate or unjustified use of this test. This could have cost implications. Concern has been expressed that genotype testing could emphasize fundamental differences between ethnic groups, or could disqualify patients from treatment or insurance coverage because of a pre-existing condition. While there may be an incentive for industry to validate the testing of drugs under development or with patent protection, there is likely no incentive to validate off-patent drugs. These issues underscore the need to identify groups of patients who are most likely to benefit from DME genotyping. Guideline development and cost-effectiveness evaluation will be key factors in defining the appropriate use of the AmpliChip CYP450 test.

Authors' methods: Overview

Project Status: Completed

URL for project: https://www.ccohta.ca/

Year Published: 2006

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: Canada

Organisation Name: Canadian Coordinating Office for Health Technology Assessment

Contact Address: 600-865 Carling Avenue, Ottawa, ON K1S 5S8 Canada. Tel: +1 613 226 2553, Fax: +1 613 226 5392;

Contact Name: requests@cadth.ca

Contact Email: requests@cadth.ca

Copyright: Canadian Coordinating Office for Health Technology Assessment (CCOHTA)