GHLIT offers genetic tests for drug response

Program starts with patients on warfarin, an anticoagulant, and tamoxifen, a drug for breast cancer
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A new genetic testing program to predict patients' response to particular drugs is now available from the AVMA Group Health and Life Insurance Trust via its pharmacy benefits manager, Medco Health Solutions Inc.

Recognizing that an individual's response to certain medications is heavily influenced by genetic variations, a growing number of physicians and pharmacy benefits managers are encouraging patients to undergo genetic testing before beginning some prescription drug regimens. Genetic testing is a way to help ensure that the patient derives maximum therapeutic benefit from the medication and, equally important, does not suffer life-threatening adverse reactions.

Although broad use of genetic testing has generated debate over legal, ethical, and confidentiality issues, the primary concern has been the possibility of discrimination arising from the ability of genetic testing to determine predisposition to diseases, rather than any concerns with the use of testing to determine response to certain drugs. Many of the fears of discrimination were alleviated in 2008 with passage of the Genetic Information Nondiscrimination Act, which paved the way for individuals to benefit from the emerging practice of personalized medicine.

A growing body of research supports the potential of genetic testing to enhance the quality of care by predicting which drugs and dosages will work best for each patient. Recently, research from the Mayo Clinic and Medco, in association with the Medco Research Institute, found that genetic testing can improve the safety and effectiveness of the anticoagulant warfarin by providing information about individual patients' sensitivities to the drug.

"Warfarin represents an excellent example of how to take the modern science of genetic testing and apply it to making an older drug more effective and safer to use," said Robert S. Epstein, MD, the lead author of the study and Medco's chief medical officer. "These results show that we can greatly reduce hospitalizations, and their significant costs, by making genetic testing routine early in a patient's therapy with warfarin."

Medco found previously that about 20 percent of its patients who start taking warfarin are hospitalized for bleeding or thromboembolism within six months. The anticoagulant is exceptionally hard to dose because of wide variances in patient response. In fact, warfarin is the leading cause of drug-related emergency room visits among the elderly and the subject of a Food and Drug Administration black-box warning about the risk for excessive bleeding.

Dr. Epstein's study, appearing March 30 in the online version of the Journal of the American College of Cardiology, found that patients receiving warfarin who participated in genetic testing to evaluate their sensitivity to the drug were 31 percent less likely to be hospitalized for any cause within six months and 28 percent less likely to be hospitalized for bleeding or thromboembolism.

Genetic testing also can benefit women with breast cancer whose treatment could include the drug tamoxifen. Research has found that up to 10 percent of women are poor metabolizers of tamoxifen. A study appearing in the Dec. 20, 2005, issue of the Journal of Clinical Oncology found that poor metabolizers of tamoxifen who take the drug for breast cancer have a higher risk of disease relapse than normal metabolizers.

"These powerful findings convinced the Trust that genetic testing was something we wanted to make available to our plan participants on a voluntary basis," said Dr. Martha O'Rourke, a GHLIT trustee. "GHLIT is committed to providing veterinarians with the kind of medical coverage that strives to deliver the highest-quality, safest possible care while still containing costs. Making targeted genetic testing available to participants whose physicians recommend it is a natural extension of that commitment."

GHLIT, in conjunction with Medco, launched its genetic testing program in March. The program is currently available at no cost to most plan participants who have been prescribed warfarin or tamoxifen.

When a GHLIT participant submits a prescription for either drug to a pharmacy or the Medco Pharmacy mail-order service, Medco will alert the physician that a genetic test is available to that patient. If the physician recommends testing, Medco will contact the patient to explain the test. Patients who decide to proceed will be mailed a kit with instructions on using a cheek swab to collect cell samples in the privacy of their own home. The sample is then returned to the test lab in a special prepaid envelope.

"Knowing how an individual's genetic makeup will impact their response to these two potentially life-saving medications is invaluable information for physicians and patients when it comes to developing the most appropriate course of therapy," Dr. O'Rourke said. "By helping to enhance the efficacy and safety of prescription medications, targeted genetic testing can ultimately improve our participants' quality of life."

Information on GHLIT benefits is available at New York Life Insurance Co. (NY, NY 10010) underwrites the GHLIT insurance program. Veterinarians and veterinary students can obtain more information—including plan details, rates, exclusions, limitations, eligibility, and renewal provisions—or find a GHLIT agent by calling the Trust office at (800) 621-6360.