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Plavix Biomarker Test Can Improve Patient Outcomes

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In January, the Agency for Healthcare Research and Quality (AHRQ) released “Outpatient Prescription Anticoagulants Utilization and Expenditures for the U.S. Civilian Noninstitutionalized Population Age 18 and Older 2007,” a study from its October 2009 Medical Expenditure Panel Survey (MEPS). This report found that anticoagulant drugs were prescribed to more than 4.2 million Americans at a cost of $900 million and were paid for by patients and/or third-party payers.

Achieving correct therapeutic levels of the drugs most often used — warfarin (Coumadin, Bristol-Myers Squibb) and clopidogrel bisulfate (Plavix, Sanofi Aventis/Bristol-Myers Squibb) — is typically described as a challenging trial-and-error process. The discovery that the genetic biomarker CYP2C19 affects an individual’s ability to properly metabolize these agents allows a more personalized approach, but this requires a test ordered by a physician and payor reimbursement.

A dramatic step forward

On March 12, FDA added a boxed warning to the clopidogrel label, highlighting “reduced effectiveness in patients who are poor metabolizers of Plavix” and encouraging physicians to consider another product and/or to test their patients for the biomarker before prescribing the drug.

For many physicians, routine testing is not yet protocol. According to Roland Valdes, PhD, co-founder and chairman of PGXL Laboratories, a pharmacogenetics company in Louisville, Ky., the millions of anticoagulant patients at risk can’t afford to wait for physicians to get on board with genomic testing.

In a novel collaboration with PBM giant CVS Caremark and its specialty pharmacy Generation Health, PGXL Laboratories will use its expertise in anticoagulants to improve the quality of patient care through pharmacogenetic testing, physician education, and drug-specific software programs.

The program, launched July 1, “will be a dramatic forward step in personalized medicine” for patients who may receive the anticoagulant Plavix, Valdes said.

“The goals of our company include providing the highest level of testing and to support the tests with follow-up interpretation at the physician level,” Valdes said, adding that his laboratory was the first to be certified as an exclusive pharmacogenomic testing facility according to the federal Clinical Laboratory Improvement Amendments of 1988.

Physician participation

Although controversy over retail genetic testing for consumers has been in the spotlight lately, Mark Linder, PhD, vice president and co-founder of PGXL laboratories, said, “We believe genetic testing needs to be ordered and authorized by a physician,” adding that this “keeps the physician at the center of patient care.”

Jeffrey D. Marrazzo, vice president of marketing and development, Generation Health, said that the program will work through integrated services to assist in the care of anticoagulant patients. The process, Marrazzo said, is a retrospective one and will be in place for as many as 50,000 CVS Caremark members.

“This program seeks to find patients who may be at risk if they take or are newly prescribed the drug Plavix,” Marrazzo said, adding that recent data show that up to 26% of this population may carry a variant of the biomarker CYP2, which has been shown to affect the proper uptake and metabolism of anticoagulants.

“Once a prescription for Plavix is filled, it is sent in for reimbursement,” he said. “Then each evening all new prescriptions for Plavix are flagged, and based on the assessment of the clinical pharmacologists, a fax about pharmacogenomic testing is sent to the prescribing physician.”

The fax notifies the physician about the availability and benefit of the test. Using a gated set of questions, the physician can decide whether to request the genetic test provided by PGXL.

The PGXL test results are sent to the physician, who may consult with the company further about the results. The physician also may elect to purchase an innovative proprietary software program developed by PGXL that aids in the predictive dosing of the drug.

Calling this user-friendly desktop program “a major breakthrough,” Valdes said that “the focus is on the interpretation and actionables of the program. We look at the genetics first, but also, what does it tell us about the pharmacology? That’s where we see the real potential.”

Linder said that the key feature of the test used with the computer program is that “the platform interprets the pharmacologic value of the genetic variance.” This tool allows physicians to see a day-by-day prediction of the therapeutic values patients can achieve at various dosing levels.

Implications for the future

The anticoagulant program does not now require the community pharmacist to play an active role in managing the physician and patient contact process, but Valdes believes that the future of genomic science and pharmacology are inextricably linked.

“This whole concept is a revolution going from intuitive to precision medicine,” he said, adding that the trend will serve to increase the role of the community pharmacist, who will increasingly be called upon for consulting services, he believes.

According to Marrazzo, this program is likely both to improve patient care and to reduce costs incurred through hospitalizations resulting from drugs that don’t work and the attendant adverse events.

Source: Drug Topics