October 28, 2010

PREDICT helps match patient with proper drug

Featured Image

Scyble Van Cleve, right, is the first patient at Vanderbilt to benefit from a new program that puts genetic information in the patient’s medical records to help physicians like John McPherson, M.D., choose the drug and dose that will benefit them the most. (photo by Susan Urmy)

PREDICT helps match patient with proper drug

Had Scyble Van Cleve, a spry 83-year-old from Brentwood, had her heart procedure done a month ago instead of one week ago, she would have been prescribed the standard dose of clopidogrel, a blood thinner used to prevent blood clots from forming around her coronary stents.

Her doctors may not have known that, based on her genes, she needed a different blood-thinning regimen to safeguard her from possible fatal complications.

Thanks to a novel program implemented at Vanderbilt called PREDICT, Van Cleve was identified as having a genetic variation that made her a poor metabolizer of clopidogrel.

“There's nothing normal about me,” joked the self-described 'pistol.'

Van Cleve is the first patient at Vanderbilt to benefit from Pharmacogenomic Resource for Enhanced Decisions in Care and Treatment (PREDICT), which puts genetic information in patients' electronic medical records to help their physicians choose the drug and dose that is best for them.

With a simple blood test, Van Cleve's cardiologist, John McPherson, M.D., was able to tell what drug his patient needed and how much of it would work for her. When he logged in to her electronic medical record, there was a red flag indicating Van Cleve carries the CYP2C19 *2*2 genotype.

“We modified her anti-platelet therapy based on information that she will not respond to standard clopidogrel dosing. She is a poor metabolizer for the drug. The genes we tested her for are for the proteins that convert clopidogrel into the active form. She was not going to have enough of the active drug in her system” McPherson said.

Because she carries the genotype, she was at high risk for heart attack or even death, so proper dosing of clopidogrel is imperative, McPherson said.

“Mrs. Van Cleve's risk for an adverse event in the next year related to her stent procedure is much higher than someone who does not have this gene; we presume that most of the risk is because she doesn't respond to standard dosing of clopidogrel so she's not getting the benefit of the drug, which people need after getting a stent,” McPherson said.

Stents are placed in about 2,500 patients per year at Vanderbilt to open up clogged arteries, and a significant number of the patients will carry a genetic variation that prevents clopidogrel from being efficiently converted in the liver into its active form. That variation will be especially severe in about 75 patients, and the drug won't work in them.

Since September, all patients undergoing cardiac catheterization at Vanderbilt University Medical Center are being offered testing for a genetic variation that can affect their response to clopidogrel. Vanderbilt is the first academic medical center in the country to deliver this form of “decision-supported, personalized” drug therapy.

The goal is to reduce the risk of future complications, including strokes, heart attacks and sudden cardiac death.

“PREDICT worked just like we hoped it would for this patient,” McPherson said. “We look forward to rapidly expanding this approach for many other patients where clear genetic evidence is available to guide drug or dose selection.”