October 9, 2008

Weill Doctor Tests New Drug To Fight Resistant Strain of HIV

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Between 25 and 30 percent of HIV-infected patients have a resistant strain of the virus which is not curable by current medications, but a recent Cornell study found that a new drug may be able to help. Dr. Roy Gulick of the Center for Special Studies at Weill Cornell Medical College, authored a 48-week study on the effects of Maraviroc, a drug approved last year by the U.S. Food and Drug Administration.
“We were able to suppress levels of HIV below the level of detection in about 40 to 50 percent of patients,” Dr. Gulick said. Furthermore, the patients did not report any negative side effects due to the new medication.
The study, “Maraviroc for Previously Treated Patients with R5 HIV-1 Infection,” appeared in last week’s issue of the New England Journal of Medicine. Over 1,000 patients infected with HIV who had been previously treated for the disease participated in the study. All patients received the most current regimen of HIV drugs. One group of patients also took Maraviroc once each day, another group twice a day, and the last group took a placebo pill.
According to Dr. Gulick, current treatments for HIV/AIDS involve a combination of three or four medications taken at the same time so that the virus won’t become resistant to any single drug. Nevertheless, HIV is constantly mutating into strains that could remain untouched by popular treatments.
“The first step of HIV infection involves the virus identifying a cell in the body called the T-Cell, or the CD4T lymphocyte. The virus binds to the CD4T receptor — like putting a key into a lock on a door, and turns the key. HIV needs a second receptor, also sitting on the surface of the cell, to be able to enter the cell. So essentially there are two doors or receptors that need to be unlocked in order to be infected with the virus,” Dr. Gulick said.
The study focused on the R5 strain of HIV, which binds to the CCR5 receptor on human cells. “The drug Maraviroc is one of a new class of drugs that are called CCR5 antagonists, which bind to a receptor on a cell and prevent entry of the virus into the cell. These drugs work in a brand new way, and can be active even in patients who are resistant to other drugs on the market,” said Dr. Gulick.
After studying cases of natural immunity to the HIV virus, scientists took a new approach to creating drugs for treatment of the disease.
“Some people lack the gene that codes the CR5 receptor; one of their “doors” is essentially not there. About 1 percent of people worldwide are lacking that gene which is necessary for the contraction of HIV. People thought this would be a good way to develop a drug because we have this natural experiment of HIV resistance,” Dr. Gulick said.
Maraviroc works in this way — “viroc” stands for “viral receptor occupant.”
Some doctors worry that the high cost of Maraviroc will make it inaccessible for patients, as a $1,900 test is necessary to determine if a person has the R5 strain of HIV. Dr. Gulick emphasized the high cost of HIV medications in general, and said that taking the wrong medication could result in hospitalization or death.
Although Gannett offers primary care only, students diagnosed with HIV/AIDS and proscribed Maraviroc can get the drug from the campus pharmacy.
“People can get it from the pharmacy here. It’s a medication available in two different strengths, and is a very expensive drug, which is usually the case with new medications and most HIV medications. It’s an overnight prescription, so students can request it and pick it up the next day. It’s not sitting on the shelf because there’s not enough demand for it yet,” said Sharon Dittman, associate director for community relations.
Dittman said that Gannett administers about 600 tests for HIV/AIDS each year.
As of Dec. 2007, 33 million people were living with HIV/AIDS around the world, and last year 2 million people died from the disease, according to statistics from the World Health Organization website. Researchers are optimistic that new drugs like Maraviroc will be able to target the virus where other medications have failed.