Studies indicate new drug can help patients with exhausted options
Monday, July 8th 2002, 12:00 am
By: News On 6
BARCELONA, Spain (AP) _ A new drug that attacks the AIDS virus in an entirely different way could dramatically restore the health of HIV patients whose infections have outfoxed all existing medicines, research indicates.
Studies presented Monday at the 14th International AIDS Conference found that patients for whom current drugs had stopped working were twice as likely to have virus concentrations decrease below detectable levels if they added the new medicine, known as enfuvirtide, or T-20, to their cocktail.
Experts said the drug, expected to be on the market next year, could save the lives of people who have exhausted treatment options.
``If you have multiple drug resistant virus, the disease will progress. We have plenty of patients that are dying with multidrug resistant virus,'' said Dr. Robert Siliciano, professor of medicine at Johns Hopkins University, who was not connected with the study.
``We have people lining up, waiting for this drug to become available.''
Previous studies have estimated about 15 percent of HIV patients have virus strains that are immune to all current types of drugs.
James Locke, 50, of London, was one such patient. He contracted HIV in 1984 and by the mid-1990s, his virus started to show resistance. By 2000, the side effects of the drugs were so bad he had to stop taking them. In April of that year, he enrolled in the T-20 study.
``It was really quite remarkable. Within three months my viral load dropped substantially, to the point of almost undetectable,'' Locke said. ``What they (the scientists) have done is given me hope, and more importantly they've brought back my dreams.''
Current HIV drugs block either of two substances the virus uses to make new copies of itself once it is inside a blood cell. Over the last seven years, those drugs have turned HIV infection from a death sentence into a manageable chronic disease, but scientists say the medicines are losing their power as the virus develops mutant varieties that are unaffected by them.
T-20 is the most advanced experimental drug in a new class of AIDS medicines, called entry inhibitors, which attack the virus by preventing it from getting into the blood cells it kills.
The drug is being developed by Trimeris Inc., a small North Carolina biotechnology company, and Swiss pharmaceutical firm Roche.
Dr. Anthony Fauci, chief of infectious diseases at the U.S. National Institutes of Health, said the results of the T-20 studies were impressive and an important advance for patients running out of options.
``To provide another class of drug can potentially give hope to these individuals. Such drugs will help suppress the virus to a level at which a person can live a healthy life, free of disease,'' said Fauci, who was not connected with the research.
The two studies involved 1,000 patients worldwide for whom all current drugs had stopped working. They kept taking their usual drug combinations, but two-thirds were also given the new medicine, a twice-daily injection under the skin.
After 24 weeks, the amount of virus in the blood dropped below detectable levels in 37 percent of those getting the drug, compared with 16 percent of people on normal treatment.
Before the study, the patients had about 80 CD4 immune cells per cubic millimeter of blood. Anything below 100 is considered dangerous.
After six months, the average number of immune cells rose by 76 cells per cubic millimeter in the T-20 group, compared with a rise of 32 for the others.
The major side effect was skin irritation around the injection site.
``Based on these results, I think it's not in any way premature to say that T-20 is likely to become a key component of a future optimized regimen both in the United States and in Europe,'' said Dr. Jacob Lalezari, director of Quest Clinical Research and a former researcher at the University of California, San Francisco.
No drug exists that can eradicate the virus.
The prospect of wiping out HIV once it has entered the body looks even less likely now, according to other findings presented at the meeting.
HIV invades a type of immune cell called CD4+ T cells, which are activated when they see germs. Some of these activated cells survive and revert to a resting state, where they wait for years until they see the same germ again.
HIV lies dormant but dangerous in these cells, and for that reason, some experts doubt that HIV can be cleared from the body.
Siliciano reported more disheartening evidence Monday, saying it would be difficult to create a drug to seek out the infected resting cells because they look no different from uninfected resting cells.
``They only carry a silent form of the viral genome, and it's going to be very hard to specifically target them,'' he said.