Drug Offers Hope With Resistant HIV, Scientists Say

A novel experimental drug is showing highly promising results in two large phase III clinical trials, offering new hope for thousands of patients with drug-resistant HIV, scientists reported at the 14th International AIDS Conference on Monday. The drug, T-20 or enfuvirtide, is a member of a new class of drugs called fusion inhibitors that attack HIV directly.

Unlike the traditional AIDS drug cocktail that inhibits the division of already infected cells, T-20 keeps the HIV cell from fusing with healthy cells. When added to combinations of standard drugs, injections of T-20 significantly reduced high levels of HIV in the blood of patients deemed infected with drug resistant virus, compared with those who took standard drugs.

In one study, the amount of HIV in the blood fell to recommended levels in 121 of 326 patients (37 percent) among the T-20 recipients compared with 27 of 165 (16 percent) among those who did not receive T-20. In the second study, the comparable figures were 95 of 335 T-20 recipients (28 percent) and 23 of 169 patients who did not receive T-20 (14 percent). The T-20 combination also led to an increase in the number of CD4 white blood cells. The studies involved 1,000 patients at 112 hospitals in the United States, Europe, Australia and South America.

AIDS experts welcomed the news about T-20. They have long pleaded for pharmaceutical companies to develop a new class of drugs to help extend the lives of the thousands of patients who are infected with drug-resistant HIV. Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md., said the trial findings "are important because they are proof of the concept" that fusion inhibitor drugs can work. The trials, Fauci said, "were meticulously done by meticulous researchers."

The Food and Drug Administration has given T-20, manufactured by Roche, fast-track designation, meaning that the FDA will expedite review of applications for drugs that have the potential to fill gaps in treatment of life-threatening diseases. If licensed, T-20 would become the fifth class of HIV drugs approved for standard use. "That would greatly broaden therapeutic options," for fighting AIDS, Fauci said.

T-20 is a synthesized version of a protein known as a peptide, made up of amino acids. It was developed by Trimeris and Roche from a discovery that Dr. Thomas Matthews and Dr. Dani Bolognesi made at Duke University in 1992.

Once started, lifetime treatment of HIV is needed. But because T-20 trials lasted 24 weeks, the long-term benefits and dangers of the drug are not known. In addition, T-20 has a drawback in that it has to be injected under the skin twice daily. The most frequent adverse effect of T-20 was a skin reaction at the site of injection. A number of T-20 recipients also experience diarrhea, nausea, dizziness, fatigue, insomnia and headaches.

Roche officials plan to file for approval of T-20 this year and are expected to manufacture enough of the drug to allow expanded use on a compassionate basis later this year.

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