Expert: Better HIV Drugs Won't Cure AIDS
Progress, Problems With New Drugs and Vaccines Revealed at Conference
Stunning bad news on the vaccine front came from Harvard's Bruce Walker, MD. Based on results in monkey experiments, the most promising crop of AIDS vaccines are those that induce virus-fighting T cells. Walker is an expert on these cells. According to an article by Laurie Garrett in Newsday, Walker reported on a patient who began effective drug treatment very soon after becoming infected with HIV. This patient developed very strong T-cell immune responses that kept the virus in check, even when he stopped taking anti-HIV drugs. But this strong T-cell immunity didn't keep him from getting a second HIV infection. It didn't even keep the new infection from making him very sick. That's very bad news for vaccines. It remains to be seen whether this finding has broad-reaching implications, or whether it's just a scientific oddity.
Better vaccine news came from several presentations. The most intriguing is a report by Julianna Lisziewicz, MD, co-director of Georgetown University's Research Institute for Genetic and Human Therapy. Lisziewicz and colleagues have developed a therapeutic DNA vaccine -- they call it DermaVir -- that can be applied directly to the skin. The vaccine prolonged the lives of monkeys infected with a monkey AIDS virus.
There was plenty of new-drug news. As reported from the conference by William A. O'Brien, MD, for WebMD Medscape, highlights included:
- Fos-amprenavir is a new version of the protease inhibitor Agenerase. It's much easier to take and may be approved by the end of 2002.
- MIV 301 was discovered 14 years ago but abandoned because of severe bone marrow toxicity. Now it turns out the drug is highly effective against HIV resistant to other nucleoside-based anti-HIV drugs such as AZT.
- DPC817 and ACH-126,443 are two different drugs from two different companies that are mirror images of each other. They differ in activity and toxicity, but they are both active against drug-resistant HIV.
- Capravirine (AG1549), a non-nucleoside reverse transcriptase inhibitor (NNRTI) that was on hold because it was toxic in dog studies. Now, it appears, it doesn't harm humans.
- SCH-C keeps HIV from getting into cells by the CCR5 entryway. Early trials showed that it might cause heart problems. Now there's SCH-D, a more active version.
- PRO 542 and the more recent PRO 140 are manmade antibodies that keep HIV from catching hold of cells. These agents have antiviral activity that continues or increases during the week after short-term administration is discontinued.
- AMD-070 keeps HIV from getting into cells through the CXCR4 entryway.
- L-870812 and L-870810 are part of a new generation of drugs that block integrase. That's the substance HIV uses to stick its genetic code into the DNA of human cells. Right now there aren't any approved integrase inhibitors, so a new class of drugs would be a big help. What's more, HIV that becomes resistant to integrase inhibitors seems to be greatly weakened.
- S-1360, another integrase inhibitor, was shown to be well tolerated in 18 healthy volunteers. Trials will continue, likely with once-daily dosing.