This week at the annual Retrovirus Conference in Chicago, researchers and clinicians gathered to discuss developments in the fight against HIV and AIDS. And from the highly technical debates and lectures, news of a new class of AIDS drugs emerged, piquing public interest and igniting hope for AIDS patients whose bodies can no longer tolerate the often toxic drug combinations currently available.
The new drugs represent a whole new approach to fighting the disease. The most commonly used drugs on the market today target the HIV virus once it has already invaded immune-system cells called CD4s. But the new class of drugs, called entry inhibitors, is designed to keep the virus from ever entering the cell walls — and therefore, scientists hope, from duplicating themselves inside the cell. And that means new hope for everyone who's concerned about AIDS, especially those who've developed resistance to existing drug courses. "This is great news, especially for HIV-positive patients," Dr. Margaret Fischl, Director of the AIDS Clinical Research Unit at the University of Miami School of Medicine, told TIME.com, "because these drugs work by blocking the virus from entering CD4 cells. Once you're infected with HIV, the virus keeps infecting new cells; it's a perpetual process of infecting healthy, uninfected cells. And these drugs represent a way to keep this from happening. It's really very exciting."
New drugs, new ways to attack the virus
There are three sub-classes of entry inhibitors: Fusion inhibitors, attachment inhibitors and co-receptor inhibitors. And while each works in a slightly different way, all entry inhibitors work on the same principle: The longer the cells can deflect attacks from HIV, the longer other drugs will have to work on destroying the existing virus already inside the cell.
Fusion inhibitors are the rising stars of the entry inhibitor group. Designed to keep the HIV virus from fusing to the cell wall, fusion inhibitors include compounds called T-20 and T-1249. The first compound, T-20, appears to be at the head of the class, so to speak; researchers report low toxicity among test cases, and relatively mild side effects like soreness and inflammation at the injection site, dizziness and nausea. For the needle-phobic, T-20 may cause a few problems — patients are required to inject themselves twice a day. But for most, even multiple injections are preferable to the incessant pill-counting and precise timing required by current drug regimens. Scientists are also optimistic about the second, more advanced compound called T-1249, which is up to 200 times more active than T-20, and is delivered via one daily shot.
For near-future treatment options, however, doctors are pinning higher hopes to T-20, which is entering Phase Three — the final stage of development. "We've been using T-20 for at least a year in clinical trials," Dr. Joel Gallant, director of the Moore AIDS Clinic at the Johns Hopkins University Medical Center, told TIME.com. The FDA will begin deliberating on the drug sometime this year, Dr. Gallant adds, and will likely consider the drug on an accelerated approval schedule. "I don't think we'll see it approved in this calendar year, although we may see improved access to the drug in certain areas," he says.