Simply Irresistible: New AIDS Drug Termed 'Resistance-Repellent'

From the WebMD Archives

Feb. 6, 2001 (Chicago) -- An almost unbelievably strong new AIDS drug has entered clinical tests, according to a report presented here at the 8th Annual Retrovirus Conference. In a display of optimism rarely seen at AIDS meetings, researchers say the experimental treatment may be the first ever to defeat the notorious ability of the AIDS virus to become drug resistant.

Early human tests of a trial product of the new drug -- dubbed TMC-126 -- are under way in Europe.

"This is really the first compound that has these resistance-repellant properties," says John Erickson, PhD, chief scientific officer of Tibotec Inc., in Rockville, Md. "It should be good for salvage therapy in treating people who are resistant to all current drugs, and it should be good for drug-naive people to keep them from developing drug resistance."

One of the reasons new AIDS drugs always are needed is HIV's amazing ability to evolve into what scientists call "escape mutants." In some people treated for a long time, escape mutants can resist combinations of the most potent drugs currently available. TMC-126 appears to be flexible enough to bind to HIV no matter how much the virus shifts its shape.

"It appears that the reason TMC-126 and related compounds can bind to multiple forms [of an essential part of HIV] is that they maintain their flexibility," Erickson says.

Efforts to make an HIV mutant that can overcome TMC-126 have been unsuccessful. Computer models of the resistance process suggest that HIV cannot develop resistance to the drug and still survive.

TMC-126 is a member of a class of drugs known as protease inhibitors, which gum up the chemical scissors HIV needs to cut new pieces of virus into the right size to copy itself. The new drug is about a thousand times more potent than the current crop of protease inhibitors. Because of this, it is hoped that TMC-126 can be taken in small amounts, thereby avoiding some of the toxicities of current anti-HIV medications.

Noted AIDS researcher David Ho, MD, introduced Erickson at a press conference at the meeting. He noted that the recent changes in HIV treatment guidelines -- which call for delaying AIDS therapy -- came about partly because of concerns over drug toxicity.

"We need not only more potent drugs but drugs that lack these side effects," Ho says. "One particular example is Dr. Erickson's drug."