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Anti-AIDS Drug Attracts Attention at Barcelona Conference - 2002-07-09

A new AIDS drug appears promising as a way to help HIV patients who have developed resistance to current therapies. It is one of two new types of AIDS compounds being discussed at the International AIDS Conference in Barcelona.

A drug known as T-20 has drawn a great deal of attention at the Barcelona session because it is the first in new class of compounds called fusion inhibitors that work differently from previous AIDS treatments.

The approved drugs attack the AIDS virus, HIV, after it has entered cells and prevent it from reproducing. But the medical director of the Swiss drug company Roche, Dr. James Thommes, said T-20 attacks HIV at an earlier stage, before it has fused to cells.

"What is really interesting about T-20 and fusion inhibitors as a class is they target a whole new step in the viral replication process. That is at the point at which virus enters cells," Dr. Thommes said.

Roche and U.S. pharmaceutical firm Trimeris have released test results from drug-resistant patients in North America, Brazil, Europe, and Australia showing that T-20 works in them. When combined with the older compounds for six-months, T-20 reduced HIV to undetectable levels in more than twice as many of the patients as the older drugs alone did 37 percent for T-20 compared to 16-percent for the others. Since one-third to one-half of all patients have an HIV strain resistant to one or more drugs, T-20 represents a potentially life-saving therapy for them. Experts at the AIDS conference say T-20 would allow doctors to expand the number of drug combinations used to treat HIV, although long-term use could cause the virus to become resistant to the new treatment, as it has to established drugs.

A drawback is that T-20 must be injected twice daily, making it more difficult to administer than a pill. This could limit its use in poor countries with inadequate medical care. But the Roche official said T-20 could be self-administered, just as many diabetics inject insulin themselves.

He added that T-20 would probably not be as medically useful in developing nations as it is in for patients in the wealthy countries.

"Those are individuals who have been under care and treatment for the longest period of time and who harbor multi-drug resistant virus. Those are individuals we see mostly in the developed world at this point in time. The patient populations you refer to have not even been able to receive medications, which are much easier to take," Dr. Thommes said.

Roche said it plans to begin distributing T-20 by the middle of next year.

A second new class of AIDS drugs is in the earliest phases of human testing by several pharmaceutical companies. Like the older therapies, these compounds called integrase inhibitors attack HIV inside the cell, but at a different point. The older drugs use either of two enzymes HIV needs to copy itself. Integrase inhibitors block a third never before targeted.

These drugs and are much farther away from production than T-20, even if they prove effective.