Studies show effectiveness of new therapies for AIDS Drug combinations erase detectable HIV, but no one says 'cure'

VANCOUVER, British Columbia -- After weeks of hints that scientists were making remarkable progress in treating AIDS, the results from several studies were released publicly for the first time at an international meeting on AIDS in Vancouver that ended yesterday.

Whether people had had AIDS for years or had been infected for a few weeks, combinations of new and older drugs suppressed the AIDS virus below the limits of detection for long periods.


But the scientists who conducted the studies and other experts said in interviews that the findings, as dramatic as they are, could not be called a cure.

No studies have documented a cure in any person infected with HIV, the virus that causes AIDS, a number of speakers emphasized.


Nonetheless, the results mark a clear watershed in the treatment of AIDS, since the available drug therapies have gone almost overnight from the unspectacular to the possibly significant.

Although leaders in AIDS research and treatment and HIV-infected individuals were generally thrilled by the new hope in AIDS treatment, they said there was no way to know how long the drugs' beneficial effects would last.

The new findings came mainly from two studies led by researchers in New York City. In each, patients took two older drugs, AZT and 3TC, in combination with a member of a new class of drugs known as protease inhibitors.

The numbers of people involved in each study are very small, but the proportions of patients responding to the treatment are high enough to give doctors confidence that they are seeing a genuine improvement.

Still, they have many cautions, chief among them the fear that the virus may, in time, develop resistance to the new drugs -- just as it has done to older ones.

At the Aaron Diamond AIDS Research Center, doctors focused on nine patients who were treated within 90 days of acquiring HIV infection.

In that study, the AIDS virus became undetectable for up to 300 days after the participants started taking a combination of the three drugs that included a protease inhibitor called ritonavir.

In the second study, researchers from New York University led a trial of combination therapy in people with AIDS for whom earlier anti-HIV therapy had failed.


Of the seven patients who had completed 48 weeks of treatment with a different combination, the new set of drugs brought HIV down to undetectable levels in six of them, or 86 percent. This group's combination therapy included another protease inhibitor, indinavir.

Until the studies began, the combination of AZT and 3TC offered the best chance of extending life, but these two drugs offered little chance of reducing the virus to undetectable levels.

These two drugs attack the same target, an enzyme component of the virus known as reverse transcriptase.

What has made the difference is adding a third drug, usually one that attacks a different viral enzyme, a protein enzyme known as protease. The task of sidestepping three different drugs appears to be more difficult for the virus.

The three-drug combinations have yielded results that have astonished the researchers who conducted the studies, and virtually everyone else involved in the fight against AIDS.

Although the third drug in the combination used in the studies reported yesterday was a protease inhibitor, a Canadian study reported earlier at this meeting by Dr. Julio S.G. Montaner of hTC Vancouver found that inclusion of a drug known as nevirapine instead of a protease inhibitor showed similar benefit.


Yet in earlier studies, nevirapine had failed when given alone because HIV quickly became resistant to it.

Experts, despite their enthusiasm, urged caution in interpreting the new findings. They said that even though the virus could not be detected in the blood of treated patients, it might still be present in other tissues.

Another concern is that the drugs could cause harmful effects as individuals take them for increasingly longer periods.

Dr. John Bartlett, chief of infectious diseases at the Johns Hopkins Medical Institutions, said the new drug combinations represent a huge leap over anything doctors have been able to offer patients before.

"What they have shown is that these are the most powerful drugs we have," he said.

"But I think it's premature to talk about a cure. There isn't &L; anybody who is cured yet."


He also noted that many patients can't tolerate the drugs because of side effects, and others have a hard time complying with complicated dosing schedules.

The treatment is very demanding on the patients; it can require taking more than 15 pills a day at precise times, often on an empty stomach, with side effects that some people cannot tolerate.

In the United States the cost of most of the drug combinations and monitoring tests can exceed $15,000 annually.

Pub Date: 7/12/96