Chicago Tribune (CT) - FRIDAY, January 24, 1997
Chuck Hutchcraft, Tribune Staff Writer.

Abbott's Norvir, he decrees, "decreases the viral load better than all other protease inhibitors," the new class of AIDS drugs that is renewing hope in the battle against the deadly disease.

Using Norvir in combination with another protease inhibitor and other AIDS drugs, Pavlatos says he has seen "a large number come back from the dead . . . who have gone off disability and back to productive work."

The Chicago physician treats 300 AIDS patients, 15 with the combination therapy.

Wonderful testimony. The only trouble is, AIDS still has the upper hand.

So it is with much anticipation that members of the AIDS community have gathered for the 4th Conference on Retroviruses and Opportunistic Infections this week in Washington.

There researchers are expected to present evidence from studies that is more conclusive about the effectiveness of protease inhibitors, as well as insight into the perplexing question of how the AIDS virus develops resistance to these drugs.

Earlier results were presented last summer at a similar conference in Vancouver, Canada.

North Chicago-based Abbott and its competitors also will be providing glimpses of the next generation of protease inhibitors they say will make up for the shortcomings of the first.

"The goal of the second-, and third-generation, protease inhibitors is to find a drug that by itself is powerful enough" to "totally suppress and possibly eradicate the virus," and that can be taken as one pill "that doesn't have to be kept under refrigeration," said Gordon Nary, executive director of the Chicago-based International Association of Physicians in AIDS Care.

In other words, a drug that can be used worldwide, Nary said. If such a drug could be discovered by 2000, "it would totally change the picture of this global epidemic," Nary said.

For Abbott, the next-generation protease inhibitor is ABT-378, for which Phase I clinical trials on humans are just starting. Results from laboratory studies are promising, says Dale Kempf, a research fellow at Abbott, who was instrumental in helping to develop Norvir and who presented a paper from ongoing studies with Norvir at the conference Thursday.

It was just over a year ago that the U.S. Food and Drug Administration approved the first of a new class of AIDS drugs, developed by Hoffman-La Roche Inc. and marketed as Invirase.

Three months later, Abbott obtained FDA approval for Norvir, and shortly after came the go-ahead for Merck & Co.'s Crixivan.

Initial results showed the protease inhibitors virtually eliminated the AIDS virus in patients. But there are problems. Patients who skip treatment for even as briefly as a day or who undertake a sequence of one-drug therapies are certain to develop strains of the virus that resist treatment, says Dr. Allan P. Frank, another Chicago AIDS physician and medical director for Home Access Health in Hoffman Estates, which produces a home AIDS test kit.

For instance, Norvir, considered the most potent of the three protease inhibitors, is also the most toxic, producing adverse side effects that many patients cannot tolerate.

Researchers have found most effectiveness by combining protease inhibitors with other AIDS drugs and with other protease inhibitors.

The combination of Invirase and Norvir has been found to be particularly effective, with one playing off the strength of the other.

But the regimens are still complicated and costly, and therefore difficult for some patients to maintain.

Kempf says early indications are that ABT-378 "will inhibit HIV replication at an amount that is 10 times lower than what is needed for" Norvir. This could lead to a regimen with a smaller dosage of Norvir, decreasing the chances of side effects but maintaining higher levels of the drug in the blood, "profoundly" raising the resistance to mutant strains of the virus, Kempf said.

Copyright 1997/The Chicago Tribune. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Permissions Desk, The Chicago Tribune, 435 North Michigan Avenue, Chicago, IL 60611.

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