The Washington Blade Inc. - Friday, November 6, 1998
Lisa Keen

One, in San Diego, involved a group of about 300 patients who had been taking the combination of indinavir-AZT-3TC and had CD4 counts above 200 and viral load below 200 for between four and six months. The patients were then divided into three subgroups: One subgroup continued on the triple-drug combination, a second subgroup dropped to taking only indinavir, and the third subgroup dropped to only AZT-3TC. Six months later, the group which stayed on all three drugs was doing much better. Only four percent of that group had seen any increase in their viral loads, while 23 percent of the other two groups saw increases.

The second study, in Paris, also divided about 300 patients into three subgroups. In France, one subgroup continued on all three drugs, a second took only AZT-3TC, and a third took only AZT-indinavir. Again, while 31 percent of the AZT-3TC group saw their viral loads go up and 22 percent of the AZT-indinavir group did, only nine percent of the three-drug group saw viral load increases.

The results appear to confirm earlier studies which found viral loads rebounding after drug therapy regimens were cut back.

Defining drug failure: Don't switch too soon

A report at the scientific conference in September suggested the new genotype and phenotype tests may not be as helpful as some have hoped. Although the tests can identify mutations in the virus that can predict the virus's ability to evade certain drugs, one report at the conference presented evidence that the presence of those mutations doesn't always predict the virus's ability to evade the drugs.

The report, presented by Doug Richman, noted that the tests did not always predict when a patient's viral load was about to shoot up again. And the study found that, in some cases, patients are doing just fine without switching to new drugs.

The Richman report was summarized on the Healthcare Communications Group web site by Dr. Joseph J. Eron Jr. Eron noted that, in Richman's study, presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), the use of the new tests did not show mutations of the virus in all patients who were beginning to fail on their drug regimen. But even more surprisingly, noted Eron, "Four out of five subjects who resumed the three-drug therapy had their virus levels fall back to below detection."

"These results have profound implications for how we manage patients who are failing a protease inhibitor-containing regimen when failure is detected early in the course of treatment," wrote Eron. "Though there are no hard data as yet to tell us exactly what to do, it is possible that some agents of a failing regimen (like the protease inhibitor) may still be useful, or that early failure can be salvaged, not by changing the entire regimen, but by intensification."

In brief ...

LITTLE CONSENSUS: During the ICAAC meeting, clinicians in the audience were given a series of case studies and asked to vote on the spot for what therapy they would recommend for each patient. According to a Healthcare web site summary prepared by Dr. William Powderly, there was very little consensus. Given a case study of a 32-year-old man who was newly diagnosed with HIV infection, had a CD4 count of 560, and a viral load of 23,000 copies, 49 percent of the experts said they would start the patient on a triple-drug regimen, 31 percent would start therapy with a protease-sparing regimen, 17 percent said they would delay therapy, and three percent had other ideas.

NEW NUKE ADVANCES: An advisory committee to the Food and Drug Administration voted Nov. 2 to recommend that the nucleoside analog abacavir (formerly known as 1592) be approved for marketing. The drug has been available since March to people with HIV who had not been benefiting from already approved drugs, and it received favorable attention at the International Conference on AIDS this year in reports looking at its use as part of a three-nuke combination with AZT-3TC. But the FDA panel also recommended that the drug manufacturer, GlaxoWellcome, be required to continue careful study of the drug (to be marketed as Ziagen). One area of concern is that patients who suffer an allergic reaction to abacavir and stop taking the drug must not resume taking the drug after their side effects resolve. Such resumption has been known to cause life-threatening reactions.
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