AIDSWEEKLY Plus, 19 August 1996
Daniel J. DeNoon, Senior Editor

Previous studies have shown that intravenous infusions of IL-2, given in the right dose for the right amount of time, can restore depleted CD4 counts in patients with HIV disease.

New studies now show that IL-2 taken on an outpatient basis, in combination with antiretroviral therapy, can have similar effects.

"While clinical significance of these findings remains to be established, it has not escaped our notice that the subcutaneous administration of IL-2 and antiretroviral therapy has the potential to maintain CD4 counts in the normal range for an extended period of time," said Richard Davey of the National Institutes of Health Clinical Center, Bethesda, Maryland.

Davey announced the study results in a presentation to the XI International Conference on AIDS, held July 7-12, 1996 in Vancouver, British Columbia, Canada.

The study compared two doses of IL-2 given subcutaneously. Study participants were randomized to one of four treatment arms: 1.5 million international units (MIU) of IL-2 twice daily for five days every four weeks; 1.5 MIU IL-2 twice daily for five days every eight weeks; 7.5 MIU IL-2 twice daily for five days every four weeks; or 7.5 MIU IL-2 twice daily for five days every eight weeks.

As of mid-June 1996, there were nine to 11 patients in each study arm.

Baseline HIV RNA levels were 12,000 to 22,000 copies/ml.

Major increases in CD4 counts were seen in all groups except the one receiving the lower dose at the longest interval (1.5 MIU bid q 8 weeks).

The toxicities were "much less intense" than those seen with subcutaneous infusions of IL-2. The most common adverse effects were fatigue, myalgia, and arthralgia and these were most frequent at the high dose.

"Perhaps the most striking finding to date is the CD4 cell count changes over time," Davey said.

In the low-dose groups, the mean CD4 count increased from 645 to 862 cells/(micro)L. In the high-dose groups, the mean CD4 count increased from 636 to 1273 cells/(micro)L, "basically a doubling of their CD4 counts," Davey said.

Within the high-dose group, 93 percent of patients had at least a 50 percent increase in CD4 count and 53 percent of patients had a 100 percent increase in CD4 count.

There were no significant effects on CD8 counts, which remained stable at 800-900 cells/(micro)L throughout the study.

Concerns that lymphocyte activation would increase viral burden appeared to be unfounded: at the time of Davey's report, a slight decrease in overall mean viral load had occurred.

"Subcutaneous IL-2 can safely be administered on an outpatient basis to patients receiving concurrent antiretroviral therapy," Davey concluded. "At a dose of 7.5 MIU bid for five days, dramatic increases in CD4 count and CD4/CD8 percentage can be seen within the first few cycles of treatment that are not associated with any sustained increases in viral load."

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