BETHESDA, Md--Intermittent infusions of interleukin-2 (IL-2, aldesleukin(Drug information on aldesleukin)) have led to significant increases in CD4+ T cell counts in HIV-infected patients with early disease, a study from the National Institute of Allergy and Infectious Diseases (NIAID) has found.
"This study provides the strongest evidence so far that it may be possible to rebuild and maintain the damaged immune systems of HIV-infected individuals," said H. Clifford Lane, MD, NIAID clinical director. Dr. Lane was the lead investigator along with Dr. Joseph A. Kovacs of the NIH Clinical Center's Critical Care Medicine Department.
Whether the increases in CD4 counts will translate into clinical benefits will be determined by ongoing trials, Dr. Lane told Oncology News International in an interview.
The study included 25 patients, 10 with baseline CD4 counts greater than 200/mm³ (early disease) and 15 with baseline CD4 counts less than 200/mm³ (advanced disease). Patients received IL-2 intravenously for 5 consecutive days every 2 months. All participants also took at least one approved antiretroviral drug such as zidovudine(Drug information on zidovudine) (AZT, Retrovir) or didanosine(Drug information on didanosine) (ddI, Videx) during the study.
In six of 10 patients with early disease, CD4 counts rose by more than 50% after 12 months. In several of these patients, the rise was dramatic, from 554 to 1,998 in one individual. The remaining four patients had stable counts or a slight decline. Follow-up of several of these patients has shown that CD4 increases have persisted for more than 2 years (N Engl J Med 332:567-575, 1995).
Dr. Lane pointed out that as a patient's CD4 counts improve with use of IL-2, infusions can be spaced out longer. One of the best responders in the study received six 5-day infusions over the course of a year. "When we stopped the infusions, his count was around 2,000; then over 8 months, it came down to around 1,000 at which time he got a single IL-2 infusion, and the count went back up," he said.
Thus, the increases in CD4 counts seen with IL-2 therapy appear to be a "reproducible phenomenon," he said, noting that unlike the antiviral drugs, resistance to IL-2 should not be a significant issue.