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IL-2 Appears Effective in Sustaining CD4 Cell Counts
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National Institute of Allergy and Infectious Diseases
National Institutes of Health
Monday, April 26, 2004
HIV PATIENTS GET LONG-TERM BOOST WITH SHORT, INTERMITTENT DRUG REGIMEN
National Institutes of Health (NIH) scientists report that brief,widely-spaced courses of the experimental immune-boosting drug interleukin-2(IL-2) allow people with HIV to maintain near normal levels of a key immunesystem cell for long periods. The researchers, from NIH's National Instituteof Allergy and Infectious Diseases (NIAID) and the Warren G. MagnusonClinical Center, describe their findings in the May 1 issue of the journalBlood.
"These data provide strong evidence that IL-2 therapy, which can beself-administered by patients, could be an important adjunct to highlyactive antiretroviral therapy (HAART)," says NIAID Deputy Director John R.La Montagne, Ph.D.
The new report summarizes the experience of 77 HIV-positive individuals whoenrolled in extension phases of three long-running AIDS clinical trials.Participants were taught to inject themselves subcutaneously with IL-2 twicedaily in 5-day-long cycles. Cycles were initiated as often as necessary tomaintain levels of immune cells called CD4+ T cells at predetermined,individually tailored amounts. HIV infection causes progressive loss of CD4+T cells. Without enough of these "helper" immune cells, people with HIVdisease have a hard time fending off infections. IL-2 can boost CD4+ T celllevels, with the goal of improving overall immune health.
Because HIV infection causes progressive immune destruction, it stands toreason that immune-stimulation therapy, such as IL-2, might play asubstantial role in treating patients with this condition, notes RichardDavey, Jr., M.D., an NIAID AIDS clinician who headed the studies reported inBlood. Indeed, during the early 1980s NIH physicians pioneered the use oflong courses of IL-2 to treat individuals whose immune systems hadmysteriously failed. Scientists now know those people were suffering fromAIDS, but at the time the virus causing AIDS had yet to be identified.
Although NIH physicians have accumulated more than 20 years of experiencewith IL-2 therapy, the most impressive results began to appear in the early1990s when the doctors started treating patients with short, intermittentcycles of the drug, Dr. Davey says. Today, HIV patients receiving IL-2therapy typically begin with 5-day-long cycles every other month whiletaking drugs, such as HAART, on a sustained basis. According to Dr. Davey,this regimen often raises an HIV patient's CD4+ T cell levels well into thenormal range after only a few cycles. The new research suggests IL-2 therapycan then be administered much less frequently without loss of benefit.
Most studies to date have looked at IL-2 therapy only over relatively shortperiods, says Dr. Davey. In contrast, the average length of patientfollow-up described in the current paper is about six years. Patients inthese trials have received an average of 10 IL-2 cycles during the course oftheir involvement, with most of the cycles occurring in the initial years ofparticipation. Of the original 77 volunteers, 61 achieved and maintainednormal or nearly normal levels of CD4+ T cells for periods ranging from twoto 91 months between IL-2 cycles. During the most recent period of study,the average time between cycles was more than 3 years. (Of the 16 people nolonger participating, one died, one developed non-Hodgkin's lymphoma, eightelected to follow other treatment plans and six experienced CD4+ T cellcount declines that did not respond to IL-2 therapy.)
"Patients described in this study are still being followed," says Dr. Davey."There are also trials planned or underway to learn if IL-2 therapy coulddelay or obviate the need for continuous HAART, thereby sparing persons withHIV disease from the serious side-effects that HAART can cause. The earlyexperience from some small preliminary studies in this area suggests thatthis may indeed be a possibility, although larger trials are clearly neededto explore this fully."
NIAID is a component of the National Institutes of Health (NIH), an agencyof the U.S. Department of Health and Human Services. NIAID supports basicand applied research to prevent, diagnose and treat infectious diseases suchas HIV/AIDS and other sexually transmitted infections, influenza,tuberculosis, malaria and illness from potential agents of bioterrorism.NIAID also supports research on transplantation and immune-relatedillnesses, including autoimmune disorders, asthma and allergies.###
Reference: CE Farel et al. Induction and maintenance therapy withintermittent interleukin-2 in HIV-1 infection. Blood 103:3282-86. Publishedonline January 15, 2004.DOI: 10.1182/blood-2003-09-3283.
Press releases, fact sheets and other NIAID-related materials are availableon the NIAID Web site at http://www.niaid.nih.gov.
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