Drug Combination and HIV in Children

Drug Combination Shows Potent Punch Against HIV in Children, According to The Children's Hospital of Philadelphia

Philadelphia, Pa. - A study headed by a physician at The Children's Hospital of Philadelphia has shown that a novel combination of drugs achieves strong, sustained results in controlling HIV infection in children, according to an article in the December 16 New England Journal of Medicine. Forty-eight weeks after the treatment began, the virus, which causes AIDS, remained at undetectable levels in more than half the children studied. "These impressive results expand our treatment options for HIV-infected children," said Stuart E. Starr, M.D., chief of Immunologic and Infectious Diseases at The Children's Hospital of Philadelphia, the lead author and chair of the multicenter study. The fact that one of the drugs, efavirenz, is taken only once a day is a step toward simplifying the complicated, often difficult treatment regimen for children with HIV.

One novel feature of the trial was that levels of efavirenz and another drug, nelfinavir, were measured in each child's bloodstream during the course of the study, and subsequent doses were individually adjusted to aim for better results in fighting the virus. Often in clinical trials, drug doses are standardized and remain the same throughout the study period.

The study was conducted in 57 HIV-infected children age 3 to 16 at 18 sites participating in the Pediatric AIDS Clinical Trial Group. The children received a combination of the drugs efavirenz, nelfinavir and one or more drugs called nucleoside reverse transcriptase inhibitors (NRTIs). Nearly all of the children had earlier been treated with NRTIs, a class of drugs that includes AZT and ddI. The virus was considered to be at undetectable levels if tests that detect as few as 50 copies of virus particles in each milliliter of blood were negative. Before the study, the children had more than 400 particles per milliliter, enough to cause signs such as failure to thrive and an enlarged liver. Children with undetectable HIV levels, said Dr. Starr, usually have minor or no signs of the disease, and they gain weight and have better appetites. Serious side effects were uncommon, although some children experienced rashes or diarrhea.

Although in the past few years, combinations of anti-HIV drugs have shown considerable progress in suppressing the AIDS virus in adults, consistent results were more difficult to achieve in children. Furthermore, compared to adult medications, fewer anti-HIV drugs have been available for children. "Our favorable results indicate that a high proportion of children can attain undetectable levels of AIDS virus when a potent combination of anti-HIV drugs is used," said Dr. Starr. Interim results from the study, reported last year after 20 weeks of treatment, led the U.S. Food and Drug Administration to approve efavirenz (trade name Sustiva(r)) in September 1998 for use in children. The current results reinforce those earlier findings.

Anti-HIV drugs are classified by the viral enzymes they inhibit, thus interfering with the virus' ability to reproduce. The NRTIs and non-nucleoside reverse transcriptase inhibitors (NNRTIs) such as efavirenz both act against the enzyme reverse transcriptase, but have different chemical structures. Nelfinavir, another drug used in the study, is a protease inhibitor, which targets the enzyme protease.

Efavirenz is taken only once a day, in contrast to other drugs in the combination therapy, which require 3 to 4 doses daily. A more convenient regimen would make it easier for children to comply with the treatment, and said Dr. Starr, "we're still looking for an overall combination of drugs that is easier for children to take." Further studies by the Pediatric AIDS Clinical Trials Group (PACTG) will study long-term effectiveness of the drug combinations, as well as results in adolescents and in children aged 2 to 8. The PACTG is a network of clinical trial sites supported by the National Insitutes of Health.

The Children's Hospital of Philadelphia, the nation's first children's hospital, is a world-renowned leader in patient care, education and research. This 373-bed multispecialty hospital provides comprehensive pediatric services, including home care, to children from before birth through age 19. The hospital has more than 17,000 admissions, and provides care in more than 600,000 outpatient visits annually.

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