AZT Found to Protect Fetuses From AIDS : Medicine: Federally sponsored study says drug sharply reduces transmission of virus from mothers.
The results of a federally sponsored study testing the AIDS drug AZT in infected pregnant women have shown that the drug has a dramatic effect in preventing transmission of the virus to the fetus, The Times has learned.
The findings, which are scheduled to be released by the National Institute of Allergy and Infectious Diseases today, are so significant that a special monitoring board--which has been examining the study on an ongoing basis--met late last week and immediately recommended that the placebo arm of the study be stopped and that all pregnant women remaining in the trial be given the drug.
The study was a randomized double-blind placebo-controlled study, meaning that one group of women had been receiving a medically worthless placebo for comparison purposes.
The NIAID, which is part of the National Institutes of Health, took the unusual step of releasing the data so that physicians across the nation would be aware of the results.
But it stopped short of recommending that doctors treating pregnant infected women automatically prescribe the drug because its long-term effects on young children are still unknown.
“The data are very encouraging, but we still want to make sure there are no long-term toxicities,” said Dr. Anthony Fauci, director of the NIAID. “We don’t see any indication of that, but we will only know that from long-term follow-up. With regard to just the efficacy, it seems to be pretty compelling.
“I think these are important data that physicians and health care providers and patients should be aware of in order to make a decision.”
Several thousand children have contracted AIDS since the epidemic began in 1981, and approximately 10,000 or more children are believed to be infected with the human immunodeficiency virus that causes the deadly disease.
Early in the epidemic, a small number of infections among children were the result of blood transfusions and contaminated blood products for treating hemophilia. But the vast majority of infections occur when an infected woman transmits the virus to her fetus during pregnancy or delivery.
The exact mechanism of transmission is unknown, but infected women have a 25% or greater chance of passing the virus on to the unborn children, studies show.
In this study, which began in April, 1991, data was obtained for 364 babies who were born to infected women. Of these, 53 babies were infected.
Of those 53 infants, only 13 were born to mothers treated with AZT, while the remaining 40 were born to mothers given placebos.
Among all babies whose mothers received AZT, only 8.3% were infected, but 25.5% of babies born to mothers who received the placebo were infected.
Fauci said the only short-term problem found in the group of babies treated with the drug was mild, reversible anemia. The health of the babies has been followed for at least 18 months, in part to accurately determine whether they carried a true infection.
It is difficult to accurately determine whether a child is infected with the AIDS virus until he or she reaches the age of about 15 months. Until then, children typically carry antibodies passed on from their mothers--rather than their own--so testing is often imprecise.
The study originally was slated to include 740 HIV-infected women, but it was stopped before full enrollment was reached.
The women were randomized into two groups, an AZT group and a placebo-control group. Women between 14 weeks and 34 weeks of pregnancy received the drug or a placebo orally. The drug or a placebo was administered intravenously during labor. After birth, the infants were also given AZT or a placebo orally for their first six weeks of life.
For the women, treatment with the drug began no earlier than 14 weeks of pregnancy in order to protect the fetus from potential damage. By that time, key organs are already formed and are considered less vulnerable.
The study took place at 59 facilities in the United States and nine in France, including 35 financially supported by the NIAID and 15 supported by the National Institute of Child Health and Human Development, also a part of the NIH.
Susan DeLaurentis, a co-founder of the Los Angeles-based Pediatric AIDS Foundation, said she welcomed the study results but that she hopes research will continue into other ways to prevent transmission from mother to fetus.
“We’re still interested in how transmission occurs to begin with, so we can find ways to block all transmission from all infected women,” she said. “But this is certainly encouraging news.”
AZT, which is manufactured by Burroughs Wellcome Co. of Research Triangle Park, N.C., is one of a class of AIDS drugs that attack the underlying viral condition.
It has also been shown to be effective in improving the quality of life for patients with fully developed AIDS, and to delay the onset of AIDS in infected individuals who have not yet experienced symptoms of disease. It was approved by the Food and Drug Administration in 1987.
