AZT reduced the risk of HIV transmission from HIV-infectedpregnant women to their babies by two-thirds in a studysponsored by the National Institute of Allergy and InfectiousDiseases (NIAID).
Of 364 evaluable infants born to women enrolled in the trial,53 were infected with HIV. Of these infants, 13 had receivedAZT (zidovudine) and 40 had received placebo. "The estimatedrate of transmission in the group that received zidovudine is8.3 percent, whereas the rate of transmission in the group thatreceived the placebo was 25.5 percent," NIAID said.
NIAID announced results of the AIDS Clinical Trials GroupStudy 076 on Monday. The trial began in April 1991 with atargeted enrollment of 748 HIV-infected women; 463 womencompleted it (50 percent African-Americans and 29 percentHispanic). The study was conducted to determine if AZT couldreduce maternal-infant HIV transmission and to evaluate thesafety of the drug for mothers and infants. AZT is believed tosignificantly reduce the level of HIV in maternal circulationand is likely to reduce it in other fluids, such as vaginalsecretions, thereby reducing the amount of virus to which theinfant is exposed.
An independent data and safety monitoring board reviewedpreliminary findings of the study on Feb. 17 and concludedthat there was significant evidence of AZT efficacy. The boardrecommended that new patient enrollment be discontinued,AZT be offered to all study participants, and infants undergolong-term follow-up to monitor possible late effects from thetreatment.
The randomized, double-blind, placebo-controlled trial wasdone in collaboration with the National Institute of Child Healthand Human Development and Institut National de la Sante et dela Recherche Medicale (INSERM) and Agence Nationale deRecherches sur le SIDA (ANRS) of France. It was conducted at59 sites, including nine in France.
Women eligible for the study were between 14 and 34 weeksinto gestation. They had had no anti-retroviral treatmentduring their pregnancy, their baseline CD4 lymphocyte countswere greater than 200 cells/mm3 and they had no clinicalindications for maternal antepartum AZT therapy.
The women received either a placebo or a standard adult doseof AZT during pregnancy and a continuous intravenous dose ofthe placebo or AZT during labor. Their infants received a syrupof the placebo or of 2 mg/kg of AZT four times a day for sixweeks.
The most common side effects for both treatment groups werereversible mild anemia, neutropenia and high bilirubin levels.
NIAID said that "because long-term effects of therapy on theinfants are currently unknown, no recommendations abouttreatment to prevent transmission of HIV during pregnancyand delivery are being made pending development ofconsensus on the balance between known benefit and unknownrisk."
However, NIAID issued a clinical alert to physicians informingthem about the study results for their consideration in makingtreatment decisions. The document also states that "whencounseling patients regarding pregnancy related decisions, it isimportant to provide information regarding the substantial 8.3(+/- 4.5) percent risk of transmission despite therapy."
The alert specifies that the results of ACTG 076 are onlydirectly applicable to women who have the same clinicalcharacteristics as those included in the study." It also notes thatthe long-term risks to infants exposed to AZT in utero andearly infancy are not known, "although there is currently noinformation in humans to suggest such toxicities will occur."
NIAID said there are approximately 10,000 to 20,000 HIV-infected children in the U.S. Of the approximately 7,000 infantsborn annually to HIV-infected women, about 25 percent areHIV-infected. Noting that AZT is not a preventive treatment,NIAID pointed out that even when mothers and infantsreceived AZT, eight out of every 100 infants born were infectedwith HIV.
Burroughs Wellcome Co., manufacturer of AZT (Retrovir),announced Monday that it will submit an abbreviated newdrug application to FDA this week to expand the drug's labelingto include treatment of HIV-infected pregnant women.
-- Brenda Sandburg News Editor
(c) 1997 American Health Consultants. All rights reserved.