AIDS Alert International: Mother-to-child advances are closer to reality
(AIDS Alert asked nevirapine researcher John L. Sullivan, MD, to discuss the drug and its potential use in preventing mother-to-child transmission of HIV in developing nations. Sullivan was involved in the discovery of nevirapine in 1990 and first proposed a mother-to-child transmission trial in 1992.
He has been involved in much of the nevirapine research since then and most recently was a chief researcher in the SAINT Study, which compares nevirapine favorably with a combination of lamivudine and zidovudine in prevention of mother-to-child transmission. The study was presented at the XIII International AIDS Conference in Durban, South Africa, in July 2000.
Sullivan is a professor of pediatrics in the Program in Molecular Medicine at the University of Massachusetts Medical School in Worcester.)
AIDS Alert: When news first came out last year that one dose of nevirapine was very effective in preventing mother-to-child HIV transmission, many people saw this drug as a possible solution to the infant HIV problem in Africa. What does the new SAINT Study add to the earlier findings?
Sullivan: I think the same trial obviously has expanded those findings in demonstrating that this result can be duplicated. In the HIVNET 012 study, the nevirapine was compared with AZT alone. In the SAINT study, nevirapine was compared with AZT and 3TC in combination, a much more potent regimen, and even with that more potent regimen, nevirapine was equivalent in potency in terms of prevention.
I think the other important aspect of SAINT is that it included women who formula-fed their babies as well as women who breast-fed their babies. And we could really look at the efficacy of nevirapine in terms of preventing maternal-to-child transmission in the intrapartum period. When we did that, the efficacy was 80%, so that a single 200 mg dose of nevirapine to the mother and a 6 mg dose to the baby was 80% effective in preventing intrapartum transmission.
AIDS Alert: To put this into perspective, how serious is the mother-to-child HIV transmission problem in Southern Africa?
Sullivan: One of the sites for SAINT was in Durban, South Africa, and at the prenatal clinics currently in Durban, approximately 35% of pregnant women are HIV-infected. So we have hospitals in South Africa where there are 12,000 to 14,000 deliveries a year, and if you think about one-third of those women are HIV-infected, and the ultimate transmission rate includes the transmission that occurs in utero, which is 7%, as well as the transmission that occurs in intrapartum period, which is 15% to 16%, and the transmission that occurs by breast-feeding, which is another 10% to 5%, we’re looking at overall transmission rates in the 25% to 40% range. So again, a third of the women who are pregnant are at risk for transmission, and a third of their babies are infected.
There are approximately 1,600 babies born a day in the world with HIV infection. So if you think about intrapartum infection accounting for 50% of those when you include in utero transmission and breast milk transmission, you could reduce the number of infected infants by half.
AIDS Alert: How should nevirapine be administered to obtain the best results in preventing HIV transmission through breast-feeding?
Sullivan: That’s the next research question that needs to be answered. We can prevent the transmission that occurs in the intrapartum period. But some of those babies who escape infection at that point in time will then become infected through breast milk. So we now have to figure out a regimen that’s going to protect breast-feeding babies.
There are studies going on now with dosing infants with nevirapine through the breast-feeding period. And I think our hope would be that we could use nevirapine to prevent transmission through the breast-feeding period, along with shortening the breast-feeding period — it looks like one can terminate breast-feeding in the range of three to six months and not lose the effect of breast milk on the prevention of enteric diseases, which obviously are a very serious problem in the developing world.
AIDS Alert: Ingelheim, Germany-based Boehringer Ingelheim GmbH announced right before the XIII International AIDS Conference in Durban, South Africa, that the company would be offering nevirapine at no charge for the use of preventing mother-to-child transmission in developing countries for a period of five years. Do you believe African nations will take advantage of this offer, and how might this impact the HIV pandemic in the developing world?
Sullivan: Absolutely. This removes cost of drug as a barrier, and I think the next barrier to implementation of this regimen is an infrastructure to ensure that the drug is going to be given to those women and babies who need it. I think that’s where additional funds are needed —
to create that infrastructure — and there are a number of organizations providing money to do that, including the Pediatric AIDS Foundation, the
USAID, and there was a bill introduced in Congress to make $1 billion available over the next two years to the developing world for HIV prevention.
So I think the monies necessary to create the infrastructure to assure that this free drug will
get to the people who need [are going to be provided]. So my guess is that we’re going to see over the next two years the implementation of this regimen throughout the developing world.
AIDS Alert: What is your greatest expectation for the next 10 years in the area of mother-to-child transmission of HIV? How might it change from what we are experiencing today?
Sullivan: I think this is really a stopgap measure, if you will. Obviously, women who are HIV-infected in the developing world are not receiving antiretroviral therapy for their own disease and eventually are going to die from their HIV infection. So even though their babies are not infected, their babies are going to end up being orphans.
What this does offer is the first hope of having treatments available in the developing world, and I think what we’re going to see and what already has happened on a really small scale is the introduction of certain very inexpensive antiretroviral therapies into the developing world for treatment of adults and children with HIV infection.
I think we’re going to see that happen increasingly over the next several years, where we’re going to be able to prevent maternal-to-child transmission, and we’re also going to be able to attenuate the serious HIV infections to the point of people being able to live longer. But this is really a stopgap in itself, as well, because the only hope for the developing world really is a vaccine, and I think we’re probably 10 years away from having a vaccine that’s efficacious.
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