High hopes for ARV-based gel
KwaZulu-Natal women will be the first in the world to test a vaginal gel containing an antiretroviral (ARV) drug which offers the hope of protecting women from HIV infection.
After three painstaking years of planning, Durban scientists Professors Salim and Quarraisha Abdool Karim and Dr Ayesha Kharsany have finally started to recruit women for the trial of the gel, known as a microbicide.
While other microbicides have been tested in the past, this is the first that has an ARV drug, tenofovir, as its active ingredient. Tenofovir can survive for a long time in the body and that is hard for people to develop resistance to.
‘I’m excited and optimistic about the trial,’ said Salim Abdool Karim, director of the Centre for the AIDS Programme of Research in SA (Caprisa), which is running the trial.
‘Tenofovir is highly efficacious and it has a good safety profile. In the nine or 10 animal studies conducted, it has shown a high level of protection in animals.’
In one recent study, two-thirds of monkeys given a rectal microbicide containing tenofovir were protected from simian immunodeficiency virus (SIV), a virus in monkeys that is similar to HIV. All the monkeys that did not get the gel became infected with SIV.
Microbicides have long been promoted as the ideal prevention method for women who are vulnerable to HIV but are unable to insist that their partners use condoms.
But although five candidate micobicides have been tested so far, none have been able to prevent HIV infection.
However, Salim Abdool Karim described the tenofovir gel as a ‘third generation microbicide’ that did not try to kill HIV or block the virus from entering the body as the earlier microbicides had.
Instead, the tenofovir gel is expected to be absorbed rapidly into the genital tissue where it is hoped that it will prevent the virus from replicating from inside the cells themselves.
An added benefit of tenofovir is that it remains active in a person’s body for a number of hours.
‘Women will be able to apply the gel up to 12 hours before they have sex and within 12 hours of having sex,’ said Quarraisha Abdool Karim. ‘This makes it easier to use than the other microbicides, which usually had to be inserted within an hour of having sex.’
The scientists intend to recruit almost 1000 HIV negative women for the trial over the next 14 months, according to Kharsany. Results are expected in two and a half years’ time.
The gel has already passed safety tests in humans and this is a ‘phase two trial’ to test whether it offers protection against HIV.
Half the women recruited will get the tenofovir microbicide and the other half will get a plain gel. The women will not know whether they have the tenofovir microbicide or the placebo.
Caprisa is recruiting women from Durban and rural Vulindlela near Howick, and recruits will range from those who mainly have migrant partners (and do not have regular sex) to sex workers.
Ethically, the trial is challenging. While the women recruited will be encouraged by counsellors to use condoms at all times, the only way that the scientists will be able to test if the gel can prevent HIV transmission is if it is used without condoms.
For this reason, sex workers who have frequent sex with multiple partners and are not always able to insist that their clients use condom will be an essential part of the trial.
‘But we expect that even this group will be motivated to use condoms as they will have received extensive counselling,’ said Salim Abdool Karim.
Beauty Mazibuko, who is recruiting the sex workers, said that it ‘isn’t easy to gain their trust’ or even to get them to listen as ‘their time is money’.
‘But they are also human and once they hear about the research, there are some that are very interested and want to help,’ said Mazibuko.
The recent suspension of the trial of another microbicide based on cellulose sulphate generated a lot of negative publicity in the media, with scientists facing accusations of using people as ‘guinea pigs’.
‘There was a lot of gossip about microbicides in our communities after this trial was stopped,’ admits Nomapondo Barnabus, who is overseeing the community involvement in the trial. Caprisa dealt with people’s concerns by calling meetings to address people’s concerns.
Gethwane Makhaye, who is overseeing the recruitment of rural women in Vulindlela, said that the fact that Caprisa had worked in the community since 2001 and was involved not just in microbicide research but also in the provision of medical care had earned the organisation the trust of her community.
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