Up to 800 Cambodian prostitutes could take part in an international study to determine whether anti-retroviral drugs can prevent the transmission of HIV, government health officials said last week.
The study, which was approved by the Ministry of Health in June, could begin here by the end of the year. HIV-negative sex workers would be given Tenofovir, an anti-AIDS drug the US Food and Drug Administration has approved to treat people with HIV, said Dr Julian Elliott, a technical adviser to the National Center for HIV/AIDS, Dermatology and Sexually Transmitted Infections.
The study will be conducted with the assistance of the University of California at San Francisco in the US and the University of New South Wales in Sydney. Similar studies are being planned for women in the African nations of Nigeria and Cameroon and for gay men in the US, said Dr Ly Penh Sun, chief of the technical bureau at the center.
Tenofovir, which is manufactured by the US company Gilead, was chosen because it has few side effects and is taken as a daily pill, which does not require supervision, Elliott said. He said the study will be conducted in three phases, the first two ensuring Tenofovir’s safety, the final phase determining its ability to block HIV infection.
An equal number of prostitutes would take a placebo. Test results would be obtained by comparing HIV rates among participants with those of prostitutes in similar conditions.
All participants would receive monthly counseling and HIV testing, unlimited free condoms and treatment for STDs. Those participants who contract HIV would receive “comprehensive treatment” in a program coordinated by the center, which would include anti-AIDS drugs that could prolong the life of someone who is HIV-positive, Elliot said.
Anti-retroviral drugs are normally given to people living with HIV to offset the effects of AIDS. In the last two years, about 800 Cambodians have undergone the free drug regimen through several hospitals and NGOs.
Ly Penh Sun said participants would have to meet several conditions. They have to be considered “high risk,” meaning they work in brothels or as “indirect” sex workers, a group that includes beer girls. They also cannot be pregnant, must be HIV-negative and must also understand the risks associated with the study.
Aside from lowering the risk of pregnant women infecting their unborn children, no anti-AIDS drug has been demonstrated to block HIV transmission between people, Elliott said Friday.
Though Tenofovir showed promising results in tests on animals, Elliott cautioned Friday “there is no evidence that this will work.” Such a drastic test is necessary now, he said, because the possibility of an AIDS vaccine is at least five years away.
Before approving the study, the Ministry of Health’s National Ethics Committee decided all participants must fill out a questionnaire to determine their understanding of the risks.
“If you ask them to use this drug, they may think they are protected and won’t use condoms.” said Dr Kannarath Chheng, who is secretary of the committee.
Elliott said a formative study to define a working definition of “informed consent” for participants will take up the bulk of time before testing begins. It will also resolve whether the women will be paid for participating.
Another difficulty is choosing participants from the very transient sex trade who would be most likely to complete the yearlong study. The study will focus on Phnom Penh, where sex workers tend to be more stationary than elsewhere in Cambodia. In such an experiment there is an ethical responsibility to get results from the research, Elliott said.
Participants will be monitored throughout the actual study, which would have a six-month staggered enrollment and would last about a year.
Elliott said observers would also monitor how the pills influence the women’s behavior and other social factors. A monitoring board with access to all data will have the power to stop the study at any time.
It is vital, Elliott continued, to discourage Cambodians from “going to market and buying Tenofovir,” which could give women a false sense of security.
Ly Penh Sun described a grimmer scenario in which using the drug without considering the proper regimen could generate strains of HIV unresponsive to the drug.
In an e-mail, Dr Robert Grant, director of the UCSF-Gladstone Laboratory of Clinical Virology, who visited Phnom Penh for the study, said Cambodia was well suited for it because of a high HIV rate and a “well-defined” population at risk.
Pok Panhavichetr, executive director of the Khmer HIV/
AIDS NGO Alli
ance, said that from a “social point of view” the study was unjust. Participants, she said, “should know whether they will receive Tenofovir or a placebo. Otherwise it’s confusing. It’s not fair for them.”
Dr Sam An Ung, the ethics committee’s second deputy chair, said Dr Mean Chhi Vun, another member, received a proposal from Khana last year for a similar study in which the participants would not wear condoms. It was rejected immediately.
Kannarath Chheng said Monday that one of the major debates in the committee was cost: How Tenofovir could be distributed in Cambodia if it proved successful. He said he hoped the price would decline.
Even if the experiment showed promising results, it would hardly be a total victory. Since Tenofovir is not a vaccine, people would have to maintain the daily regimen for it to remain effective.
“It is impossible to say” how Tenofovir could be distributed on a wide scale in a place such as Cambodia, where it is unaffordable to almost everyone who would benefit from it, Elliott said. Condom use would still be emphasized, he said.
Despite the obstacles, Kannarath Chheng was guardedly optimistic, and he noted that Cambodia has the highest rate of AIDS among adults in Asia.
“We are a country with a high burden of AIDS, so for the humanitarian benefit we can allow the study to proceed and monitor it closely,” he said.
