IAS: Activists and investigators debate future of trials of drug that may prevent HIV

Gus Cairns
Published: 09 August 2005

Salvaging an HIV prevention approach that has been jeopardised by poorly run studies and adverse publicity was one of the hot topics at last month’s Third International AIDS Society Conference in Rio de Janeiro. Three studies using tenofovir (Viread) as pre-exposure prophylaxis (treatment to prevent infection, PREP in short) have been halted in Cambodia, Nigeria and Cameroon, and there are continued concerns around a fourth study in Thailand.

“I hope pre-exposure prophylaxis doesn’t become the sacrificial lamb to enable other prevention ideas to go ahead,” was the comment of Sinata Koulla-Sivo, the Cameroon Minister of Health.

The fact that she had just presided over the closure of a trial of tenofovir as PREP in her own country reflects the divided feelings these trials have aroused.

On the one hand it is seen as a desperately needed and workable intervention: in the second debate on PREP, delegates voted 60/40 in favour of PREP as a potentially more effective intervention than microbicides.

On the other hand the trials have become the focus point for questions being asked about prevention trials in general.

In the case of Cameroon a statement from investigators from Family Health International, released just after the IAS Conference, said: “One of the major reasons for the trial suspension was the need to work out a system for the site to ensure long-term treatment for any participant who became infected with HIV during the trial. This important international issue - how to access long-term HIV treatment for participants in research – is still being discussed.”

That communities are already taking HIV pills to prevent HIV was evidenced by a study where researchers asked attendees at minority pride festivals in four US cities whether they had heard of the idea of “HIV-negative people using AIDS medicines before engaging in risky behaviour,” and whether they had tried it themselves.

Around 25 per cent of those interviewed had heard of the idea and a “surprisingly” high seven per cent had actually taken antiretrovirals (ARVs) as a prevention measure. The study didn’t ask where they’d got the pills, what they had taken or on what schedule, and clearly more research needs to be done into “underground PREP”.

At the first debate on PREP, Mary Fanning of the National Institute of Health's (NIH) AIDS division admitted that mistakes had been made in Cambodia, where the first trial collapsed.

“We could have intervened earlier in retrospect,” she said. “Cambodia had very limited experience of clinical trials, and community groups did not know with whom to air their concerns about an adequate standard of conventional prevention methods. There should have been more discussion about the provision of treatment for seroconverters and difficult concepts like the use of placebos in a prevention trial should have been explained better.”

The PREP trial in Thai drug-users continues to cause controversy. Gregg Gonsalves of Gay Men’s Health Crisis read out an open letter from the Thai Drug Users’ Network (TDN), which demanded a ‘halt or redesign’ to the trial there and accused the principal investigator, Dr Kachit Choopanya of the Bangkok Metropolitan Authority, of reneging on agreements he had made at a stakeholders’ meeting in Seattle earlier this year.

TDN said they were concerned about unethical and coercive recruitment procedures, the fact that needle-exchange was not being offered despite half the participants being given a placebo, and the fact that, should tenofovir prove effective, there was no guarantee of an uninterrupted supply. Karyn Kaplan of TDN, who was unable to attend the IAS Conference, told aidsmap that the open letter had resulted in a “positive conversation” with the US Centers for Disease Control, who had the ultimate responsibility for the trial.

One PREP trial yet to begin is among men who have sex with men in Lima, Peru. Carlos Caceres of the Lima School of Public Health said that concerns were already being raised there. These included the effect PREP would have on condom use, concerns about inappropriate use and the development of HIV drug resistance, and questions on why investigators moved into phase III trials without clear evidence from smaller human trials that PREP might work.

This last question was asked at both forums. Renee Ridzon of trial funders the Bill and Melinda Gates Foundation said safety data was known for tenofovir, and that contrary to impressions given, vulnerable communities were “desperate” to be included in trials and it was difficult to find communities in the developed world where HIV incidence was high enough for a moderate-sized trial to be able to demonstrate an effect. (The news that HIV incidence among black MSM in Baltimore is currently running at eight per cent a year ( – see aidsmap news story – rather brings into question this last assertion.)

At the second debate, the idea of using 3TC (lamivudine, Epivir) instead of tenofovir for PREP was aired, as this drug appears to have the best safety record of all. Because of its low resistance threshold, one result would be an inevitable increase in the amount of HIV circulating with the M184V 3TC resistance mutation, though whether this would have good or bad clinical consequences was debatable.

Former IAS President Joep Lange said that manufacturers might ultimately have to agree to ‘reserve’ specific drugs – and he named the CCR5 inhibitors as ones for prevention rather than treatment in order to ‘compartmentalise’ resistance. Andrew Hill of the University of Liverpool, and formerly of Roche, said manufacturers would be reluctant to reserve drugs for an area where profit margins had traditionally been slim.

Renee Ridzon was robust in her defence of the PREP trials and the Gates Foundation’s backing for them.

She said: “The trials will not be all-answering. But PREP can only be tested in humans, and the derailment of prevention trials and the loss of focus on the urgent need for prevention interventions show that ‘the good can be the enemy of the perfect’. The definition of ‘community’ can be elusive, and we have heard many voices from the community on this issue, rather than one.”

Unfortunately the damage may already have been done. Ward Cates of Family Health International predicted that with numbers so depleted, “no useful efficacy data” would come out of the remaining PREP studies, and safety would be all we would learn about.

Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

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