Microbicides 2004 marks new wave of HIV prevention trials

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The Microbicides 2004 meeting, which took place this week at London’s Hilton Metropole hotel, drew 800 participants from 53 countries for four days of intensive discussion.

In keeping with the location, all were presented on arrival with handbag-sized umbrellas, neatly printed with the conference logo! The third conference in this series, it marked a coming of age for the field, as six microbicidal gels are set to enter full-scale clinical efficacy trials this year. If any one of these proves successful, the first microbicide could be on the market in as little as five years, though manufacturing and licensing issues are still challenging.

While the mood of the meeting was positive and friendly, there were powerful reminders of the grim realities facing far too many women today.

Glossary

microbicide

A product (such as a gel or cream) that is being tested in HIV prevention research. It could be applied topically to genital surfaces to prevent or reduce the transmission of HIV during sexual intercourse. Microbicides might also take other forms, including films, suppositories, and slow-releasing sponges or vaginal rings.

placebo

A pill or liquid which looks and tastes exactly like a real drug, but contains no active substance.

Food and Drug Administration (FDA)

Regulatory agency that evaluates and approves medicines and medical devices for safety and efficacy in the United States. The FDA regulates over-the-counter and prescription drugs, including generic drugs. The European Medicines Agency performs a similar role in the European Union.

formulation

The physical form in which a drug is manufactured or administered. Examples of formulations include tablets, capsules, powders, and oral and injectable solutions. A drug may be available in multiple formulations.

phase II

The second stage in the clinical evaluation of a new drug or intervention, in which preliminary data on effectiveness and additional information about safety is collected among a few hundred people with the disease or condition.

Secretary of State for International Development Hilary Benn and Minister of State Gareth Thomas chaired sessions and spoke of the need for expanded access to treatment and better options for HIV prevention. The British government is a major funder of microbicide research (having spent £17 million so far, according to Hilary Benn, speaking before the conference on BBC radio), and this support is set to continue and grow.

Princess Anne, who handed out awards to some of the presenters, spoke up for the women with whom the Save the Children Fund is working, in a number of countries heavily affected by AIDS.

Geeta Rao Gupta - of the International Center for Research on Women - spoke of meeting a woman in India who had been forced by her family to abort her girl children and another terrified of what would happen to her children if she were to leave her violent husband.

UN Secretary General Kofi Annan’s special envoy on AIDS in Africa, Stephen Lewis, won a standing ovation after speaking of his rage at the reality of a generation of children literally watching their mothers die.

If microbicides are to contribute to improving women’s ability to protect themselves from HIV and its consequences, then it is essential that some of the products which have been shown to block HIV transmission in cell cultures, and to prevent transmission of viruses to monkeys and other animals, are now taken forwards into full-scale trials.

The six products which are due to start testing this year are all formulated as gels (although other kinds of product are equally possible).

First to go is Carraguard, for which the first of several thousand volunteers have now been recruited in South Africa. Carraguard is made from a seaweed, and has been developed by an NGO, the Population Council, which is sponsoring the trial. This trial will compare Carraguard with a placebo gel over a period of twelve months and is expected to take several years to complete.

The UK DfID-funded Microbicide Development Partnership is a consortium including two Medical Research Councils - those of Britain and South Africa - and trial sites in South Africa, Tanzania, Uganda, Cameroon and Zambia. It will be testing two products - PRO 2000 and Emmelle (dextran-2-sulphate) - against placebo. Both of these are in the same broad class as Carraguard. Most of the thousands of volunteers will be expected to participate for only nine months, although some will be followed for longer.

The US government-backed HIV Prevention Trials Network, another international consortium, is sponsoring a “Phase IIb” trial of Buffergel, PRO 2000, a placebo gel and a ‘condom-only’ trial arm. Buffergel is a product designed to neutralise the alkalinity in semen, which should have the effect of destroying any HIV which it might contain.

This trial is to take place in eight sites in South Africa, Malawi, India and the USA, and is seeking 3100 volunteers in total, which means it will only be conclusive if either product proves highly efficacious or completely useless. Otherwise, a much larger study will be needed for conclusive results, which might be hard to recruit if there was reasonably strong, but not conclusive, evidence of efficacy. The 200 women to be recruited in the USA will primarily take part in safety studies to assist a licensing application to the FDA, as they are at lower HIV risk than the African and Indian women. The condom-only arm was included at the insistence of the US Food and Drug Administration and is highly contentious. Many at the conference doubted if this trial could enrol and retain all the volunteers it needed, especially in the condom-only arm, desirable though this might or might not be in theory.

A third major project, for which preliminary trials have been run in the USA, involves the two US-based agencies CONRAD and Family Health International. These are to compare a cellulose sulphate gel (in the same broad class as Carraguard) with a placebo gel. CONRAD will be seeking more than 2500 volunteers at six sites in Benin, Burkina Faso, India, Kenya, Uganda and South Africa. FHI will conduct an additional separate trial on a similar scale in Nigeria.

Finally, there are trials planned in the USA and Africa for a product called Savvy or C31G, from a US company called Biosyn. This is a spermicidal detergent similar to the failed microbicide nonoxynol-9, which inevitably raises questions about its safety.

Few expect any of these products to be more than moderately effective. There was some agonising at Microbicides 2004 over whether too many similar products are being tested at this stage. There are concerns over how many "failed products" the field could afford, before funders and affected populations would lose interest. Against this, the longer trials are delayed, the more they will cost. All of these products have shown some efficacy against HIV in laboratory tests. Products may vary more in characteristics such as acceptability to users, or their distribution in the body over time, than can be detected before full-scale trials. Above all, of course, the need for these products is likely to remain as urgent as ever. The next conference in this series will be held in South Africa in 2006.

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