Eighth International Congress on Drug Therapy in HIV Infection Glasgow, UK - 12-16 November 2006

Int Cong Drug Therapy HIV 2006 Nov 12-16;8:Abstract No. PL1.2

Myron S Cohen
The University of North Carolina at Chapel Hill, NC, USA

PURPOSE OF THE STUDY: Antiretroviral therapy (ART) can be used for HIV prevention as pre-exposure prophylaxis (PREP), post-exposure prophylaxis (PEP), and to reduce the infectiousness of people with established infections:

1. Using a model in which animals are repeatedly challenged through weekly rectal exposure, (Garcia-Lermer et al. Conf Retrovir Opportunistic Infect 2006 Feb 5-8;13:abstract no. 32LB) have shown that a combination of oral tenofovir (TDF) and emtricitabine (ETC) daily can provide substantial (but still incomplete) protection from infection. Five clinical trials using TDF alone or the TDF/ETC combination to protect high-risk subjects are in progress. A trial of TDF completed in Ghana (Peterson et al, Int Conf AIDS. 2006 Aug 13-18;16 Abstract No. ThLB0103) demonstrated safe utilization of TDF for PREP; 2 subjects receiving TDF and 6 receiving placebo acquired HIV (NS).
2. Animal experiments demonstrate that ART PEP offered shortly after exposure (within 72 hours) and for at least 28 days can reliably prevent HIV acquisition. However, observational studies have demonstrated many PEP failures, and in some subjects recurrent courses of PEP suggesting some failure of counseling.
3. Combination antiretroviral therapy can rapidly and durably reduce the concentration of HIV in the blood and genital secretions. ART has reduced transmission of HIV within discordant couples. ART provided to at least some large populations (e.g. Taiwan) appears to have offset continued spread of HIV. A clinical trial to better understand the potential of this approach in discordant couples (NIH HPTN052) has completed a pilot phase.

Substantial limitations for ART for prevention include the treatment of the right people at the right time(s), viral resistance, and the potential inspiration of risky sexual behavior.

Plenary Session: Treatment Strategies

2006-11-12
PL1.2

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