Monthly HIV pill may expand prevention options

A new antiretroviral pill has shown promising results and is now entering large-scale trials. Spotlight reports on new findings on the pill. By Elri Voigt

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There are several antiretroviral formulations proven to prevent HIV infection: a daily pill, two different jabs that offer protection for two and six months, respectively, and a vaginal ring for women that has to be replaced monthly. In a few years, a long-acting pill may join the ranks, if it works.

The pill, for now called MK-8527, has the potential to prevent HIV infection for up to a month in its current formulation. It is a nucleoside reverse transcriptase translocation inhibitor, which means it disrupts a specific step in the cycle by which the virus makes copies of itself.

The pill is now moving on to pivotal phase-three trials after promising results from a smaller phase-two study presented at the International Aids Society (IAS) conference held in Kigali, Rwanda.

The phase-two study, conducted in trial sites in South Africa, the US and Israel, showed that MK-8527 was well tolerated and had a safety profile similar to a placebo. It also showed the levels of the antiretroviral were at the required levels in participants' bodies, although the study was not designed to determine whether it is effective.

Whether MK-8527 actually prevents HIV infection will now be tested in two large phase-three studies in multiple countries, including South Africa. In these studies, the efficacy of the monthly pill will be compared with that of a daily HIV prevention pill already widely available in South Africa's public sector. The daily pill contains the antiretroviral drugs tenofovir disoproxil fumarate and emtricitabine.

Latest findings

The phase-two study looked at three different doses of the monthly pill 3mg, 6mg and 12mg as well as a placebo. The 350 participants, about one third of whom were from South Africa, were given one pill (either an active pill or placebo) every month for six months. They were monitored for at least two months afterwards. None of the participants acquired HIV during the study.