US regulators have approved Gilead Science's Truvada making it the first licensed drug that has been shown to reduce the risk of HIV infection acquired through sexual intercourse.
The US Food and Drug Adminsitration (FDA) said the drug can be used along with safer sex practices by people at high risk of infection as part of an HIV prevention strategy called pre-exposure prophylaxis (PrEP).
The approval follows a positive recommendation from an FDA advisory committee in May, 2012, that was based on favourable results from two large placebo-controlled trials.
The first of these trials evaluated the drug's use in 2,499 men or transgender women without HIV who were deemed to be at high risk of infection due to such behaviour as inconsistent condom use or having a high number of sexual partners.
This study, known as iPrEx demonstrated Truvada was effective in reducing the risk of HIV infection by 42 percent compared with placebo in this population.
A second trial, named Partners PrEP, involved 4,758 heterosexual couples where one partner was HIV-infected and the other was not and demonstrated that a combination of Truvada and tenofovir reduced the risk of becoming infected by 75 percent compared with placebo.
Despite these demonstrations of efficacy, the FDA's decision has been criticised from some in the HIV community, including the AIDS Healthcare Foundation (AHF) – an organisation that provides care and support for people with HIV/AIDS across the world.
The group described the approval as “reckless” because HIV testing for people taking the drug was not a required part of the approval and voiced concerns that Truvada could increase the risk of kidney damage in patients.
“While FDA recommends a negative HIV test prior to use of Truvada as PrEP and states that use by people with an 'unknown or HIV positive status' is 'contraindicated', it in no way actually requires HIV testing in any manner - just strengthening of the 'Boxed Warning' on Gilead's packaging,” said president of the AHF, Michael Weinstein.
“The FDA's move today is negligence bordering the equivalence of malpractice which will sadly result in new infections, drug resistance and serious side effects among many, many people.”
The HIV charity Avert had also previously raised concerns about Truvada as a preventive measure, stating that some healthcare professionals “believe that use of PrEP in this way may give rise to complacency, an increase in risky sexual behaviour and a false perception about an AIDS cure”.
However, the FDA's commissioner Dr Margaret Hamburg said the decision was an “important milestone” to tackle the US' HIV “epidemic”, with 50,000 people in the country diagnosed with HIV infection each year.
As well as the boxed warning contraindicating the drug's use in patients with unknown or positive HIV, the approval also requires a risk evaluation and mitigation strategy to reduce the risk of uninfected individuals acquiring the infection.
This includes a training and education programme to assist prescribers in counselling people who are taking or considering Truvada for PrEP and provide information about the importance of adherence and understanding that infection was still a spossibility when taking the drug..
In addition, Gilead is required to collect viral isolates from individuals who acquire HIV while taking Truvada and to evaluate these isolates for the presence of resistance.
The company will also collect data on pregnancy outcomes for women who become pregnant while taking Truvada for PrEP and conduct a trial to evaluate drug adherence and its relationship to adverse events and the risk of developing HIV.