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A Dose Of Caution : Petition Filed To Block HIV Prevention Pill

A Dose Of Caution : Petition Filed To Block HIV Prevention Pill
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There has been much debate regarding Truvada ever since Gilead Sciences Inc. (GILD: Quote) sought regulatory approval to market its HIV treatment medication Truvada as a HIV prevention pill. Some public health advocates are concerned about Gilead's move as they fear that the expanded use of the drug would lead to individuals engaging in unprotected sex, and would, in fact, increase the incidence of HIV and other infections.

Truvada, a combination of Gilead's two drugs - Viread and Emtriva, received an accelerated approval from the FDA in August 2004, followed by traditional approval in March 2006, for the treatment of HIV in combination with other antiretroviral drugs.

Last December, Gilead filed a supplemental New Drug Application with the FDA seeking approval of its once-daily Truvada for HIV prevention. This prevention approach is known as pre-exposure prophylaxis or PrEP. The idea behind PrEP is that people who do not have HIV may protect themselves against HIV infection by taking Truvada, which is already approved as a daily treatment for people infected with HIV or living with AIDS.

The sNDA application was based on two large phase III trials known as Pre-Exposure Prophylaxis Initiative, or iPrEx, and Partners PrEP.

In the iPrEx study, which involved 2,499 high-risk HIV-negative homosexuals in the US and other countries, the once daily use of Truvada reduced the risk of acquiring HIV by 44 percent compared with placebo and by up to 73 percent in men who took the drug consistently. In men with enough detectable drug presence, the risk was reduced by more than 90 percent.

In the other trial, Partners PrEP, which involved 4,758 heterosexual couples in Kenya and Uganda in which only one partner was infected with HIV, once-daily use of oral Truvada by the HIV-negative participants reduced their risk of acquiring HIV by 73 percent compared with placebo.

Despite the impressive results, experts remain wary about expanding the use of antiretrovirals to include HIV prevention.

An article that appeared in The Lancet, a British medical journal, last year, cautions that "pre-exposure prophylaxis is unlikely to be 100%, and making drugs available as prophylaxis could encourage high-risk sexual behaviour among those who believe themselves to be protected".

On March 1st, two UK organizations, the British HIV Association and the British Association for Sexual Health and HIV issued a statement stating that the existing data on the efficacy of pre-exposure prophylaxis is not compelling enough for it to be offered to patients on demand, and therefore needs more study.

In light of experts voicing concern over the new pharmaceutical prevention approach to HIV, AIDS Healthcare Foundation, the largest global AIDS organization, is gearing up to block the regulatory approval of Gilead's AIDS treatment, Truvada, for expanded use as a method of preventing HIV infection in non-infected people.

The AIDS Healthcare Foundation, or AHF, filed a citizen's petition on March 7 asking the FDA not to approve the pending sNDA submitted by Gilead, which seeks permission to market once-daily Truvada for pre-exposure prophylaxis to reduce the risk of HIV transmission in uninfected adults.

Under law, the FDA has 180 days to respond to AHF's complaint. However, the FDA can approve Gilead's supplemental New Drug Application for expanded use of Truvada during that same time window.

The supplemental New Drug Application for Truvada, which has been granted a six-month Priority Review, has a decision date set for June 15, 2012. The application of Truvada for PrEP is also expected to be discussed at the FDA Antiviral Drugs Advisory Committee meeting scheduled in May.

According to the AHF, the prevention approach to HIV, will not work on a large-scale basis because, "consistent with poor medication adherence rates for most diseases, people will not be able to take Truvada as directed. Because of this, there will be little or no preventative effect, and drug resistance and drug resistant strains of HIV will develop. In addition, people who falsely believe they are fully protected against HIV very likely may engage in riskier behavior, thereby increasing their risk of HIV infection".

A new analysis by UCSF (University of California at San Francisco) researchers, published last month in the journal AIDS, reveals that Tenofovir - the active ingredient in Viread, ( one of the two drugs that make up Truvada) is associated with an increased risk for kidney disease and damage that increases over time and doesn't appear to be reversible.

According to Michael Weinstein, AHF's president, it is sheer corporate greed that is behind the idea of giving healthy people a toxic drug that will damage their kidneys in order to possibly prevent HIV - when a simple condom use is 95% effective.

Truvada, Gilead's second-best selling product, generated sales of $2.88 billion in 2011 compared to $2.65 billion in 2010. If the sNDA is approved, Truvada would be the first agent indicated for uninfected individuals to reduce the risk of acquiring HIV.

The first mention of the HIV virus was made in a report by the Centers for Disease Control and Prevention, or CDC, on June 5, 1981, which marked the official beginning of the HIV/AIDS epidemic. It is estimated that over 33 million people are living with HIV worldwide and 28 million have died from an AIDS-related illness since 1981, mostly in Africa.

There has been a tremendous progress in the treatment of HIV/AIDS since the introduction of antiretroviral therapy in 1996. Advancing to HIV prevention from HIV treatment may mark the beginning of the end of AIDS.

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by RTT Staff Writer

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