[Viva] Fwd: CATIE-News - Study drops oral tenofovir as HIV prevention in a women’s study

Tami Starlight tamistarlight at gmail.com
Wed Oct 12 13:31:43 PDT 2011 

---------- Forwarded message ----------
From: <mailing at mercury.catie.ca>
Date: Wed, Oct 12, 2011 at 1:22 PM
Subject: CATIE-News - Study drops oral tenofovir as HIV prevention in a
women’s study
To: cosmictami at shaw.ca


*CATIE-News - Study drops oral tenofovir as HIV prevention in a women’s
study*

The burden of HIV infection is largely borne by people in sub-Saharan
Africa, particularly girls and women. Behavioural messages that encourage
abstinence, monogamy and use of condoms have had, according to researchers,
only a limited long-term impact on the spread of HIV in that region. This
situation arises in part because women do not have control over their
sexuality and face many obstacles to achieve social, economic and political
equality. Needless to say, more options for preventing HIV transmission are
needed.
PrEP

Pre-exposure prophylaxis (PrEP) is a term given to any anti-HIV therapy that
can be taken *prior* to exposure to HIV in the hope that it will protect the
user from HIV infection. PrEP can take the form of pills taken orally or
creams or gels applied to the vagina, anus or penis. Creams or gels with
anti-HIV activity that are applied to the genitals are called microbicides.
Creams or gels that contain anti-HIV drugs are considered a topical form of
PrEP.

Topical and oral forms of PrEP continue to be studied so that researchers
can be certain about their effectiveness. Many formulations of PrEP use the
antiviral drug tenofovir (called Viread when used in pill form) or
combinations of tenofovir and another drug called FTC (sold as a fixed-dose
co-formulation pill called Truvada).

Clinical trials have found that PrEP can reduce a person’s relative risk of
becoming infected with HIV. However, the preventive effect of anti-HIV drugs
taken in this way is less than 100% and is *strongly* dependent on a
person’s ability to take the drug as directed, a behaviour called adherence.
Indeed, in a trial called Caprisa, in which researchers tested a
tenofovir-containing vaginal gel used before and after sex against a placebo
gel in heterosexual women, they found that the gel reduced the risk of
becoming infected with HIV by 39%.

Another trial (called iPrEx) in gay and bisexual men found that when
compared to placebo a Truvada pill taken daily reduced the relative risk of
HIV infection by 44%.

Two other studies (TDF2 and Partners PrEP) found that a daily Truvada or
tenofovir pill was able to reduce the risk of acquiring HIV in heterosexual
people. Surprisingly, a study called FEM-PrEP was stopped early because it
seemed that daily Truvada was not able to reduce the risk of HIV infection
among heterosexual women. The reason(s) for the disappointing results in
FEM-PrEP are not yet known.
VOICE

In Southern Africa, researchers are conducting a study called VOICE (Vaginal
and Oral Interventions to Control the Epidemic), sponsored by the
Microbicide Trials Network and the U.S. National Institutes of Health (NIH).
It has recruited more than 5,000 women. Researchers randomly assigned women
to each of the following five study arms:

   - daily tenofovir vaginal gel
   - daily placebo vaginal gel
   - daily tenofovir tablet
   - daily Truvada tablet
   - daily placebo tablet

This type of study design will enable researchers to compare the
effectiveness of different regimens in preventing HIV infection when VOICE
is completed.
Monitoring

Many trials have an independent oversight committee called a Data and Safety
Monitoring Board (DSMB). The role of a DSMB is to periodically review the
data collected from the study and to stop or modify the study if there are
concerns about the safety of participants or the effectiveness of
interventions being studied.

The Microbicide Trials Network recently stated that after reviewing the
available data the DSMB concluded that “it is not possible to show whether
oral tenofovir tablets were any better than placebo” in their ability to
prevent HIV infection (similar to the FEM-PrEP study that was stopped
early). The DSMB recommended that women in VOICE who were receiving
tenofovir tablets stop taking them, but it had no concerns about the safety
of tenofovir. The DSMB noted that women in the other four arms of the study
should continue taking their assigned intervention(s).

These results are surprising because the Partners PrEP study found that a
daily tenofovir pill *did* reduce the risk of HIV infection when used by
heterosexual women.

All participants in VOICE will be told about the DSMB’s recommendations.
Although the use of a daily tenofovir pill for PrEP has been stopped, women
in the study are continuing to take the daily Truvada pill and the daily
tenofovir gel.

Researchers are not certain why oral tenofovir did not significantly protect
women in VOICE but this may become apparent when the full results of the
study are released next year. As the trial is continuing, a complete
analysis of the data is not expected to become available until the end of
2012.

Resources:

CATIE *Prevention in Focus* article on
PrEP<http://www2.catie.ca/en/pif/february-2011/preparing-pre-exposure-prophylaxis>
CATIE Fact Sheet on
PrEP<http://www.catie.ca/en/fact-sheets/prevention/pre-exposure-prophylaxis-prep>
CATIE-News story on iPrEx
trial<http://www.catie.ca/en/catienews/2010-11-25/truvada-for-hiv-prevention---some-good-news-but-caution-is-still-needed>
CATIE-News story on FEM-PrEP trial
<http://www.catie.ca/en/catienews/2011-04-27/prep-study-closes---questions-remain-unanswered>
CATIE-News story on TDF2 and Partners
PrEP<http://www.catie.ca/en/catienews/2011-08-03/prep-reduces-hiv-transmission-heterosexual-men-and-women>



*—Sean R. Hosein*

REFERENCES:

   1. Abdool Karim Q, Abdool Karim SS, Frohlich JA, et al. Effectiveness and
   safety of tenofovir gel, an antiretroviral microbicide, for the prevention
   of HIV infection in women. *Science*. 2010 Sep 3;329(5996):1168-74.
   2. Baleta A. Antiretroviral vaginal gel shows promise against HIV. *
   Lancet*. 2010 Jul 31;376(9738):320.
   3. Baeten J. *Antiretroviral pre-exposure prophylaxis for HIV-1
   prevention among heterosexual African men and women: the Partners PrEP
   Study. **In: Program and abstracts of the **6th International AIDS
   Society Conference on HIV Pathogenesis, Treatment and Prevention*, 17-20
   July 2011, Rome. Abstract MOAX0106, 2011.
   4. Thigpen M, Kebaabetswe PM, Smith DK, et al. *Daily oral antiretroviral
   use for the prevention of HIV infection in heterosexually active young
   adults in Botswana: results from the TDF2 Study.* *In: Program and
   abstracts of the **6th International AIDS Society Conference on HIV
   Pathogenesis, Treatment and Prevention*, 17-20 July 2011, Rome. Abstract
   WELBC01.
   5. Microbicide Trials Network. MTN statement on decision to discontinue
   use of oral tenofovir tablets in VOICE, a major HIV prevention study in
   women. *Press release*. 28 September 2011.



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