* Bolsters hopes for new way to slow AIDS pandemic
* Gilead pills cut heterosexual infection 62-73 pct
* Studies tested drugs in Kenya, Uganda, Botswana
* WHO says findings "could have enormous impact"
(Adds comment from US CDC, investigators)
By Ben Hirschler
LONDON, July 13 AIDS drugs designed to treat
HIV can also be used to reduce dramatically the risk of
infection among heterosexual couples, two studies conducted in
Africa showed for the first time on Wednesday.
The findings add to growing evidence that the type of
medicines prescribed since the mid-1990s to treat people who
are already sick may also hold the key to slowing or even
halting the spread of the sexually transmitted disease.
The research involving couples in Kenya, Uganda and
Botswana found that daily AIDS drugs reduced infection rates by
an average of at least 62 percent when compared with placebo.
"Effective new HIV prevention tools are urgently needed and
these studies could have enormous impact in preventing
heterosexual transmission," Margaret Chan, director-general of
the World Health Organization (WHO), said in a statement.
She said the United Nations health agency would now work
with countries to use the new findings to implement better
The U.S. Centers for Disease Control and Prevention plans
to review the data and issue its own guidelines -- taking into
account issues such as whether behavior may change when people
know they are taking a drug that reduces infection risk, said
Dr. Jonathan Mermin, CDC director HIV/AIDS prevention.
In its first official guidance on the topic, the CDC said
in January that only high-risk gay and bisexual men should use
a daily AIDS pill to protect themselves from the virus.
NEW OPTION IN PREVENTION TOOL KIT
The larger of the two new studies examined 4,758
"discordant" couples in Kenya and Uganda in which one partner
was HIV-positive and one was negative. Those negative partners
taking Gilead Sciences Inc's tenofovir, or Viread, had on
average 62 percent fewer infections.
For couples on Truvada -- another Gilead drug combining
tenofovir and emtricitabine -- the infection risk was cut by an
estimated 73 percent in the clinical trial, which was led by
researchers at the University of Washington.
Dr. Jared Baeten, principal investigator of the study
funded by the Bill & Melinda Gates Foundation, said real-life
application of the results has not been determined. But Baetennoted that "discordant" couples who want to have children may
now have an alternative to condoms.
The second study, involving just over 1,200 sexually active
men and women in Botswana, found those on daily Truvada reduced
their risk of HIV infection by 62.6 percent.
Lead investigator, Dr. Michael Thigpen, said Truvada proved
to be safe and effective. He said the drug -- along with things
like male circumcision, topical microbicide gels and condoms --
could be another tool for preventing the spread of HIV.
The idea of such "pre-exposure prophylaxis," known as PrEP,
has gained traction in the past year, following results of
other research showing a fall in infection rates among gay men
taking AIDS drugs.
However, PrEP took a knock earlier this year when another
study failed to demonstrate a protective effect in high-risk
women. The latest strong evidence is likely to restore
confidence in the approach.
"TIPPING POINT" IN HIV FIGHT
Around 33 million people worldwide have the human
immunodeficiency virus (HIV) that causes AIDS, most living in
Africa and Asia. Only about half know their HIV status, and the
WHO hopes that news of an effective approach to prevention will
encourage more people to get tested.
Michel Sidibe, head of the UN's program on HIV/AIDS, said
the new studies "could help us to reach the tipping point in
the HIV epidemic."
The larger study, conducted in Kenya and Uganda, had been
scheduled to run until late 2012 but its placebo arm was
stopped early because the evidence of efficacy was so strong.
Results of the Botswana study, led by the CDC, had been due
to be unveiled next week at an international AIDS congress in
Rome but were released ahead of time to coincide with the
University of Washington research.
AIDS drugs are available as generics in many poor countries
at prices as low as 25 U.S. cents a tablet, according to the
WHO. Prices could fall further and supplies increase following
an agreement by Gilead, the leading maker of HIV drugs, to
share intellectual property rights on its medicines in a new
patent pool. The California-based group Tuesday became the
first drugmaker to sign up to the Medicines Patent Pool.
(Additional reporting by Deena Beasley)
(Reporting by Ben Hirschler; Editing by Will Waterman)