* GSK to start large trials testing protective injection
* Under-skin implants seen as promising long-term option
* New HIV cases still running at 1.9 million annually
By Ben Hirschler
LONDON, Nov 29 Scientists are taking the battle
to prevent HIV to the next level with large-scale trials set to
start using injections to protect vulnerable groups such as gay
men and women in Africa for at least two months.
Further down the road, the hope is to produce
matchstick-sized implants containing slow-release drugs -
similar to existing under-the-skin contraceptive devices - that
could offer year-long protection.
Companies with drugs involved include GlaxoSmithKline
, Gilead Sciences and Merck.
The initiatives build on the success of Gilead's once-daily
pill Truvada, which has proved remarkably effective at stopping
HIV infection during sex.
Clinical studies show such pre-exposure prophylaxis, or
PrEP, can cut the risk of catching the virus by more than 90
percent, as long as people take their pills regularly. The
problem is many do not.
Some women in trials in Africa, for example, said they were
reluctant to have HIV tablets in the house for fear of what
partners or neighbours would think.
An injection given in a clinic, experts argue, would add
privacy and ensure steady drug levels. An implant in the arm
might even combine contraception and HIV protection in one go.
"The more options there are the better and I think for some
individuals injections will be great," said Jean-Michel Molina,
professor of infectious diseases at Hospital Saint-Louis in
"Now that we know antiretrovirals have great potential to
prevent HIV infections, it is time to really assess other ways
to deliver these drugs."
The need remains acute. Despite treatment advances that have
slashed AIDS deaths, around 1.9 million people still catch HIV
each year - a number that hasn't budged since 2010. New
infections among gay men are actually increasing.
The United Nations AIDS programme warned last week that the
problem now threatened progress in ending the global epidemic,
while the World Health Organization has recommended PrEP for all
groups at substantial risk of HIV infection.
STILL NO VACCINE
GlaxoSmithKline's majority-owned ViiV Healthcare unit,
working with U.S. government agencies and the Bill & Melinda
Gates Foundation, hopes to add the first injectable PrEP.
It plans to start a four-year trial as soon as next month
testing its experimental drug cabotegravir in gay men in the
Americas and Thailand, with a second trial next year assessing
the medicine in African women.
Two separate studies evaluating cabotegravir in combination
with another drug for HIV treatment were launched this month.
"The holy grail is a vaccine, but we don't have a vaccine
yet," said Myron Cohen of the University of North Carolina at
Chapel Hill, who is involved in the ViiV prevention study
programme and believes new options can help rein in HIV.
He is also working on another prevention trial giving people
antibodies via an intravenous drip.
Gilead, meanwhile, is running a late-stage study assessing
its next-generation HIV drug Descovy as an alternative oral
PrEP, since it has milder side effects than Truvada.
In the long run, Cohen and other HIV experts are especially
excited by slow-release drug implants. Implants have yet to
prove themselves in human trials, although an experiment in
beagles last year with a Gilead drug produced promising results.
Products from GSK and Merck are also seen as implant options.
The size of the HIV prevention market remains uncertain and
price will be an issue, especially in Africa, but some industry
analysts believe it could be substantial.
Truvada, the only medicine so far approved for HIV
prevention, is now being used for PrEP by 80,000-90,000 people
in the United States, accounting for 35-45 percent of the drug's
revenue in the third quarter.
It is starting to gain traction, too, in Europe, with France
offering free supplies, while in Britain and other markets,
where it is not paid for by the government, people are turning
to online "buyers clubs" to get cut-price generics.
There is resistance, however. A French government campaign
this month promoting HIV awareness, including PrEP, was attacked
by several French mayors.
Some have also criticised PrEP for diluting the "safe sex"
message of condom use, especially as it will not prevent other
sexually transmitted infections (STIs).
But Sheena McCormack of University College London argues
this misses the point. "Sometimes people can't see the wood for
the trees. The STI that lasts a lifetime and costs governments a
lot of money is HIV."
(Editing by Alexandra Hudson)