* Experimental drug kept monkeys free of HIV-like virus
* Monkeys free of HIV-like virus for nearly 2 years
* Treatment hits same target as Takeda's Crohn's disease
* Human safety trials underway to test Takeda drug in HIV
By Julie Steenhuysen
CHICAGO, Oct 13 A new drug combination helped
stave off a monkey version of HIV for nearly two years after
stopping all treatments, raising hopes for a functional cure for
HIV, U.S. researchers said on Thursday.
The treatment involved standard HIV drugs, known as
antiretroviral therapy or ART, plus an experimental antibody
that hits the same target as Takeda Pharmaceutical's
Entyvio, a drug approved in more than 50 countries for
ulcerative colitis and Crohn's disease.
The findings, published Thursday in the journal Science, are
promising enough that scientists at the National Institutes of
Health, which funded the research, have already begun testing
the Takeda drug, known generically as vedolizumab, in people
newly infected with HIV.
"The experimental treatment regimen appears to have given
the immune systems of the monkeys the necessary boost to put the
virus into sustained remission," said Dr. Anthony Fauci,
director of the National Institute of Allergy and Infectious
diseases, part of the NIH, who co-led the study.
Sustained remission - known as a "functional cure" - could
have sweeping implications for people infected with the human
immunodeficiency virus or HIV, which attacks the immune system.
Highly effective treatments known as antiretroviral therapy
push the virus down to undetectable levels in the blood, but
they must be taken every day over a person's lifetime to remain
effective, said Aftab Ansari of Emory University School of
Medicine who co-lead the study.
Ansari said the study was based on the understanding that in
the early days of infection, HIV attacks a specific class of
immune cells that congregate in large quantities in the gut.
They theorized that if they could protect these immune cells,
they could buy the immune system enough time to mount an
To do this, the team tested an antibody that blocks a
protein called alpha-4/beta-7 integrin that HIV uses to attack
immune cells in the gut.
For the study, they infected 18 monkeys with simian
immunodeficiency virus or SIV, the monkey version of HIV. They
then treated all of the animals with ART for 90 days, and, as it
does in humans, the ART controlled the virus, reducing it to
Antiretroviral drugs used in this stage of the experiment
included Gilead's tenofovir and emtricitabine, sold in
a combination drug for people as Truvada, and a Merck
integrase inhibitor known as L-870812.
In 11 monkeys, the scientists then gave infusions of the
antibody for 23 weeks, and seven monkeys got a placebo. Three of
the 11 monkeys developed a reaction to the treatment and had to
stop the therapy.
In the eight monkeys that got the treatment, six initially
showed signs that SIV was rebounding, but eventually their
immune systems were able to control the virus. In two others,
the virus never rebounded. All eight have continued to suppress
SIV to undetectable levels for up to 23 months after all
treatment stopped. In the control group, SIV rebounded and all
seven animals died.
The study did not look at whether the monkeys were still
able to transmit the virus, but studies in people have shown
that reducing HIV to undetectable levels cuts transmission rates
by nearly 100 percent.
Ansari said the study is promising because it could
eventually lead to a treatment for HIV in people that would not
require a lifetime of ART therapy.
Scientists have recently focused on efforts to cure HIV,
reducing the burden of lifelong treatment, but prior efforts
have been frustrated by the HIV virus' ability to form hidden
reservoirs that replenish the virus when treatments are halted.
In one dramatic case, Timothy Ray Brown, the so-called
"Berlin patient," was cured of HIV after an elaborate treatment
for leukemia in 2007 that involved the destruction of his immune
system and a stem cell transplant from a donor with a rare
genetic mutation that resists HIV infection.
Ansari cautioned that not all treatments that work in
monkeys will work in people. He said the findings are still very
early, and said many more experiments are needed to understand
why the antibody protected the monkeys.
Still, he said Takeda's antibody vedolizumab is "identical"
to the one the team used on the monkeys.
NIH researchers already have begun a study to see if a
30-week course of Takeda's drug vedolizumab is safe and helps
control HIV when patients are temporarily taken off conventional
ART treatments. Preliminary results are expected by the end of
2017 with further data becoming available into 2018.
If proven safe, the drug would need to be studied in larger
trials to prove it is also effective.
Takeda spokeswoman Elissa Johnsen said the company is
"pleased to support the trial and contribute to scientific
discovery" but said it was too early to comment on future
(Reporting by Julie Steenhuysen; Editing by Bernard Orr)