| CNN | - |
(CNN)
-- Two more HIV patients have no signs of the virus in their blood
following bone marrow transplants, according to the Boston researchers
who treated them.
Patients HIV-free for now after transplant
updated 10:30 AM EDT, Wed July 3, 2013
Experts are hailing a new development as a potentially important step in the fight against HIV.
STORY HIGHLIGHTS
- Two men show no sign of HIV after bone marrow transplants
- But experts say it's too early to know if the two are cured
- The transplant isn't a viable option for the vast majority of patients
However, experts stopped
short of calling the two cured and said the treatment is not a viable
option for the majority of HIV patients.
The findings were presented Wednesday at the International AIDS Society Conference in Kuala Lumpur, Malaysia.
The two men, whose
identities are being withheld, had been on antiretroviral (ARV) drug
therapy for years before being diagnosed with lymphoma, a cancer of the
lymph nodes.
Both underwent intensive
chemotherapy followed by bone marrow transplants to treat the cancer.
They remained on antiretroviral therapy.
Approximately four months
after the transplant doctors were still able to detect HIV in their
blood, but six to nine months later, all traces of the virus were gone.
"Because of those
findings, we thought it was justified to take the patients off of their
therapy to see what happens," said Dr. Timothy Henrich, who conducted
the clinical trial.
"Now, in a normal person
who has HIV, who has been on long-term antiretroviral therapy for years,
usually the virus comes back within two to four weeks after stopping
therapy, it comes right back. "
Some patients make it up
to eight weeks before the virus returns, said Henrich, a researcher at
Harvard Medical School and Brigham and Women's Hospital in Boston, but
the virus returns eight to 10 weeks after therapy is stopped in the vast
majority of patients.
Not so for these two, however.
"We are now recording 15
weeks after therapy and eight weeks after therapy for our two patients,
and to date we are unable to detect HIV rebounding in the bloodstream
after we stopped the therapy," Henrich said.
"We do weekly
monitoring, as well. We've been looking at the virus in the blood and
the cells in the blood essentially every week since we've taken them off
therapy, and we have not been able to detect virus at this time."
The two men are being compared to Timothy Ray Brown, also known as the "Berlin Patient." Brown is thought to be the first person ever "cured" of HIV/AIDS.
In 2007, Brown had a
stem cell transplant to treat his leukemia. His doctor searched for a
donor with a rare genetic mutation called CCR5 delta32 that makes stem
cells naturally resistant to HIV infection.
Today, the virus is
still undetectable in Brown's blood, and he is still considered to be
"functionally cured." A functional cure means the virus is controlled
and will not be transmitted to others.
The stem cell transplant
procedure, however, is very dangerous because a patient's immune system
has to be wiped out in order to accept the transplant.
Using a bone marrow
transplant to treat HIV is not a feasible treatment for most patients,
and only 1% of Caucasians -- mostly Northern Europeans -- and no
African-Americans or Asians have the CCR5 delta32 mutation, researchers
say.
The transplant is still
not a practical strategy for the majority of HIV patients, and the risk
of mortality is up to 20%, Henrich says.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, agreed.
"This is not a practical
approach for someone who does not need a stem cell transplant since the
transplant and its preparation and its subsequent need for chronic
immunosuppression is a risky procedure," Fauci said.
"If you have an underlying neoplasm (tumor)
like these patients had, then the risk outweighs the benefit," he said.
"However, if you are doing well on ARVs and you merely want to get off
antiretroviral therapy, then the risk seems greater than the benefit."
Even though the two
patients showed a reduction of the virus in the blood, it could still be
in some tissue -- the brain or gastrointestinal tract, for instance,
Henrich said.
The virus "could certainly return," he said.
"It's possible, again,
that the virus could return in a week, it could return in a month -- in
fact, some mathematical modeling predicts that virus could even return
one to two years after we stop antiretroviral therapy, so we really
don't know what the long-term or full effects of stem cell
transplantation and viral persistence is."
Still, he feels the information will help move the curative field of HIV research forward.
"We're going to learn
different strategies about how we can attack the viral reservoir, how we
can harness the immune system better and what exactly caused the lack
of virus in the two patients at least in the short term."
Earlier this year, researchers said an HIV-positive baby in Mississippi was
given high doses of three antiretroviral drugs within 30 hours of her
birth, with doctors hoping that would control the virus.
Two years later, there is no sign of HIV in the child's blood, making her the first child to be "functionally cured" of HIV.
The Foundation for AIDS Research, or amfAR, helped fund the study.
"These findings clearly
provide important new information that might well alter the current
thinking about HIV and gene therapy," said amfAR CEO Kevin Robert Frost.
"While stem cell
transplantation is not a viable option for people with HIV on a broad
scale because of its costs and complexity, these new cases could lead us
to new approaches to treating, and ultimately even eradicating, HIV."
"Dr. Henrich is charting
new territory in HIV eradication research," said Dr. Rowena Johnston,
amfAR vice president and director of research.
"Whatever the outcome,
we will have learned more about what it will take to cure HIV. We
believe amfAR's continued investments in HIV cure-based research are
beginning to show real results and will ultimately lead us to a cure in
our lifetime."
In the meantime, Henrich says he and other groups are actively enrolling patients for these types of studies.
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