* Drug killed 99 percent of TB bacteria in two weeks
* Treatment could be used with HIV drugs
By Julie Steenhuysen
WASHINGTON, July 23 A new combination of three
drugs killed 99 percent of patients' tuberculosis bacteria in
two weeks, raising hope for a new weapon against increasingly
resistant forms of TB.
The midstage study, presented on Monday at the International
AIDS Conference in Washington, needs to be confirmed in larger
and longer trials. Scientists say the dr ug c ocktail could speed
treatment and help reduce the emergence of resistant forms of
"TB is the largest killer of AIDS patients, and so in order
to contain the AIDS epidemic, we have to contain TB to a much
greater extent," said Dr. Mel Spiegelman, chief executive
officer of the TB Alliance, a non-profit research group that
conducted the study, which was published in the Lancet.
The combination of drugs includes one existing TB drug,
pyrazinamide, a repurposed antibiotic from Bayer AG
called moxifloxcin that is now used off-label for patients with
drug-restistant TB, and a new drug called PA-824 being developed
by the New York-based TB Alliance.
What the combination lacks are any drugs in the class called
rifamycins, which pose the greatest threat of side effects for
patients who also are being treated for infections with HIV, the
human immunodeficiency virus that causes AIDs.
"The results of this clinical trial give us the first
indication that a new TB drug regimen - a combination of drugs -
could be more effective than any of the existing TB drug
regimens," Spi egelman said.
He said the combination is especially promising because it
could be used to treat patients with both treatment-sensitive TB
and TB strains that are resistant to two or more of the common
drugs, known as multiple-drug resistant TB.
The findings come as the TB bacterium Mycobacterium
tuberculosis is rapidly developing resistance to the world's
most effective tools.
STANDARD TREATMENTS FALTER
Standard treatment for TB usually includes a mix of four
drugs over a period of six months and multi-drug resistant TB
can take 18 to 24 months to treat.
Since most of the disease is cleared in the first few
months, people often do not finish their full regimen of TB
drugs, which can lead to drug resistance, making TB more
dangerous and more difficult to treat.
According to the World Health Organization, in some parts of
the world, one in four people with TB has a form of the disease
that can no longer be treated with standard drug cocktails.
Even more deadly forms of TB are emerging. Dr. Zarir Udwadia
of the National Hospital in Mumbai, India, has identified more
than a dozen cases of TB that cannot be killed by any existing
form of treatment.
TB kills an estimated 1.4 million people each year, and
some 9 million people are newly infected.
In the midstage study conducted at two sites in South
Africa, researchers tested the drug combination on 85 patients
with TB. After two weeks, they found the new treatment
combination was 99 percent effective at killing off TB bacteria
in these patients.
A follow-up study of the treatment testing the drug
combination over a two-month period already has begun and should
be completed next year, Spiegelman said. Once that study is
done, the group hopes to start large-stage clinical trials.
"The results look strongly promising from this early trial,"
Dr. Mario Raviglione, director of the World Health
Organization's Stop TB Partnership, said in a statement.
"If further trials hold up, we may have a major solution for
drug-sensitive TB and drug-resistant TB."
The study was funded by the Bill & Melinda Gates Foundation,
the U.S. Agency for International Development and the British
and Irish governments.
Besides the promise of a new treatment for TB, the design of
the trial, which tested several combinations of drugs at once to
find the most effective treatment, may help advance the study of
other TB treatments, Raviglione said.