Drug cocktail could halt spread of resistant TB as it kills 99% of patient's bacteria in two weeks
In some countries one in four
people with TB has a form that can no longer be treated
with standard drug cocktails
08:06 GMT, 24 July 2012
Scientists have successfully tested a new drug treatment for tuberculosis which could be an effective weapon against increasingly resistant forms of the disease.
The combination of three drugs killed 99 per cent of patients' tuberculosis bacteria in two weeks.
'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,' said Dr Mel Spiegelman, chief
executive officer of the TB Alliance, a non-profit research group that
conducted the study.
A woman with TB rests at a hospital
in Tamatave, Madagascar. The disease killed 1.7million in 2009
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 cocktail 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.
The findings, published in The Lancet, come as the TB bacterium Mycobacterium tuberculosis is rapidly developing resistance to the world's most effective tools.
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.
Tuberculosis virus: Some strains of the disease are becoming increasingly resistant to drug combinations
In the mid-stage 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 per cent 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, Dr 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,' said Dr Mario Raviglione, director of the World Health Organization's Stop TB Partnership.
'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.
The study, which needs to be confirmed in larger and longer trials, was presented at the
International AIDS Conference in Washington.
The new treatment doesn't contain 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.
Dr Spiegelman said: '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.'