Study raises hope for new drugs for resistant tuberculosis

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 drug cocktail could speed treatment and help reduce the emergence of resistant forms of tuberculosis.

"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-resistant 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," Spiegelman 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.

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Study raises hope for new drugs for resistant tuberculosis