Need for Speed: Faster-acting tuberculosis drugs now in testing would limit deaths

Drugs that would take only 2 months to cure tuberculosis instead of the usual 6 months could prevent millions of TB infections and deaths, a new analysis finds.

“It’s hard to get people to finish a 6-month course, since a lot of patients start to feel better after a few months,” says Joshua A. Salomon, a public health analyst at the Harvard School of Public Health in Boston.

Patients who don’t finish the standard treatment fail to wipe out Mycobacterium tuberculosis, the microbe that causes TB. They typically survive but are prone to relapses and can remain intermittently contagious, Salomon says.

Scientists are now testing two promising new drugs—diarylquinoline TMC207 and a compound in the nitroimidazopyran family called PA-824. Tests in animals and lab dishes against M. tuberculosis indicate that drug therapy with these compounds might require only 2 to 4 months. Both candidate drugs are in early stages of testing in people.

“We’re at a point where these new drugs are starting to look like a reality,” Salomon says.

He and his colleagues theorized that a drug with a shorter treatment schedule would increase patient compliance, prevent relapses, reduce the development of drug resistance, and ultimately limit the spread of TB because fewer people would harbor the microbe. Moreover, a shorter regimen “would free up resources and enable [health workers] to detect more cases,” Salomon says.

He and his team built a mathematical model that considered the various implications of a 2-month cure for TB. The group applied its model to the Asian region that includes India, Bangladesh, Burma, Thailand, and Indonesia.

If made available to the region by 2012, such a regimen would reduce new cases of TB by 20 percent and decrease deaths by 25 percent between 2012 and 2030, the team reports in the August PLoS Medicine. That would eliminate 11 million new active cases of TB and would prevent 5 million deaths, compared with the standard treatment, which requires combinations of four drugs taken over 6 months, Salomon says.

Worldwide each year, 2 million people die from TB and 9 million people develop the active disease.

The fight against TB had progressed steadily during the 20th century until the AIDS pandemic rendered millions of people newly susceptible to it. That has made TB harder to control, particularly in sub-Saharan Africa, says Ann Ginsburg, a pathologist and molecular biologist at the Global Alliance for TB Drug Development, a New York City–based nonprofit group that manages public-private research projects.

Both new drugs use “novel mechanisms of action,” says Ginsburg. “Both theoretically should be effective and potent against multidrug-resistant

TB strains.”