TB Drug Shows Promise in Mice

MIAMI BEACH--A new drug has been shown to cure laboratory mice of tuberculosis much more quickly than standard treatments. If the treatment, described here this week at the annual meeting of the American Society for Microbiology, works in humans, it could help prevent the emergence of resistant strains of the bacteria.

Each year, 25,000 patients in the United States are treated for tuberculosis with a mix of three drugs, which they must take diligently for 6 months. But many don't finish the regimen, and the bacteria surge back in hundreds of cases each year--sometimes as drug-resistant strains. To counter the threat, many researchers have been trying to pump up the potency of rifamycin, the most effective tuberculosis drug. After testing several versions of the molecule in lab cultures, the Japanese chemical company Kaneka turned to microbiologists for a test in mice.

Michael Cynamon of the Veterans' Administration Medical Center in Syracuse, New York, and his colleagues substituted Kaneka's leading candidate, KRM-1648, for rifamycin in tubercular mice. The new drug cleared the mice of all tuberculosis bacteria after only 10 weeks of treatment. Although the comparable benefit for humans isn't established yet, if it works, the drug could drastically cut the length of time patients must pop pills. "We're hoping that maybe a 3- to 4-month regimen should be feasible," Cynamon says. What's more, KRM appears to kill 20% of rifamycin-resistant strains.

"It's a promising new drug, and it's one of the few that are in the late stages of development," says Jerrols Ellner, director of the tuberculosis-research unit at Case Western Reserve University in Cleveland. Ellner will join other clinics in planning clinical trials to test KRM in humans.