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Scientists Develop Promising New TB Drug

For the first time in four decades, a new antibiotic has emerged that researchers say will revolutionize the fight against tuberculosis. Scientists have just begun to test the compound in humans after what they describe as very promising results in mice. Experts say the drug compound could cut in half the amount of time it takes to treat tuberculosis in humans, but observers are cautious.

After AIDS, tuberculosis is the leading cause of death around the world, killing two to three million people every year. The two diseases are also linked. Eleven million people are infected with both HIV and TB.

Keon Andries is an anti-microbial researcher with the drug company Johnson and Johnson Belgium who led the effort to develop the new anti-tuberculosis drug. "I think our drug is the first one to be really tested in humans in 40 years. The last drug that was developed in humans was rifampin in 1963. So, that is really a reason to be really delighted today," he says.

In 1963, rifampin became the last targeted antibiotic introduced to fight TB. Experts say drugs to protect against TB have become ineffective against the TB mycobacterium in many regions of the world because it has developed defenses against them. The resistance has occurred even though patients have taken combinations of antibiotics to try to boost their effectiveness. Doctors say misuse of TB antibiotics, which people with tuberculosis took sporadically, have resulted in widespread resistance.

Now comes an experimental drug candidate from a family of compounds known as "DARQ's," which experts say has a completely different mechanism of action from the other antibiotics. Where the older antibiotics work by interfering with the manufacture of the mycobacterium's various systems, Dr. Andries says the new drug chokes its energy supply.

In laboratory experiments, there is no evidence the TB mycobacterium is resistant to the DARQ compound. But Dr. Andries says the experimental drug appears to be most effective when given in combination with older TB drugs, a measure that should also stave off resistance.

Drug testing on mice is the standard way of seeing whether an experimental compound has any promise for humans. And human trials of the TB drug candidate have just begun.

Christopher Dye is head of tuberculosis monitoring at the World Health Organization in Geneva. He cautions against premature optimism, noting the experimental drug may not work as well in humans as it appears to in mice. "The tendency to hype things prematurely really comes from the fact that we really have not had a new drug for tuberculosis control for over 30 years. So, we desperately need a new drug. And anytime a promising new compound comes along which seems to have very activity in killing TB as this new drug does, then people in the TB world get very excited about it and that can lead to some hype," he says.

Nevertheless, Dr. Dye hails what appear to be the compound's anti-drug resistance properties. He also hopes the compound does in people what it has been shown to do in mice - cut treatment times in half. "The current drugs that we use require six to eight months of treatment in patients. And although we refer to that as short-course chemotherapy, in fact it is a very long period time for any patient to take drugs. And we would really like to see those drug regimens shortened to something like two months," he says.

Researchers describe the experimental TB drug in the journal Science.