Hiroshi Ishikawa spent half of his career searching for a tuberculosis cure. Now, after a quarter century, he may have the drug industry's most effective weapon to fight resistant strains of the deadly lung disease.

In 1982, when tuberculosis was brought under control in developed nations, Ishikawa, a researcher at Otsuka Pharmaceutical Co. in Tokushima Prefecture, began looking for new ways to attack the bacterium plaguing poor nations in Asia. The result is OPC-67683, the first new drug against TB in more than 40 years and one of the three most advanced in development worldwide.

Ishikawa's success comes at a time when drug-evading bacteria are transforming an infectious disease that could be treated with $20 worth of medication into an unstoppable scourge.