The U.S. Food and Drug Administration's approval Monday of a new AIDS medicine is a first for Japan Tobacco Inc.Japan Tobacco Inc. , which spent a quarter-century researching drugs without having a product of its labs cleared for the big U.S. market.

The FDA approved a combination AIDS pill to be sold in the U.S. by Gilead Sciences Inc. under the brand name Stribild, as Jennifer Corbett Dooren reports. The Gilead product combines four different medicines, one of which is a substance called elvitegravir. That was discovered...