Jul. 20, 2009 (United Press International) -- The experimental drug Benlysta shows great promise in treating lupus and could be available to the public late next year, its Maryland-based developer said.

Benlysta is the first promising new treatment for lupus, an autoimmune disease, in nearly 50 years, researchers at Human Genome Sciences (NASDAQ:HGSI) , of Rockville, said.

Pending the results of another round of tests, the company plans to file for U.S. Food and Drug Administration approval early next year, said David C. Stump, the firm's head of drug development.

Benlysta could be worth worth billions of dollars to the firm and its partner in developing it, GlaxoSmithKline (NYSE:GSK) , The Washington Post reported Monday.

An estimated 1.5 million Americans have some form of lupus, currently treated with steroids and chemotherapy, which can have harsh side effects, said Sandra C. Raymond, the chief executive of the Lupus Foundation of America.

"This is a big deal for a lot of people," Raymond said of Benlysta.