ADELPHI, Md. – Federal health experts on Tuesday voted in favor of the first new drug to treat Lupus in over 50 years, setting aside concerns that the experimental therapy does not work in some key patient groups, including African-Americans.

The recommendation from a panel of Food and Drug Administration advisers brings the biotech drug from Human Genome Sciences one step closer to market. The drug was co-developed with GlaxoSmithKline PLC.

Known as Benlysta, the drug is designed to treat flare-ups and pain caused by lupus, a little-understood and potentially fatal ailment in which the body attacks its own tissue and organs. Ninety percent of lupus patients are women. The disease causes skin rashes, joint pain and inflammation of the kidneys and the fibrous tissue surrounding the heart.

The FDA panel voted 13-2 in favor of approving the drug. The agency is not required to follow the advice of its panelists, though it often does.

The FDA is scheduled to make a decision on Benlysta by Dec. 9, and company executives suggested the drug could be available in the first quarter 2011.

Shares of Human Genome Sciences rose $2.41, or 9.3 percent, to $28.29 in after-hours trading, while GlaxoSmithKline stock gained 94 cents, or 2.4 percent, to $39.48.

Throughout Tuesday's meeting, FDA's experts stressed that Benlysta will not work for all patients and that more effective therapies are still needed.

I think it's very exciting that this is the first new drug in five decades, but it's not magic bullet," said Dr. Maria Suarez-Almazor of the MD Anderson Cancer Center in Houston.

Panelists who voted against the drug's approval said the studies submitted by Human Genome Sciences did not show that patients taking Benlysta fared significantly better than those taking older therapies.

I have all the hopes and dreams that we have heard expressed today, and I know my lupus patients want a medicine that is more effective, but I have not seen data that says this drug is it," said Dr. David Blumenthal of Case Western Reserve University.

Only 30 percent of patients studied by Human Genome Sciences responded to the drug, as measured by a comprehensive list of lupus symptoms. The drug did not help African-Americans — who are three times more likely to have lupus than Caucasians. Additionally, studies conducted in Latin America and Eastern Europe showed significantly better results than those conducted in the U.S. and Canada, leading some panelists to question the accuracy of the results.

Despite such concerns, panelists appeared swayed by more than 30 lupus patients — several of whom currently take Benlysta — who urged the FDA to approve the drug during a public comment session. Many of the patients said the side effects of current drugs are as debilitating as the disease itself. Current treatments include steroids, which can cause bone fractures, and chemotherapy drugs, which cause hair loss, anemia and diarrhea.

The drugs help keep the immune system in check, but aren't designed to treat lupus itself.

Living with lupus is a daily fight simply to see another day, and often survival means letting go of things you love and wanted to do," said Wendy Rogers, a spokeswoman for the Lupus Foundation of America.

In separate votes the panel voted 10-5 in favor of the drug's effectiveness and 14-1 in favor of its safety.

I found the personal stories today particularly compelling, and I see this as an important opportunity to advance a challenging area of medicine and serve a previously underserved population," said Dr. Robert Kerns of the Veterans Affairs Connecticut Healthcare System.

An estimated 1.5 million people in the U.S. have lupus. Benlysta, known chemically as belimumab, is a once-a-month infusion that works by blocking the antibodies that cause the disease in a subset of patients.

If approved, analysts estimate Benlysta could eventually post sales of over $2 billion annually. Human Genome Sciences Inc., of Rockville, Md., and GlaxoSmithKline PLC, of Britain, which would split the profits, are also seeking approval to market the injectable drug in Europe.