UPDATE 2-U.S. advisers back Acorda walking drug for MS

* FDA advisers say drug is effective, safe

* Panelists still want lower doses tested

* Approval decision expected by Oct. 22 (Recasts first paragraph with panel backing; adds testimony to panel, background on drug, byline)

By Susan Heavey

ADELPHI, Md, Oct 14 (Reuters) - U.S. health advisers backed an Acorda Therapeutics Inc (ACOR.O) drug aimed at improving the ability of multiple sclerosis sufferers to walk.

A U.S. Food and Drug Administration panel of outside experts voted on Wednesday that the drug -- known chemically as fampridine -- was safe and effective.

But the FDA advisory panel said fampridine should not be used in people with known seizure problems. They also said lower doses should be studied, but that could wait until after approval.

Acorda is seeking U.S. approval to sell its 10-milligram, twice-daily drug to treat walking problems that are a common symptom of MS. It has proposed the brand name Ampriva.

There is no cure for multiple sclerosis, a chronic disease affecting about 400,000 Americans. It attacks the central nervous system and can result in numbness or paralysis of arms and legs.

The FDA will weigh the panel's advice before making its approval decision, which the company expects by Oct. 22.

At the meeting, representatives for Acorda told the panel that even a small increase in walking speed could help patients with such simple tasks as getting to the bathroom quickly.

Acorda conducted two major studies of the drug, measuring how fast a total of more than 500 patients given either fampridine or a placebo could walk a distance of 25 feet (eight metres).

Roughly one-third of patients taking the drug responded to it, the company said.

Dr. Christine Short, a medical professor at Dalhousie University in Canada who spoke on behalf of Acorda, said the drug's ability to shave a few seconds off a 25-foot walk could lead patients to pack in as many as 900 extra feet (270 metres) over the course of an hour.

FDA staff scientists told the panelists that more patients responded to fampridine but the difference in actual walking speed with either group was very small. That made it unclear what impact it actually had on patients' walking overall, they added.

Nearly a dozen patients and advocates urged the FDA advisers to support the drug, saying any improvement in mobility had a huge impact on their lives.

"This isn't about a 25-foot walk. It's about quality of life," patient Elissa Levy, whose nonprofit group MS Hope For a Cure has received funding from Acorda. Levy, who also owns some Acorda stock, said she had been wheelchair-bound before taking a form of fampridine already available at some pharmacies.

Having MS has "led to nothing but falls... and lots of broken bones," said Robert Engel, who was diagnosed seven years ago and said there was a need for a pharmaceutical option along with physical therapy and exercise programs.

Panelists expressed concern about the availability of compounded versions of the drug from pharmacies, noting potential dosage problems. Fampridine has been linked to seizures, particularly at higher doses.

FDA staff and Acorda said there was little sign of seizure problems with the company's proposed 10 mg dose. Other side effects can include urinary tract infections, falls and multiple sclerosis relapses, according to the company.

Acorda Therapeutics President and Chief Executive Ron Cohen welcomed the advisory panel's support and would continue to work with the FDA. Trading in Acorda shares was halted Wednesday on Nasdaq because of the advisory meeting.

Biogen Idec Inc (BIIB.O), which currently sells two widely used multiple sclerosis treatments -- Avonex and Tysabri -- is developing fampridine outside the United States. (Reporting by Susan Heavey; editing by Andre Grenon and Tim Dobbyn)