Despite the deaths of two people among the thousands treated with a promising multiple sclerosis drug, MS patients are trying to persuade the U.S. government to allow the drug back onto the market.
They are hoping a federal advisory panel will shortly recommend that the Food and Drug Administration will again allow the sale of the drug Tysabri.
Multiple sclerosis, a disease of the central nervous system, afflicts about 350,000 Americans.
There is no cure and the cause is unknown.
MS causes progressive disability that can include blurred vision, weakness, poor muscle coordination and loss of memory and mental function as nerves lose their insulating sheath.
Drug manufacturer Biogen who make Tysabri have promised a U.S. panel of health experts if the drug is made available it will ensure there are tight controls in place to monitor for cases of life-threatening brain infections during treatment and for at least five years thereafter, to minimise the risk of infection.
Biogen voluntarily suspended sales of the drug, Tysabri, in February 2005 after three patients developed the rare brain disease progressive multifocal leukoencephalopathy, or PML. Two of the patients died.
The companies have asked the Food and Drug Administration to allow the drug back on the market with restrictions, such as giving the medicine only to patients, who join a registry to track side effects.
According to the FDA about 7,000 patients received the drug while it was on the market.
Many patients suffering from MS remain supporters of the drug.
The drug is given intravenously once a month and reduces relapses by two-thirds.
Biogen says in future, the drugs use should be reserved for patients who are not taking other MS drugs and do not have weakened immune systems.
The company proposes the drug carries a strong "black-box" warning that patients could develop the rare and potentially fatal infection PML.
The FDA expects additional cases of PML to occur, and many are likely to be fatal as there is currently no way to tell who is at risk for the complication.
The advisory panel, a group of experts from outside the FDA, is scheduled to soon make recommendations on Tysabri.
The FDA will make the final decision, but the agency usually follows advice from its outside panels.