By Randall Osborne

Cypress Bioscience Inc. said the FDA has granted "special review" status to the company's premarket approval supplement (PMA) related to its Prosorba column, for which Cypress is seeking to broaden the indication.

Having won FDA approval more than five years ago for Prosorba as a device to treat idiopathic thrombocytopenic purpura (ITP), an immune-mediated bleeding disorder, Cypress is seeking to expand its use into rheumatoid arthritis patients.

"We've submitted a huge amount of the PMA already, and the next big submission is on July 15," said Debby Jo Blank, president and chief operating officer of San Diego-based Cypress. A "special review" means expedited consideration by the agency.

Prosorba is a disposable filter that uses protein A to remove circulating immune complexes, such as antibodies and antigens, that are believed responsible for autoimmune diseases.

The PMA is based on strongly favorable data from a Phase III clinical trial. In January, an independent Data Safety and Monitoring Board recommended stopping the trial early because of the positive results.

How It Works Still A Mystery

Blank told BioWorld Today the column works against arthritis, but the company is not sure how. "It's probably not working by filtering out immune complexes or rheumatoid factor in arthritis, because the amount of protein filtered is quite small," she said.

"Also, the long-term effect is longer than a year or two years," Blank added. "How could this small, non-specific filtering of immunoglobulins lead to such a response? We don't know, but we're learning a lot. Any question that is logical to ask, we've tried to answer it."

Cypress estimates 200,000 severe, refractory arthritis patients in the U.S. are eligible for Prosorba treatment. Used against ITP, the treatment costs $1,090 per column, and six columns are used. Arthritis requires 12 treatments.

"When we launch for rheumatoid arthritis, we will definitely price the column at less than that — certainly less than $900 and possibly less than $800," Blank said.

The FDA granted restricted approval of Prosorba for ITP in 1993, saying the device could be used for patients "critically in need." Prosorba was developed by Imre Corp., of Seattle, which since has changed its name to Cypress and moved.

Cypress' stock (NASDAQ:CYPB) closed Wednesday at $2.937, down $0.062. *