By Mary Welch
An FDA panel has recommended that the agency approve Cypress Bioscience Inc.'s Prosorba column for the treatment of moderate to severe rheumatoid arthritis (RA). The Gastroenterology and Urology Device Advisory Panel ruling, which came on a 10-1 vote, would extend the labeling to include treating RA for use in moderate to severe patients who have failed second-line, or disease-modifying anti-rheumatic drugs (DMARDs), such as methotrexate. The final labeling is to be negotiated with the FDA prior to year-end.
"The FDA has been extraordinarily proactive in this particular application," said Jay Kranzler, CEO of the San Diego-based company. "It's been tough for us to keep up with their pace. Our goal is for FDA approval by the end of the year."
The one dissenting vote came from University of Maryland scientist and rheumatologist Barbara White, who was sitting temporarily on the device side of the panel, and who regularly sits on the biologics panel. "We have a lot of respect for her. She felt that it did not meet the threshold for approval on the biologics side because there were not two well-controlled studies. For a device, only one well-controlled study is required. She said she wouldn't have had any problem if there were two such studies."
In May, the FDA granted "special review" status to the company's premarket approval supplement (PMA) related to broadening the Prosorba column's indication. It was the first such special status for a device, Kranzler said. The company's PMA was submitted in July. (See BioWorld Today, May 28, 1998, p. 1.)
In 1987, Cypress received FDA approval for Prosorba as a device to treat idiopathic thrombocytopenic purpura (ITP), an immune-mediated bleeding disorder.
The Prosorba column is a polycarbonate (plastic) cylinder that contains highly purified protein A immobilized on an inert silica matrix. The protein A binds to and removes antibodies, including clusters of Circulating Immune Complexes (CICs) and antigens, that contribute to the symptoms characteristic of RA. The device has additional immunomodulatory effects, and the mechanism of these effects will continue to be studied by Cypress.
The standard course of treatment is 12 two-hour weekly outpatient apheresis sessions. Similar to a kidney dialysis system, a patient's blood is removed from an arm and passed through a machine that separates the blood cells from the plasma. The plasma is then passed through the Prosorba column, recombined with the blood cells and then returned to the patient via the other arm.
There is no reliable data on the potential market size, Kranzler said. "It could be anywhere from 100,000 in the U.S. to 300,000 in the U.S. Ultimately, the labeling will determine which end of the spectrum we are. Since we were recommended for moderate RA, I think it could put us in an even higher potential market."
Phase II Trial Ended Early
Rheumatoid arthritis is a chronic autoimmune disease that affects more than 2.5 million Americans — 70 percent of whom are women.
The advisory panel's decision was based, in part, on a review of Cypress' Phase II trial, which ended more than a year ahead of schedule on the recommendation of an independent Data Safety and Monitoring Board after getting favorable safety and statistically significant efficacy results.
In a double-blinded, sham-apheresis procedure controlled trial, nearly half who completed all 12 treatments showed significant clinical improvement. In addition, the response was often durable, lasting up to 75 weeks in some patients. Some 109 patients with severe RA participated in the 12-center trial.
Cypress hopes to announce two partnering agreements for this new indication by the end of the year, Kranzler said.
Cypress' stock (NASDAQ:CYPB) closed Friday at $2.937, up $0.406. *