This article is part of the Arthritis Archives.
Additional Note: Fresenius Medical Care discontinued PROSORBA production due to decreasing demand and other business reasons at the end of 2006..
Note: On March 16, 1999, the Prosorba column was FDA approved for the treatment of moderate to severe adult rheumatoid arthritis in those patients who have failed treatment with DMARDs.
Dateline: January, 27, 1999
Prosorba Column Approval Delayed
In October 1998, an advisory panel to the FDA (U.S. Food and Drug Administration) recommended approval of the Prosorba column to treat severe cases of rheumatoid arthritis. However, in January 1999 the FDA issued a letter of deficiency in regard to the pending review of Prosorba, delaying its expected approval.
The Prosorba Column
The Prosorba column is a device which filters harmful immune complexes or antibodies from a patient's blood. Each treatment takes approximately two hours and is done weekly for a course of 12 weeks. During the treatment, the patient's blood channels through tubing attached to a catheter in the patient's arm and passes into the Prosorba column. Another apparatus attached to the column serves to separate plasma from red blood cells. The plasma is then filtered through the column, which is a plastic cylinder containing highly purified Protein A on a silica matrix. Protein A binds to antibodies in the plasma. The plasma is then combined again with the red blood cells and reinfused into the patient through another catheter in the opposite arm.
Phase III trials were stopped ahead of schedule last year (1998) when it was decided that the Prosorba column was safe and effective for patients with severe rheumatoid arthritis. The pivotal trial participants had rheumatoid arthritis for an average of 15 1/2 years and had unsuccessfully tried an average of more than 5 DMARDs (disease-modifying anti-rheumatic drugs).
Of the patients completing 12 treatments, 45% showed improvement based on strict criteria. Of the people showing improvement, the average response lasted 20 weeks beyond the last treatment. Some of the patients were able to remain off all rheumatoid arthritis drugs for up to 75 weeks.
The advisory committee attached two conditions when it recommended approval of Prosorba column last fall. It was suggested that the column be indicated for people with severe arthritis who failed all drugs. Also, the committee requested a post-market (Phase IV) study to track use of the column in combination with other drugs and to track data following long-term use.
The letter of deficiency issued by the FDA to Cypress Bioscience, Inc., developers of the Prosorba column, raised questions relating to certain documentation from Cypress' pivotal trial and also regarding the requirement of gaining FDA agreement on the Phase IV study design. Cypress has already responded to these questions and executives feel the issues can be resolved within a relatively short time.
Cost for the Prosorba column falls between $1500-$1800 per treatment. The column was previously approved in 1987 for an unrelated bleeding disorder known as idiopathic thrombocytopenic purpura (ITP).
Sources: New Device For Those With Severe RA, Arthritis Today, January-February 1999; FDA Panel Recommends Blood Filter Treatment For RA, CNN, October 30, 1998; FDA Requests Additional Information In Its Review Of Prosorba Column For RA, BusinessWire, 1/25/99
First published: 1/27/1999