Note: Fresenius Medical Care discontinued PROSORBA production due to decreasing demand and other business reasons at the end of 2006..
On March 15, 1999, the Prosorba column was approved by the FDA for the treatment of rheumatoid arthritis. The Prosorba column was previously approved in 1987 for an unrelated bleeding disorder known as idiopathic thrombocytopenic purpura (ITP).
Which rheumatoid arthritis patients are considered good candidates for treatment with the Prosorba column?
What Is The Prosorba Column? What Is Apheresis?
The Prosorba column is a device which filters harmful immune complexes or antibodies from a patient's blood. The actual Prosorba column itself is a small cylinder made of plastic about the size and shape of a small soda can. Apheresis involves the collection of whole blood from patients with subsequent separation of its blood components. It is used to remove a specific component from the blood. The Prosorba column, which is also called "Protein-A Immunoadsorption Therapy", contains a sand like substance coated with Protein A, which has the ability to bind antibodies.
According to the American College of Rheumatology (ACR), "it consists of an inert silica matrix to which a component of Staphylococcus bacterium is covalently bound. This protein (protein A) has the propensity to bind immunoglobin G (IgG) and IgG bound to antigen."
Prosorba Column Treatment
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.
Which Rheumatoid Arthritis Patients Are Good Candidates For The Prosorba Column?
The Prosorba column has proven safe and effective for treating moderately severe, active, treatment resistant rheumatoid arthritis. According to Dr. Raymond Federman, "Although the precise mechanism of action is not known, it is felt that absorption of immunoglobulin occurs, binding the unwanted autoantibodies that attack the body in rheumatoid arthritis patients. Short-term relief has been demonstrated by early studies, but long-term benefits have not yet been established."
The Prosorba column is not a first line therapy option, and is usually only recommended for rheumatoid arthritis patients who have failed conventional treatment with/or are intolerant of DMARDs (disease-modifying anti-rheumatic drugs).
Sources: Interview with Dr. Raymond Federman; FDA Approval of Prosorba Immunoadsorption Column, American College of Rheumatology, May 27, 1999