A Randomized Double‐Blind Sham‐Controlled Trial of the Prosorba Column for Treatment of Refractory Rheumatoid Arthritis

Abstract

The Prosorba column has been studied as a novel therapy for rheumatoid arthritis in several clinical settings over the last 5 years. In this article, we summarize the pivotal clinical trial study supporting the safety and efficacy of the Prosorba column as it is applied to treatment of rheumatoid arthritis. The Prosorba column is a medical device that contains purified staphylococcal protein A covalently bound to a silica matrix. This device is used to treat patient plasma in conjunction with a plasmapheresis machine. In this ex vivo treatment, blood is withdrawn from the patient, cells are separated from plasma in the machine, and the plasma is passed through the Prosorba column. The plasma then is recombined with the cells and returned to the patient. The Prosorba column was approved for the treatment of idiopathic thrombocytopenic purpura in 1987 and, in 2 open-label trials (1,2), showed promising evidence of efficacy in rheumatoid arthritis. A subsequent Phase 3 pivotal trial demonstrated statistical superiority of Prosorba treatments to sham column apheresis (3). Analysis of the pivotal trial of patients who completed all treatments indicated that 41.7% of the Prosorba treated patients met American College of Rheumatology defined response criteria as compared to 15.6% of the sham treated patients. This difference was significant at a level of p < or = 0.02.