Arthritis News – 1999
As a follow-up to the open label studyFurst et al (Arthritis & Rheumatism 42:2153, 1999) have published the results of a randomized, double-blind, controlled multicenter trial comparing Prosorba versus sham apheresis. [The Prosorba column is a medical device that contains highly purified Staphylococcal protein A bound to silica matrix, and is used in conjunction with a plasmapheresis machine.] Ninety-one patients were enrolled in the study. The patients had an average disease duration of 15.5 years, and had failed an average of 4.2 disease modifying antirheumatic drugs (DMARDs).
They had an average of 36 tender joints and 24 swollen joints. Mean HAQ scores were 1.9 and mean CRP levels were 4.2 mg/dl.
Patients were randomized to 12 weekly treatments with either Prosorba (n=47) or sham pheresis (n=44), and evaluations were performed at the end of 20 weeks. Response was evaluated according to the ACR 20 response critieria. 31.9% of patients who underwent Prosorba treatment, compared to only 11.4% of sham treated patients, met ACR 20 response criteria. Time to improvement was 3 to 4 months, on average. Side effects were common in both groups but there were no treatment-specific adverse events noted. Approximately 80% of patients in both groups experienced worsening of their joint pain around the time of apheresis. Transient hypotension was reported in one third, and worsening anemia in one fourth, of patients in both groups.
Editorial comment: This trial confirms that the Prosorba column has a favorable response in relieving the signs and symptoms of rheumatoid arthritis. Its effect is slow in onset and is relatively modest compared to treatments such as methotrexate, leflunomide, etanercept and infliximab where ACR 20 responses are in the range of 50-70%. However, it should be noted that the patients selected for the Prosorba study had very severe disease (15 years of disease; failed 4.2 DMARDs; HAQ scores of 1.9), and perhaps it is remarkable that they responded to this therapy at all. As of the time of this report, there are no radiographic data to indicate whether Prosorba is itself a disease modifying therapy (i.e., does it slow progression of radiologic disease).
