Investigation of the Clinical Effect of Large Volume Leukocytapheresis on Methotrexate-Resistant Rheumatoid Arthritis

: Leukocytapheresis (LCAP) is already being used in a clinical setting for the treatment of autoimmune diseases such as inflammatory bowel disease and rheumatoid arthritis, and it has been reported to be effective. However, it is totally or partially ineffective in some patients, which has forced clinicians to rethink therapeutic strategies and concurrent treatment. With the aim of enhancing the therapeutic effect, we carried out large volume leukocytapheresis, with a throughput of 5000 mL instead of the 3000‐mL throughput of conventional leukocytapheresis in nine patients with rheumatoid arthritis resistant to methotrexate treatment. Using Cellsorba, the column filled with the unwoven fabric made of the polyethylene phthalate, a leukocyte removal filter, large volume leukocytapheresis was carried out once a week for a total of five sessions. The observation period was the 12‐week period following completion of treatment. The American College of Rheumatology (ACR) core set was used for assessment of efficacy. Eight weeks after completion of treatment, a 20% improvement in ACR was observed in 77.8% (7/9) of subjects, a 50% improvement in ACR was seen in 55.6% (5/9) of subjects, and a 70% improvement in ACR was observed in 22.2% (2/9) of subjects. C‐reactive protein decreased gradually as treatment progressed, and a significant decrease was observed 4 weeks after completion of treatment. The fact that some subjects had an ACR70 response, few reports of which are observed in the case of conventional leukocytapheresis, and the fact that the effect continued up to 12 weeks after completion of treatment suggests that the degree and duration of the effect of large volume leukocytapheresis might be longer than those of conventional leukocytapheresis.