The efficacy and safety of reinstitution of tocilizumab in patients with relapsed active rheumatoid arthritis after long-term withdrawal of tocilizumab: retreatment of patients with rheumatoid arthritis with novel anti-IL-6 receptor antibody after a long-term interval following SAMURAI: the RONIN study.

We have evaluated the efficacy and safety of tocilizumab (TCZ) re-administration in patients with active rheumatoid arthritis (RA) who had previously received TCZ treatment for about 31 months. Four patients whose RA had been well-controlled with 8 mg/kg TCZ treatment every 4 weeks and had withdrawn from the treatment were enrolled. They resumed TCZ treatment after TCZ was authorized for RA treatment in Japan. Disease activity was assessed by the Disease Activity Score 28 using erythrocyte sedimentation rate (DAS28-ESR), and synovitis in the wrists and elbows was measured by ultrasonography at baseline and during follow-up. The mean DAS28-ESR was 6.32 before the first TCZ infusion. After fewer than 20 months of initial TCZ treatment, the mean DAS28-ESR decreased to 1.87. However, after withdrawal of TCZ treatment, the disease activity could not be sufficiently controlled with conventional disease-modifying antirheumatic drugs or biologic agents. The maximum interval between TCZ treatments was approximately 34 months. Following reinstatement of the TCZ treatment, within 12 months the mean DAS28-ESR improved from 5.21 to 2.87, with the synovitis in the wrists and elbow joints also showing great improvement. These findings demonstrate that TCZ retreatment in active RA patients who had relapsed after long-term discontinuation of TCZ treatment led to an improvement in the signs and symptoms of RA and in synovitis without any severe adverse events.