Psoriatic arthritis successfully treated with second-line anti-interleukin-6 treatment: a case report and review of the literature 

BACKGROUND: Psoriatic arthritis treatment with antitumor necrosis factor has been shown to reduce disease activity. Nonetheless, more than 30% of patients do not achieve a sufficient response to tumor necrosis factor blockers. Currently, treatment with interleukin-6 inhibitors is expected to be effective and suppress the joint destruction in patients with psoriatic arthritis; however, evidence regarding their efficacy is limited to a few reports. CASE PRESENTATION: A 78-year-old Japanese woman with psoriatic arthritis associated with rapid joint destruction was successfully treated with a second-line anti-interleukin-6 receptor agent. In this case, a tumor necrosis factor inhibitor induced an inadequate response, and the right knee and left hip joints required artificial joint replacement surgery. However, second line treatment with anti-interleukin-6 treatment was effective, and the right elbow joint function was preserved. CONCLUSIONS: We experienced a case of psoriatic arthritis, in which anti-interleukin-6 treatment repaired a bone cyst in the lateral epicondyle of the humerus and enthesitis of the distal interphalangeal joints. The patient is currently in clinical remission with no restrictions in daily life activities. Anti-interleukin-6 treatment may address the unmet needs of patients with psoriatic arthritis who are resistant or intolerant to antitumor necrosis factor treatment, with rapidly destructive large joints but with well-managed skin manifestations.