Proliferation Signal Inhibitors for the Treatment of Refractory Autoimmune Rheumatic Diseases A New Therapeutic Option

Sirolimus and everolimus belong to the novel class of immunosuppressant agents known as proliferation signal inhibitors (PSIs). They act by preventing antigen-driven T cell proliferation. While PSIs are widely used in transplantation, there are few reports of PSI usage in the treatment of autoimmune rheumatic diseases. The author has presented a series in the APLAR 2006 conference. This report summarizes the clinical experience with PSIs in the treatment of resistant or relapsed rheumatic diseases where conventional immunosuppressive agents have failed. This is a retrospective review of patients with various autoimmune rheumatic diseases who had sirolimus and everolimus treatment from the rheumatological clinics of Changi Hospital or the Arthritis and Rheumatism Specialist Medical Centre. The period of review was from April 2006 to April 2008. A total of 46 patients were reviewed, 39 females and 7 males. The racial distribution was 33 Chinese, 7 Malays, and 6 Indians. Their disease conditions were as follows: 26 (57%) rheumatoid arthritis, 7 psoriatic arthritis, 4 systemic lupus erythematosus, 3 scleroderma, 2 anti-Jo-1 syndrome, 2 spondyloarthropathy, 1 MCTD, and 1 vasculitis. All patients had failed at least three DMARDs or immunosuppressants. Twenty-eight patients received sirolimus and 28 patients received everolimus. Overall positive response rate was 48.2%. Twenty-seven percent had adverse events. 20% had no response. 7% relapsed after initial response. PSIs, namely sirolimus and everolimus, are a novel class of immunosuppressants that can be added to the armamentarium of rheumatologists for the treatment of patients with refractory autoimmune rheumatic diseases.