Objectives: To assess long-term safety and clinical efficacy of etanercept 25 mg subcutaneously twice weekly up to 5 years in subjects with ankylosing spondylitis (AS).
Methods: An open-label (OL), multicentre, phase 4, 156-week extension study of subjects with AS who had completed a 12-week randomised, placebo-controlled study (N=84; n=45 etanercept, n=39 placebo) followed by a 96-week OL study (n=81; n=42 etanercept/etanercept; n=39 placebo/etanercept); 59 subjects who completed the 96-week OL extension enrolled in the current OL trial and continued etanercept 25 mg BIW for an additional 156 weeks (total duration: 264 weeks, original etanercept group; 252 weeks, original placebo group). Safety was based on spontaneous reports of adverse events (AEs). Last observation carried forward was used for imputation of missing values.
Results: Thirty-seven of 59 subjects (63%) completed 5 years of etanercept treatment. Serious non infectious AEs and serious infections occurred at a rate of 0.17 and 0.03 events per subject years, respectively; inflammatory bowel disease and uveitis (including iritis and iridiocyclitis) occurred at 0.01 and 0.14, respectively. No cases of tuberculosis or opportunistic infections were reported. Assessment in Ankylosing Spondylitis (ASAS) responses and improvements in Bath Ankylosing Spondylitis Functional Index and spinal mobility were sustained from week 108 through week 264.
Conclusions: Etanercept was well tolerated with no new safety signals detected in subjects with AS over 5 years. Clinical efficacy and improvements in function and mobility seen during the double-blind and first OL study were sustained. These results support etanercept therapy for the long-term management of this chronic disease.