No study has been performed in patients with psoriatic arthritis using the 50 mg once-weekly dosing regimen. Evidence of efficacy for the once-weekly dosing regimen in this patient population has been based on data from the study in patients with ankylosing spondylitis. Adult patients with ankylosing spondylitis The efficacy of etanercept in ankylosing spondylitis was assessed in 3 randomised, double-blind studies comparing twice-weekly administration of 25 mg etanercept with placebo. A total of 401 patients were enrolled, from which 203 were treated with etanercept.
The largest of these trials (n = 277) enrolled patients who were between 18 and 70 years of age and had active ankylosing spondylitis defined as visual analog scale (VAS) scores of ≥ 30 for average of duration and intensity of morning stiffness plus VAS scores of ≥ 30 for at least 2 of the following 3 parameters: patient global assessment; average of VAS values for nocturnal back pain and total back pain; average of 10 questions on the Bath Ankylosing Spondylitis Functional Index (BASFI). Patients receiving DMARDs, NSAIDS, or corticosteroids could continue them on stable doses. Patients with complete ankylosis of the spine were not included in the study.
Doses of 25 mg of etanercept (based on dose-finding studies in patients with rheumatoid arthritis) or placebo were administered subcutaneously twice a week for 6 months in 138 patients. The primary measure of efficacy (ASAS 20) was a ≥ 20% improvement in at least 3 of the 4 Assessment in Ankylosing Spondylitis (ASAS) domains (patient global assessments, back pain, BASFI, and inflammation) and absence of deterioration in the remaining domain. ASAS 50 and 70 responses used the same criteria with a 50% improvement or a 70% improvement, respectively.
Compared to placebo, treatment with etanercept resulted in significant improvements in the ASAS 20, ASAS 50 and ASAS 70 as early as 2 weeks after the initiation of therapy. Responses of patients with ankylosing spondylitis in a placebo-controlled trial a: p b: p = 0.002, etanercept vs. placebo Among patients with ankylosing spondylitis who received etanercept, the clinical responses were apparent at the time of the first visit (2 weeks) and were maintained through 6 months of therapy. Responses were similar in patients who were or were not receiving concomitant therapies at baseline. Similar results were obtained in the 2 smaller ankylosing spondylitis trials.
22 Percent of Patients Ankylosing Spondylitis Response Placebo N = 139 Etanercept N = 138 ASAS 20 2 weeks 22 46a 3 months 27 60a 6 months 23 58a ASAS 50 2 weeks 7 24a 3 months 13 45a 6 months 10 42a ASAS 70 2 weeks 2 12b 3 months 7 29b 6 months 5 28b