SAN ANTONIO — The clinical safety and efficacy of etanercept persist for more than 2 years in patients with active ankylosing spondylitis, according to the results of an open-label extension study.
Among 26 patients who entered the open, observational phase following a 12-week blinded study, 21 have continued with etanercept, 25 mg twice weekly, for an additional 102 weeks, Xenofon Baraliakos, M.D., said at the annual meeting of the American College of Rheumatology.
Response was evaluated according to a core set of end points proposed by the Assessments in Ankylosing Spondylitis (ASAS) working group. These included the Bath AS Disease Activity Index (BASDAI) and the ASAS 40, which represents a 40% improvement in several disease domains such as pain, function, and inflammation.
The primary end point was an improvement of 50% or more on the BASDAI, a 10-point visual analog scale that assesses fatigue, spinal pain, peripheral arthritis, enthesitis, and morning stiffness.
At 102 weeks, an intent-to-treat analysis of all 26 patients indicated that 54% maintained both a BASDAI 50% response and an ASAS 40. At week 54, the corresponding percentages were 58% and 62%, said Dr. Baraliakos, who is of the department of rheumatology, Benjamin Franklin Hospital, Free University Berlin.
An analysis that included only the 21 study completers also found that disease activity improved significantly, with a mean BASDAI score of 2.7 at week 102. The baseline BASDAI score in this group of patients had been 6.3, on a 0–10 scale, with 10 being the most severe, Dr. Baraliakos said in a poster session.
The mean C-reactive protein level at week 102 was 5 mg/dL, and the mean erythrocyte sedimentation rate was 9 mg/dL, which represented significant improvements over baseline levels, which had been 15.3 and 22.8, respectively. Similar improvements also were seen on the Bath AS functional and mobility indexes.
This study differed from previous investigations of etanercept in AS in that no concomitant corticosteroids or disease-modifying antirheumatic drugs (DMARDs) were permitted. In an earlier study, 40 patients were treated with the tumor necrosis factor-α blocking agent but were allowed to continue other medications (N. Engl. J. Med. 2002;346:1349–56).
In an interim analysis, the authors of this latest study noted that it was important to evaluate etanercept alone (Arthritis Rheum. 2003;48:1667–75).