Long-term Etanercept Response for Patients with Radiographic Axial Spondyloarthritis Based on Achievement of Early, Intermediate, or Late Responses During Index Studies

IntroductionShort-term placebo (PBO)- or active-controlled clinical studies have demonstrated that etanercept (ETN) is effective and well tolerated in patients with radiographic axial spondyloarthritis (r-axSpA) with long-term efficacy and safety continuing for up to 7 years after treatment start. Short-term randomized controlled trials (RCTs) have shown the efficacy of ETN after 12-24 weeks, with statistically significant improvements as early as week 2. This post hoc analysis investigated the timeframe (i.e., temporal responses) in which patients with r-axSpA achieved their first clinical response with ETN and how patients responded over a longer period according to different temporal responses in index studies.MethodsData were analyzed from three phase 3/4 PBO- or sulfasalazine-controlled RCTs of ETN for the treatment of r-axSpA (index studies). Long-term open-label extension (OLE) studies assessed how patients responded over a longer period according to different temporal responses ("Early," "Intermediate," "Late," or "Non-response") in their corresponding index studies.ResultsWithin each index study, patient responses differed significantly between ETN and control arms for achievement of Assessment in SpondyloArthritis international Society (ASAS) 20 and other measures of treatment response. In general, the proportion of responders in the OLE studies was high for those with "Early" and "Intermediate" responses as defined in the index studies. Despite patients being considered non-responders in the index studies, a large proportion achieved response on continued treatment in the OLE studies over the longer term, including through 48 weeks.ConclusionsResponse in the index studies was maintained in the long term, and continued treatment was warranted in a large proportion of patients despite initial non-response. Absence of an early response in index studies did not predict non-response over the long term, and early response to treatment was not always a predictor for later response.Trial RegistrationNCT00421915; NCT00247962; NCT00356356; NCT00421980; NCT00410046.