Effectiveness of a Short Term Induction Regimen of a Biosimilar Adalimumab in the Long Term Management of Symptomatic Ankylosing Spondylitis: A Community Based Proof of Concept Observational Study

IntroductionCost and drug toxicity often deter prolonged therapeutic use of anti-TNF agents in ankylosing spondylitis (AS). A planned study was completed to endorse our clinic-based observation of long-term relief following short-term administration of an anti-TNF agent. Methods50 consenting patients with symptomatic active chronic AS under rheumatology care in a community clinic were enrolled; naive for anti-TNF. 40 mg standard biosimilar Adalimumab (Bs-ADA, Exemptia) was injected subcutaneously every fortnight for six injections (10 weeks). Patients were monitored at several predetermined time points. Improvement was assessed with standard indices (Assessment Spondyloarthritis International Society/ASAS and Bath). An intention to treat analysis was performed: significant p <0{middle dot}05 ResultsPatients showed early and substantial significant improvement in pain, NSAID requirement, function, and in several indices (ASAS 20 & 40, ASAS partial remission, BASDAI, BASFI, ASDAS) which persisted after stopping injections. 84% and 52 % of patients respectively showed ASAS 20 improvement at weeks 12 and 48: corresponding to ASAS partial remission at 34% and 24%. Over 50% of patients maintained prolonged improvement and provided proof of concept (defined apriori). Serum Interleukin-6 assay showed a sharp reduction at 24 weeks. None developed TB or serious drug toxicity. 11 patients withdrew (mostly inadequate response). The absence of control was a limitation. ConclusionA ten-week administration of biosimilar adalimumab in difficult-to-treat AS showed early substantial improvement which often persisted for 24 weeks. This unconventional strategy was socioeconomically appealing. It merits further validation and acceptance, especially in resource strained settings.