Long-term safety and effectiveness of etanercept in JIA: an 18-year experience from the BiKeR registry

BACKGROUND: At present, etanercept represents the most commonly prescribed biologic agent for juvenile idiopathic arthritis (JIA) treatment. Children and adolescents with JIA are often treated with etanercept over long periods, sometimes even into adulthood. The objectives of this analysis were to determine the long-term safety of etanercept compared to a biologic-naïve cohort and to assess the long-term treatment response upon continuous etanercept exposure using data from the German biologics registry (BiKeR). METHODS: JIA patients newly exposed to etanercept were documented in the BiKeR registry from January 2001 to March 2019, and baseline characteristics, effectiveness, and safety parameters were analysed. Response to treatment was assessed according to 10-joint Juvenile Arthritis Disease Activity Score (JADAS10), JADAS-defined minimal disease activity and remission, JIA-American College of Rheumatology (ACR) improvement criteria, and ACR-inactive disease definition. Safety assessments were based on adverse event (AE) reports. RESULTS: A total of 2725 new etanercept users with a diagnosis of JIA were registered. Of these, etanercept was received as a first-line biologic by 95.8% and as monotherapy without concomitant methotrexate by 31.5%. After nine years on continuous treatment, 68.1% of patients presented minimal disease activity, 43.1% JADAS-defined remission on drug, and 36.6% ACR-inactive disease. JIA-ACR30/50/70/90 response rates were still 82/79/71/54% after nine years of treatment. Overall, 2053 AEs (34.3/100PY), including 226 serious AEs (SAE, 3.8/100PY), were observed upon etanercept, compared to 1345 AEs [35.6/100PY; p = 0.3] and 52 SAEs (1.4/100PY; p = 0.0001) in the biologic-naïve cohort. Respective exposure-adjusted rates for etanercept and biologic-naïve patients were 0.9/100PY and 0.2/100PY (p = 0.0001) for serious infections, 0.4/100PY and 0.1/100PY (p = 0.01) for zoster reactivation, 0.3/100PY and 0.03/100PY (p = 0.015) for inflammatory bowel disease, and 1.9/100PY and 1.4/100PY (p = 0.09) for uveitis. Three and two malignancies were documented in the etanercept and biologic-naïve groups, as well as three and one deaths, respectively. CONCLUSIONS: No new safety signal was observed, especially no increased risk for malignancies or autoimmune disorders other than inflammatory bowel disease. However, SAEs and serious infections, though infrequent, were more often reported on etanercept than in biologic-naïve patients. In addition, etanercept demonstrated a long-term maintenance of clinical benefits up to nine years of continuous treatment.