By Phoebe Starr
Chicago, IL—An excellent response to etanercept (Enbrel) in patients with juvenile idiopathic arthritis (JIA) was significantly associated with younger age and less disability at disease onset, as well as less use of antirheumatic drugs before initiating etanercept. A poor response was significantly associated with onset of systemic JIA and with female sex.
The results from an observational study by Marieke H. Otten, MD, MSc, of the Department of Pediatrics/Pediatric Rheumatology, Erasmus Medical Center Sophia Children’s Hospital, Rotterdam, the Netherlands, and colleagues will be useful for selecting patients with JIA who are likely to respond to etanercept and for avoiding use of this expensive drug in patients unlikely to benefit from receiving it.
The use of disease-modifying antirheumatic drugs (DMARDs) earlier in the course of disease has improved outcomes in patients with JIA. “A treatment goal of reaching inactive disease now seems realistic. However, inactive disease is still not achieved in a substantial number of patients, and current approaches need to be optimized even more,” said Dr Otten, lead author of the study.
The study was published online (Otten MH, et al. JAMA. 2011; 306: 2340-2347) to coincide with its presentation at the 2011 American College of Rheumatology meeting.
Although etanercept has been approved in Europe and the United States for approximately a decade, no studies have explored predictors of response in children. The study was based on the Arthritis and Biologicals in Children Register that includes all patients with JIA in the Netherlands who are currently or were previously receiving treatment with biologic agents since 1999, when biologics were first introduced. The study population included 262 patients with JIA who were previously biologically naïve when they initiated treatment with etanercept. Of the participants, 71% were female, the median age at JIA onset was 6.9 years, and the median age at the start of etanercept was 12.4 years; 46 (18%) patients had systemic-onset JIA, and the median age at initiation of etanercept was 12.4 years.
Responses evaluated at 15 months were categorized as excellent, intermediate, and poor. An excellent response (defined as inactive disease or discontinuation as a result of disease remission) was observed in 85 patients (32%). An intermediate response (defined as >50% improvement from baseline but no evidence of inactive disease) was seen in 92 patients (46%). A poor response (defined as <50% improvement from baseline or discontinuation because of ineffectiveness or intolerance) was seen in 85 patients (32%).
During the first 15 months of the study, 1 or more adverse events (AEs) were reported in 119 patients, including infectious, noninfectious, and serious AEs. AEs were reported in 37 patients with an excellent response, 36 patients with an intermediate response, and 46 patients with a poor response.
A secondary analysis was performed in 262 patients with a median follow-up of 35.6 months after initiation of etanercept. Over a period of 4 to 7 years, 37% to 49% of patients achieved inactive disease. Only 39 patients (15%) tried to discontinue etanercept (of which 15 relapsed and needed to restart etanercept).
There were no head-to-head comparisons with other DMARDs, so it is not known whether patients with a suboptimal response could have had a better response to another agent, Dr Otten stated.