Author Affiliations: Department of Pediatrics/Pediatric Rheumatology, Erasmus MC Sophia Children's Hospital, Rotterdam, the Netherlands (firstname.lastname@example.org).
In Reply: Dr Pang and colleagues bring up the importance of the differences in etiology and pathogenesis between systemic JIA compared with other JIA categories. As more insight into the pathogenesis of systemic JIA has been gained, systemic JIA has been considered by many as a different disease entity because of its clinical features and the involvement of different cytokines, such as interleukin 1 (IL-1), IL-6, and IL-18, in addition to tumor necrosis factor (TNF). While newer biological agents targeting the IL-1 and IL-6 cytokines seem important for systemic JIA, since 1999 many patients with systemic JIA have been treated successfully with etanercept, a TNF antagonist, in daily clinical care.1
Otten MH, Prince FHM, van Suijlekom-Smit LWA. Response to Etanercept in Juvenile Idiopathic Arthritis—Reply. JAMA. 2012;307(11):1140-1141. doi:10.1001/jama.2012.329