Introduction: Recombinant interleukin-1 receptor antagonist (rIL-1RA or anakinra) is a recombinant IL-1RA protein capable of binding with high affinity to the IL-1 receptor type I, thus competitively blocking IL-1 signaling in IL-1-receptor-expressing cells. It is FDA-approved for a periodic fever syndrome called cryopyrin-associated periodic syndrome, one of the monogenetic auto-inflammatory disorders. It was initially registered for (adult) rheumatoid arthritis, but is rarely used for this indication nowadays. Here, we discuss its use as an orphan drug in an acquired childhood auto-inflammatory disorder: systemic juvenile idiopathic arthritis (sJIA). Areas covered: Rationale for IL-1 blockade in sJIA, clinical efficacy, timing of rIL-1RA in the treatment of sJIA, safety issues and side effects. Expert opinion: Clinical efficacy of anakinra in sJIA was shown in one placebo-controlled trial and several cohort studies. Anakinra seems to yield impressive response rates, especially in the early phase of sJIA...
