PURPOSE: Interleukin -1 receptor antagonist ( IL-1Ra ) is a new option among 
biotherapies against rheumatoid arthritis ( RA ).
THE AIM: of this review is to recall the rationale of use of IL-1Ra and to 
analyse the results available in the current literature.
CURRENT KNOWLEDGE AND KEY POINTS: Pathophysiological data of RA give a specific 
position for IL-1 as a potential target for immunotherapy in this disease, 
confirmed in animal models. Phase II and III studies with IL-1Ra (Anakinra) 
demonstrated clinical efficacy versus placebo (42% responders in ACR 20 in 
Anakinra + methotrexate, and 23% in the placebo + methotrexate group at 24 
weeks) and a structural effect (slowing of radiological progression at six 
months). Anakinra has obtained an European license and is indicated in RA not 
controlled by methotrexate, in daily subcutaneous administration (100 mg/day), 
in combination with methotrexate. Tolerance is fair; the most frequent side 
effect is represented by injection site reactions.
FUTURE PROSPECTS AND PROJECTS: This ambulatory biotherapy offers new 
perspectives in combination with other slow acting drugs as well as biologic 
agents such as anti-TNF, currently under evaluation.