A Pilot Open-Label Study of Rilonacept (Arcalyst) in the Deficiency of the Interleukin-1 Receptor Antagonist (DIRA)

Autoinflammatory diseases are illnesses characterized by episodes of inflammation that, unlike autoimmune disorders, lack the production of high titer autoantibodies or antigen-specific T cells. There is growing genetic and clinical evidence that specific cytokine pathways are dysregulated. Monogenic defects in the IL-1 pathway cause cryopyrin associated periodic syndromes (CAPS) and deficiency of the IL-1 receptor antagonist (DIRA), the latter is caused by mutations affecting the IL-1-receptor antagonist gene (IL1RN). Both disorders respond with complete resolution of the inflammatory response to treatment with the short acting IL-1 blocking agent anakinra. This exploratory study aims to examine the utility of the long acting IL-1 inhibitor rilonacept (rilonacept; Regeneron Pharmaceuticals, Inc.)

This pilot study is designed to address: 1) the utility and dosage of rilonacept needed to achieve inflammatory remission in children with DIRA who have shown a response to treatment with anakinra [Kineret[registered]]; and 2) to evaluate the safety and pharmacokinetics in young children on rilonacept.

Rilonacept is a recombinant fusion protein with picomolar affinity for IL-1 and a half-life of approximately 7.5 days in humans. It is approved by the Food and Drug Administration (FDA) for the treatment of adults and children 12 years of age and older with Cryopyrin-Associated Periodic Syndromes (CAPS), and was tested in the clinically milder forms of CAPS including Familial Cold Autoinflammatory Syndrome (FCAS) and Muckle-Wells Syndrome (MWS).

In this study, clinical, and laboratory parameters will initially be measured at baseline following a withdrawal of anakinra for 24 hours. Subjects will receive a course of therapy with rilonacept that is predicted to induce inflammatory remission. Clinical and laboratory measures of inflammation will be assessed; rilonacept dose escalation will be implemented as necessary to achieve clinical and laboratory remission. Subjects will remain on study for 12 months and primary end point will be evaluated at 6 months.

Those subjects who complete the 1-year treatment period and maintain improved clinical and laboratory parameters compared to baseline values, may continue to receive study medication at their current dose. Principal investigator will help to obtain insurance coverage for rilonacept for their continued treatment, and will discuss with Regeneron Pharmaceuticals, Inc. for additional supplies of rilonacept for these subjects.