Objective. To describe the efficacy and safety of IL-1-targeting drugs, anakinra and canakinumab, in patients with mevalonate kinase deficiency (MKD).

Methods. A questionnaire was sent to French paediatric and adult rheumatologists to retrospectively collect information on disease activity before and after treatment with IL-1 antagonists from genetically confirmed MKD patients. We assessed the frequency of crises and their intensity using a 12-item clinical score built for the purpose of the study.

Results. Eleven patients were included. Anti-IL-1-targeting drugs were used continuously in all but one patient who received anakinra on demand. Daily anakinra (nine patients) or canakinumab injections every 4–8 weeks (six patients, in four cases following anakinra treatment) were associated with complete remission in four cases and partial remission in seven. The median score during MKD attacks decreased from 7/12 before treatment to 3/12 after anakinra and 1/12 after canakinumab. The number of days with fever during attacks decreased from 5 before treatment to 3 after anakinra and 2 after canakinumab. Marked decrease of C-reactive protein and serum amyloid A protein were recorded. Side effects were mild or moderate; they consisted of local pain and inflammation at injection site, infections and hepatic cytolysis.

Conclusion. Continuous IL-1 blockade brings substantial benefit to MKD patients. Controlled trials are necessary to further assess the clinical benefit and treatment modalities in these patients.