Efficacy of interleukin-1-targeting drugs in mevalonate kinase deficiency

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