Real-world outcomes of interleukin-17 inhibitors in familial Mediterranean fever-associated inflammatory conditions: a retrospective study

Aims To evaluate the real-world effects of interleukin-17 (IL-17) inhibitors on familial Mediterranean fever (FMF) activity and associated immune-mediated inflammatory diseases (IMIDs).Patients and methods We retrospectively evaluated 16 patients with FMF who received IL-17 inhibitors primarily for coexisting IMIDs between 2015 and 2026. FMF attack frequency, C-reactive protein (CRP) levels, spondyloarthritis activity indices, treatment duration, discontinuation reasons, and adverse events were assessed.Results Among 13 patients with available FMF activity data, attack frequency remained unchanged in 9 (69%), increased in 3 (23%), and decreased in 1 (8%). CRP levels did not significantly improve. In six patients with FMF-spondyloarthritis overlap and available 3-month data, BASDAI and ASDAS-CRP showed improvement. IL-17 inhibitor therapy was discontinued in 14 patients, most commonly because of inadequate control of the associated IMID.Conclusions IL-17 inhibition did not consistently improve core FMF activity in this highly selected, treatment-refractory cohort, although some domain-specific benefit was observed in spondyloarthritis. These findings are hypothesis-generating and require confirmation in prospective controlled studies.