Background/Purpose: Cryopyrin-associated periodic syndrome (CAPS) is a spectrum of rare autoinflammatory disorders caused by mutations in the NLRP3 gene, leading to excessive interleukin-1β (IL-1 β) activity. IL-1 inhibitors, such as anakinra and canakinumab, are primarily used to treat these patients. In South Korea, anakinra has been the initial treatment of choice for CAPS patients, as canakinumab was only recently reimbursed by the National Health Insurance. Despite varying symptoms and different doses of anakinra, most CAPS patients transitioned from anakinra to canakinumab around the same time following a standardized protocol. The aim of this study is to report the efficacy and potential issues associated with switching from anakinra to canakinumab.

Methods: This study included CAPS patients with confirmed molecular diagnoses who switched from anakinra to canakinumab following its reimbursement approval in August 2024. Canakinumab was injected subcutaneously at a dose of 2mg/kg for patients under 40kg and 150mg for those over 40kg. If clinical response was satisfactory, the same dose was injected every 8 weeks. If not, additional dose was given within one week, up to twice. We prospectively analyzed clinical efficacy, adverse events, and quality of life.

Results: Five patients, including a pair of identical twins, were enrolled in this study (3 NOMID/CINCA, 1 MWS, 1 FCAS). The mean age at the time of the study and at diagnosis was 12.6 years (range: 4-23 years) and 15.8 months (range:1-24 months) respectively. All patients experienced recurrent fever and skin rash. Four patients had sensorineural hearing loss, three patients had hydrocephalus, and one patient had severe bone destruction. The mean dose and duration of anakinra were 3.9 mg/kg (range: 2-5.17 mg/kg) and 8.15 years (range: 1.25-14 years), respectively. Canakinumab was initiated at 2 mg/kg in three patients and 150mg in two patients. An additional dose of canakinumab was required twice in four patients, except for the FCAS patient. One patient, the most severe case, discontinued canakinumab and returned to anakinra at week 26 due to an incomplete response despite the use of the maximum dose. The mean final dose of canakinumab was 5.6 mg/kg (range: 2.8-6.6 mg/kg). Reported adverse events included headache, skin rash, infection, dysaesthesia, dizziness, and hypothermia. These adverse events improved with supportive care and diminished over time. Despite several adverse events, both patients and their families reported high satisfaction, with improvements in physical and emotional functioning.

Conclusion: Canakinumab was effective in CAPS patients, particularly in improving quality of life. However, adjustments in both dosage and dosing interval were necessary from the time of switching from anakinra to canakinumab, depending on the severity of clinical symptoms from the initiation.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/dose-adjustment-was-necessary-in-patients-with-cryopyrin-associated-periodic-syndrome-switching-from-anakinra-to-canakinumab/