OBJECTIVE: Recurrent pericarditis (RP) incurs significant morbidity. Rilonacept 
inhibits both interleukin-1 alpha (IL-1α) and IL-1β; these cytokines are thought 
to play a major role in RP. This phase II study evaluated rilonacept efficacy 
and safety in RP.
METHODS: This multicentre, open-label study enrolled adult patients with 
idiopathic or postpericardiotomy RP, symptomatic (≥2 pericarditis recurrences) 
or corticosteroid (CS) dependent (≥2 recurrences prior).Patients received 
rilonacept 320 mg SC load/160 mg SC weekly maintenance in a 6-week base 
treatment period (TP) followed by an optional 18-week on-treatment extension 
period (EP) (option to wean background therapy).
RESULTS: Outcomes: pericarditis pain (numeric rating scale (NRS)) and 
inflammation (C reactive protein (CRP)) for symptomatic patients; disease 
activity after CS taper for CS-dependent patients.
SECONDARY OUTCOMES: health-related quality of life (HRQOL), pericarditis 
manifestations and additional medications. 25 unique patients enrolled, while 23 
completed the EP (seven colchicine failures and five CS failures). In 
symptomatic patients, NRS and CRP decreased; response was observed after first 
rilonacept dose. NRS decreased from 4.5 at baseline to 0.7, and CRP decreased 
from 4.62 mg/dL at baseline to 0.38 mg/dL at end of TP. Median time to CRP 
normalisation: 9 days. Pericarditis manifestations resolved. 13 patients on CS 
at baseline completed the EP; 11 (84.6%) discontinued CS, and 2 tapered; CRP and 
NRS remained low without recurrence. Mean HRQOL scores improved in symptomatic 
patients. One serious adverse event (SAE) resulted in discontinuation of 
rilonacept.
CONCLUSIONS: Rilonacept led to rapid and sustained improvement in pain, 
inflammation (CRP and pericarditis manifestations) and HRQOL. CSs were 
successfully tapered or discontinued; safety was consistent with known 
rilonacept safety profile.
TRIAL REGISTRATION NUMBER: NCT03980522.