IL1R1 and pericarditis: In contrast, rilonacept is an IL-1R trap fusion protein that binds IL-1α and IL-1β to prevent their binding to IL-1R.681 Rilonacept was first approved by the FDA for the treatment of familial cold autoinflammatory syndrome (FCAS) and has since been approved in several countries for the treatment of Muckle-Wells syndrome (MWS), DIRA, and recurrent pericarditis.677 A phase III clinical trial (NCT03737110) has established that long-term use of rilonacept reduces the risk of recurrence of persistent pericarditis.682