The Food and Drug Administration (FDA) has approved Arcalyst® (rilonacept) for the treatment of recurrent pericarditis and reduction in risk of recurrence in adults and pediatric patients 12 years and older.

Arcalyst is a weekly, subcutaneously-injected, recombinant fusion protein that blocks interleukin (IL)-1, a key cytokine that mediates the pathophysiology of many inflammatory processes, and has been implicated as a causative factor in pericarditis. The approval was based on data from the phase 3 RHAPSODY trial ( NCT03737110).

The double-blind, randomized withdrawal study compared the efficacy and safety of rilonacept to placebo in 61 actively symptomatic recurrent pericarditis patients who were failing standard of care treatment, including nonsteroidal anti-inflammatory drugs, colchicine, or corticosteroids, and who achieved and maintained clinical response on rilonacept monotherapy during the run-in period. Results showed that treatment with rilonacept reduced the risk of recurrent pericarditis events by 96% compared with placebo (hazard ratio [HR] 0.04; P <.0001).

Additionally, patients who received rilonacept experienced no or minimal pericarditis pain for 92% of trial days compared with 40% of trial days for placebo recipients (P <.0001). The most common adverse events reported were injection site reactions and upper respiratory tract infections.

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“Data have shown that recurrent pericarditis stems from an underlying autoinflammatory pathophysiology mediated by IL-1α and IL-1β,” said Allan Klein, MD, of Cleveland Clinic, co-principal investigator of RHAPSODY and compensated member of a 2019 Kiniksa scientific advisory committee. “This approval supports the concept of a targeted immunomodulation therapeutic strategy as a paradigm shift in the management of patients with this devastating disease.”

Arcalyst is supplied as 220mg of lyophilized powder in a single-dose vial for reconstitution. A patient assistance program called Kiniksa One Connect™ has also been made available to support patients receiving Arcalyst.


Kiniksa announces FDA approval of ARCALYST ® (rilonacept) for recurrent pericarditis. [press release]. Hamilton, Bermuda: Kiniksa Pharmaceuticals; March 18, 2021.