Kiniksa Pharmaceuticals announced positive data from the phase 3 RHAPSODY trial evaluating rilonacept for the treatment of recurrent pericarditis.

Rilonacept is a weekly, subcutaneously-injected, recombinant fusion protein that blocks interleukin (IL)-1α and IL-1β signalling. 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. 

Clinical responders (11-point pain Numerical Rating Scale ≤2.0 and C-reactive protein ≤0.5mg/dL) were randomized 1:1 to receive rilonacept once weekly via subcutaneous injection (n=30) or placebo (n=31). The primary end point was time to first adjudicated pericarditis recurrence.

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). The study also met all key secondary end points with 81% of rilonacept-treated patients maintaining clinical response at week 16 compared with 20% of the placebo group (P =.0002); these results were consistent with those observed at week 8 (P <.0001) and week 24 (P =.0022). 

Moreover, a greater percentage of patients receiving rilonacept had minimal or no pericarditis symptoms at week 16 compared with placebo-treated patients (81% vs 25%, respectively; P =.0006); this effect was consistent at week 8 (P <.0001) and week 24 (P =.0002).

“Rilonacept patients experienced no or minimal pericarditis pain for nearly 95% of study days through week 16 compared to less than half of study days for placebo recipients, which was highly statistically significant,” said John F. Paolini, MD, PhD, Chief Medical Officer of Kiniksa. “We believe that, by treating and preventing disease recurrence, rilonacept has the potential to be a transformational therapeutic advancement in the treatment of patients with recurrent pericarditis and to become the first FDA-approved therapy for this debilitating autoinflammatory disease.”

The FDA previously granted Breakthrough Therapy designation to rilonacept for this indication.

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Rilonacept is currently approved by the Food and Drug Administration under the brand name Arcalyst for the treatment of cryopyrin-associated periodic syndromes, including familial cold autoinflammatory syndrome and Muckle-Wells syndrome.

For more information visit kiniksa.com.