Rilonacept Receives Orphan Drug Designation for Pericarditis Treatment


This past week, biopharmaceutical company Kiniksa Pharmaceuticals announced that their drug, rilonacept, received Orphan Drug Designation from the FDA. Following positive data from the RHAPSODY Phase 3 clinical trial, rilonacept could be an effective solution for patients with pericarditis and recurrent pericarditis.

Orphan Drug Designation

To begin, what is Orphan Drug Designation? According to the FDA, Orphan Drug Designation is given to drugs or biologics designed to treat rare diseases (those with under 200,000 patients in the country). Generally, drugs given this status have been shown to improve patient outcomes compared to other therapies. Additionally, drug developers are given tax credits, extra communication with the FDA, and market exclusivity.


Rilonacept was initially developed by Regeneron and is currently used to treat cryopyrin-associated periodic syndromes (CAPS). However, Kiniksa licensed the drug in 2017. The goal was to understand rilonacept’s efficacy in treating conditions relating to IL-1α and IL-1β. In patients with recurrent pericarditis, rilonacept blocks IL-1α and IL-1β from signaling. The drug is administered subcutaneously (beneath the skin) each week. Outside of Orphan Drug Designation, rilonacept also received Breakthrough Therapy Designation in 2019.


In part, Orphan Drug Designation was granted following reported data from the RHAPSODY Phase 3 clinical trial. The randomized trial sought to understand the efficacy of rilonacept for patients with recurrent pericarditis. Altogether, the study consisted of 4 specific periods:

  • Screening
  • Single-blind run-in period: participants received 320mg of rilonacept initially, followed by 160mg each week
  • Double-blind, placebo-controlled withdrawal period: participants either received 160mg of rilonacept each week, or a placebo
  • Long-term extension: up to 2 years where patients received 160mg rilonacept each week

The trial ultimately met its primary and secondary endpoints.


Pericarditis is a condition causing pericardium inflammation and irritation. The pericardium is a thin membrane which surrounds your heart. Though the cause of pericarditis is unknown, some believe that the condition is associated with infections or autoimmune disorders. For example, recurrent pericarditis, which occurs within 1.5 months of an acute pericarditis flare, usually results from autoimmune conditions such as lupus.

Symptoms may differ based on classification (acute, chronic, recurrent, incessant). However, they may include:

  • Severe chest pain that generally occurs behind the breastbone or on the left side of the chest
  • Pericardial effusion (fluid around the heart)
  • Chest pressure
  • Neck and shoulder pain that worsens when breathing deeply or coughing
  • Shortness of breath
  • Fever
  • Heart palpitations
  • Fatigue
  • General malaise

Learn more about pericarditis here.

What are your thoughts about Orphan Drug Designation? Share your stories, thoughts, and hopes with the Patient Worthy community!

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

Share this post

Share on facebook
Share on google
Share on twitter
Share on linkedin
Share on pinterest
Share on print
Share on email