Horizon Therapeutics plc announced the first patient has enrolled in a Phase 2b pivotal trial to evaluate its development-stage medicine HZN-825, a lysophosphatidic acid receptor 1 antagonist to treat people with IPF, the most common interstitial lung disease. IPF is a rare, progressive lung disease caused by inflammation and fibrosis, or scarring, of the lungs. It is characterized by dyspnea, chronic cough and potentially death.

There are approximately 100,000 people who live with IPF in the United States, and the disease has a median survival of less than five years. Approximately 360 subjects who meet the trial eligibility criteria will be randomized in a 1:1:1 ratio to receive HZN-825 at 300 mg once daily, HZN-825 at 300 mg twice daily or placebo for 52 weeks. The primary endpoint is change in forced vital capacity (FVC) after 52 weeks.

This is an objective endpoint that measures lung capacity and is used to assess the progression of lung disease and the effectiveness of the treatment. Secondary endpoints include the 6-Minute Walk Test, the King's Brief Interstitial Lung Disease Questionnaire, rate of hospitalization due to respiratory distress, and a composite endpoint of progression-free survival. Enrollment is expected to take approximately two years.

The Phase 2b pivotal trial initiation follows encouraging efficacy and safety data in a Phase 2a trial in patients with early diffuse cutaneous systemic sclerosis.2 The placebo-controlled 8-week trial of HZN-825 in diffuse cutaneous systemic sclerosis, completed in 2018,showed a positive trend in response, with an improvement in the modified Rodnan skin thickness score, or mRSS, which is a secondary endpoint in the Phase 2b pivotal trial.