This clinical trial is focused on studying a condition known as Diffuse Cutaneous Systemic Sclerosis, a rare disease that affects the skin and internal organs by causing them to harden and tighten. The study will evaluate a treatment called HZN-825, also known by its code name Fipaxalparant. This medication is taken in the form of a tablet and is being tested to see if it can help improve the symptoms of this disease.

The purpose of the study is to assess how effective and safe HZN-825 is for patients with this condition. Participants in the study will receive either the medication or a placebo, and their progress will be monitored over a period of 52 weeks. The main focus will be on changes in lung function, specifically looking at something called forced vital capacity (FVC), which measures how much air a person can exhale after taking a deep breath.

Throughout the study, participants will have regular check-ups to monitor their health and any changes in their condition. The study aims to provide valuable information on whether HZN-825 can be a beneficial treatment option for people living with Diffuse Cutaneous Systemic Sclerosis.