L606A Phase 3 Study to Evaluate the Safety and Efficacy L606 in Participants With PH-ILD

The purpose of this study is to find out if L606 is safe and if it helps people with high blood pressure in the lungs (pulmonary hypertension) caused by interstitial lung disease (PH-ILD, WHO Group 3). One of the main ways the study will check this is by seeing if people can walk further in six minutes (called the "six-minute walk test"). Another important (secondary) goal is to see how long it takes for PH-ILD to get worse while people are taking L606. One way the study will measure this is by looking at the distance people walk at different times in the study on different doses of L606. Throughout the study, doctors will also closely monitor for any side effects people have to make sure L606 is safe. People who decide to join this study will be randomly (like tossing a coin) placed into one of two groups: one group will get L606 and the other group will get a placebo, which will look like L606 but will not contain any active medicine. At the end of the initial blinded portion of the study, study participants may have the opportunity to enroll in an open-label extension portion of the study where all participants will receive L606.