Study to Evaluate Safety and Efficacy of Mirivadelgat in PH-ILD (Windward)

The goal of this clinical trial is to see if mirivadelgat will work in patients with Pulmonary Hypertension Associated with Interstitial Lung Disease (PH-ILD). It will also learn about the safety of mirivadelgat. The main question it aims to answer is if mirivadelgat will improve pulmonary vascular resistance (PVR). Pulmonary vascular resistance is a way to measure blood flow in the lungs. Researchers will compare mirivadelgat to a placebo (a look-alike capsule that contains no drug) to see if mirivadelgat works to improve the symptoms of PH-ILD. The symptoms of PH-ILD that are being looked at are exercise tolerance, heart function, and general well-being. Participants will: Take mirivadelgat or a placebo once a day for 12 weeks Visit the clinic once every 4 weeks for checkups and tests Receive phone calls every one or two weeks to check on how things are going

Inclusion Criteria: 1. A clinical diagnosis of PH-ILD. 2. Subject voluntarily gives informed consent. 3. Subjects aged between 18 and 85 years at the time of signing informed consent. 4. Subjects must agree to practice protocol-defined birth control during the study period. * Males with a partner of childbearing potential must practice protocol-defined birth control for the duration of treatment and at least 96 hours after discontinuing the IP. * Female subjects of childbearing of potential (including those \9.5%, urine glycosuria \>1.0 g/dl, or presence of diabetic ketoacidosis * History of significant coronary disease within 6 months of screening as demonstrated by any of the following: 1. History of myocardial infarction or acute coronary syndrome (unstable angina), or 2. Percutaneous coronary intervention or percutaneous transluminal angioplasty, or previous coronary artery bypass graft, or 3. Evidence of coronary artery disease (\>50% stenosis in at least one major coronary artery) or abnormal nuclear stress test. 4. The subject is receiving \>10 L/min of oxygen supplementation by any mode of delivery at rest. 5. The subject has received any PH-approved therapy, including phosphodiesterase type 5 inhibitor, soluble guanylate cyclase inhibitor, endothelin receptor antagonist, or parenteral or oral prostacyclin therapy (excluding vasoreactivity testing) within 60 days of randomization or 5 half-lives. Inhaled prostacyclin (e.g., inhaled treprostinil) on stable doses for ≥30 days prior to screening will be allowed irrespective of local approval (as per ESC/ERS 2022). 6. Use of any potent inhibitors and potent inducers of cytochrome P450 3A4 (CYP3A4) (e.g., boceprevir, cobicistat, danoprevir and ritonavir, elvitegravir and ritonavir, grapefruit juice, indinavir and ritonavir, itraconazole, ketoconazole, lopinavir and ritonavir, paritaprevir and ritonavir and (ombitasvir and/or dasabuvir), posaconazole, ritonavir, saquinavir and ritonavir, telaprevir, tipranavir and ritonavir, telithromycin, troleandomycin, voriconazole, clarithromycin, idelalisib, nefazodone, nelfinavir, carbamazepine, enzalutamide, mitotane, phenytoin, rifampin, St. John's wort). 7. Recent exacerbation of underlying lung disease or active pulmonary/upper respiratory tract infection within 4 weeks of randomization. 8. Any current active malignancy (this does not include localized cancers such as basal or squamous cell carcinoma of the skin). Any history of malignancy that is likely to result in mortality or require significant medical or surgical intervention within the following year. 9. Chronic kidney disease Stage IV or greater (i.e., eGFR ˂30 mL/min/1.73m2) or evidence of acute kidney injury. 10. The subject has a history of congenital heart disease irrespective of any prior treatment of surgical intervention 11. Use of tobacco, e-cigarette, nicotine, or marijuana products or significant history of drug or alcohol abuse within 6 months of screening. 12. Acute pulmonary embolism within 90 days of screening. 13. Participation in pulmonary rehabilitation within 90 days of screening. 14. Prior or concurrent use of any investigation drug/device/therapy or participation in any investigational study with therapeutic intent within 30 days or 5 half-lives, whichever is longer before the first dose of the IP. 15. BMI ≥40 kg/m2. 16. Uncontrolled hypertension as evidenced by systolic blood pressure \>160 mmHg or diastolic blood pressure \>100 mmHg during the screening period. Subjects who fail screening due to high blood pressure can be re-screened once, after their antihypertensive medicines have been adjusted and doses have been stable for at least 4 weeks. 17. Concomitant disease that confers a life expectancy of \