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

Inclusion Criteria:

1. A clinical diagnosis of PH-ILD.

2. Participant voluntarily gives informed consent.

3. Male or female participants aged between 18 and 85 years at the time of signinginformed consent.

4. Participants must agree to practice protocol-defined birth control during the studyperiod, unless they meet criteria for not being of childbearing potential.

• Male participants with female partners of childbearing potential must practiceprotocol- defined birth control for the duration of treatment and at least 96hours after discontinuing the IP.

• Female participants of childbearing of potential (including those <1-yearpost-menopausal) must practice protocol-defined birth control during theconduct of the study and for 30 days after the last dose of IP (males onlyduring exposure to IP).

• Female participants not of childbearing potential (as defined below) areeligible for enrolment without contraception requirements:

1. Post-menopausal women (at least 12 months with no menses without analternative medical cause); in women <45 years of age, a highfollicle-stimulating hormone (FSH) level in the post-menopausal range maybe used to confirm a post-menopausal state in women not using hormonalcontraception or hormonal replacement therapy; OR

2. Have had a hysterectomy and/or bilateral oophorectomy, bilateralsalpingectomy, or bilateral tubal ligation/occlusion, at least 6 weeksprior to screening; OR

3. Have a congenital or acquired condition that prevents childbearing.

4. The participant has a confirmed diagnosis of any form of interstitial lung diseasebased on high-resolution computed tomography (HRCT) of the chest within 180 daysprior to screening or at screening or a historical surgical biopsy (or otherappropriate tissue sampling (e.g., cryobiopsy). The participant can have otherfindings (e.g., emphysema) if this is not the predominant feature on the scan.

5. Participants have undergone RHC during the screening period with the followingdocumented parameters:

• Pulmonary vascular resistance (PVR) ≥4 Wood units and

• Pulmonary capillary wedge pressure (PCWP) of ≤12 mmHg [if PVR ≥4 Wood units to <6.25 Wood units] or PCWP ≤15 mmHg [if PVR ≥6.25 Wood units] Note: If areliable PCWP cannot be obtained, left ventricular end-diastolic pressure (LVEDP), measured via left heart catheterization (LHC), will be acceptable,with the same numerical thresholds as the PCWP criterion: LVEDP of ≤12 mmHg [ifPVR ≥4 to <6.25 Wood units], or LVEDP ≤15 mmHg

• A mean pulmonary arterial pressure (PAP) of >20 mmHg.

7. Participants must have a 6-minute walk distance ≥100 meters and ≤500 meters at theScreening Visit (Visit 1).

8. Participants agree to a repeat RHC, Chest CT, and MRI prior to study completion.

9. Participants on chronic treatment for underlying lung disease (i.e., nintedanib orpirfenidone or immunosuppressive agents etc.) must be on a stable/optimized dose for ≥30 days prior to screening and have been receiving treatment for ≥90 days.

10. Participants on supportive medications (e.g., inhalers for asthma) must be on stabledoses for ≥30 days prior to screening.

11. In the Investigator's opinion, the participant must be able to consent forthemselves and communicate with local staff using interpreters if necessary.Participants must agree to attend all study visits and be contactable through acellular device or landline.

12. Participants must have clinical laboratory values within normal ranges or <1.5 timesthe upper limit of normal (ULN) as specified by the testing laboratory.

13. Participants must meet the following requirements for the pulmonary function test (PFT) at screening:

• Forced vital capacity (FVC) <90% of predicted

• Diffusion capacity of carbon monoxide (DLCO) <70% of predicted, or <70% ofpredicted corrected for hemoglobin (Hb), if correction is required. (Correctionapplies if Hb value is ≥25% and ≤90% of normal.) Note: DLCO must be determinedlocally at screening, using American Thoracic Society (ATS) standards.Hemoglobin correction should reference ATS normal values: Men = 14.6 g/dL,Women = 13.4 g/dL.

14. Negative serology test for hepatitis B surface antigen and hepatitis C antibody atScreening Visit.

Exclusion criteria:

Medical Conditions

1. Participant has another concomitant diagnosis of pulmonary hypertension nototherwise considered to be PH-ILD. This would include and is not limited to theconcomitant presence of thromboembolic disease, untreated/inadequately treatedobstructive sleep apnea, human immunodeficiency virus (HIV), methamphetamine oranorexigenic drug use, and other conditions of the WHO Group 1, 2, 4, and 5classifications.

2. Participant has evidence of clinically significant left-sided heart disease within 6months of screening as defined by:

• Left ventricular ejection fraction <40% as assessed by echocardiography.

• More than mild left-sided valvulopathy (e.g., worse than mild mitral stenosisor regurgitation and worse than mild aortic stenosis or regurgitation).

• LVEDP or PCWP >15 mmHg (or >12 mmHg if PVR ≥4 to 6.25 Wood units).

3. Participants must NOT have 3 or more of the following left ventriculardisease/dysfunction risk factors at screening:

• Body mass index (BMI) ≥30 kg/m2.

• Uncontrolled diabetes, as evidenced by HbA1C >9.5%, or urine glycosuria >1.0g/dl, or presence of diabetic ketoacidosis.

• History of significant coronary disease within 6 months of screening asdemonstrated by any of the following:

1. History of myocardial infarction or acute coronary syndrome (unstableangina), or

2. Percutaneous coronary intervention or percutaneous transluminalangioplasty, or previous coronary artery bypass graft, or

3. Evidence of coronary artery disease (>50% stenosis in at least one majorcoronary artery) or abnormal nuclear stress test.

4. The participant is receiving ≥10 L/min of oxygen supplementation by any mode ofdelivery at rest.

5. The participant has received any PH-approved therapy, including soluble guanylatecyclase inhibitors, endothelin receptor antagonists, or parenteral or oralprostacyclin therapy (excluding vasoreactivity testing) within 60 days ofrandomization or 5 half-lives. Use of phosphodiesterase type 5 inhibitors andinhaled prostacyclin (e.g., inhaled treprostinil) on stable doses for ≥30 days priorto screening will be allowed irrespective of local approval (as per ESC/ERS 2022).

6. Use of any inhibitors and inducers of cytochrome P450 3A4 (CYP3A4) (e.g.,boceprevir, cobicistat, danoprevir and ritonavir, elvitegravir and ritonavir,grapefruit juice, indinavir and ritonavir, itraconazole, ketoconazole, lopinavir andritonavir, paritaprevir and ritonavir and (ombitasvir and/or dasabuvir),posaconazole, ritonavir, saquinavir and ritonavir, telaprevir, tipranavir andritonavir, telithromycin, troleandomycin, voriconazole, clarithromycin, idelalisib,nefazodone, nelfinavir, carbamazepine, enzalutamide, mitotane, phenytoin, rifampin,St. John's wort). For a comprehensive list, please refer to the FDA's Examples ofDrugs that Interact with CYP Enzymes and Transporter Systems (FDA 2025).

7. Recent exacerbation of underlying lung disease or active pulmonary/upper respiratorytract infection within 4 weeks of randomization.

8. Any current active malignancy (this does not include localized cancers such as basalor squamous cell carcinoma of the skin). Any history of malignancy that is likely toresult in mortality or require significant medical or surgical intervention withinthe following year.

9. Chronic kidney disease Stage IV or greater (i.e., eGFR ˂30 mL/min/1.73m2) orevidence of acute kidney injury.

10. The participant has a history of congenital heart disease, irrespective of any priortreatment or surgical intervention

11. Use of tobacco, e-cigarette, nicotine, or marijuana products or a significanthistory 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. However,participants who were on stable pulmonary rehabilitation for more than 90 daysbefore screening may be considered for the study, provided they meet all otherinclusion criteria.

14. Prior or concurrent use of any investigational drug/device/therapy or participationin 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 ordiastolic blood pressure >100 mmHg during the screening period. Participants whofail screening due to high blood pressure can be re-screened once after theirantihypertensive medications have been adjusted and their doses have been stable forat least 4 weeks.

17. Concomitant disease that confers a life expectancy of <6 months at screening.

18. The Investigator judges that the participant will be unable to fully participate inthe study and complete it for any reason, including inability to comply with thestudy procedures and treatment of addiction or any other relevant medical orpsychiatric conditions.

19. High likelihood of lung transplantation (in the opinion of the Investigator) within 4 months after randomization.

20. History of liver dysfunction, including participants with moderate (Child-Pugh B) orsevere (Child-Pugh C) impairment or disordered coagulation.

21. Female participants who are pregnant or breastfeeding.

22. Worse than mild untreated sleep apnea (5-14.9 events/hour). Treated sleep apnea ispermitted.

23. Participants with a prior diagnosis of connective tissue diseases, e.g., systemicsclerosis (scleroderma), systemic lupus erythematosus, Sjogren's disease,polymyositis/dermatomyositis/antisynthetase syndrome, or rheumatoid arthritis. Other Exclusions

24. History of allergic or anaphylactic reaction to mirivadelgat or to any component ofthe excipient.

25. Previous exposure to mirivadelgat. Diagnostic Assessments

26. The following laboratory parameters are excluded:

• Hemoglobin <10 g/dL (100 g/L).

• White blood cells (WBC) <3000/µL (<3000/mm3).

• Platelet count <70,000/µL (70,000/mm3).

• Estimated glomerular filtration rate (eGFR) <30 mL/min/1.73m2 or evidence ofacute kidney injury.