Inclusion Criteria:
1. Age 18-80 years (\>70 y/o requires medical monitor approval)
2. Diagnosis of PH-ILD as defined by CT imaging within 1 year of screening that demonstrates diffuse parenchymal lung disease or abnormal PFTs (see IC #3) associated with one of the following:
1. Idiopathic interstitial pneumonia (IIP) including:
* Idiopathic pulmonary fibrosis (IPF)
* Idiopathic nonspecific interstitial pneumonia
* Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD)
* Unclassifiable idiopathic interstitial pneumonia
2. Chronic hypersensitivity pneumonitis (CHP)
3. CTD ILD patients with lung disease findings of \<65% predicted FVC in the setting of diagnosed Connective Tissue Disease
3. Pulmonary function tests within 6 months prior to Screening as follows:
* Forced vital capacity (FVC \<65% predicted and a DLCO \>30) for patients with confirmatory high- resolution computed tomography (CT) indicating fibrotic lung disease
* For subjects with a history of lobectomy or pneumonectomy, and for whom there are no population- based normalization methods, assessment based on residual lung volume will be permitted to assess eligibility.
4. Hemodynamics consistent with a diagnosis of precapillary PH (mPAP \> 25 mmHg, PCWP \< 15 mmHg, PVR \> 4.0 WU)
5. Symptomatic pulmonary hypertension classified as WHO Functional Class II or III
6. 6MWD ≥ 100 and ≤ 450 meters repeated twice during Screening Period and both values within 15% of each other, calculated from the highest value.
7. On a standard of care PH therapy at stable (per SOC) dose levels for at least 90 days prior to screening.
* Stable dose is defined as no change in dose
* CTD ILD patients are not required to be on SOC ILD therapy but if they are, must be a stable dose for 90 days
8. Females of childbearing potential must satisfy following:
* Have 2 negative pregnancy tests as verified by the investigator prior to starting study and must agree to ongoing pregnancy testing during the study and at end of study treatment.
* If sexually active, must have used, and agree to continue to use, highly effective contraception without interruption, for at least 30 days prior to starting investigational product (IP), during the study (including dose interruptions), and for 90 days after discontinuation of study treatment.
* Refrain from breastfeeding a child or donating blood, eggs, or ovum for the duration of the study and for at least 90 days after the last dose of study treatment.
9. Male participants must:
* Agree to use a condom, defined as a male latex condom or nonlatex condom NOT made from natural (animal) membrane (for example, polyurethane), during sexual contact with a pregnant female or a female of childbearing potential while participating in the study, during dose interruptions, and for at least 90 days following IP discontinuation, even if he has undergone a successful vasectomy.
* Refrain from donating sperm for the duration of the study and for 90 days after the last dose of study treatment.
10. Ability to adhere to the study visit schedule and understand and comply with all protocol requirements.
11. Ability to understand and provide written informed consent
Exclusion Criteria:
1. Clinical and/or radiologic evidence of moderate to severe emphysema
2. Clinical diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH), supported by imaging study (e.g. ventilation-perfusion (VQ) scan, CT pulmonary angiogram (CTPA) or pulmonary angiography with findings that establish CTEPH. In the absence of a clinical diagnosis of CTEPH, an imaging study is not required.
3. Received IV inotropes (e.g., dobutamine, dopamine, norepinephrine, vasopressin) within 30 days prior to Week 0 Visit
4. History of more than moderate obstructive sleep apnea that is untreated
5. Prior exposure to oral sirolimus or any other mTOR inhibitor within the last 90 days
6. Smoking, vaping or e-cigarette use within 90 days of Week 0 visit
7. Initiation of an exercise program for cardiopulmonary rehabilitation within 90 days prior to Week 0 Visit or planned initiation during the study (participants who are stable in the maintenance phase of a program and who will continue for the duration of the study are eligible)
8. Uncontrolled systemic hypertension as evidenced by sitting systolic BP \> 170 mmHg or sitting diastolic BP \> 100 mmHg during Screening Visit after a period of rest
9. Systolic BP \< 90 mmHg during Screening Visit or at baseline
10. History of known pericardial constriction
11. RHC contraindicated during the study per investigator
12. Personal or family history of long QTc syndrome or sudden cardiac death
13. Cerebrovascular accident within 90 days of the Week 0 Visit
14. History of restrictive or constrictive cardiomyopathy
15. Left ventricular ejection fraction \< 45% on echocardiogram performed within 6 months prior to Screening Period (or done as a part of the Screening Period)
16. Any current symptomatic coronary disease (myocardial infarction, percutaneous coronary intervention, coronary artery bypass graft surgery, or cardiac anginal chest pain in the past 6 months prior to Screening Visit).
17. Known diagnosis (as determined by echocardiography) of significant (≥ 2+ regurgitation) mitral valve regurgitation or aortic regurgitation valvular disease
18. Any of the following clinical laboratory values during the Screening Period prior to Week 0 Visit:
* Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels \> 3x upper limit of normal (ULN) or total bilirubin \> 1.5 x ULN within 28 days of Week 0 Visit
* Estimated glomerular filtration rate \< 30 mL/min/1.73 m2 (4-variable Modification of Diet in Renal Disease equation) within 28 days of Week 0 Visit or required renal replacement therapy within 90 days
19. History of opportunistic infection (e.g., invasive candidiasis or Pneumocystis pneumonia) within 6 months prior to Screening; serious local infection (e.g., cellulitis, abscess) or systemic infection (e.g., septicemia) within 3 months prior to Screening
20. History of severe allergic or anaphylactic reaction or hypersensitivity to recombinant proteins or lactose excipients in IP
21. Major surgery within 8 weeks prior to Week 0 Visit. Participants must have completely recovered from any previous surgery prior to Week 0 Visit
22. Prior heart or heart-lung transplants
23. Life expectancy of \< 12 months (per PI determination)
24. Pregnant or breastfeeding females
25. At any time in the 30 days prior to the Screening Period received \> 20 mg/day of prednisone (or equivalent) or started or changed the dose of a systemic corticosteroid. Participants receiving stable doses of ≤ 20 mg prednisone (or equivalent) in 30 days prior to the Screening Period are permitted in the study.
26. History of active malignancy within the past 5 years, with the exception of fully excised or treated basal cell carcinoma, cervical carcinoma in-situ, or ≤ 2 squamous cell carcinomas of the skin
27. History of clinically significant (as determined by the investigator) non-PH related cardiac, endocrine, hematologic, hepatic, immune, metabolic, urologic, pulmonary, neurologic, neuromuscular, dermatologic, psychiatric, renal, and/or other disease that may limit participation in the study
28. Participation in another clinical trial involving intervention with another investigational drug or approved therapy for investigational use within 4 weeks prior to Week 0 Visit, or if the half-life of the previous product is known, within 5x the half-life prior to Week 0 Visit, whichever is longer
29. Participation in another clinical trial involving an investigational device within 4 weeks prior to Week 0 Visit
30. Any recreational drug use (cocaine, marijuana, etc.) within 90 days
31. Unwillingness or inability to comply with the protocol- required procedures
