The primary purpose of this study is to assess the effect of TX000045 on pulmonary vascular resistance (PVR) in participants with pulmonary hypertension secondary to interstitial lung disease (PH-ILD) and to assess the safety and tolerability of TX000045 in participants with PH-ILD.

Inclusion Criteria:

• Confirmed diagnosis of ILD based on imaging: chest computed tomography (CT) performed within the past 12 months with fibrotic lung disease (greater than or equal to (>=) 10 percent (%) lung parenchyma with fibrosis) consistent with idiopathic interstitial pneumonia, ILD in association with connective tissue disease, occupational ILD, or chronic hypersensitivity pneumonitis. Chest CTs will be centrally read for eligibility
• 40% predicted less than or equal to (<=) forced vital capacity (FVC) <= 80% predicted at screening
• At least ONE of the following is required to undergo the first screening visit: Documented diagnostic right heart catheterization (RHC) within 18 months of screening with mean pulmonary arterial pressure (mPAP) >= 25 millimeters of mercury (mm Hg), pulmonary capillary wedge pressure (PCWP) <=15 mm Hg, and pulmonary vascular resistance (PVR) >=4 Wood units; Documented echocardiogram (ECHO) within 18 months of screening with right ventricular (RV) (or pulmonary artery) systolic pressure >46 mm Hg or tricuspid annular plane systolic excursion (TAPSE)/ systolic pulmonary artery pressure (SPAP) <=0.38 and absence of clinically significant left ventricular dysfunction as assessed by the investigator

Exclusion Criteria:

• Participants have a confirmed or suspected diagnosis of pulmonary hypertension in World Health Organization (WHO) Group 1, WHO Group 2, WHO Group 4, or WHO Group 5
• Participants have received phosphodiesterase type 5 inhibitors, endothelin receptor antagonists, soluble guanylate cyclase stimulators, intravenous (IV) or subcutaneous (SC) prostacyclin analogues within 30 days before the first screening visit, or sotatercept within 180 days before the first screening visit
• Participants have any type of pulmonary and cardiovascular comorbidities as defined n protocol
• Participants who are taking disease-modifying therapy for the underlying interstitial lung disease (ILD) (anti-fibrotics, immunosuppressives, and anti-inflammatory medications) who are not on stable doses for >30 days before the first screening visit or have initiated new ILD-directed therapies within 90 days before the first screening visit