STX-100 in Patients With Idiopathic Pulmonary Fibrosis (IPF)

Key Inclusion Criteria: 1. Clinical features consistent with IPF prior to screening (based on the American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society (JRS)/Latin American Thoracic Association (ALAT) consensus criteria for the diagnosis of IPF). 2. Forced (expiratory) Vital Capacity (FVC) ≥ 50% of predicted value. 3. DLco (corrected for hemoglobin) ≥ 30% predicted value. 4. Oxygen saturation > 90% at rest by pulse oximetry while breathing ambient air or receiving ≤2 L/minute of supplemental oxygen. 5. Residual volume ≤ 120% predicted value. 6. Ratio of Forced Expiratory Volume over 1 second (FEV1) to FVC ≥ 0.65 after the use of a bronchodilator. 7. Other known causes of interstitial lung disease have been excluded (e.g., drug toxicities, environmental exposures, connective tissue diseases). 8. High Resolution Computed Tomography (HRCT) image fulfills the criteria for 'Usual Interstitial Pneumonia (UIP) pattern'. 9. If the HRCT image does not fulfill the criteria for 'UIP pattern' a surgical lung biopsy is necessary for the diagnosis of IPF (lung biopsy performed prior to screening is acceptable). If a lung biopsy has been performed, it must fulfill the histopathological criteria for either 'UIP pattern' or 'probable UIP pattern' with the appropriate HRCT correlate. 10. Adequate bone marrow and liver function. 11. Patient has a life expectancy of at least 12 months. Key Exclusion Criteria: 1. Findings that are diagnostic of a condition other than UIP on surgical lung biopsy (performed either before or after screening), HRCT imaging, transbronchial lung biopsy, or bronchoalveolar lavage (BAL). 2. Serious local infection or systemic infection within 3 months prior to screening. 3. Treatment with another investigational drug, investigational device, or approved therapy for investigational use within 4 weeks of initial screening. 4. Currently receiving high dose corticosteroid, cytotoxic therapy (e.g., chlorambucil, azathioprine, cyclophosphamide, methotrexate), nintedanib (Ofev®), vasodilator therapy for pulmonary hypertension (e.g., bosentan), unapproved and/or investigational therapy for IPF or administration of such therapeutics within 5 half-lives of the agent prior to initial screening in this study. 5. End-stage fibrotic disease requiring organ transplantation within 6 months NOTE: Other protocol defined Inclusion/Exclusion Criteria may apply.