This study in China is open to people with progressive lung fibrosis (chronic fibrosing ILDs with progressive phenotype) who are at least 18 years old. The purpose of this study is to find out whether a medicine called nintedanib helps people with progressive lung fibrosis.

Participants are put into 2 groups randomly, which means by chance. 1 group gets nintedanib as capsules twice a day. The other group gets placebo as capsules twice a day. Placebo capsules look like nintedanib capsules but do not contain any medicine.

Participants are in the study for about 1 year. During this time, they visit the study site about 10 times. At some visits, participants perform a lung function test. The doctors check whether study treatment can slow down the loss of lung function. The doctors also regularly check participants' health and take note of any unwanted effects.

Inclusion Criteria:

• Written Informed Consent consistent with International Council on Harmonisation-Good Clinical Practice (ICH-GCP) and local laws signed prior to entry into the study (and prior to any study procedure including shipment of High-Resolution Computed Tomography (HRCT) to reviewer.

• Male or female patients aged ≥ 18 years at Visit 1.

• Patients with physician diagnosed Interstitial Lung Disease (ILD) who fulfil at least one of the following criteria for Progressive Phenotype within 24 months of screening visit (Visit 1) despite treatment with unapproved medications used in clinical practice to treat ILD, as assessed by the investigator:

  • Clinically significant decline in Forced Vital Capacity (FVC) % predicted based on a relative decline of ≥10%
  • Marginal decline in FVC % predicted based on a relative decline of ≥5-<10% combined with worsening of respiratory symptoms
  • Marginal decline in FVC % predicted based on a relative decline of ≥5-<10% combined with increasing extent of fibrotic changes on chest imaging
  • Worsening of respiratory symptoms as well as increasing extent of fibrotic changes on chest imaging [Note: Changes attributable to comorbidities e.g. infection, heart failure must be excluded. Unapproved medications used in the clinical practice to treat ILD include but are not limited to corticosteroid, azathioprine, mycophenolate mofetil (MMF), n-Acetylcysteine (NAC), rituximab, cyclophosphamide, cyclosporine, tacrolimus].

• Fibrosing lung disease on HRCT, defined as reticular abnormality with traction bronchiectasis with or without honeycombing, with disease extent of >10%, performed within 12 months of Visit 1 as confirmed by central readers.

• For patients with underlying Connective Tissue Disease (CTD): stable CTD as defined by no initiation of new therapy or withdrawal of therapy for CTD within 6 weeks prior to Visit 1.

• FVC ≥ 45% predicted at Visit 2.

Exclusion Criteria:

• Aspartate Aminotransferase (AST) and / or Alanine Aminotransferase (ALT) > 1.5 x Upper Level of Normal (ULN) at Visit 1
• Bilirubin > 1.5 x ULN at Visit 1
• Creatinine clearance <30 milliliter (mL)/minute (min) calculated by Cockcroft-Gault formula at Visit 1.

[Note: Laboratory parameters from Visit 1 have to satisfy the laboratory threshold values as shown above. Visit 2 laboratory results will be available only after randomization. In case at Visit 2 the results do no longer satisfy the entry criteria, the Investigator has to decide whether it is justified that the patient remains on study drug. The justification for decision needs to be documented. Laboratory parameters that are found to be abnormal at Visit 1 are allowed to be re-tested (once) if it is thought to be a measurement error (i.e. there was no abnormal result of this test in the recent history of the patient and there is no related clinical sign) or the result of a temporary and reversible medical condition, once that condition is resolved].

• Patients with underlying chronic liver disease (Child Pugh A, B or C hepatic impairment).
• Previous treatment with nintedanib or pirfenidone.
• Other investigational therapy received within 1 month or 6 half-lives (whichever was greater) prior to screening visit (Visit 1).
• Use of any of the following medications for the treatment of Interstitial Lung Disease (ILD): azathioprine (AZA), cyclosporine, Mycophenolate Mofetil (MMF), tacrolimus, oral corticosteroids (OCS) >20mg/day and the combination of OCS+AZA+ n-Acetylcysteine (NAC) within 4 weeks of Visit 2, cyclophosphamide within 8 weeks of Visit 2, rituximab within 6 months of Visit 2.

Note: Patients whose Regulatory Authority (RA)/Connective Tissue Disease (CTD) is managed by these medications should not be considered for participation in the current study unless change in RA/CTD medication is medically indicated.

Further exclusion criteria apply.

After the study is completed and the primary manuscript is accepted for publishing, researchers can use this following link https://www.mystudywindow.com/msw/datasharing to request access to the clinical study documents regarding this study, and upon a signed "Document Sharing Agreement".

Also, Researchers can use the following link https://www.mystudywindow.com/msw/datasharing to find information in order to request access to the clinical study data, for this and other listed studies, after the submission of a research proposal and according to the terms outlined in the website.

The data shared are the raw clinical study data sets.

After all regulatory activities are completed in the US and EU for the product and indication, and after the primary manuscript has been accepted for publication.

For study documents - upon signing of a 'Document Sharing Agreement'. For study data - 1. after the submission and approval of the research proposal (checks will be performed by both the independent review panel and the sponsor, including checking that the planned analysis does not compete with sponsor's publication plan); 2. and upon signing of a 'Data Sharing Agreement'.