A Study to Test Whether Nerandomilast Helps People With Lung Fibrosis Related to Rheumatic Diseases

Inclusion Criteria: * Participant has systemic autoimmune rheumatic diseases associated interstitial lung diseases (SARD-ILD), defined as * Diagnosis by a rheumatologist (or equally qualified medical physician) with at least 1 of the following SARDs: Rheumatoid arthritis (RA), systemic sclerosis (SSc) (participants must be anticentromere auto-antibody negative), idiopathic inflammatory myopathy (IIM), Sjögren's disease, or mixed connective tissue disease (MCTD) (participants must be anti-U1-ribonucleoprotein particle (RNP) auto-antibody positive) * Presence of fibrotic interstitial lung disease (ILD) on high-resolution computed tomography (HRCT), defined as presence of reticular abnormality with traction bronchiectasis with or without honeycombing (HC), with disease extent \>10% on HRCT performed within 12 months of Visit 1 or, if historical scan is not available, on baseline HRCT taken prior to Visit 2, as confirmed by central review * No lung function improvement and no clinically significant ILD improvement as a treatment response to immunosuppressant (IS) therapy according to both criteria: * No improvement in absolute forced vital capacity (FVC) % predicted \>5% within the 15 months prior to Visit 1, as measured by 2 spirometry assessments that must be ≥3 months apart. (Note: 1: In the case of multiple PFTs over the 15 months prior to screening, exceptional values of absolute change in FVC % predicted \>5% are acceptable if the overall trend of FVC % predicted is declining or stable; note 2: Visit 1 spirometry may be used to fulfill the inclusion criterion if there is only 1 spirometry reading in the 15 months prior to Visit 1) * No clinically significant improvement in ILD based on clinician's judgement (including symptoms, imaging/HRCT, or other assessments as considered relevant and documented by the Investigator) * FVC ≥45% of predicted normal at Visit 1 * Diffusing capacity of the lungs for carbon monoxide (DLCO) ≥25% of predicted normal corrected for haemoglobin (Hb) within 3 months prior to or at Visit 1 * Participants must be on stable treatment with any IS agent for ≥6 months (or ≥3 months for participants with IIM-ILD) prior to visit 2, with the following specifications: * If using prednisone, participants must be on stable dose for ≥4 weeks prior to Visit 2 * If using rituximab, participants must have completed their first cycle \>6 months prior to Visit 2 * If using nintedanib, participants must be on a stable dose for ≥12 weeks prior to Visit 2 * In the opinion of the Investigator, no change in background standard of care (SoC) treatment with immunosuppressant (IS), immunomodulator (IM), or nintedanib is planned * Further inclusion criteria apply Exclusion Criteria: * Organising pneumonia as predominant pattern in the HRCT * Prebronchodilator forced expiratory volume in 1 second (FEV1)/ forced vital capacity (FVC) \<0.7 at Visit 1 * Acute ILD exacerbation within 3 months prior to Visit 1 and/or during the screening period, based on Investigator judgement * Active vasculitis, unstable or uncontrolled within 8 weeks prior to Visit 1 or during the screening period * Any suicidal behaviour in the past 2 years * Any suicidal ideation of type 4 or 5 on the Columbia-Suicide Severity Rating Scale (C-SSRS) in the past 3 months or at Visit 1, and/or at Visit 2 * Use of any of the following medications: cyclophosphamide within 6 months of Visit 1, pirfenidone within 8 weeks of Visit 1 * Further exclusion criteria apply