The purpose of this study is to evaluate the efficacy, safety, and tolerability at Week 24 (Part A) of 2 doses of CHF10067 (zampilimab), with an optional 24-week double-blind, placebo-controlled extension phase (Part B) in participants with idiopathic pulmonary fibrosis.

It is a phase IIb, multicentre, randomised, double-blind, placebo-controlled, three-arm parallel-group study.

A total of 240 participants with IPF (Idiomatic Pulmonary Fibrosis) will be randomised in approximately 150 investigational sites in North and Latin America, Europe, Asia, and Oceania. The optional extension phase (Part B) is only applicable to the European Union and Macedonia.

Inclusion Criteria:

• Informed consent: Participant's written informed consent obtained prior to any study-related procedure.
• Sex and age: Male or female, of any race and ethnicity, aged ≥40 years with a life expectancy of at least 1 year at screening in the opinion of the Investigator.
• Body weight ≥45 kg.
• Diagnosis of IPF: Diagnosis as defined by the 2018 and 2022 American Thoracic Society/European Respiratory Society/Japanese Respiratory Society/Latin American Thoracic Society Guidelines for a maximum 8 years before screening. The most recent HRCT(High-resolution computed tomography) ≤6 months prior to screening, reviewed by central reading, should be used to confirm the diagnosis.
• Lung function: Forced vital capacity (FVC) ≥45% of predicted normal value and a ratio of forced expiratory volume in the first second/FVC ≥0.7 at screening.
• Diffusing capacity of the lung for carbon monoxide (DLCO) corrected for haemoglobin ≥25% of predicted normal at screening.
• Oxygen saturation measured by pulse oximetry (peripheral capillary oxygen saturation [SpO2]) >90% at rest when the maximum oxygen flow is 4 L/min by standard nasal cannula or the equivalent oxygen delivery via reservoir nasal cannula (≤2 L/min).

Exclusion Criteria:

• Participant with a documented diagnosis of coeliac disease.
• Low respiratory tract infection: Documented low respiratory tract infection in the last 4 weeks prior to screening or documented acute exacerbation of IPF (defined as acute worsening or development of dyspnoea typically <1 month duration;
• Lung cancer: Active diagnosis or history of lung cancer.
• Emphysema: HRCT (refer to inclusion criterion #5 [Diagnosis of IPF]), reviewed by central reading, shows the presence of emphysema ≥20% or that the extent of emphysema is greater than the extent of fibrosis.
• Organ transplantation: End-stage fibrotic disease expected to require organ transplantation within 6 months from screening.
• Other medical conditions: Clinically relevant and uncontrolled pulmonary (including any non-IPF pulmonary diagnosis), cardiac, hepatic, gastrointestinal, renal, endocrine, metabolic, neurologic, psychiatric disorders, active or untreated latent tuberculosis/tuberculosis infection that may interfere with the participant's ability to complete this study according to the Investigator's judgement.
• Any other comorbid non-IPF pulmonary condition that may impact FVC according to the Investigator's judgement. Emphysema is allowed, unless it meets the above exclusion criterion regarding emphysema.
• Participant currently treated, or been treated with cytotoxic and immunosuppressant/modulator drugs within 48 weeks prior to screening. Systemic (IV, intramuscular, or oral) corticosteroids prednisone- equivalent dose of >10 mg/day used for >10 days.
• Hypersensitivity: Known intolerance and/or hypersensitivity to any of the excipients contained in the formulation or any other substance used in the study.
• History of allergic or anaphylactic reaction to human, humanised, chimeric Igs (immunoglobulins), or murine monoclonal antibodies.

The Investigational Medicinal Product (IMP) is blinded for the participant, investigators, and the sponsor. At the study site an unblinded pharmacist (or designee) will prepare the IMP and an unblinded clinical research associate will check the IMP related documentation Unblinded Sponsor and Clinical Research organization's Study Managers and Clinical Supplies representative will be also assigned.