This study is a prospective, multicenter, randomized, double-blind, placebo-controlled study to investigate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and exploratory efficacy of nebulized CSL787 after administrations of single (SAD) ascending doses in healthy subjects and multiple (MAD) ascending doses in subjects with NCFB.

Inclusion Criteria:

• Male or female, aged ≥ 18 years at the time of providing written informed consent

For Part A (SAD) Only:

• Healthy and free of medical conditions that could in the opinion of the investigator affect's the subject's participation in the study or the interpretation of results.

For Part B (MAD) Only:

• Diagnosis of NCFB made by a respiratory physician, confirmed per CT showing bronchial wall dilatation with or without bronchial wall thickening, with a FEV1 ≥ 40% of the predicted value regarding age, height, gender, ethnicity, and FEV1 ≥ 1 L (pre-bronchodilator values) at the Screening Visit.
• No antibiotic use within 1 month before the Screening Visit.
• Presence of one or more of the following bacteria (H. influenzae, P. aeruginosa, M. catarrhalis, S. pneumoniae, members of Enterobacterales family or S. aureus) in the sputum culture at the Screening Visit.
• Has been fully vaccinated against COVID-19 (as per country recommendations) at least 7 days prior to Day 1

Exclusion Criteria:

• Evidence of a clinically significant medical condition, disorder, or disease, including but not limited to any of the following: hepatic (hepatitis, cirrhosis); biliary; renal; cardiac; bronchopulmonary; vascular; hematologic; gastrointestinal; allergy; endocrine / metabolic (diabetes, thyroid disorders, adrenal disease); neurologic; psychiatric; immunodeficiency; cancer.
• History of chronic respiratory disease (eg, COPD or bronchiectasis) or current asthma with regular treatment including occasional use of an inhaler for exercise induced asthma.
• Current moderate-severe allergic disease (eg, allergic rhinitis) with regular treatment.
• Diagnosis of cystic fibrosis, mycobacterial disease, connective tissue disease, or alpha-1 antitrypsin deficiency as underlying disease for bronchiectasis.
• Oral/parenteral corticosteroid 28 days before the Screening Visit until EOS Visit. Use of long acting bronchodilators (long acting muscarinic antagonists (LAMA) and / or long acting beta2 agonists (LABA) and/or inhaled corticosteroids that have been at a stable dose for at least 3 months before the Screening Visit is permitted; inhalation with hypertonic saline solution is permitted up to and including Day -1.
• Any systemic or inhaled antibiotic for acute pulmonary exacerbation within 1 month before the Screening Visit until EOS Visit.

CSL will consider requests to share Individual Patient Data (IPD) from systematic review groups or bona-fide researchers. For information on the process and requirements for submitting a voluntary data sharing request for IPD, please contact CSL at clinicaltrials@cslbehring.com.

Applicable country specific privacy and other laws and regulations will be considered and may prevent sharing of IPD.

If the request is approved and the researcher has executed an appropriate data sharing agreement, IPD that has been appropriately anonymized will be available.

IPD requests may be submitted to CSL no earlier than 12 months after publication of the results of this study via an article made available on a public website.

Requests may only be made by systematic review groups or bona-fide researchers whose proposed use of the IPD is non-commercial in nature and has been approved by an internal review committee.

An IPD request will not be considered by CSL unless the proposed research question seeks to answer a significant and unknown medical science or patient care question as determined by CSL's internal review committee.

The requesting party must execute an appropriate data sharing agreement before IPD will be made available.