This is a randomized, double-blind, placebo-controlled, parallel-arm, Phase 2b adaptive dose-finding study of BLU-5937 in participants with Refractory Chronic Cough (RCC).

The primary objective of this study is to determine the therapeutic dose of BLU-5937 in patients with refractory chronic cough by assessing the change from baseline to week 4 in the 24-hour cough frequency with BLU-5937 relative to placebo.

Inclusion Criteria:

• Capable of giving signed informed consent
• Refractory chronic cough (including unexplained chronic cough) for at least one year
• Women of child-bearing potential must use a highly effective contraception method during the study and for at least 14 days after the last dose

Exclusion Criteria:

• Current smoker/vaper (all forms of smoking and inhaled substances, including , cannabis/tobacco smoke and nicotine vapors) or individuals who have given up smoking within the past 6 months, or those with >20 pack-year smoking history
• Diagnosis of Chronic Obstructive Pulmonary Disease (COPD), bronchiectasis, idiopathic pulmonary fibrosis or uncontrolled asthma
• Respiratory tract infection within 4 weeks before screening
• Laboratory confirmed Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection at screening
• History of malignancy in the last 5 years
• History of alcohol or drug abuse within the last 3 years
• Has a positive serologic test for human immunodeficiency virus (HIV), hepatitis B virus surface antigen, or hepatitis C virus.
• Previous participation in a BLU-5937 trial