The purpose of this study is to evaluate the safety, tolerability, and pharmacokinetics of ARO-RAGE in normal healthy volunteers (NHVs) and in participants with inflammatory lung disease (asthma). In Part 1 of the study, NHVs will receive a single dose of ARO-RAGE or placebo. In Part 2 of the study, adult participants with asthma will receive 2 doses of ARO-RAGE or placebo. Additional NHVs may be randomized to receive 1 or 2 doses of ARO-RAGE or placebo at Sponsor discretion. Dose levels in Part 2 will be determined based on cumulative safety and pharmacodynamic data from Part 1.

Inclusion Criteria:

• Normal pulmonary function tests at Screening (NHVs only)
• Confirmed diagnosis of asthma based on source verifiable medical record (asthma patients only)
• No abnormal finding of clinical relevance at Screening (other than asthma for asthma patients)
• Stable dose of asthma controller medications prior to Screening (asthma patients only)
• If on allergen-specific immunotherapy, participants must be on a stable maintenance dose
• Non-smoking
• Women of childbearing potential must have a negative pregnancy test, cannot be breastfeeding, and must be willing to use contraception. Males must not donate sperm during the study and for at least 12 weeks following the last dose of study drug
• Willing to provide written informed consent and to comply with study requirements

Exclusion Criteria:

• Acute lower respiratory infection or asthma exacerbation within 30 days prior to first dose
• Positive COVID-19 test during Screening window
• Use of immunosuppressive medication within 90 days prior to first dose
• Receipt of any intranasal vaccine within 30 days prior to first dose
• Use of systemic corticosteroid therapy within 90 days prior to first dose
• Clinically significant health concerns (other than asthma in asthma patients)
• Human Immunodeficiency virus (HIV) infection, seropositive for Hepatitis B Virus (HBV), seropositive for Hepatitis C Virus (HCV)
• Uncontrolled hypertension
• Unwilling to limit alcohol consumption to within moderate limits for the duration of the study
• Use of illicit drugs
• Use of an investigational agent or device within 30 days prior to first dose

Note: additional inclusion/exclusion criteria may apply per protocol