This study is a randomized, double-Blind, placebo-controlled, Single and Multiple-ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, Immunogenicity, Pharmacodynamics and Clinical Activity of BBT002 in Healthy Volunteers and Participants with Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) and Comorbid Asthma.

The study consists of two parts:

• Part A (single dose in HVs in sequential ascending dose cohorts, SAD in HVs part)
• Part B (five repeated doses in patients with CRSwNP, MAD in patients part)

Inclusion Criteria: Part (A&B):

1. Age of 18-55 years (HVs), 18-75 years (patients)
2. Body mass index between 18-30 kg/m², capped at 120 kg
3. Negative pregnancy tests for women of childbearing potential
4. Willingness to refrain from alcohol consumption for 24 hours prior to each study visit
5. Non-smokers, healthy current smokers (≤5 cigarettes/day), or ex smokers

Key Inclusion Criteria (Part B only)

1. Participants with physician-diagnosed CRSwNP for at least 12 months prior to randomization
2. SNOT-22 total score ≥30 at screening and randomization.
3. Documented systemic corticosteroid use (or contraindication/intolerance) within past 24 months.
4. Diagnosed asthma per GINA 2025, stable for ≥12 months. Stable on GINA Step 3 or higher therapy for 6 weeks before screening.

Exclusion Criteria:Part (A&B):

1. Positive viral serology for human immunodeficiency virus (HlV), hepatitis C virus (HCV), or hepatitis B (HBV)
2. Immunodeficiencies, autoimmune diseases, or cancer, history of conditions predisposing to infections
3. History of major metabolic, dermatological, liver, kidney, hematological or other significant disorders
4. Clinically relevant abnormal lab results, including low blood counts, liver enzymes, or abnormal kidney function
5. Positive drug/alcohol tests or abnormal vital signs at screening or Day -1
6. Abnormal Electrocardiogram(ECG) findings
7. History of drug/alcohol abuse in the past 2 years
8. History of severe allergic reactions or hypersensitivity

Key Exclusion Criteria for (Part B only):

1. Any sinus/nasal surgery (including polypectomy) within 6 months before screening, History of ≥2 prior sinus/nasal surgeries
2. Concurrent nasal conditions that may interfere with study assessments
3. Significant or unstable cardiovascular diseases
4. Recent clinically significant infection