The goal of this clinical trial is to learn if GR1802 works to treat severe chronic rhinosinusitis with nasal polyps (CRSwNP) in adults. It will also learn about the safety of GR1802. The main questions it aims to answer are:

1. Does GR1802 reduce the need for surgery and systemic corticosteroid use？
2. What medical problems do participants have when taking GR1802?

Researchers will compare GR1802 to a placebo (a look-alike substance that contains no drug) to see if GR1802 works to treat CRSwNP.

Participants will:

Take GR1802 or a placebo once every 2 weeks for 13months. Visit the clinic once every 2 weeks for checkups and tests. Keep a diary of their symptoms and the dosage and number of times they use mometasone furoate nasal spray.

A randomized, double-blind, placebo-controlled, multi-center clinical trial was designed. The clinical trial was divided into 4 stages: screening/introduction period, double-blind treatment period , maintenance treatment period and safety follow-up period.

The clinical trial aimed to evaluate the efficacy, safety and immunogenicity of GR1802 injection in CRSwNP participants.

Inclusion Criteria:

• Diagnosed as CRSwNP and treated with systemic glucocorticoid within 2 years before screening; and/or those who had undergone surgery for nasal polyps before screening.
• An endoscopic bilateral NPS at screening/lead-in period and the baseline period of at least 5 out of a maximum score of 8 (with a minimum socre of 2 in each nasal cavity).
• Nasal congestion/blockade/obstruction with moderate or severe symptom severity at at screening period (score 2 or 3 ) .
• Willing to sign an informed consent, able to comply with clinic visits and study-related procedures as per protocol.

Exclusion Criteria:

• Biologic therapy within 5 half-lives or within 10 weeks before baseline.
• Anti-IL-4Rα antibody before screening.
• An experimental drug within 5 half-lives or 1 months before baseline.
• Systemic immunosuppressant to treat inflammatory disease or autoimmune disease within 2 months or 5 half-lives before baseline.
• Initiation of allergen immunotherapy within 3 months before screening.
• Participants receiving leukotriene antagonist/modifier before screening unless on continous treatment for at least 30 days.
• Participants with FEV1 50% or less of predicted normal were excluded.
• Participants who have undergone any intranasal and/or sinus surgery within 6 months before screening.
• Acute sinusitis or upper respiratory infection within a defined time period before screening.
• A nasal cavity tumor (malignant or benign).
• Evidence of fungal rhinosinusitis.
• Presence of another diagnosis associated with nasal polyps (i.e., eosinophilic granulomatosis with polyangiitis, granulomatosis with polyangiitis, Young's syndrome, cystic fibrosis).
• Rhinitis medicamentosa.
• Nasal septal deviation occluding at least one nostril.
• Antrochoanal polyps.
• Pregnant or lactating woman.