This is a multi-center, randomized, double blind, placebo-controlled Phase III study to evaluate the efficacy and safety of CM310, and to observe the life quality of subjects, the Pharmacokinetics, Pharmacodynamics and immumogenicity of CM310 in patients with chronic rhinosinusitis with nasal polyposis (CRSwNP).

The study consists of a Screening Period (up to 4 weeks), Treatment Period (24 weeks for double-blind treatment period and 28 weeks for open-label maintenance treatment) and Safety Follow-up Period (8 weeks).

180 patients who meet eligibility criteria will be randomized 1:1 to receive either CM310 300 mg or matched placebo subcutaneously every two weeks (Q2W) for a total of 12 times at the double-blind treatment period and 14 times at the open-label treatment period. All patients will receive MFNS on a daily basis as a background treatment throughout the study.

Central reading will be implemented to nasal endoscopic nasal polyp score (NPS) , CT scans to Lund-Mackay score and volume of the involved area of nasosinusitis on 3D-construction images, and nasal polyp biopsy tissue analysis to eosinophil counts & percentage.

Inclusion Criteria:

• with chronic rhinosinusitis with nasal polyposis (CRSwNP).
• Nasal Polyp Score (NPS) of ≥5 with a minimum score of 2 in each nasal cavity.
• NCS score of 2 or 3 at screening period, and at least 2 at baseline.
• Contraception.

Exclusion Criteria:

• Not enough washingout period for previous therapy, e.g., less than 10 weeks or 5 half-lives (whichever is longer) for IL-4Rα antagonists, less than 8 weeks or 5 half-lives for biologic therapy/systemic immunosuppressant, less than 6 months for sinus surgery (including polypectomy).
• Participated and any studies of CM310.
• With malignant or benign tumor of nasal cavity.
• Vaccination with live attenuated vaccine within 12 weeks before randomization or during the planned study period.