This is a multi-center, randomized, double blind, placebo-controlled study to evaluate the efficacy, safety, PK, PD and immumogenicity of GR1802 injection in comparison to placebo in addition to a background treatment of mometasone furcate nasal spray (MFNS) in patients with chronic rhinosinusitis with nasal polyposis (CRSwNP). Patients will receive GR1802 injection or Placebo every 2 Weeks.

This is a multicenter, randomized, double-blind, placebo-controlled phase II clinical trial evaluating the preliminary efficacy and safety of GR1802 injection in patients with chronic rhinosinusitis with nasal polyps.

The study consists of a Screening/run-in Period (up to 4 weeks), a Randomized, Double Blind Treatment Period (16 weeks) and a Safety Follow-up Period (8 weeks).

70 subjects will be randomized 1:1 into the 300 mg first dose doubling Q2W group and the placebo Q2W group. Throughout the dosing period, all subjects continued treatment with standard therapy at a stable dose.

Patient-reported outcome including Nasal congestion score will be collected using patient diary. Central reading will be implemented to Nasal endoscopic nasal polyp score (NPS) and nasal polyp biopsy tissue analysis to eosinophil counts & percentage.

Inclusion Criteria:

1. Bilateral CRSwNP with prior treatment with systemic corticosteroids (SCS), and/or contraindicate to or intolerance to SCS, and/or with prior surgery to nasal polyps
2. Bilateral NPS of ≥5 with a minimum score of 2 in each nasal cavity at screening and at baseline.
3. Ongoing symptoms of nasal congestion/obstruction(NCS score of 2 or 3 at screening and at baseline).
4. Recorded use of intranasal corticosteroids for at least 4 weeks before screening

Exclusion Criteria:

1. Insufficient washout time for drugs that have an impact on the evaluation of efficacy and safety。
2. Concurrent disease that may interfere with the evaluation of safety and efficacy in subjects, or affect the risk- benefit evaluation of subjects. eg. specific ongoing nasal diseases, severe asthma, active infection, Severe cardiovascular disease, Severe laboratory test abnormalities.
3. Other.

Double blind