The primary objective of the study was to evaluate the efficacy and safety of 611 in Chinese adults with moderate to severe COPD.

The maximum study duration was 28 weeks per participants, including a screening period of up to 4 weeks, a 16-week randomized treatment period, and a 8-week follow-up period.

Inclusion Criteria:

1. Subject must be able to understand and comply with the requirements of the study. and must participate voluntarily and sign the written informed consent.
2. Male or female adults ages 40 to 85 years old when signing the informed consent.
3. BMI≥16 kg/m2.
4. Documented diagnosis of COPD for at least one year prior to enrolment.
5. Post-bronchodilator FEV1/FVC < 0.70 and post-bronchodilator FEV1 % predicted >30% and ≤70%.
6. Current or former smokers with a smoking history of ≥10 pack-years or environmental exposure to biofuel fumes ≥10 years
7. Documented history of ≥ 2 moderate or ≥ 1 severe COPD exacerbations within 12 months prior to enrolment.
8. Background triple therapy (ICS + LABA + LAMA) for 3 months prior to randomization with a stable dose of medication for ≥1 month prior to randomization; Double therapy (LABA + LAMA) allowed if ICS is contraindicated.
9. Patients with blood eosinophils ≥200 cells/microliter at screening.
10. Female subjects of reproductive age (and their male partners) and male subjects (and their female partners) must use highly effective contraception throughout the study period and for at least 3 months after the last dose. The subjects had no plans to pregnancy, donate sperm or donate egg during the whole study period and for at least 3 months after the last dose.

Exclusion Criteria:

1. Significant pulmonary disease other than COPD (e.g., active tuberculosis，lung cancer, bronchiectasis, sarcoidosis, lung fibrosis, pulmonary hypertension, interstitial lung disease, etc)
2. Diagnosed pulmonary or systemic disease associated with elevated peripheral eosinophil counts.
3. A current diagnosis of asthma or history of asthma according to the Global Initiative for Asthma (GINA) guidelines or other accepted guidelines.
4. Diagnosis of α-1 anti-trypsin deficiency.
5. Cor pulmonale, evidence of right cardiac failure
6. Any history of vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC).
7. A participant with a history of clinically significant renal, hepatic, cardiovascular, metabolic, neurologic, hematologic, ophthalmologic, respiratory, gastrointestinal, cerebrovascular or other significant medical illness or disorder which, in the judgment of the Investigator, could interfere with the study or require treatment that might interfere with the study.
8. Patients who have active Hepatitis B, Hepatitis C or HIV infections as determined by positive results at Screening.
9. Hypercapnia requiring Bi-level ventilation.
10. AECOPD as defined in inclusion criteria within 4 weeks prior to screening or randomization.
11. History of, or planned pneumonectomy or lung volume reduction surgery.
12. Treatment with oxygen of more than 12 hours per day.
13. Known with allergic or intolerant to mometasone furoate spray or 611/placebo.
14. Any reason which, in the opinion of investigator, would prevent the subject from participating in the study.