Inclusion Criteria:
1. Capable of understanding the nature of the study and voluntarily signing the informed consent form (ICF).
2. Aged ≥18 and ≤75 years (inclusive) at the time of signing the ICF, male or female.
3. Confirmed diagnosis of bilateral CRSwNP meeting the diagnostic criteria of the Chinese Guidelines for the Diagnosis and Treatment of Chronic Rhinosinusitis (2024).
4. Continuous concurrent presence of the following symptoms for ≥4 weeks prior to the screening period:
* Nasal congestion;
* Any one of the other symptoms: sticky or mucopurulent nasal discharge, facial pain/pressure/fullness, hyposmia or anosmia.
5. Bilateral Nasal Polyp Score (NPS) ≥5 points (out of a total of 8 points) at screening and prior to randomization, with a score of ≥2 points in each nasal cavity (based on central reading results).
6. Participant-reported moderate to severe nasal congestion at screening and prior to randomization: Nasal Congestion Score (NCS) of 2 or 3 points at the screening visit (V1); weekly average NCS ≥2 points prior to randomization (baseline).
7. Received systemic corticosteroids (SCS) within 2 years prior to screening but still has bilateral CRSwNP, AND/OR has contraindications to or intolerance of SCS therapy, AND/OR underwent nasal polyp surgery \>6 months prior to screening but still has bilateral CRSwNP.
8. Received a stable dose of intranasal corticosteroids (INCS) for at least 4 weeks prior to screening, and received mometasone furoate nasal spray (MFNS) for at least 2 weeks prior to randomization.
9. MFNS dosing compliance ≥80% during the run-in period based on daily diary (Compliance = actual administered dose / planned total dose \* 100%, where planned total dose = number of dosing days \* 2 \* 2 \* 50 μg, and actual administered dose = number of actuations \* 50 μg).
10. Female participants of childbearing potential and male participants (and their female partners) must have no plans for childbearing, sperm donation, or egg donation from screening until at least 6 months after the last dose of study drug. During this period, female participants of childbearing potential and male participants whose partners are women of childbearing potential must use highly effective contraception. Male participants with azoospermia (resulting from vasectomy or other underlying conditions) and their partners are not required to take contraceptive measures.
Exclusion Criteria:
1. Receipt of the following treatments prior to screening:
* Treatment with any systemic monoclonal antibody or biologic agent within 3 months or 5 half-lives (whichever is longer) prior to baseline, such as IL-4Rα monoclonal antibodies (dupilumab, stapokibart, etc.), IL-5/IL-5Rα pathway drugs (mepolizumab, benralizumab, depemokimab, etc.), anti-IgE monoclonal antibodies (omalizumab, etc.), anti-TSLP/TSLPR pathway drugs (tezepelumab, etc.), or other biologics evaluated by the investigator that may affect the efficacy evaluation of CRSwNP;
* Treatment with systemic immunosuppressants (including but not limited to methotrexate, cyclosporine, mycophenolate mofetil, tacrolimus, penicillamine, sulfasalazine, hydroxychloroquine, azathioprine, cyclophosphamide) for inflammatory or autoimmune diseases (e.g., rheumatoid arthritis, inflammatory bowel disease, primary biliary cirrhosis, systemic lupus erythematosus, multiple sclerosis, etc.) within 4 weeks or 5 half-lives (whichever is longer) prior to baseline;
* Initiation of leukotriene receptor antagonist (LTRA) treatment within 4 weeks prior to baseline (except for participants who have been on a stable dose of LTRA for at least 4 weeks prior to randomization);
* Initiation of allergen-specific immunotherapy (desensitization therapy) within 3 months prior to baseline, or planned initiation during the study period;
* Receipt of short- or medium-acting SCS (including oral, intravenous, and intramuscular corticosteroids) or Traditional Chinese Medicine (TCM, including systemic and topical TCM preparations) for chronic rhinosinusitis within 4 weeks prior to screening; or receipt of long-acting SCS (e.g., triamcinolone acetonide injection) within 6 weeks prior to screening; or planned treatment with the above medications during the study period;
* Participation in other drug clinical studies within 3 months or 5 half-lives (whichever is longer) prior to randomization, or planned participation in other drug clinical studies during the study period;
* Prior use of interleukin-4 receptor alpha subunit (IL-4Rα) monoclonal antibody drugs with development of drug resistance or drug-related serious AEs as judged by the investigator;
* Prior participation in an MG-K10 clinical trial and receipt of MG-K10 study drug.
2. Receipt of systemic (oral or intravenous) antibacterial, antiviral, or antifungal therapy within 4 weeks prior to randomization; or current presence of any symptoms, signs, or laboratory abnormalities suggestive of potential acute or subacute infection (such as fever, cough, urinary urgency, dysuria, abdominal pain, diarrhea, infectious skin wounds, etc.).
3. Confirmed active parasitic infection; or suspected parasitic infection or high risk of infection, unless active infection has been ruled out prior to randomization by clinical assessment and (if necessary) laboratory evaluation.
4. Patients with comorbid asthma who meet any of the following conditions will be excluded:
* Asthma exacerbation within 3 months prior to screening requiring systemic (oral and/or parenteral) steroid therapy or hospitalization (\>24 hours);
* For asthma participants receiving inhaled corticosteroids (ICS), treatment with a stable dose of ICS for \<4 weeks prior to screening, or an ICS daily dose of \>2000 μg fluticasone propionate or equivalent of another ICS \[participants who have been on a stable dose of ≤2000 μg fluticasone propionate or equivalent of another ICS for ≥4 weeks prior to screening and assessed by the investigator as capable of maintaining the current ICS regimen during the double-blind treatment period are eligible\].
5. Forced expiratory volume in 1 second (FEV1) ≤50% of predicted value at screening.
6. Comorbid with other nasal conditions or symptoms, such as:
* Nasal surgery within 6 months prior to screening (including polypectomy, except for nasal biopsy solely for diagnostic purposes); or participants with prior surgery that altered nasal anatomy resulting in an inability to assess NPS;
* Unilateral antrochoanal polyp;
* Severe nasal septal deviation causing obstruction of at least one nostril;
* Cystic fibrosis;
* Persistent rhinitis medicamentosa;
* Acute sinusitis, nasal infection, or acute upper respiratory tract infection at screening or within 2 weeks prior to screening;
* Symptomatic or CT scan suggestive of allergic fungal rhinosinusitis;
* Malignant or benign tumors of the nasal cavity.
7. Accompanied by eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), granulomatosis with polyangiitis (Wegener's granulomatosis), Young's syndrome, Kartagener's syndrome, or other ciliary dyskinesia syndromes.
8. Known hypersensitivity to MFNS, anti-IL-4Rα monoclonal antibody drugs, or any components of MG-K10.
9. Presence of significant cardiovascular, pulmonary, gastrointestinal, hepatic, renal, hematologic, neurological, or psychiatric diseases that are unstable or poorly controlled and deemed clinically significant by the investigator, such as: life expectancy \<3 months; uncontrolled diabetes mellitus (glycated hemoglobin \[HbA1c\] ≥9%); cardiovascular disease \[such as New York Heart Association (NYHA) Class ≥III heart failure\]; severe renal disease (such as patients receiving dialysis); hepatobiliary disease (such as Child-Pugh Class B or C); neurological disease (such as demyelinating disease); active autoimmune disease (such as systemic lupus erythematosus, inflammatory bowel disease, and rheumatoid arthritis), etc. "Clinically significant" is defined as the investigator determining that participation would pose a safety risk to the participant, or that worsening of the disease/condition during the study would affect efficacy or safety analyses.
10. Planned major surgery during the study period, including inpatient surgery and day-case/outpatient surgery.
11. Any of the following infectious disease screening criteria met at screening:
* Evidence of active tuberculosis (TB), or past history of active TB without appropriate documented treatment; chest X-ray (posteroanterior and lateral) or chest CT within 3 months prior to screening or during the screening period indicating active TB infection;
* Active hepatitis during screening, or positive hepatitis B surface antigen (HBsAg), or positive hepatitis B core antibody (HBcAb) with positive hepatitis B virus deoxyribonucleic acid (HBV DNA), or positive hepatitis C virus (HCV) antibody with positive HCV ribonucleic acid (HCV RNA);
* History of human immunodeficiency virus (HIV) infection, or positive HIV antibody at screening;
* Positive Treponema pallidum antibody (TP-Ab) at screening, except for those with a negative rapid plasma reagin (RPR) test or toluidine red unheated serum test (TRUST).
12. History of malignancy within 5 years (Note: 1. Patients with cervical carcinoma in situ that has been resected with no evidence of recurrence or metastasis for at least 3 years may participate in this study. 2. Patients with basal cell carcinoma or squamous cell carcinoma that has been completely resected with no recurrence for at least 3 years may participate in this study).
13. Any of the following laboratory criteria met at screening or prior to randomization and judged by the investigator as unsuitable for inclusion: severe hepatic impairment, such as aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \>2 × upper limit of normal (ULN), or total bilirubin \>2 × ULN; severe renal impairment, such as serum creatinine \>2 × ULN judged clinically significant by the investigator; complete blood count: platelet count \<75 × 10\^9/L, neutrophil count \<1.2 × 10\^9/L; or other clinically significant laboratory abnormalities judged by the investigator as unsuitable for enrollment.
14. Abnormal 12-lead electrocardiogram (ECG) at screening considered clinically significant by the investigator or sponsor and likely to pose an unacceptable risk to the patient's participation in the study (e.g., Fridericia's corrected QT interval \[QTcF\] \>500 msec).
15. Receipt of a live vaccine within 12 weeks prior to screening, or planned vaccination with a live (attenuated) vaccine during the study period.
16. Pregnant or breastfeeding women, or women planning to become pregnant or breastfeed during the study period.
17. History of illicit drug use, substance abuse, or alcohol abuse (defined as consuming \>14 units of alcohol per week \[1 unit = 360 mL of beer, 45 mL of spirits with 40% alcohol content, or 150 mL of wine\]).
18. Patients with ocular diseases judged by the investigator as unsuitable for study participation, such as a history of atopic keratoconjunctivitis involving the cornea within 6 months prior to screening; if the investigator cannot make a determination, an ophthalmologist must be consulted for diagnosis.
19. Any other medical or non-medical condition that, in the opinion of the investigator, makes the participant unsuitable for participation in the study.
