Test of SKB575 in adults with asthma

Inclusion Criteria:

1. The participant is able to understand and comply with the requirements of this study, and voluntarily signs the informed consent form.
2. Aged between 18 and 70 years inclusive at the time of signing the informed consent form, with no restriction on gender.
3. Body Mass Index (BMI) shall be ≥ 18.0 kg/m² and ≤ 32.0 kg/m².
4. Diagnosis of asthma consistent with the Global Initiative for Asthma (GINA) 2025 diagnostic criteria.
5. Pulmonary function test during the screening period must meet either of the following criteria: After albuterol inhalation, the forced expiratory volume in one second (FEV₁) increases by ≥ 12% with an absolute FEV₁ increment of ≥ 200 mL; or the participant has a positive result from a bronchodilator reversibility test or bronchial provocation test within the past 12 months.
6. Participants must have received a stable dose of controller medication for a minimum of 3 months prior to randomization. Subjects shall be on maintenance therapy with low-, medium- or high-dose inhaled corticosteroids (ICS), which may be combined with other asthma controller medications including long-acting beta₂ agonists (LABA), long-acting muscarinic antagonists (LAMA), and leukotriene receptor antagonists (LTRA). The treatment regimen and dosage shall remain unchanged throughout the study period.
7. Pre-bronchodilator forced expiratory volume in one second (FEV₁) ≥ 50% of predicted value during screening.
8. Male and female participants must agree to use highly effective contraceptive methods for the specified duration of the study.

Exclusion Criteria:

1. Within 3 months prior to randomization, the participant experienced an acute asthma exacerbation requiring continuous systemic corticosteroid therapy for ≥3 consecutive days, or presented to the emergency department or was hospitalized due to asthma with administration of systemic corticosteroids (calculated from the completion date of treatment for the asthma exacerbation).
2. Known hypersensitivity to the investigational product or its excipients, or a history of allergic reactions to any biological products.
3. Concomitant clinically significant pulmonary diseases, including but not limited to pulmonary infection, chronic obstructive pulmonary disease (COPD), bronchiectasis, interstitial lung disease, pulmonary vascular disease, pulmonary neoplasm, or any other diseases affecting pulmonary function other than asthma.
4. Concomitant diseases that may impair pulmonary function, including but not limited to clinically significant pleural disorders, mediastinal diseases, diaphragmatic lesions, myasthenia, thoracic deformities, etc.
5. Concomitant autoimmune diseases such as rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, multiple sclerosis, primary biliary cholangitis, etc.
6. Known or suspected history of immunosuppression, including a history of invasive opportunistic infections (e.g., histoplasmosis, listeriosis, coccidioidomycosis, pneumocystosis and aspergillosis), even if the infection has resolved.
7. Confirmed parasitic infection within 6 months prior to randomization; upper or lower respiratory tract infection occurring within 6 weeks prior to randomization; other active infections requiring systemic treatment identified within 1 month prior to randomization.
8. Previous history of malignant neoplasm, regardless of whether treatment was administered, or whether there is evidence of local recurrence or metastasis.
9. Presence of any history of severe clinically significant diseases involving cardiovascular and cerebrovascular systems, hematological system, liver, kidney, digestive tract, nervous system, respiratory system, psychiatric disorders, metabolic abnormalities, or any other diseases or physiological conditions that may interfere with the trial results.
10. Participants who have undergone or are planning to undergo major surgery within 3 months prior to randomization.
11. Current smoker at screening, or having quit tobacco (including e-cigarettes) for less than 6 months.
12. History of drug or alcohol abuse within 2 years prior to randomization.
13. Female participants who are pregnant or breastfeeding.
14. Any condition deemed by the investigator to interfere with the evaluation of the investigational product, compromise participant safety, or confound the interpretation of study results.