This study will assess the safety, tolerability, pharmacokinetics and preliminary efficacy of 610 as an adjunctive therapy in adult subjects with severe eosinophilic asthma.

This is a multicenter, randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, pharmacokinetics and preliminary efficacy of 610 in adults with severe eosinophilic asthma. Plan to recruit 24 subjects, and the subjects divided into 3 groups: 610 30mg group，100mg group, 610 300mg group，8 subjects in each dose group, of which 6 received the trial drug and 2 received placebo. The study is divided into screening period of 2 weeks, treatment period of 32 weeks and follow-up period of 12 weeks.

Inclusion Criteria:

• Diagnosed with asthma for ≥12 months
• Within 3 months before screening, treatment with medium to high dose inhaled corticosteroid（ICS，inhaled fluticasone at a dosage of at least 500 μg, or equivalent, daily.）and at least one other additional controller medication, such as long-acting β₂ receptor agonist (LABA), leukotriene receptor antagonist (LTRA), theophylline, long-acting Anticholinergic drugs (LAMA), etc. Those medicine must be stable for ≥ 28 days prior to screening and baseline and must continue without dosage changes throughout the study
• In the past 12 months prior to screening， at least one time asthma exacerbations history
• Pre-bronchodilator FEV1 <80% predicted value
• Asthma-related blood eosinophils ≥ 150 cells/μL within 3 months before administration

Exclusion Criteria:

• With clinically important lung diseases other than asthma that may affect safety or efficacy and evaluated by investigator. This includes lung infection, chronic obstructive pulmonary disease, bronchiectasis, hypersensitivity pneumonitis, pulmonary fibrosis, Allergic bronchopulmonary aspergillosis, etc.
• With other conditions that could lead to elevated eosinophils such as hypereosinophilic syndromes, eosinophilic granulomatosis with polyangiitis (EGPA), or eosinophilic esophagitis
• In past 12 months prior to screening，patients has done bronchial thermoplasty or radiotherapy or plan to do it during of the trial
• with severe cardiac disease or uncontrolled or severe cardiac arrhythmia
• poorly controlled systemic disease
• Active infection 7 day before screening
• Parasitic infection within 6 months before screening
• At screening, HBsAg or HCV Ab or HIV Ab or TP Ab positive; HBsAg or HCV Ab positive need to be further tested of HBV DNA titer detection or HCV RNA detection (More than normal value range needs to be excluded)
• Subjects who have received any monoclonal antibody treatment of anti IL-4Ror anti-IL-5/5R
• Vaccination history with live vaccines (including live attenuated vaccines) within 4 weeks before screening, or plan to receive during of the trial
• Participated in any interventional clinical trial and received intervention within 3 months before screening