This is a randomized, double-blind phase II clinical study to evaluate the efficacy and safety of AK139 in the treatment of participants with moderate to severe asthma.

Inclusion Criteria:

1. Diagnosed with asthma at least one year;
2. Evidence of the reversibility of airflow limitation meets the requirements of the protocol;
3. Pre-bronchodilator forced expiratory volume (FEV1) meets the requirements of the protocol at screening and baseline;
4. Asthma Control Questionnaire 5-question version (ACQ-5) score≥1.5 at screening and baseline;
5. The participants agree to use highly effective contraception methods from the moment of signing of the ICF to 3 months after the last dose of the investigational product.

Exclusion Criteria:

1. Concomitant respiratory diseases that, as determined by investigators, may affect the evaluation of therapeutic effects or safety of the investigational product;
2. A participant who experiences a severe asthma exacerbation at any time from 4 weeks prior to the screening up to and including the baseline;
3. Allergic to any component of the investigational product or intolerant to basis treatment;
4. Ongoing use of prohibited treatments. Washout periods detailed in the protocol have to be adhered to;
5. Other reasons the investigators believe that the participants are not suitable to enrolled in this study.