This is a phase I clinical study on dose escalation evaluating the safety, tolerability, PK and PD of a single dose of AK139 administered subcutaneously in healthy subjects.

This is a phase I, dose escalation clinical study aimed to evaluate the safety, tolerability, PK and PD of AK139 in healthy subjects. This study will be conducted in a dose escalation design, sequentially increasing the dosage of the drug from low to high to complete a single subcutaneous dose escalation.

Inclusion Criteria:

• Subjects voluntarily agree to participate and sign an informed consent form (ICF) before any study procedures begin.
• Male and female healthy subjects aged 18 to 55 at the time of signing the ICF.
• Male weight ≥ 50.0kg, female weight ≥ 45.0kg; Body Mass Index (BMI)=Weight (kg)/Height² (m²), within the range of 19.0~26.0 kg/m².
• Female subjects with fertility tested negative for pregnancy during the screening period.
• The subjects are able to communicate well with the investigator and understand and comply with the requirements of this study.

Exclusion Criteria:

• Allergies to AK139 components and any monoclonal antibodies.
• Positive results of confirmatory serology test for hepatitis B, hepatitis C,HIV or syphilis at screening.
• have participated in any drug clinical study within 3 months prior to randomization, or are still within 5 half-lives after the last administration of other investigational drugs (whichever is longer)
• Previously or currently suffering from any diseases of the circulatory, endocrine, neurological, digestive, respiratory, urogenital, blood, immune, psychiatric, or metabolic systems that may interfere with the test results.
• History of parasitic infection.
• Drug abusers or individuals with positive urine drug results during screening.
• Have donated blood or experienced significant blood loss, received blood transfusions, or used blood products 3 months before screening.
• Investigator assessed that it is not suitable to participate in the study.