1. Evidence of a personally signed and dated informed consent document indicating that the subject has been informed of all pertinent aspects of the study
2. Males or females aged 18-75 years old
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1
4. Has a life expectancy of ≥ 3 months
5. Has at least one measurable lesion as defined by RECIST v1.1
You may not be if
1. Plan to receive any other anti-tumor treatments during the study treatment period of this study
2. Received other clinical investigational products or treatments within 4 weeks before the first dose of the study
3. Underwent a major surgery other than diagnosis or biopsy within 4 weeks before the first dose of the study
4. Previously received gastrectomy (only for subjects of the dose-escalation part)
5. Subjects with known brain metastases
6. Grade II-IV cardiac insufficiency as per the New York Heart Association (NYHA) criteria; arrhythmia requiring long-term drug control; unstable angina or acute myocardial infarction within 6 months before the first dose of the study
7. Presence of accompanying diseases (such as poorly controlled hypertension, serious diabetes mellitus, thyroid disorder, psychosis, etc.) that may pose serious risks to the safety of the subject or may affect the subject's ability to complete the study, or any other situation as judged by the investigator
