This is a multi-center, open-label, dose escalation and dose expansion, Phase 1 study to evaluate the safety, tolerability, PK and preliminary anti-tumor activity of CMG901.

The dose escalation phase (Part A) will determine the MTD of CMG901 in subjects with relapsed and/or refractory advanced solid tumor for which there is no available standard therapy likely to confer clinical benefit, or the subject is not a candidate for such available therapy based on a modified 3+3 dose escalation design (an accelerated dose titration design followed by traditional 3+3 dose escalation design).

The dose expansion phase (Part B) will be conducted in subjects with advanced solid cancer with failure of standard treatment or no standard treatment who are Claudin 18.2 positive to preliminarily explore the efficacy and to determine the RP2D of CMG901.

Key Inclusion Criteria:

• Subjects with histologically or cytologically confirmed advanced solid tumors, who have failed to respond to standard of care (progression after treatment or intolerance) or who have no available standard of care regimen.
• Part A: Must provide archival tumor tissue specimen or agree to undergo a fresh biopsy if archival specimen is unavailable for retrospective Claudin 18.2 testing prior to enrollment;Subjects enrolled in Part A are not required to be positive for Claudin 18.2.
• Part A: Measurable or evaluable lesions per RECIST v 1.1.Part B: At least one measurable lesion per RECIST v1.1.
• Part B: Subjects shall provide fresh or archival tumor tissue samples before enrollment for assessment of Claudin 18.2 expression level (central laboratory) and should be positive for Claudin 18.2 as determined by the central laboratory. If the subject can provide positive Claudin 18.2 expression results which had been reported by the same central laboratory using the same method, there is no need for another test.
• Women of childbearing potential and male subjects must agree to remain abstinent or use contraceptive methods as defined by the protocol.
• Eastern Cooperative Oncology Group Performance Status 0-1.
• Side effects of any prior therapy or procedures for any medical condition has recovered to NCI-CTCAE v.5.0 Grade ≤ 1 or stable status by investigator.

Key Exclusion Criteria:

• Received: chemotherapy or any investigational anti-tumor agents within 28 days of the start of CMG901 treatment; molecularly-targeted agents, immunoconjugate, or antibody drug conjugate within 28 days or or 5 half-lives (whichever is shorter) of the start of CMG901 treatment; major surgery within 28 days of the start of CMG901 treatment; radiotherapy within 21 days of the start of CMG901 treatment; potent cytochrome P450 3A4 (CYP3A4) inhibitors within 14 days or or 5 half-lives (whichever is longer) of the start of CMG901 treatment.
• Diagnosis of immunodeficiency or requiring another form of chronic immunosuppressive therapy. Or is receiving chronic systemic steroid therapy (in doses exceeding 10 mg daily of prednisone or equivalent) within 7 days prior to the first dose.
• History of severe hypersensitivity to any component or excipient of CMG901.
• Ongoing or active infection or interstitial pneumonia assessed by investigator.
• Any severe cardiac dysfunction including left ventricular ejection fraction <50%, congestive heart failure ≥Grade 2 (New York Heart Association), QTc >480 msec, major cardiovascular and cerebrovascular diseases (e.g., congestive cardiac failure, acute myocardial infarction, unstable angina, stroke, transient ischemic attack, deep vein thrombosis or pulmonary embolism) within 6 months prior to the first dose of study drug.
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis.
• Subjects with uncontrolled ascites, pleural effusion, or pericardial effusion by investigator.
• Preexisting sensory and/or motor neuropathy Grade ≥2.
• Uncontrolled diabetes mellitus or diabetic neuropathy within 3 months of the first dose of CMG901.
• Subjects with active hepatitis B or C, i.e., positive for anti-HCV antibody and positive for HCV RNA, or positive for HBsAg with detectable positive for HBV DNA (i.e., ≥ 2000 IU/mL).
• Any other conditions such as medical history, treatment, laboratory abnormalities that may confound the study results, interfere with the subject's compliance, or impair the interests of the subject, as assessed by the Investigator.