• Phase I (Dose Escalation)：

∙ Patients are willing and able to provide written informed consent or where consent is provided by legally authorized representatives.

‣ Age ≥18 years old when signing the informed consent form.

‣ Patients with a histologically or cytologically-confirmed, locally advanced or metastatic solid tumor, which has failed on standard therapy or is intolerable to available standard therapy, or there is no available standard therapy for the tumor. The advanced solid tumors include but are not limited to gastric and gastroesophageal junction adenocarcinoma, pancreatic adenocarcinoma, esophageal adenocarcinoma, ovarian cancer, lung cancer, colorectal cancer, andbiliary tract cancer.

‣ The enrollment is not restricted to patients with tumor expressing CLDN18.2. However patients are required to provide tumor tissue sections for CLDN18.2 expression confirmation.

‣ Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.

‣ Estimated life expectancy \> 12 weeks.

‣ At least one measurable cancer lesion as defined by the Response Evaluation Criteria in Solid Tumors (RECIST version 1.1).

‣ Adequate organ function, evidenced by the following laboratory results:

‣ Absolute neutrophil count (ANC) ≥ 1.5 × 109/L.

⁃ Platelet count ≥ 100 × 109/L.

⁃ Hemoglobin ≥ 9.0 g/dL.

⁃ Total bilirubin ≤ 1.5 × the upper limit of normal (ULN).

⁃ Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 1.5 × ULN (if liver metastases are present, ≤ 3 × ULN).

⁃ Creatinine clearance (Ccr) ≥60 mL/minute as calculated using themodified Cockcroft-Gault equation.

⁃ QTc prolongation to ≤480 milliseconds (ms) (based on the average of 3 screening electrocardiograms) (QTc interval corrected by Fridericia's Correction Formula, QTcF = QT/(RR0.33).

⁃ Echocardiographic LVEF (left ventricular ejection fraction) ≥ 50%.

‣ Female patients of childbearing potential, who are willing to use a highly effective method of birth control during the study, and for at least 180 days after the last dose of study medication.

‣ Childbearing potential is defined as any female who has experienced menarche and does not meet the criteria for postmenopausal, which is defined as the past 12 months with no menses without an alternative medical cause or permanently sterilized (e.g., has undergone bilateral tubal occlusion/ligation, hysterectomy, bilateral oophorectomy, bilateral salpingectomy).

⁃ A highly effective method of birth control is defined as one that results in a low failure rate (i.e., \<1% per year) when used consistently and correctly, such as implants, injectables, combined oral contraceptives, intrauterine devices, sexual abstinence, or a vasectomized partner.

∙ Male patients with female sexual partners of childbearing potential are eligible for inclusion if they agree to use medically acceptable birth control during the study, and for 180 days after the last dose of study medication. Sexual abstinence, vasectomy, or a condom used with a spermicide are medically acceptable birth control methods for males. Male subjects must agree not to donate sperm for a period of 180 days after the last dose of study treatment.

∙ PHASE Ⅱ (DOSE EXTENSION)：

⁃ Subjects are willing and able to provide written informed consent or where consent is provided by legally authorized representatives.

⁃ Age ≥18 years old when signing the informed consent form.

⁃ Patients with histologically or cytologically confirmed, locally advanced or metastatic solid tumors, which have failed on standard therapy, or are intolerable to available standard therapy, or for which there is no available standard therapy.

⁃ Patients are grouped by anatomic locations of solid tumors:

⁃ Group A: gastric adenocarcinoma/gastroesophageal junction adenocarcinoma. Group B: pancreatic adenocarcinoma. Group C: ovarian cancer. Group D: other cancer including esophagus adenocarcinomas, lung cancer, colorectal cancer, and biliary tract cancer.

⁃ Only patients with tumor expressing CLDN 18.2 will be enrolled. The most recently available tumor samples of patients will be examined by IHC at a central laboratory. If no archived tumor samples are available or the archived tumor samples are deemed to be inappropriate for the confirmation of CLDN18.2 expression, a new biopsy must be performed to obtain the tumor sample to confirmation of CLDN18.2 expression.

⁃ Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.

⁃ Estimated life expectancy \> 12 weeks.

⁃ At least one measurable cancer lesion as defined by the Response Evaluation Criteria in Solid Tumors (RECIST version 1.1).

⁃ Adequate organ function, evidenced by the following laboratory results:

• Absolute neutrophil count (ANC) ≥ 1.5 × 109/L.

∙ Platelet count ≥ 100 × 109/L.

∙ Hemoglobin ≥ 9.0 g/dL.

∙ Total bilirubin ≤ 1.5 × the upper limit of normal (ULN).

∙ Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 1.5× ULN (if liver metastases are present, ≤ 3 × ULN).

∙ Creatinine clearance (Ccr) ≥50 mL/minute as calculated using the modified Cockcroft-Gault equation.

∙ QTc prolongation to ≤ 480 millisecond (ms) (based on the average of 3 screening electrocardiograms) (QTc interval corrected by Fridericia's Correction Formula, QTcF = QT/(RR0.33).

∙ Echocardiographic LVEF (left ventricular ejection fraction) ≥ 50%.

⁃ Female patients of childbearing potential, who are willing to use a highly effective method of birth control during the study and for at least 180 days following the last dose of study medication.

• Childbearing potential is defined as any female who has experienced menarche and does not meet the criteria for postmenopausal, which is defined as the past 12 months with no menses without an alternative medical cause or permanently sterilized (e.g., has undergone bilateral tubal occlusion/ligation, hysterectomy, bilateral oophorectomy, bilateral salpingectomy).

∙ A highly effective method of birth control is defined as one that results in a low failure rate (i.e., \<1% per year) when used consistently and correctly, such as implants, injectables, combined oral contraceptives, intrauterine devices, sexual abstinence, or a vasectomized partner.

‣ Male patients with female sexual partners of childbearing potential are eligible for inclusion if they agree to use medically acceptable birth control for 180 days following the last dose of study medication. Sexual abstinence, vasectomy, or a condom used with a spermicide are medically acceptable birth control methods for males. Male subjects must agree not to donate sperm for a period of 180 days after the last dose of study treatment.