Inclusion Criteria:

          1. According to RECIST 1.1 criteria, all patients must have at least one measurable
             lesion, and the tumor lesions must be accurately measured in at least one dimension,
             and lesions previously treated with radiotherapy or local therapy are only evaluated
             as non-target lesions. Bone metastatic lesions are not considered as measurable
             lesions;

          2. ECOG performance status (PS) 0-1;

          3. The results of the laboratory tests must meet all the following criteria:

        （1）Haemoglobin≥9 g/dL；platelet count≥ 100 × 109/L；absolute neutrophil count≥ 1.5 × 109/L；

        （2）Albumin≥ 3.0g/dL；total bilirubin ≤ 1.5 times the upper limit of normal (ULN)；aspartate
        transaminase and alanine aminotransferase≤ 2.5 times ULN if no demonstrable liver
        metastases ( ≤5 times ULN in the presence of liver metastases);

        （3）Creatinine clearance≥ 50ml/min；

        （4）Prothrombin time, international normalized ratio, and activated partial thromboplastin
        time≤1.5×ULN (except for patients receiving anticoagulant therapy)

        4.Life expectancy of at least 3 months;

        5.Patients who are supposed to be enrolled into the monotherapy dose escalation study must
        meet all the following criteria:

          1. Patients of either gender, aged from 18 years old to 70;

          2. Patients with histologically or cytologically confirmed diagnosis of advanced
             unresectable or metastatic malignant solid tumor, for whom have no standard therapy or
             have no access to standard therapy for various reasons.

        6.Patients who are supposed to be enrolled into the monotherapy dose expansion study must
        meet all the following criteria:

          1. Patients of either gender, aged from 18 years old to 75；

          2. Patients with histologically or cytologically confirmed diagnosis of advanced
             unresectable or metastatic gastric cancer, gastroesophageal junction adenocarcinoma
             and pancreatic cancer, for whom have no standard therapy or have no access to standard
             therapy for various reasons, and that tumor tissue samples are CLDN18.2 positive
             detected by central laboratory (medium-high expression)；

          3. Other tumor types with good potential benefits will be included according to the
             results of the clinical results of same target products (CLDN18.2-positive tumors).

        7.Patients who are supposed to be enrolled into the dose escalation of ASKB589 combined
        with chemotherapy should meet all the following criteria:

          1. Patients of either gender, aged from 18 years old to 70.

          2. Patients with gastric cancer, gastroesophageal junction adenocarcinoma and pancreatic
             cancer who are tolerant to CAPOX, GEM+Nab-P chemotherapy.

          3. Patients with gastric cancer, gastroesophageal junction adenocarcinoma who are
             intolerant to anti-human epidermal growth factor receptor 2 (anti-HER2) drug therapy.

          4. Other tumor types with good potential benefits will be included according to the
             results of mono-therapy dose expansion and the clinical results of same target
             products.

        8.Patients who are supposed to be enrolled into the dose expansion of ASKB589 combined with
        chemotherapy should meet all the following criteria:

          1. Patients of either gender, aged from 18 years old to 75.

          2. Patients with gastric cancer, gastroesophageal junction adenocarcinoma and pancreatic
             cancer who are tolerant to CAPOX, GEM+Nab-P chemotherapy, and that tumor tissue
             samples are CLDN18.2 positive detected by central laboratory (medium-high expression).

          3. Patients with gastric cancer, gastroesophageal junction adenocarcinoma that who are
             intolerant to anti-HER2 drug therapy.

          4. Other tumor types with good potential benefits will be included according to the
             results of this study and the clinical results of same target products.

        Exclusion Criteria:

          1. Patients have a history of severe allergic reactions to monoclonal antibodies or are
             intolerance to monoclonal antibodies, or those who are allergic to experimental drug
             and any component of the drug.

          2. Patients have received a treatment of whole blood or blood component transfusion or
             various growth factor treatments within 14 days prior to enrollment.

          3. Patients have received anti-tumor therapy within 14 days prior to enrollment，including
             but not limited to radiotherapy, chemotherapy, targeted therapy, treatment with herbal
             medications or other treatments that have known antitumor activity . Patients who have
             undergone palliative radiotherapy for bone metastases and whose acute toxicity has
             returned to normal can be selected;

          4. Patients have received systemic immunosuppressive therapy（such as systemic
             corticosteroids）within 14 days prior to enrollment. However, patients using a
             physiologic replacement dose of hydrocortisone or its equivalent (defined as up to
             30mg per day of hydrocortisone or 10mg per day of prednisone) are allowed；patients are
             allowed to receive a single dose of systemic corticosteroids treatment；

          5. Patients have participated in other clinical trials within 28 days prior to
             enrollment; patients who have participated monoclonal antibody clinical trials within
             2 months prior to sign written informed consent form also cannot participate in this
             trial；

          6. Patients have received major surgical operation within 28 days prior to enrollment or
             schedule to perform major surgery during the period of this clinical trial;

          7. Patients have gastrointestinal diseases such as gastrinoma, duodenitis, gastric ulcer,
             duodenal ulcer, pancreatitis or upper gastrointestinal hemorrhage, caused by
             nonmalignant tumor (gastric cancer, gastroesophageal junction adenocarcinoma and
             pancreatic cancer)；

          8. Known to have irritable bowel syndrome, ulcerative colitis, Crohn's disease, gastric
             outlet obstruction, etc., or any other causes that can cause long-term chronic
             nausea,persistent repeated vomiting or diarrhea, and uncontrolled or severe
             gastrointestinal bleeding;

          9. Have a history of diagnosed neurological or mental disorders, including epilepsy or
             dementia;

         10. Patients with any other malignant tumors within the past 5 years, cured cervical
             carcinoma in situ, basal cell, or squamous cell skin cancer are not included.

         11. Known active central nervous system (CNS) metastasis or suspected cancerous
             meningitis;

         12. There are moderate to large amounts of abdominal and pleural fluid. However, a small
             number of asymptomatic and pleural effusion patients who do not need treatment are
             allowed to be included;

         13. Patients currently suffering from diseases that affect intravenous injection and
             venous blood sampling;

         14. Patients suffering from major cardiovascular diseases, including:

        （1）Congestive heart failure (defined as New York Heart Association Class III or IV),
        myocardial infarction, unstable angina, coronary angioplasty, stenting, coronary artery
        bypass graft, cerebrovascular accident (CVA) or hypertensive crisis within 6 months before
        the first drug treatment；

        （2）History of clinically significant ventricular arrhythmia (such as sustained ventricular
        tachycardia, ventricular fibrillation or torsade de pointes)；

        （3）Patients have an abnormality in the 12-lead electrocardiogram (ECG) including a
        Fridericia's corrected QT interval (QTcF) greater than 450 milliseconds (ms) (males) or
        greater than 470 ms (females).

        （4）History or family history of congenital long QT syndrome；

        （5）Cardiac arrhythmias requiring anti-arrhythmic drug therapy (patients suffering from
        atrial fibrillation >1 month before the first administration of drug can be selected
        according to the condition of patients);

        （6）Left ventricular ejection fraction <50%；

        15.Pregnant or lactating women; or women of childbearing age who have a positive blood
        pregnancy test during screening period; or women of childbearing age and their spouses who
        are unwilling to take effective contraceptive measures during the period of this clinical
        trial and within 6 months after the end of the clinical trial;

        16.Patients who are not meet the inclusion criteria based on the judgment of investigator；

        17.Patients included in dose-escalation and expansion study of combined chemotherapy should
        also exclude:

          1. Patients with gastric cancer, gastroesophageal junction adenocarcinoma who are
             allergic, intolerant or contraindicated to any other components of capecitabine and
             oxaliplatin.

          2. Patients with pancreatic cancer who are allergic, intolerant or contraindicated any
             components of gemcitabine and albumin bound paclitaxel for injection.