Phase I/IIa Study for PM1032 in the Treatment of Patients With Advanced Solid Tumors

Inclusion Criteria:

• Voluntary participation in clinical study; fully understand the study and signinformed consent voluntarily;
• Male or female aged 18 to 75 years;
• Subjects with malignant tumor confirmed by histology or cytology, subjects withadvanced malignant solid tumors who have no standard treatment, have failed standardtreatment or are not eligible for standard treatment:

1. Phase I dose escalation stage: gastric/gastroesophageal junction adenocarcinoma,esophageal cancer, etc.;
2. Phase I dose expansion stage, phase IIa dose expansion stage:gastric/gastroesophageal junction adenocarcinoma, esophageal cancer, othertumors; CLDN18.2-positive tumor expression as determined by the CLDN18.2 IHCassay in central laboratory.

• Adequate organ function;
• ECOG score was 0-1;
• Expected survival≥12 weeks;

Exclusion Criteria:

• History of severe allergic, severe allergy to drugs or known allergy to any componentof the drug in this study;
• Previous exposure to immune co-stimulatory molecule agonists such as 4-1BBmono/bispecific antibodies, etc;
• Patients who received CLDN18.2-targeted mono/bispecific antibodies or cell therapy;
• Cerebral parenchymal metastasis or meningeal metastasis with clinical symptoms weredeemed unsuitable for this study by the investigator;
• Current definite interstitial lung disease or non-infectious pneumonitis, except forlocal radiotherapy;
• Current presence of uncontrolled pleural, pericardial, and peritoneal effusions;
• Adverse reactions to previous anti-tumor therapy have not recovered to NCI-CTCAE V5.0rating≤1;
• Patients ever received the following treatments or drugs prior to the study treatment:

1. Major organ surgery within 28 days prior to initiation of trial treatment orrequiring elective surgery during the trial period;
2. Received live attenuated vaccine within 28 days prior to the study treatment;
3. Received chemotherapy, radical/extensive radiation, biotherapy, endocrine therapyand other anti-tumor drug therapy within 4 weeks of the first administration;
4. Received systemic glucocorticoid or other immunosuppressive therapy within 2weeks before the trial treatment;

• Active bleeding within 3 months of the first administration;
• History of allogeneic hematopoietic stem cell transplantation or allogeneic organtransplantation;
• Pregnant or lactating women;
• Other conditions considered unsuitable for this study by the investigator.