A Study of FG-M108+Chemotherapy vs Placebo+Chemotherapy in Claudin18.2-positive Pancreatic Cancer

Inclusion Criteria: * Voluntarily sign the informed consent form, understand the study, are willing to comply with and have the ability to complete all trial procedures; * Age 18-80 years (inclusive), any gender; * Histologically or cytologically confirmed unresectable locally advanced or metastatic pancreatic ductal adenocarcinoma, without prior systemic therapy; or for subjects who have received prior neoadjuvant/adjuvant chemotherapy, the time from the last treatment to disease recurrence is \>6 months; * Able to provide archived or fresh pathological tissue for CLDN18.2 testing, with central laboratory testing confirming tumor tissue CLDN18.2 positive (defined as ≥40% of tumor cells with CLDN18.2 membrane staining ≥2+ by central laboratory IHC); * Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1; * Have at least one measurable tumor lesion according to RECIST 1.1 criteria; * Expected survival ≥3 months; * Adequate cardiac, bone marrow, liver, renal function; Exclusion Criteria: * Have received a live vaccine within 4 weeks prior to randomization; * Have received radiotherapy within 2 weeks prior to randomization; * Have received other anti-tumor drug therapy within 4 weeks or within 5 half-lives of the anti-tumor drug prior to randomization; * Have undergone major surgery within 4 weeks prior to randomization; * Have received any clinical study drug treatment within 4 weeks prior to randomization; * Have previously received any treatment targeting CLDN18.2, such as CLDN18.2 monoclonal/bispecific antibodies, CLDN18.2 CAR-T, or CLDN18.2 ADC; * Have a history of other (non-study tumor) malignancies within 3 years prior to randomization; * Have a history of central nervous system metastases and/or carcinomatous meningitis; * Have adverse reactions from prior treatments that have not recovered to CTCAE v5.0 Grade ≤1 (excluding alopecia and anemia) prior to randomization; * Have had clinically significant cardiovascular or cerebrovascular diseases within 6 months prior to randomization; * Have uncontrolled systemic diseases assessed by the investigator, including diabetes, hypertension, pulmonary fibrosis, interstitial lung disease, etc.; * The investigator judges the subject to have obvious active gastrointestinal bleeding; * Known history of Hepatitis C or chronic active Hepatitis B; * Require systemic treatment with corticosteroids (dose \>10 mg/day prednisone or equivalent dose of similar drugs) or other immunosuppressants within ≤14 days prior to randomization; * Any other condition of the subject (e.g., psychological, geographical, or medical condition) that does not permit compliance with the study and follow-up procedures; * Are pregnant or breastfeeding;