Inclusion Criteria:
* Voluntary participation, written informed consent, complied well and cooperated with the follow-up visits;
* Age ≥ 18 years old, female or male individuals;
* Eastern Cooperative Oncology Group (ECOG) Performance status score of 0 or 1, the expected survival is more than 3 months;
* Patients with locally advanced unresectable or metastatic pancreatic cancer confirmed by histopathology or cytopathology (islet cell tumor is not eligible for inclusion) who meet the following requirements:
* For the A/B/C/ cohort: Had failed of at least first-line systemic therapy; disease recurrence or progression within 6 months of the last treatment of neoadjuvant or adjuvant chemotherapy was also allowed to be enrolled;
* For the D/E/F cohort: No prior systemic treatment; patients with recurrence or progression of disease more than 6 months after the last treatment of neoadjuvant or adjuvant chemotherapy were also allowed to be enrolled;
* Had at least one measurable lesion according to RECIST v1.1.
* Patients had adequate major organs function;
* Women of childbearing potential must undergo serum pregnancy test within 7 days prior to the first dose and the result must be negative. Female subjects of childbearing potential and male subjects whose partners are women of childbearing potential must agree to use highly effective contraceptive methods during the study period and within 180 days after the last dose of study drug.
Exclusion Criteria:
* Previously received drugs with the same target as the planned investigational therapy;
* radiotherapy (except for palliative reasons), endocrine therapy, chemotherapy, immunotherapy, or molecular targeted therapy within 4 weeks prior to initial administration, except for bisphosphonates (which can be used for bone metastasis);
* Uncontrolled central nervous system metastases (meaning symptoms or the use of glucocorticoids or mannitol to control symptoms);
* A history of clinically significant or uncontrolled heart disease, including congestive heart failure, angina pectoris, myocardial infarction, or ventricular arrhythmia, in the 6 months prior to initial dosing;
* Patients with Grade 1 and above adverse reactions caused by previous treatment, including Grade 1 peripheral neurotoxicity; hair loss is not included and the investigator should clearly record the reasons;
* Malignant tumors within 5 years prior to the first dose (except for cured skin basal cell carcinoma and cervical carcinoma in situ);
* Active autoimmune disease requiring systemic treatment within 2 years prior to first administration, except for vitiligo, type I diabetes, residual hypothyroidism due to autoimmune thyroiditis requiring hormone replacement therapy only;
* History of rapid allergic reaction, eczema or asthma that cannot be controlled by topical corticosteroids;
* Patients who have lung disease, such as drug-induced interstitial lung disease or pneumonia, obstructive pulmonary disease that severely affects lung function, and symptomatic bronchospasm;
* Serious infections requiring antibiotic treatment within 14 days prior to initial administration (\>CTCAE grade 2), such as severe pneumonia, bacteremia, comorbidifications, etc., resulting in the need for hospitalization;
* Vaccination of live vaccine within 4 weeks before the first dose or during the study period;
* Known human immunodeficiency virus (HIV) infection, allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation;
* History of prior allergy to any component or excipient of the investigational drug to be received;
* Other conditions assessed by the investigator as unsuitable for participation in the trial.
