Inclusion Criteria:  Age: 18 to 80 years old, male or female. Patients with histologically confirmed metastatic pancreatic ductal adenocarcinoma; The Eastern Cooperative Oncology Group (ECOG) score is 0 to 1. The life expectancy is no less than 12 weeks. According to the RECIST v1.1 evaluation criteria, the patient has at least one measurable lesion (exclude if there is only a target lesion located at a site previously treated with radiation); The patient who is suitable for first-line treatment with a combined regimen of paclitaxel (albumin-bound type) and gemcitabine;  Exclusion Criteria:  The patients who have been previously treated with chemotherapy or other drugs for pancreatic carcinoma, or who have been treated with other anti-cancer drugs, including chemotherapy, targeted therapy, immunotherapy, or biologics. The patients who are known to be allergic to the investigatinal drug (CEND-1 analogue) or its any excipient; The patients with the following conditions: myocardial infarction, severe/unstable angina, NYHA grade 2 or above cardiac dysfunction, and clinically significant supraventricular or ventricular arrhythmia requiring clinical intervention within 6 months before signing the ICF; The patients with symptomatic CNS metastasis, leptomeningeal metastases, or spinal cord compression due to metastasis. However, the patients with symptomatic CNS metastasis before first administration of the investigational drug, who is treated and stable for no less than 4 weeks, and the systematic hormone (any dose) treatment has been stopped for over 2 weeks, can be enrolled; The patients with other active malignant tumors within 3 years before signing the ICF. The cured skin basal cell carcinoma or squamous cell carcinoma, superficial bladder cancer, carcinoma in situ of the cervix, carcinoma in situ of the breast ductal, and papillary thyroid cancer are excluded. The patients with human immunodeficiency virus (HIV) infection or known acquired immunodeficiency syndrome (AIDS), active hepatitis or co-infection with hepatitis B and C. The patients who participated in any other drug clinical trial and administrated the investigational drug within 4 weeks before first dose;