SOX Sequential S-1 in Advanced Biliary Tract Carcinoma（BTC）and Pancreatic Cancer

Inclusion Criteria: * Written Informed consent * Male or female patients \>=18 years old * Histologically or cytologically confirmed diagnosis of adenocarcinoma * No previous treatment is allowed including chemotherapy, radiotherapy,immunotherapy or others. * In case the patient received adjuvant therapy before, enrollment is allowed if the adjuvant therapy does not contain L-OHP or S-1 and at the same time, the last day of chemotherapy is ≥180 days before screening. * Target lesion more than 1cm in diameter by enhanced CT or MRI 21 days before enrollment * The laboratory parameter meets the following criteria 7 days before enrollment * Hemoglobin ≥90g/L * Absolute neutrophil count≥1.5×10\^9/L, platelets 100×10\^9/L； * ALT and AST≤2.5 ULN(in case of the patients with liver metastasis,ALT and AST≤5.0 ULN) * ALP ≤2.5 ULN (in case of the patients with liver metastasis,≤5.0 ULN) * Total Serum bilirubin ≤1.5 ULN * Serum creatinine ≤1.0 ULN * serum albumin(ALB)≥30g/L； * can tolerate oral drug administration； * KPS ≥70 * Estimated survival ≥90 days * Women of childbearing potential must have a negative serum or urine pregnancy test within 7 days of enrollment and must be willing to use adequate methods of contraception during the study and for 30 days after last study durg administration. Exclusion Criteria: * Known sensitivity to 5-HT3 antagonist and hypersensitivity to the other treatment agents including irinotecan, cisplatin and octreotide lar * Any participation in trials simultaneously or 4 weeks before screening. * 15 days prior to enrollment, received a blood transfusion, blood products and hematopoietic growth factors such as G-CSF. * Undergone major surgery ≤ 4 weeks prior to starting study drug or who have not recovered from side effects of such surgery. * Uncontrolled severe diarrhea * Uncontrolled active infection (fever ≥38 degrees due to infection) * S-1 oral drug administration difficulty due to difficulty swallowing, complete or incomplete digestive tract obstruction, gastrointestinal active bleeding, perforation; * severe hepatopathy including active hepatitis and hepatic cirrhosis, renal dysfunction, severe pulmonary diseases including interstitial pneumonia, pulmonary fibrosis and severe pulmonary emphysema, uncontrolled diabetes, hypertension and other chronic systematic diseases. * Chronic treatment with steroids.(In case of the patients with short-term use of steroids, the enrollment is permitted if the administration is stopped 2 weeks before screening.) * confirmed or suspected CNS metastasis * the history of peripheral nervous system impairment, obvious mental disorder or CNS impairment * clinically significant heart disease, including congestive heart failure, symptomatic coronal heart disease, arrythmia uncontrolled by medication and acute myocardial infarction or cardiac insufficiency within 6 months before screening * Drainage of pleural effusion, peritoneal effusion and pericardial effusion * pregnant women or women in lactation period * Fertile male or women of child-bearing potential refuse to take highly effective methods of birth control * Incidence of other second primary malignant tumors within 5 years, except for cured basal cell carcinoma and cervical carcinoma in situ. * patients of legal incapacity or who have the potential of influence the whole trial due to medical or ethic reasons. * Other patients who are not eligible to the trial under investigators' discretion