A Phase Ib/II Study Of JS015 Combination Therapy in Advanced Solid Tumors

Inclusion Criteria: 1\. Patients who meet the following criteria for each indication cohort: 1. Esophageal cancer cohort, patients with histologically or cytologically confirmed esophageal squamous cell carcinoma with locally advanced unresectable or with distant metastasis, who progressed during or after prior first-line PD-(L)1 antibody and platinum-based chemotherapy; 2. Gastric cancer cohort, patients with histologically or cytologically confirmed gastric/gastroesophageal junction adenocarcinoma with locally advanced unresectable or distant metastases, HER2-negative, who progressed during or after prior first-line PD-(L)1 antibody and platinum-based chemotherapy; 3. 1L gastric cancer cohort, patients with histologically or cytologically confirmed gastric/gastroesophageal junction adenocarcinoma with HER2-negative results and no prior systemic antitumor therapy; 4. Colorectal cancer cohort, patients with histologically confirmed adenocarcinoma of the colon or rectum, who progressed during or after first-line 5-FU-based combination therapy; 5. Pancreatic cancer cohort, patients with histologically or cytologically confirmed locally advanced unresectable or distant metastatic pancreatic ductal adenocarcinoma, who have not received any previous systemic antitumor therapy 2 . Eastern Cooperative Oncology Group (ECOG) 0 or 1; 3. Life expectancy \>=12 weeks; 4. At least one measurable lesion according to RECIST 1.1; 5. Adequate organ function; Exclusion Criteria: 1. Leptomeningeal metastases and /or active brain metastases; 2. Pleural, peritoneal, or pericardial effusion with clinical symptoms or requiring repeated management (puncture, drainage, etc.); 3. History of interstitial lung disease or a previous history of noninfectious pneumonia with corticosteroid therapy, or evidence of active pneumonia on screening imaging; 4. History of immunodeficiency; 5. History of serious cardiovascular and/or cerebrovascular diseases; 6. History of abdominal or tracheo-esophageal fistula, gastrointestinal (GI) perforation, or intra-abdominal abscess within 6 months before the first dose of administration