First in Human Study of IBI308 in Chinese Subjects With Advanced Solid Tumors

Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) performance status grade 0 or 1 * Adequate bone marrow, liver, and renal function defined as: 1) Absolute neutrophil count \>= 1.5\* 10\^9 cells/litre (L); 2) Platelets \>=100 x 10\^9 cells/L; 3) Hemoglobin \>= 9 gram/deciliter (g/dL); 4) Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) \<= 2.5 \* upper limit of normal (ULN) for participants without hepatic cell cancer and hepatic metastasis, ALT and AST \<= 5 \* ULN for participants with hepatic cell cancer or hepatic metastasis; 5) Total bilirubin (TBIL) \< 1.5 \* ULN for participants without hepatic cell cancer, hepatic metastasis and confirmed/suspicious Gilbert syndrome, TBIL \< 3 \* ULN for participants with hepatic cell cancer, hepatic metastasis or confirmed/suspicious Gilbert syndrome; 6) Creatinine determined by serum creatinine levels \<=1.5 \* ULN or a calculated creatinine clearance of \>= 50 mL/min/1.73 m\^2; 7) urine protein -\~+, 24 hour urine \< 1 gram for participants with urine protein ++ or above; 8) activated partial thromboplastin time and international normalized ratio \<= 1.5 \* ULN; 9) thyroid stimulating hormone and free thyroxine 4 within normal range * Tumor type * Phase 1a: advanced solid tumors after failure of standard therapy * Phase 1b Cohort A: cytologically or histologically confirmed advanced melanoma * Phase 1b Cohort B: cytologically or histologically confirmed advanced malignancies of the digestive system after failure of at least 1 line of standard therapy * Phase 1b Cohort C: cytologically or histologically confirmed advanced NSCLC without known epithelial growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangement after failure of 1st line standard therapy * Phase 1b Cohort D: treatment naive cytologically or histologically confirmed inoperable locally advanced (stage IIIB) or advanced (stage IV) nsNSCLC without known EGFR mutation and ALK rearrangement, participants with disease recurrence or progression within 6 months after completion of prior platinum doublet-based chemotherapy regimen as neoadjuvant or adjuvant therapy are not eligible * Phase 1b Cohort E: Cytologically or histologically confirmed, treatment naïve locally advanced, recurrent or metastatic squamous NSCLC without known EGFR mutation and ALK rearrangement. Participants with Stage IIIB NSCLC who progressed within 6 months after completion of platinum-based chemotherapy are not eligible. * Phase 1b Cohort F: Histologically confirmed locally advanced, recurrent or metastatic gastric or esophagogastric junction adenocarcinoma without known HER2 amplification. * Phase 1b Cohort G: Cytologically or histologically confirmed, treatment naïve locally advanced, recurrent or metastatic high grade(G3) neuroendocrine tumor with Ki-67\>20%. * Phase 1b Cohort H: Cytologically or histologically confirmed advanced high grade(G3) neuroendocrine tumor with Ki-67\>20% after failure of first line standard therapy. Participants progressed within 6 months after completion of adjuvant or neoadjuvant chemotherapy are eligible. * At least 1 measurable site of disease per RECIST v1.1 Exclusion Criteria: * Prior treatment of any antibody of PD-1 or PD-L1 * Prior treatment of ipilimumab, unless all the following requirements are met: * Full resolution of ipilimumab related adverse effects (including immune related adverse effects) and no treatment for these adverse events (AEs) for at least 4 weeks prior to the time of enrollment * Minimum of 12 weeks from the first dose of ipilimumab and \>6 weeks from the last dose * No history of severe immune related adverse effects from ipilimumab (CTCAE Grade 4; CTCAE Grade 3 requiring treatment \>4 weeks) * Unequivocal PD following a dose of ipilimumab * HIV infection * Active HBV or HCV infection * Uncontrolled complication including but not limited to : * Clinically significant cardiovascular disease such as uncontrolled or symptomatic arrhythmias or congestive heart failure * History of stroke, myocardial infarction or intracranial hemorrhage within 6 months prior to the enrolment * History or risk of autoimmune disease * Known interstitial lung disease