Study of Efficacy and Safety of PDR001 in Patients With Advanced or Metastatic, Well-differentiated, Non-functional Neuroendocrine Tumors of Pancreatic, Gastrointestinal (GI), or Thoracic Origin or Poorly-differentiated Gastroenteropancreatic Neuroendocrine Carcinoma (GEP-NEC)

Inclusion Criteria: * Pathologically confirmed, advanced (unresectable or metastatic): * Well-differentiated (G1 or G2) based on local pathology report, non-functional neuroendocrine tumor of GI, pancreatic or thoracic (including lung and thymus) origin. * Poorly-differentiated GEP-NEC based on local pathology report * No active symptoms related to carcinoid syndrome during the last 3 months prior to start of study treatment. * Patients must have been pretreated for advanced disease - the number of prior systemic therapy/regimen depended on which origin for NET and for GEP-NEC * Tumor biopsy material must be provided for all patients for the purpose of biomarker analysis * Radiological documentation of disease progression: * Well-differentiated NET group: Disease progression while on/or after the last treatment, and this progression must have been observed within 6 months prior to start of study treatment (i.e. maximum of 24 weeks from documentation of progression until study entry). Disease must show evidence of radiological disease progression based on scans performed not more than 12 months apart. * Poorly-differentiated GEP-NEC group: Disease progression while on or after prior treatment. Exclusion Criteria: * Well-differentiated grade 3 neuroendocrine tumors; poorly-differentiated neuroendocrine carcinoma of any origin (other than GEP-NEC); including NEC of unknown origin, adenocarcinoid, and goblet cell carcinoid * Pretreatment with interferon as last treatment prior…