Nivolumab With Ipilimumab in Subjects With Neuroendocrine Tumors

Inclusion Criteria: * Subjects with histologically confirmed advanced, progressive, well-differentiated nonfunctional NET of the pancreas, lung or gastrointestinal (GI) tract per the 8th International Association for the Study of Lung Cancer classification (IASLC) or the American Joint Committee on Cancer (AJCC) Staging Handbook, 7th edition. Progression must be documented over the prior 12 months. * Measurable disease by CT or MRI per RECIST 1.1 criteria (Appendix 3); radiographic tumor assessment performed within 28 days before treatment. Target lesions may be located in a previously irradiated field if there is documented (radiographic) disease progression in that site after the completion of radiation therapy. * Prior therapy, including everolimus, octreotide, surgery, chemoradiation, is all permitted after being properly noted. This prior therapy must have been completed at least 28 days prior to study enrollment. * Patients with lung NETs must have progressed after at least 1 line of therapy. Patients with GI NETs must have had at least 2 lines of prior therapy. * Subjects are to have tumor tissue sample available at central lab for programmed cell death ligand 1 (PD-L1) immunohistochemistry (IHC) testing during the screening period. Subjects can initiate therapy before the result of IHC testing. * (Stage 2 only) Subjects must be willing to undergo 2 sets of core needle biopsies (pre-treatment and at 6-8 weeks on therapy) if there are lesions amenable to bio…