The investigators propose a trial to evaluate if the addition of ipilimumab to nivolumab after primary resistance to anti-PD-1 axis therapy can lead to objective radiographic tumor regression. It is hypothesized that ipilimumab will enable more effective immune priming in some patients, resulting in the trafficking of tumor-specific cytotoxic T cells to the tumor, as well as depletion of tumor-permissive T regulatory cells. With concurrent nivolumab, PD-1 inhibition in the tumor will enable effective anti-tumor attack by tumor-specific T cells. Serial tumor biopsies and blood collections will allow interrogation of changes in the tumor microenvironment (and periphery) that support this hypothesis.