While checkpoint inhibitors facilitate activation of cytotoxic T cells, the agents do not impact T cell trafficking. X4P-001, a CXCR4 antagonist, is hypothesized to impact the trafficking of immune cell types, for example, decreasing myeloid-derived suppressor cells and increasing cytotoxic T cells at the tumor. Giving X4P-001 treatment in combination with nivolumab is hypothesized to increase the clinical response to by providing an influx of T cells that can be further activated by the checkpoint inhibitor. Additionally, CXCR4 plays a role in trafficking of endothelial progenitor cells which mediate angiogenesis. RCC is known to be responsive to anti-angiogenic agents, and thus X4P-001 targets a second mechanism of tumor growth inhibition.