ABSTRACT In a recent study published in Nature Nanotechnology, we demonstrated that cancer cells form physical nanoscales tentacles (nanotubes) to connect with and harvest mitochondria from immune cells. Such mitochondria hijacking metabolically depleted the immune cells and augmented the cancer cells. These findings have significant implications as it emerges as a novel mechanism of immune evasion by cancer cells, which can limit the efficacy of immune checkpoint inhibitors. Here we propose to develop next- generation immunotherapies that can perturb this novel immune evasion phenomenon. We are specifically developing novel small molecule inhibitors of the exocyst complex, which we have implicated in the above phenomenon. Our preliminary results show that such small molecules can exert a powerful antitumor efficacy, augment classical immune checkpoint inhibitors and display an excellent safety profile. In Aim 1. We will synthesize and characterize exocyst inhibitors in vitro to test the hypothesis that rationally designed small molecule inhibitors of the exocyst complex can inhibit nanotube assembly. In Aim. 2. We will establish the safety pharmacology of exocyst inhibitors in vivo. In Aim 3, we will test the hypothesis that exocyst inhibitors can improve antitumor outcomes with immune checkpoint inhibitors. Achieving these aims will lead to fundamental insights into a new mechanism of cancer-immune cell communication. Our preliminary results indicate exocyst inhibitors can emerge as a new class of immunotherapy.