VISTA is an inhibitory immune checkpoint that is increased after ipilimumab therapy in patients with prostate cancer

Prostate cancer is refractory to anti-CTLA-4 therapy, but the reason why is unclear. Padmanee Sharma and colleagues report that the inhibitory molecule VISTA, which negatively regulates T cells, is upregulated on macrophages in prostate tumors that have been treated with anti-CTLA-4 and may play a role in resistance to this immunotherapy. To date, anti-CTLA-4 (ipilimumab) or anti-PD-1 (nivolumab) monotherapy has not been demonstrated to be of substantial clinical benefit in patients with prostate cancer. To identify additional immune-inhibitory pathways in the prostate-tumor microenvironment, we evaluated untreated and ipilimumab-treated tumors from patients in a presurgical clinical trial. Levels of the PD-L1 and VISTA inhibitory molecules increased on independent subsets of macrophages in treated tumors. Our data suggest that VISTA represents another compensatory inhibitory pathway in prostate tumors after ipilimumab therapy.