CTLA4 and posterior cortical atrophy: Similar to other aggressive PCa models17,19 (e.g., PtenPC−/−; Trp53PC−/−; Smad4PC−/−), PtenPC−/−; Arid1aPC−/− mice exhibited primary resistance to ICB treatment containing anti-CTLA4 and anti-PD1 antibodies (Fig. 7f and Supplementary Fig. 7e).