PTEN and prostate cancer: In a murine model of castration-resistant prostate cancer, the combination of deletions of Pten, transformation-related protein 53 (Trp53) and Smad4 led to resistance to anti-PD1 and anti-CTLA4 antibodies.113 Interestingly, PTEN deficiency alone was not associated with PD-L1 expression in prostate cancer.