PDCD1 and hereditary clear cell renal cell carcinoma: Tumor bearing PD-1 deficient mice treated with stereotactic ablative radiotherapy showed better survival than wild type mice in preclinical melanoma and renal cell carcinoma models, and PD-1 blockade in wild type mice recapitulated the anti-tumor effect observed in PD-1 deficient mice (Park et al., 2015).