PDCD1 and non-small cell lung carcinoma: Consistent with an assumption that the rate-limiting step for immune-deserted tumors is the generation of tumor-specific T cells, non-small cell lung cancers exhibiting inactivating mutations in LKB1 exhibit a poor response to anti-PD1 immunotherapy, despite a high TMB, due to impaired antigen presentation resulting from reduced expression of the immunoproteasome.