PDCD1 and non-small cell lung carcinoma: Mutations in the STK11 (or liver kinase B1 [LKB1]) gene (STK11m), found in approximately 5–30% of NSCLC cases [21, 25, 26], have recently been identified as an important regulator of resistance to anti-PD-1/PD-L1 therapies [18, 19, 22].