PDCD1 and neoplasm: Recently, STK11/LKB1 co-mutated with KRAS (KL subtype) were found to be resistant to anti-PD1 treatment due to the presence of a strong association between STK11/LKB1 genomic alterations and lack of PD-L1 expression on tumor cells (Jure-Kunkel et al., 2018; Skoulidis et al., 2018).