KRAS and colorectal carcinoma: In addition, recently published preclinical data suggest that KRAS mutations enhance resistance to PARPi and anti-PD-L1 therapy in CRC PDX models, which may be related to PMEK1/2 and pMAPK, and the addition of MEKi to the combination of PARPi and anti-PD-L1 therapy reverses drug resistance in KRAS-mutated tumors [23].