EGFR and colorectal cancer: Any grade rash was reported in 43%-89% of patients across monotherapy and combination therapy studies.21,28,32,40,58 The frequency of rash is lower with other EGFR-targeted therapy, with osimertinib associated with the lowest frequency (34%-58%) compared with the earlier generation EGFR TKIs gefitinib (49%-85%), erlotinib (71%-80%), and afatinib (67%-89%).44 The anti-EGFR monoclonal antibodies cetuximab and panitumumab, used in colorectal cancer treatment, are associated with rates of any grade rash ≥80%,59-61 though less frequently severe.