KRAS and colorectal carcinoma: Verissimo et al. (61) constructed KRAS wild-type versus KRAS mutant CRC organoids edited by CRISPR-Cas9 for assessment of the EGFR-RAS-ERK pathway drugs and the EGFR inhibitor afatinib alone or in combination with the MEK inhibitor selumetinib and found that the combination strengthened the effect on KRAS wild-type tumors that were sensitive to only afatinib previously, but still there was no significant efficacy in the KRAS mutant-type, which was caused by the fact that this combination of inhibitors only stalled the cell cycle but did not kill cells.