A third patient with BRAF-mutant colorectal cancer was treated with combined RAF/MEK inhibition with dabrafenib and trametinib…WES revealed that a tumor biopsy taken after progression on BRAF/MEK therapy retained the original BRAFV600E mutation, but also identified the presence of two candidate resistance mutations that were not present in the pretreatment biopsy (Fig. 4B and Supplementary Table S2). One mutation was a Q489L missense mutation in another RAF kinase, ARAF