The profile of concomitant EGFR mutations and subclonal RAS mutations mirrors prior studies that have shown associations between these mutations and post-EGFR resistance.29 Interestingly, prior series performed in tissue have associated fusions with RAS wild-type CRC tumors.9-12 In our series, 23 of 24 (96%) of the ctDNA fusion–positive patients with tissue testing available for RAS mutational status were RAS wild type, whereas 25 of 44 (57%) of fusion-positive ctDNA samples in our series had one or more RAS mutations. The gene discussed is EGFR; the disease is colorectal carcinoma.