Figure 3: EGFR C797S is an infrequent mechanism of rociletinib resistance.

(a) The prevalence of EGFR C797S mutations reported in post-treatment tissue biopsies or plasma samples following treatment with the third-generation EGFR TKIs rociletinib¹⁷ and osimertinib¹⁶. Only patients with detectable EGFR-activating mutations in progression tissue or plasma are considered (*=only patients unique to the Piotrowska et al. study were included). (b) An acquired EGFR C797S mutation was observed in cis with T790M in progression plasma from CO43. The allele fraction of each mutation in pre-treatment and progression plasma is shown. (c) Serial tumor and ctDNA measurements from CO43. Representative CT scans at the time points indicated are provided; the largest target lesion is outlined and the emergence of a new lesion is indicated with an arrow. The upper panel displays the tumor volume represented by the sum of longest diameters (SLD) of target lesions. The lower panel displays alterations in EGFR detected in plasma. ND, not detected.