Fig. 2

Landscapes of known molecular mechanisms of acquired targeted drug resistance to first- and second-generation EGFR-TKIs in lung cancer. The frequencies of each known mechanism are estimates acquired from studies based on tumor rebiopsies and repeat molecular tumor genotyping/genomic profiling at the time of acquired drug-resistant progression. The discovery of various mechanisms of acquired drug resistance further highlights the issues of tumor heterogeneity and adaptability of tumor cells to therapeutic pressure