While KRAS activation is a known mechanism of acquired resistance to mAb-based EGFR blockade in colorectal cancer patients25, 26, 31, 32, to our knowledge, this is the first report of emergent KRAS alterations in NSCLC following treatment with an EGFR-directed therapy10, 11, 23. Here, KRAS is linked to non-small cell lung carcinoma.