Franciele H. Knebel detected significant and unequal amplification of EGFR ex19del copy number in the blood of a patient with EGFR ex19del/T790M/C797S mutated osimertinib-resistant NSCLC, suggesting that selective amplification of the EGFR-ex19del allele may represent a novel resistance mechanism to osimertinib [76]. Here, EGFR is linked to non-small cell lung carcinoma.