Fast Five Quiz: Genetics of Non–Small Cell Lung Cancer

Daniel S. Schwartz, MD, MBA


February 03, 2021

The exon 20 T790M mutation is associated with acquired resistance to first-generation (eg, erlotinib, gefitinib) and second-generation (eg, afatinib and dacomitinib) TKIs.

For patients with exon 20 T790 mutation, osimertinib, a third-generation TKI, is the standard treatment and has been shown to have some anti-tumor activity.

Although exon 20 T790M mutations are linked to acquired resistance to first- and second-generation TKIs, exon 18, 19, and 21 mutations are associated with TKI susceptibility. These and other activating EGFR mutations are most commonly found in female patients, patients with adenocarcinoma who do not have a history of smoking, and patients of Asian descent. Estimates suggest that approximately half of patients of Asian descent have an activating EGFR mutation compared with one out of 10 patients not of Asian descent. These statistics emphasize the importance of genetic testing for EGFR mutations in exons 18 through 21 in all patients with NSCLC.

Learn more about acquired resistance to EGFR mutations.


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