LAUSR

Targeted therapy is a novel, promising approach to anticancer treatment that endeavors to overcome drug resistance to traditional chemotherapies. Patients with the L858R mutation in epidermal growth factor receptor (EGFR) respond to the first generation tyrosine kinase inhibitors (TKIs); however, after one year of treatment, they may become resistant. The T790M mutation is the most probable cause for drug resistance. Third generation drugs, including Osimertinib (AZD9291), are more effective against T790M and other sensitive mutations. Osimertinib is effective against the L844V mutation, has conditional effectiveness for the L718Q mutation, and is ineffective for the Cys797Ser (C797S) mutation. Cells that have both the T790M and C797 mutations are more resistant to third generation drugs. Although research has shown that Osimertinib is an effective treatment for EGFR L844V cells, this has not been shown for cells that have the C797S mutation. This molecular mechanism has not been well‐studied.