This study is a prospective multi-center observational study, and 11 institutions will participate to enroll 200 subjects competitively. We will evaluate the efficacy and safety of Lazertinib according to maintenance of the 240mg dose and reduction of the 160mg dose for 12 weeks after the first administration of Lazertinib in non-small cell lung cancer patients confirmed to be T790M mutation-positive after treatment failure with first- or second-generation EGFR-TKIs. The study period is up to 3 years from the date of IRB approval. Follow-up is 2 years from the last subject enrollment, and data will be collected through periodic medical record review during Lazertinib administration for enrolled subjects.
