This study is designed as a prospective, open-label, single-arm, multicenter, phase II, investigator-initiated trial. A total of 77 patients will participate in the study who have undergone definitive platinum-based concurrent chemoradiation therapy and have no disease progression. Patients are to be enrolled within 1 to 42 days after concurrent chemoradiation therapy and to be administrated with lazertinib 240mg oral once daily until disease progression, or unacceptable toxicity. Patients will visit every 8 weeks and perform CT/MRI tumor evaluation by investigator, and will be followed up for survival every 3 months by phone thereafter. Patients will be followed up till maximum of appropriately 4 years of which 3 years since the last patient enrollment must be.
