• Provision of informed consent before any study-specific procedures, sampling and analyses.

• Male or female, age at least 18 years.

• Histologically or cytologically confirmed diagnosis of primary non-small lung cancer (NSCLC) on predominantly non-squamous pathology who present with locally advanced, unresectable (Stage III) disease (according to AJCC 8th edition lung cancer classification). Recommended by not required: In addition to obvious cT4 disease, lymph node status N2 or N3 should be confirmed by intrabronchial ultrasound, mediastinoscopy or thoracoscopy biopsy, and under the condition of no biopsy or negative biopsy, the whole body screening of 18F-Fluro-deoxyglucose positron emission tomography (PET)or contrast agent-enhanced computed tomography (CT) to confirm.

• The tumor harbours one of the two common EGFR mutations known to be associated with EGFR-TKI sensitivity (Ex19Del, L858R), either alone or in combination with other EGFR mutations including T790M, assessed by cobas® EGFR Mutation Test (Roche Diagnostics) or Xiamen AmoyDx EGFR (ADx-ARMS, Super-ARMS method) kit in site or central laboratory.

• Patients must have received either concurrent chemoradiation or sequential chemoradiation including at least 2 cycles of platinum based chemotherapy and a total dose of radiation of 60 Gy ±10% (54 to 66 Gy).

• Chemoradiation must be completed ≤6 weeks prior to randomization.

• Patients must not have had disease progression during or following definitive platinum-based, chemoradiation therapy.

• A WHO performance status of 0-1 with no deterioration over the past 2 weeks and a minimum life expectancy of 12 weeks.

• Female patients should be using adequate contraceptive measures and should not be breastfeeding at the screening period, during the study, and six months after the last dosing of study. A pregnancy test should be done before first dosing unless having evidence of non-child-bearing potential.

⁃ Male patients should be willing to use barrier contraception (condoms)