PD-L1 and Other Immuno-markers Influenced by Osimertinib Treatment in Advanced NSCLC Patients

Inclusion Criteria: 1. The patient enrolled in ASTRIS or patient who are eligible for the ASTRIS study. 2. The patient is willing to provide informed consent form to provide specimen before osimertinib treatment and at the time of PD. 3. Patients must be able to undergo a fresh tumor biopsy during screening or to provide an available tumor sample taken \<2 months prior to screening. 4. Fine needle aspirate specimens are not acceptable. 5. Specimens from metastatic bone lesions are typically unacceptable unless there is confirmed soft tissue component. 6. The tumor specimen submitted to establish eligibility should be of sufficient quantity to allow for PD-L1 IHC and other biomarker analyses (if applicable) and is preferred in formalin-fixed paraffin embedded blocks. Exclusion Criteria: 1. The patient does not have sufficient tumor tissue specimen available for detection. 2. The Patient who is unwilling to use the existing data from medical practice for scientific research. 3. The patient who received immunotherapy therapy before.