NSCLC Stage IIIB~IV

The goal of this observational study is to better understand how the immune system and certain tumor markers are linked to treatment response in patients with advanced non-small cell lung cancer (NSCLC) who receive immunochemotherapy. The investigators aim to answer the following questions: * Can the investigators successfully analyze immune markers and gene activity from small tumor samples (biopsies)? * Are these markers connected to how well patients respond to immunochemotherapy and how their disease progresses? What will participants do? * Provide tumor tissue samples (biopsies) at key points: before treatment, about 6 weeks after starting immunochemotherapy, and if the cancer grows or treatment changes. * Allow their tumor samples to be analyzed in the lab using advanced techniques to measure immune and genetic markers. * Share clinical information (such as treatment response and disease progression) so investigators can study how it relates to these markers. This study does not test a new drug or treatment.