RecruitingDiagnostic testStudy of Longitudinal Plasma PD-L1 Testing With Immunotherapy in Lung CancerThis is a prospective pilot study to assess dynamic changes of plasma cell-free RNA (cfRNA) PD-L1 expression in patients with lung cancer undergoing immune checkpoint inhibitor (ICI) based therapy. Results will be correlated with radiographic assessment of immunotherapy treatment response and plasma NGS ctDNA.