Peripheral Blood ETASTs for Predicting Efficacy of Chemoimmunotherapy in NSCLC

The goal of this observational study is to explore whether changes in peripheral blood effector tumor antigen-specific T cells (ETASTs) can predict treatment outcomes in patients with advanced non-small cell lung cancer (NSCLC) receiving chemoimmunotherapy. The study aims to: * Evaluate the relationship between ΔETAST levels (baseline to cycle 2) and progression-free survival * Compare the predictive performance of ΔETASTs with traditional biomarkers (PD-L1, TMB) * Assess whether ΔETASTs can identify patients more likely to benefit from PD-1 inhibitor plus chemotherapy Participants will: * Provide peripheral blood samples at baseline and after cycle 2 of treatment * Undergo ETAST quantification using the CTT-NanoDT technology with TATAN nanoparticles * Have standard tumor assessments every 2 cycles according to RECIST 1.1 criteria * Be followed for progression-free survival and overall survival up to 24 months