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
Histologically or cytologically confirmed stage IIIB-IV non-small cell lung cancer (NSCLC)
Planned to receive PD-1 inhibitor combined with platinum-based chemotherapy (e.g., pembrolizumab + pemetrexed/carboplatin)
Age 18-80 years
ECOG performance status 0-1
No measurable disease per RECIST 1.1 criteria
Tumor emergencies requiring immediate intervention (spinal cord compression, superior vena cava syndrome)
Active untreated central nervous system metastases or leptomeningeal disease
Prior treatment with immune checkpoint inhibitors within 4 weeks before enrollment