This study aims to evaluate the efficacy and safety of SBRT combined with Puterizumab immunotherapy for non-small cell lung cancer with pulmonary metastases, and to determine the correlation between MRD and treatment efficacy. Through single-cell sequencing and spatial transcriptome information analysis, the underlying mechanisms will be analyzed to provide a basis for improving the new precision treatment methods for tumor immunotherapy resistance.

Inclusion Criteria:

1. age≥18
2. Non small cell lung cancer patients who have experienced pulmonary metastasis after PD-1 immunotherapy in the past
3. Voluntarily participate in this study and sign an informed consent form
4. The presence of evaluable size and number of pulmonary metastases on chest CT
5. There are indications for lung puncture biopsy
6. General physical condition (ECOG) 0-1
7. The laboratory test meets the following standards: white blood cell count>3.5 × 109/L, absolute value of neutrophils>1.8 × 109/L, platelet count ≥ 75 × 109/L, hemoglobin ≥ 100g/L; NR ≤ 1.5, and APTT ≤ 1.5 times the upper limit of normal value or partial prothrombin time (PT) ≤ 1.5 times the upper limit of normal value; Total bilirubin ≤ 1.25 times the upper limit of normal value; ALT and AST<5 times the upper limit of normal values; 24-hour creatinine clearance rate>50mL/min or blood creatinine<1.5 times the upper limit of normal value.

Exclusion Criteria:

1. Unable to tolerate or refuse further immunotherapy
2. Vulnerable groups, including individuals with mental illness, cognitive impairment, critically ill patients, minors, pregnant women, illiteracy, etc

After the research is completed, the statistical results will be published as an article.