Circulating Tumor DNA and T Cell Repertoire Predict Radiotherapeutic Outcomes in NSCLC Patients With Brain Metastasis

Inclusion Criteria:

1. Age \> 18 years
2. Patients must have histologically or cytologically confirmed NSCLC and imaging-confirmed primary non-small cell lung cancer with brain metastases
3. ECOG PS score of 0-2
4. At least 1 lesion meeting RECIST 1.1 target lesion (TL) criteria at baseline. Must have baseline assessment imaging of the tumor by CT or MRI scan within 28 days prior to treatment
5. No prior radiation therapy to the tumor, including but not limited to whole brain radiotherapy, prophylactic brain irradiation, stereotactic radiation therapy, etc.
6. Major organ function indicators meet the criteria for conventional radiation therapy Adequate organ and bone marrow function is defined as follows

   1. Hemoglobin ≥ 9.0 g/dL
   2. absolute neutrophil count ≥ 1.5 × 109 / L
   3. Platelet count ≥ 100 × 109 / L
   4. Serum bilirubin ≤ 1.5 × the upper limit of normal (ULN). The above criteria were not applied to patients diagnosed with Gilbert's syndrome, but these patients were allowed to be enrolled after consultation between the study physician and their primary care physician.
   5. Alanine aminotransferase ALT or aspartate aminotransferase AST ≤ 2.5 × ULN
   6. Creatinine clearance (CL) \> 40 mL/min calculated or actually measured according to the Cockcroft-Gault method (based on actual body weight) Men. Creatinine CL = Body weight (kg) × (140 - age) (mL/min) 72 x serum creatinine (mg/dL) Females. Creatinine CL = Body weight (kg) × (140 - age) × 0.85 (mL/min) 72 × serum creatinine (mg/dL)
7. Female subjects of childbearing age must exclude pregnancy
8. Life expectancy \>12 weeks
9. Body weight \>30Kg

Exclusion Criteria:

1. History of allogeneic organ transplantation
2. Active or previously documented autoimmune or inflammatory disease (including inflammatory bowel disease \[e.g., colitis or Crohn's disease\], diverticulitis (except diverticular disease), systemic lupus erythematosus, Sarcoidosis syndrome, or Wegener's syndrome \[granulomatous vasculitis, Graves' disease, rheumatoid arthritis, pituitary inflammation, uveitis, etc.\])
3. History of active primary immunodeficiency
4. Other malignancies within the last 3 years.
5. Presence of uncontrolled co-morbidities including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, uncontrolled cardiac arrhythmias, active interstitial lung disease, a severe chronic gastrointestinal disease with diarrhea or mental illness that limits compliance with study requirements, significantly increases the risk of AE or affects the patient's life/ social conditions
6. Active infection at the time of treatment, including tuberculosis (clinical assessment includes history, physical examination, imaging findings, and tuberculosis screening consistent with local clinical practice), hepatitis B (known hepatitis B surface antigen positive \[HBsAg\] result), hepatitis C virus (HCV) or human immunodeficiency virus (HIV 1/2 antibody positive). Patients with previous hepatitis B virus (HBV) infection or cured HBV infection (defined as the presence of positive hepatitis B core antibodies and negative HBsAg) may participate in this study. patients with positive HCV antibodies who are negative for HCV ribonucleic acid (RNA) by polymerase chain reaction only may participate in this study.
7. Stage IV NSCLC according to the 8th edition of the International Society for the Study of Lung Cancer Thoracic Oncology Staging Manual
8. Histological findings of NSCLC with mixed small cell component