• Age at least 18 years.

• ECOG PS 0-1.

• Patients with pathologically confirmed stage IV NSCLC by tumor biopsy and/or fine-needle aspiration.

• Negative for driver genes including EGFR, ALK, and ROS-1.

• Oligo-residual disease after effective treatment with PD-1/PD-L1 inhibitors that would be amenable to SBRT in the opinion of the investigator.

• Patients with brain metastasis are eligible if they are asymptomatic, neurologically stable, and off corticosteroids.

• Patients with a history of radiotherapy are eligible if they satisfy the following criteria:

‣ Radiotherapy administered more than 4 weeks before study entry.

⁃ At least one measurable lesion outside the radiation field.

• Patients with no indications for palliative radiotherapy in the opinion of the investigator.

• Patients with a prior history of surgery are eligible if they have sufficiently recovered from the toxicity and/or complications of surgery.

• Signed informed consent for the use of fresh tumor biopsies before and during the treatment.

• Women of childbearing age and men must agree to use effective contraception during the trial.

• Life expectancy of more than 3 months.

• Adequate organ function within 1 week prior to enrollment:

‣ Adequate bone marrow function: hemoglobin ≥80g/L, white blood cell (WBC) count ≥ 4.0 \* 10 \^ 9/L or neutrophil count ≥ 1.5 \* 10 \^ 9/L, and platelet count ≥ 100 \* 10 \^ 9/L;

⁃ Adequate hepatic function: total bilirubin \< 1.5 x upper limit of normal (ULN). Note: If total bilirubin is \> 1.5 x ULN, direct bilirubin must ≤ ULN, Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) ≤2.5 ULN;

⁃ Adequate renal function: serum creatinine ≤ 1.5 x ULN or creatinine clearance ≥ 50 mL/min;

• Ability to understand and willingness to provide the informed consent.