Patients were randomized to microwave ablation plus camrelizumab group or camrelizumab group.

Patients in the camrelizumab group were treated with camrelizumab with the dose of 200mg on day 1, repeated every 21 days.Patients in the combination group were treated with MWA in the primary tumor followed by camrelizumab with the dose of 200mg on day 1, repeated every 21 days.

The primary end point is overall survival. The second end points include progression free survival, objective response rate and safety.

Inclusion Criteria:

1. Aged 18 to 75 years old
2. Cytologically or pathologically verified non-small cell lung cancer (NSCLC)
3. Patients with distant metastases or postoperative recurrence
4. EGFR or ALK sensitive mutations are negative (all patients, including non-adenocarcinoma patients)
5. At least one line of platinum-based doublet chemotherapy was administrated
6. Eastern Cancer Cooperative Group（ECOG）Performance Status（PS）of 0 to 1
7. At least two measurable tumors (in other words a measurable tumor lesion exclusive primary tumors)
8. Asymptomatic brain metastases or symptomatic brain metastases under control
9. If treated with irradiation，at least one month interval between radiation and randomization 10）Cardiopulmonary function, laboratory test indicators without ablation or chemotherapy contraindications

11) Informed conssent can be obtained 12) Sufficient tissue specimens for PD-L1 or TMB or blood samples were provided (1 week before treatment, 1 week after ablation, and once every two months for immune evaluation) for subsequent analysis

Exclusion Criteria:

1. Mixed lung cancer contains neuroendocrine tumor, small cell lung cancer or sarcoma
2. Suffering from other malignant tumors within five years
3. EGFR, ALK sensitive mutations are positive or unknown
4. ECOG PS≥2
5. Uncontrolled pleural effusion or pericardial effusion
6. Uncontrolled symptomatic brain metastases
7. Previously anti-PD-1, anti-PD-L1, anti-CTLA-4 or Car-T immunotherapy
8. severe interstitial pneumonia with severe diffuse dysfunction
9. Autoimmune diseases require long-term hormone therapy patients
10. Patients required consistent application of prednisone
11. Uncontrolled pulmonary infection or antibiotics stopped within 1 month
12. Acute cardiovascular and cerebrovascular diseases such as acute cerebral infarction and acute coronary syndrome within 1 month
13. Patients during pregnancy or lactation
14. Life expectance of 3 months or less

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