Brain metastasis of lung cancer is one of the most important metastasis pathways in patients with life-threatening diseases. This study explore the efficacy and safety of Tislelizumab combining with platinum-containing drug chemotherapy in the first-line treatment of Lung Adenocarcinoma With Asymptomatic Brain Metastatic. Meanwhile, Related biomarkers were explored to provide theoretical basis for efficacy evaluation and resistance mechanism.

Inclusion Criteria:

1. Patients with metastatic (stage IV) lung adenocarcinoma who have not been systematically treated and are histologically or cytologically confirmed as unable to undergo radical surgery or radiotherapy based on AJCC Stage VIII;
2. Patients with brain metastases confirmed by imaging;
3. Patients with asymptomatic BMS after initial diagnosis, local BMS surgery or radiotherapy;
4. ECOG PS: 0-1;
5. Measurable target lesions outside the skull (as per RECIST 1.1);
6. Life expectancy greater than 3 months;

Exclusion Criteria:

1. Patients had been treated with immune checkpoint inhibitors such as anti-PD-1, PD-L1, or CTLA-4 therapy;
2. The patient had received systemic chemotherapy as advanced treatment;
3. Patients with EGFR mutation or ALK gene translocation;
4. The patient had received approved systemic anticancer therapy or systemic immunomodulators (including but not limited to interferon, interleukin 2, and tumor necrosis factor) within 4 weeks prior to initial administration;
5. Clinically uncontrolled pleural fluid or ascites requiring puncture drainage within 2 weeks prior to initial administration;