This phase II study aims to evaluate the efficacy and safety of low-dose radiation + SBRT + Tislelizumab plus platinum-based chemotherapy as neoadjuvant therapy for stage II-III non-small cell lung cancer.

All eligible patients will receive LDRT combined with partial SBRT, followed by PD-1 inhibitors plus platinum-based chemotherapy, initiated within 7 days after completing radiation. PD-1 inhibitors and chemotherapy will be administered at the recommended doses according to the instruction manual every 3 weeks, with 3 cycles planned as neoadjuvant therapy. Surgery will be performed within 4 to 6 weeks (+7 days) after completing the final cycle of immunochemotherapy.

Main objective and endpoint: the rate of pathological complete response (pCR) in the resected primary tumor and lymph nodes.

Inclusion Criteria:

1. Age ≥ 18 and ≤ 75 years;
2. Patients with untreated stage IIA-IIIB non-small cell lung cancer, diagnosed cytologically or histologically (according to the AJCC 9th edition of thoracic tumor staging);
3. Pulmonary lesions will be assessed as resectable or potentially resectable by a multidisciplinary team, including a thoracic surgeon;
4. At least one imaging-measurable lesion according to the Response Evaluation Criteria in Solid Tumors (RECIST v1.1);
5. Ability to provide tumor tissue or cell wax blocks that meet quality control standards for PD-L1 expression testing.

Exclusion Criteria:

1. The pathology is small cell lung cancer (SCLC), including lung cancer mixed with SCLC and non-small cell lung cancer (NSCLC)；
2. Patients with known EGFR-sensitive mutations or ALK fusion.
3. Previously received the following therapies: anti-PD-1, anti-PD-L1 or anti-PD-L2 drugs or another drug that stimulates or synergistically inhibits T cell receptors;
4. Subjects with any known or suspected autoimmune disorder or immunodeficiency, with the following exceptions: hypothyroidism, hormone therapy is not needed, or well controlled at physiological dose; controlled type I diabetes;
5. Active infection requiring systemic treatment.