The target population for this study includes patients with pathologic stage IB, IASLC grade 3 invasive lung adenocarcinoma without EGFR active mutations or ALK rearrangement who have undergone radical resection at Shanghai Pulmonary Hospital. Patients are screened and enrolled within 4 to 12 weeks after surgery. Following surgery, adjuvant chemotherapy may be administered based on the patient's treatment needs or the attending physician's assessment. Subsequently, patients will receive adjuvant immunotherapy with the PD-L1 inhibitor Benmelstobart (TQB2450 injection) at a dose of 1200 mg every 3 weeks by intravenous injection, for a maximum of 16 cycles. The primary endpoint is the 2-year disease-free survival (DFS) rate. The secondary endpoints include the 3-year and 5-year DFS rates, the 5-year overall survival (OS) rate, and drug safety. The sample size is 62 patients.