Sintilimab or Observation After Surgery in High-Risk Non-Small Cell Lung Cancer

Who can take part

• Male or female participants aged 18 to 75 years
• Histologically or cytologically confirmed non-small cell lung cancer
• Completion of 2 to 4 cycles of neoadjuvant immune checkpoint inhibitor therapy combined with chemotherapy, followed by complete (R0) surgical resection
• At least one of the following protocol-defined high-risk features for postoperative recurrence:; Pathologic lymph-node involvement; Postoperative pathologic T2 or higher disease; Failure to achieve a major pathologic response, defined as more than 10% residual viable tumor cells in the primary tumor; Pleural invasion; Intravascular tumor emboli; High-risk histologic components, including solid, micropapillary, or adenosquamous components; Detectable molecular residual disease
• For participants with lung adenocarcinoma, absence of sensitizing EGFR mutations and ALK rearrangements. Molecular testing is not mandatory for participants with squamous cell carcinoma according to the current protocol
• Eastern Cooperative Oncology Group performance status of 0 or 1
• Adequate organ function within 7 days before randomization, as demonstrated by all of the following:; Hemoglobin of at least 90 g/L; Absolute neutrophil count of at least 1.5 × 10\^9/L; Platelet count of at least 75 × 10\^9/L; Total bilirubin no greater than 1.5 times the upper limit of normal; Alanine aminotransferase and aspartate aminotransferase no greater than 2.5 times the upper limit of normal; Serum creatinine no greater than 1.5 times the upper limit of normal or creatinine clearance of at least 60 mL/min; Left ventricular ejection fraction of at least 50%; International normalized ratio or prothrombin time no greater than 1.5 times the upper limit of normal
• Women of childbearing potential must have a negative pregnancy test within 7 days before the first dose and must agree to use effective contraception during the study and for 3 months after the last dose of study treatment. Male participants with partners of childbearing potential must agree to use effective contraception during the study and for 8 weeks after the last dose
• Ability to understand the study requirements, willingness to provide written informed consent, and ability to comply with study treatment and follow-up procedures

Who cannot take part

• Incomplete resection, including R1 or R2 resection, or salvage surgery
• A history of clinically significant immune-related adverse events during prior treatment, including grade 3 or higher immune-mediated pneumonitis, myocarditis, or another serious immune-related adverse event that, in the investigator's judgment, makes further immune checkpoint inhibitor therapy unsafe
• A concurrent active malignancy, except for malignancies specifically permitted by the final protocol
• Long-term treatment with systemic immunosuppressive therapy or systemic corticosteroids, except for protocol-permitted physiologic replacement therapy
• Small cell lung cancer or non-small cell lung cancer containing a small cell carcinoma component
• Signs, symptoms, or a known history of clinically significant interstitial lung disease
• An active autoimmune disease or another immune-mediated disease requiring systemic treatment
• An active psychiatric disorder, cognitive impairment, or another condition that would prevent provision of informed consent or adherence to study treatment and follow-up
• Any other condition that, in the investigator's judgment, makes the participant unsuitable for the study
• Any severe or uncontrolled concurrent medical condition, including:; Inadequately controlled hypertension; Grade 2 or higher myocardial ischemia, myocardial infarction, clinically significant arrhythmia, corrected QT interval of at least 480 milliseconds, or New York Heart Association class II or higher heart failure; Active or uncontrolled infection of grade 2 or higher; Decompensated liver disease, active hepatitis, or chronic viral hepatitis requiring antiviral therapy; Renal failure requiring hemodialysis or peritoneal dialysis; Known human immunodeficiency virus infection, another acquired or congenital immunodeficiency disorder, or a history of organ transplantation; Poorly controlled diabetes mellitus, defined as fasting blood glucose greater than 10 mmol/L; Urine protein of 2+ or greater with a 24-hour urinary protein level greater than 1.0 g; Clinically significant coagulation abnormalities or an increased risk of bleeding; A seizure disorder requiring treatment
• Clinically significant malnutrition as determined by the investigator