The primary purpose of this study is to demonstrate Pharmacokinetic similarity in exposure after the initial dose and at steady state of QL2107 compared with Keytruda.

Inclusion Criteria:

• Adult participants (male or female) more than and equal to 18 years of age on the day of signing the ICF.
• Disease status: Participants with completely resected, histologically- or cytologically-confirmed (Stage II or IIIA) NSCLC
• Treatment with platinum-based chemotherapy; • Chemotherapy must have begun within 12 weeks after the resection surgery. The last chemotherapy dose must have been completed at least 3 weeks and no more than 12 weeks before the participant is randomized.
• No evidence of disease (NSCLC) for the post-surgery baseline assessment must be documented by full chest/abdomen/pelvis computed tomography (CT) and/or magnetic resonance imaging (MRI) and brain CT/MRI within 12 weeks prior to the randomization date.
• Eastern Cooperative Oncology Group performance status of 0 or 1.

Exclusion Criteria:

• Surgical-related adverse events (AEs) or chemotherapy-related toxicity not resolved to Grade 1, with the exception of Grade <=2 alopecia, fatigue, neuropathy, and lack of appetite/nausea.
• Participants who have received systemic corticosteroids (more than [>] 10 mg prednisone daily or equivalent) or other immunosuppressive drugs (such as cyclophosphamide, azathioprine, methotrexate, thalidomide, or tumor necrosis factor alpha inhibitors) within 2 weeks prior to the first dose.
• Participants with known epidermal growth factor receptor (EGFR)-sensitive mutations or anaplastic lymphoma kinase (ALK) gene translocations are not allowed.
• Received prior therapy with an anticytotoxic T-lymphocyte antigen-4 mAb (example, ipilimumab); anti-programmed cell death 1 (PD-1), anti-programmed cell death ligand 1 (Programmed Death-Ligand 1), or anti-programmed cell death ligand 2 (PD-L2) agent; or agent directed to another stimulatory or co-inhibitory T cell receptor.
• Participants with any active autoimmune disease or history of autoimmune diseases including but not limited to autoimmune hepatitis, interstitial pneumonia, pulmonary fibrosis, uveitis, enteritis, hypophysitis, vasculitis, nephritis, hyperthyroidism, and hypothyroidism.