This is an international, multicenter, open-label, randomized, three-armed, modular phase II study. Patients with histologically confirmed non-small cell lung cancer (NSCLC) of clinical stages I B, II and selected stage III A (T3 N1, T4 with satellite nodule in the same lung N0/N1, selected T1a-T2b N2 cases considered suitable for primary surgical approach by the multidisciplinary tumor board), who are eligible for anatomic resection will be included.

Subjects in all arms will receive 2 preoperative treatment cycles with a cycle duration of 14 days. Study treatment consists of nivolumab q2w in Arm A, and nivolumab q2w plus relatlimab q2w in Arms B and C.

Arm C: Nivolumab/Relatlimab (240 mg) 2 cycles, every two weeks (q2w) o nivolumab 240 mg i.v. over 30 min o relatlimab 240 mg i.v. over 30 min (within 30 min of nivolumab)

Patients with histologically (core biopsy) or cytologically (e.g. bronchoscopy-guided biopsy) confirmed non-small cell lung cancer (NSCLC) eligible for anatomic resection, with the following specifications:

• Clinical stages I B, II and selected stage III A (T3 N1, T4 with satellite nodule in the same lung N0/N1, selected T1a-T2b N2 cases considered suitable for primary surgical approach by the multidisciplinary tumor board) according to UICC 8th edition

Exclusion of extensive mediastinal lymph node metastases (multilevel N2, N3) by PET/CT and/or mediastinal lymph node sampling by EBUS-TBNA and/or staging mediastinoscopy.

Exclusion of distant metastases by standard of care imaging studies, which include but are not limited to PET/CT or PET/MRI, or CT or MRI of thorax, abdomen, pelvis, and bone scan. Asymptomatic brain metastases will be excluded by MRI or contrastenhanced CT as indicated by current guidelines

Subjects are to be excluded from the study if they display any of the following criteria: • Active or history of autoimmune disease or immune deficiency, including, but not limited to, myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, anti-phospholipid antibody syndrome, Wegener granulomatosis, Sjögren syndrome, Guillain-Barré syndrome, multiple sclerosis, vasculitis, or glomerulonephritis. Patients with the following conditions are not excluded from participation:

• Patients with a history of autoimmune-related hypothyroidism who are on thyroid-replacement hormone are eligible for the study.
• Patients with controlled type 1 diabetes mellitus who are on an insulin regimen are eligible for the study. o Skin disorders (such as vitiligo, psoriasis, or alopecia) not requiring systemic immunosuppressive treatment, in particular corticosteroids are permitted to enroll.

Subjects with a condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of study drug administration. Inhaled or topical steroids, and adrenal replacement doses > 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease.