This study will enroll adult participants with early-stage (stage II-IIIB) non-small cell lung cancer for whom surgery is planned.

The aim is to find out whether an investigational treatment (consisting of the immunotherapy drug cemiplimab plus chemotherapy plus a third drug) works better than cemiplimab plus chemotherapy without the additional drug.

The study is also looking at several other research questions, including:

• What are the side effects associated with the investigational treatments in comparison to the control treatment?
• Do the investigational treatments or the control treatment have an effect on the type of surgery that is performed?
• How much of the study drug(s) are in the blood at a given time?
• Does the body make antibodies against the study drug(s) (which could make the drug(s) less effective or could lead to side effects)?

General Key Inclusion Criteria:

1. Histologically confirmed stage II through IIIB (N2) NSCLC, that is considered resectable with curative intent, as described in the protocol
2. Measurable disease per Response Evaluation Criteria In Solid Tumors (RECIST) criteria version 1.1
3. Available formalin-fixed paraffin-embedded (FFPE) tumor sample blocks for submission, as described in the protocol
4. Eastern Cooperative Oncology Group Performance Status scale (ECOG PS) of 0 to 1
5. Adequate organ and bone marrow function, as described in the protocol

General Key Exclusion Criteria:

1. Any systemic anti-cancer therapy or radiotherapy for the current tumor, as described in the protocol
2. Presence of known oncogenic alterations in epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) in the tumor prior to randomization, as described in the protocol
3. Presence of grade≥ 2 peripheral neuropathy
4. Another malignancy that is progressing or requires active treatment, as described in the protocol

Arm Specific Exclusion Criteria:

Arm 1:

1. Grade ≥3 hypercalcemia, as defined in the protocol
2. Any central nervous system (CNS) pathology that could increase the risk of immune effector cell-associated neurotoxicity syndrome (ICANS), as described in the protocol
3. Has marked baseline prolongation of the time from the start of the Q wave to the end of the T wave in electrocardiogram (QT)/corrected QT interval (QTc) interval or risk factors for prolonged QTc, as described in the protocol

Note: Other protocol-defined Inclusion/Exclusion criteria apply.

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

When Regeneron has:

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made the study results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf