Study of Pembrolizumab (MK-3475) Monotherapy Versus Sacituzumab Govitecan in Combination With Pembrolizumab for Participants With Metastatic Non-small Cell Lung Cancer (NSCLC) With Programmed Cell Death Ligand 1 (PD-L1) Tumor Proportion Score (TPS) ≥50% (MK-3475-D46)

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Has a histologically or cytologically confirmed diagnosis of metastatic non-smallcell lung cancer (NSCLC)

• Has confirmation that epidermal growth factor receptor (EGFR), anaplastic lymphomakinase 1 (ALK-1), or ROS proto-oncogene 1 (ROS-1)-directed therapy is not indicatedas primary therapy

• Has provided tumor tissue that demonstrates PD-L1 tumor proportion score (TPS) ≥50%of tumor cells as assessed by immunohistochemistry (IHC) at a central laboratory

• Has a life expectancy of at least 3 months

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Has history of a second malignancy, unless potentially curative treatment has beencompleted with no evidence of malignancy for 3 years

• Has received prior systemic chemotherapy or other targeted or biologicalantineoplastic therapy for their metastatic NSCLC

• Has previously received treatment with Topoisomerase 1 inhibitors or Trop-2 targetedtherapy

• Has received prior therapy with an anti-programmed cell death 1 protein (anti-PD-1),anti-programmed cell death ligand 1 (anti-PD-L1), or anti anti- programmed celldeath ligand 2 (PD-L2) agent or with an agent directed to another stimulatory orcoinhibitory T-cell receptor

• Has received prior radiotherapy within 2 weeks of start of study intervention or hasradiation-related toxicities requiring corticosteroids

• Has received radiation therapy to the lung that is >30 Gray (Gy) within 6 months ofthe first dose of study intervention

• Has received a live or live-attenuated vaccine within 30 days before the first doseof study intervention

• Has received an investigational agent or has used an investigational device within 4weeks before study intervention administration

• Has cardiac disease

• Myocardial infarction or unstable angina pectoris within 6 months of enrollment

• History of serious ventricular arrhythmia, high-grade atrioventricular block,or other cardiac arrhythmias requiring antiarrhythmic medications; history ofQT interval prolongation

• New York Heart Association (NYHA) Class III or greater congestive heart failureor left ventricular ejection fraction of <40%

• Has active chronic inflammatory bowel disease

• Has diagnosis of immunodeficiency or is receiving chronic systemic steroid therapyor any other form of immunosuppressive therapy within 7 days prior the first dose ofstudy medication

• Has known active central nervous system (CNS) metastases and/or carcinomatousmeningitis

• Has severe hypersensitivity (≥Grade 3) to pembrolizumab or sacituzumab govitecanand/or any of their excipients

• Has active autoimmune disease that has required systemic treatment in past 2 yearsexcept replacement therapy

• History of (noninfectious) pneumonitis/interstitial lung disease that requiredsteroids or has current pneumonitis/interstitial lung disease

• Has active infection requiring systemic therapy

• Has history of human immunodeficiency virus (HIV) infection

• History of hepatitis B or known active hepatitis C virus infection

• Has history or current evidence of any condition, therapy, laboratory abnormality,or other circumstance that might confound the results of the study or interfere withthe participant's participation for the full duration of the study, such that it isnot in the best interest of the participant to participate, in the opinion of thetreating investigator

• Have not adequately recovered from major surgery or have ongoing surgicalcomplications