Sacituzumab Tirumotecan (MK-2870) in Combination With Pembrolizumab Versus Pembrolizumab Alone in Metastatic Non-small Cell Lung Cancer (NSCLC) With Programmed Cell Death Ligand 1 (PD-L1) Tumor Proportion Score (TPS) ≥ 50% (MK-2870-007)

Inclusion Criteria:

* Histologically or cytologically confirmed diagnosis of squamous or nonsquamous NSCLC

  * Confirmation that epidermal growth factor receptor- (EGFR-), anaplastic lymphoma kinase- (ALK-), or proto-oncogene tyrosine-protein kinase ROS (ROS1-) directed therapy is not indicated as primary therapy
  * Provided tumor tissue that demonstrates programmed cell death ligand 1 (PD-L1) expression in ≥50% of tumor cells as assessed by an immunohistochemistry (IHC) central laboratory
  * An Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 assessed within 7 days before randomization.
  * A life expectancy of at least 3 months.
  * Human immunodeficiency virus (HIV)-infected participants must have well controlled HIV on antiretroviral therapy (ART)

Exclusion Criteria:

* Diagnosis of small cell lung cancer or, for mixed tumors, presence of small cell elements.
* Has Grade ≥2 peripheral neuropathy.
* History of documented severe dry eye syndrome, severe Meibomian gland disease and/or blepharitis, or severe corneal disease that prevents/delays corneal healing.
* Has active inflammatory bowel disease requiring immunosuppressive medication or previous clear history of inflammatory bowel disease (eg, Crohn's disease, ulcerative colitis, or chronic diarrhea).
* Has uncontrolled, significant cardiovascular disease or cerebrovascular disease within the 6 months preceding study intervention.
* Received prior systemic anticancer therapy for their metastatic NSCLC.
* Received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent, or with an agent directed to another stimulatory or coinhibitory T-cell receptor Note: Prior treatment with an anti-PD-1, anti-PD- L1, or anti-PD-L2 agent in the neoadjuvant or adjuvant setting for nonmetastatic resectable NSCLC is allowed as long as therapy was completed at least 12 months before diagnosis of metastatic NSCLC.
* Received prior systemic anticancer therapy including investigational agents within 4 weeks before randomization.
* Received radiation therapy to the lung that is \>30 Gy within 6 months of start of study intervention.
* Received prior radiotherapy within 2 weeks of start of study intervention, or radiation-related toxicities, requiring corticosteroids.
* Received a live or live-attenuated vaccine within 30 days before the first dose of study intervention. Administration of killed vaccines are allowed.
* Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy
* Known additional malignancy that is progressing or has required active treatment within the past 3 years.
* Known active central nervous system (CNS) metastases and/or carcinomatous meningitis.
* Known intolerance to sacituzumab tirumotecan or pembrolizumab and/or any of their excipients; for pembrolizumab, severe hypersensitivity (≥Grade 3) is exclusionary.
* Known hypersensitivity to sacituzumab tirumotecan or other biologic therapy.
* Active autoimmune disease that has required systemic treatment in the past 2 years.
* History of (noninfectious) pneumonitis/interstitial lung disease (ILD) that required steroids or has current pneumonitis/ILD.
* Active infection requiring systemic therapy
* Concurrent active Hepatitis B and Hepatitis C virus infection.
* Human immunodeficiency virus (HIV)-infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease.
* History of allogeneic tissue/solid organ transplant.
* Requires treatment with a strong inhibitor or inducer of Cytochrome P450 3A4 (CYP3A4) at least 14 days before the first dose of study intervention and throughout the study.