A Study to Assess Efficacy and Safety of Pembrolizumab With or Without Sacituzumab Tirumotecan (MK- 2870) in Adult Participants With Resectable Non Small Cell Lung Cancer (NSCLC) Not Achieving Pathological Complete Response (pCR) (MK-2870-019)

The key inclusion and exclusion criteria include but are not limited to the following:

Inclusion Criteria:

• Has histological or cytological confirmation of squamous or nonsquamous non-smallcell lung cancer (NSCLC), resectable clinical Stage II, IIIA or IIIB (with nodalinvolvement [N2]) per AJCC eighth edition guidelines

• Has confirmation that either epidermal growth factor receptor (EGFR)-directed oranaplastic lymphoma kinase (ALK)-directed therapy is not indicated as primarytherapy

• Is able to undergo surgery based on opinion of investigator after consultation withsurgeon

• Is able to receive neoadjuvant pembrolizumab and platinum-based doublet chemotherapy

• Applies to screening for the adjuvant period only, before randomization: Has notachieved pathological complete response (pCR) at surgery by local review ofpathology.

• Applies to screening for the adjuvant period only, before randomization: Tumortissue sample from surgical resection has been provided for determination ofprogrammed cell death ligand 1 (PD-L1) and trophoblast cell surface antigen 2 (TROP2) status by central vendor before randomization into the adjuvant period

• Applies to screening for the adjuvant period only, before randomization: Confirmedto be disease-free based on re-baseline radiological assessment as documented bycontrast enhanced chest/abdomen/pelvis computed tomography (CT) (or magneticresonance imaging (MRI)) within 28 days before randomization

• Participants who have AEs due to previous anticancer therapies must have recoveredto ≤Grade 1 or baseline. Participants with endocrine-related AEs who are adequatelytreated with hormone replacement are eligible

• Human immunodeficiency virus (HIV)-infected participants must have well controlledHIV on antiretroviral therapy (ART)

• Participants who are hepatitis B surface antigen (HBsAg) positive are eligible ifthey have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks,and have undetectable HBV viral load at screening

• Participants with history of hepatitis C virus (HCV) infection are eligible if HCVviral load is undetectable at least 4 weeks before the start of study intervention

Exclusion Criteria:

• Has one of the following tumor locations/types:

• NSCLC involving the superior sulcus

• Large cell neuro-endocrine cancer (LCNEC)

• Sarcomatoid tumor

• Diagnosis of SCLC or, for mixed tumors, presence of small cell elements

• Has Grade ≥2 peripheral neuropathy

• Has history of documented severe dry eye syndrome, severe Meibomian gland diseaseand/or blepharitis, or corneal disease that prevents/delays corneal healing

• Has active inflammatory bowel disease requiring immunosuppressive medication orprevious history of inflammatory bowel disease

• Has uncontrolled, significant cardiovascular disease or cerebrovascular disease,including New York Heart Association Class III or IV congestive heart failure,unstable angina, myocardial infarction, uncontrolled symptomatic arrhythmia,prolongation of QT corrected for heart rate by Fridericia's cube root formula (QTcF)interval to >480 ms, and/or other serious cardiovascular and cerebrovasculardiseases within the 6 months preceding study intervention

• Has received prior neoadjuvant therapy for their current NSCLC diagnosis

• Has received prior systemic anticancer therapy including investigational agentswithin 4 weeks before the first dose of study intervention

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

• Has received a live or live-attenuated vaccine within 30 days before the first doseof study intervention. Administration of killed vaccines is allowed

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

• Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form ofimmunosuppressive therapy within 7 days prior the first dose of study medication

• Has a known additional malignancy that is progressing or has required activetreatment within the past 5 years

• Has an active autoimmune disease that has required systemic treatment in the past 2years

• Has a history of (noninfectious) pneumonitis/interstitial lung disease that requiredsteroids or has current pneumonitis/interstitial lung disease

• Has an active infection requiring systemic therapy

• Is an HIV-infected participant with a history of Kaposi's sarcoma and/orMulticentric Castleman's Disease

• Has a concurrent active Hepatitis B (defined as HBsAg positive and/or detectable HBVdeoxyribonucleic acid (DNA)) and Hepatitis C virus (defined as anti-HCV antibody (Ab) positive and detectable HCV ribonucleic acid (RNA)) infection

• Has a history of allogeneic tissue/solid organ transplant

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

• Severe hypersensitivity (≥Grade 3) to study intervention, any of its excipients,and/or to another biologic therapy