Has untreated CNS metastases and/or carcinomatous meningitis
Participation in an interventional clinical study with any investigational drug within 4 weeks prior to the first dose of study treatment OR participation in any clinical study with petosemtamab at any time prior to the first dose of study treatment, regardless of whether petosemtamab was received
Participants who received prior treatment with a PD-(L)1 inhibitor
Participants who have received prior systemic chemotherapy, targeted or biological antineoplastic therapy for metastatic NSCLC
Any systemic anticancer therapy within 4 weeks prior to the first dose of study treatment
Persistent Grade \> 1 clinically significant toxicities related to prior antineoplastic therapies using NCI-CTCAE v5.0
History of hypersensitivity reaction to any of the excipients of petosemtamab or pembrolizumab
Unstable angina; history of congestive heart failure of Class II-IV New York Heart Association criteria or serious cardiac arrhythmia requiring treatment (except atrial fibrillation, paroxysmal supraventricular tachycardia); or history of myocardial infarction within 6 months prior to the first dose of study treatment
History of prior malignancies within the last 5 years, with the exception of excised local cancer
Current dyspnea at rest of any origin or other diseases requiring continuous oxygen therapy, including participants with a history of ILD (eg, pneumonitis or pulmonary fibrosis) or evidence of ILD on baseline chest CT scan
Current serious illness or medical condition, including but not limited to uncontrolled active infection and clinically significant pulmonary, metabolic, or psychiatric disorders
