Adding the Immunotherapy Drug Cemiplimab to Usual Treatment for People With Advanced Non-Small Cell Lung Cancer Who Had Previous Treatment With Platinum Chemotherapy and Immunotherapy (An Expanded Lung-MAP Treatment Trial)

Inclusion Criteria: * Participants must have been assigned to S1800E by the Southwest Oncology Group (SWOG) Statistics and Data Management Center (SDMC). Assignment to S1800E is determined by the LUNGMAP protocol * Participants must have measurable or non-measurable disease documented by CT or MRI. The CT from a combined positron emission tomography (PET)/CT may be used to document only non-measurable disease unless it is of diagnostic quality. Measurable disease must be assessed within 28 days prior to randomization. Pleural effusions, ascites and laboratory parameters are not acceptable as the only evidence of disease. Non-measurable disease must be assessed within 42 days prior to randomization. All disease must be assessed and documented on the Baseline Tumor Assessment Form. Participants whose only measurable disease is within a previous radiation therapy port must demonstrate clearly progressive disease (in the opinion of the treating investigator) prior to registration * Participants must have a CT or MRI scan of the brain to evaluate for central nervous system (CNS) disease within 42 days prior to randomization * Participants must have received exactly one anti-PD-1 or anti-PD-L1 therapy for advanced disease (stage IV or recurrent disease, or stage I-III disease in certain circumstances outlined below). Anti-PD-1 or anti-PD-L1 therapy may have been given alone or in combination with other therapy. For participants who received neoadjuvant, adjuvant, and/or consolidat…