LUNAR-4: Effect of Tumor Treating Fields (TTFields) (150 kHz) Concurrent With Pembrolizumab for Treatment of Metastatic Non-small Cell Lung Cancer (NSCLC)

INCLUSION CRITERIA: * ≥18 years of age * Histologically or cytologically confirmed diagnosis of NSCLC. * Documented positive tumor PD-L1 expression (TPS≥1%). * Eastern Cooperative Oncology Group (ECOG) Score of 0-1. * Diagnosis of radiological progression while on or after first platinum-based systemic therapy administered for advanced or metastatic disease. * Subjects must have received one line of PD-1/PD-L1 inhibitor therapy for advanced or metastatic NSCLC. PD-1/PD-L1 inhibitor may have been given alone or in combination with other therapy. * Subjects who received PD-1/PD-L1 inhibitor for advanced disease, must have had a best response on PD-1/PD-L1 inhibitor of stable disease (SD), partial response (PR) or complete response (CR). * Subjects must have experienced disease progression more than 84 days following Cycle 1 Day 1 (C1D1) of their most recent PD-1/PD-L1 inhibitor therapy. EXCLUSION CRITERIA - All individuals meeting any of the following exclusion criteria will be excluded from study participation: * Mixed small cell and NSCLC histology. * Subject must not have leptomeningeal disease or spinal cord compression. * Subject must not have untreated, symptomatic brain metastases, or residual neurological dysfunction. * Subjects must not have received more than one line of PD-1/PD-L1 inhibitor for advanced disease. * Subjects with a known sensitizing mutation for which the Food and Drug Administration (FDA)-approved targeted therapy for NSCLC exists (e.g., EGFR, ALK, ROS1) are excluded unless previously received at least one of the approved therapy(ies). * Subjects with more than 2 lines of therapy in the advanced setting. * Pregnant or breastfeeding. * Implantable electronic medical devices (e.g. pacemaker, defibrillator) in the upper torso. * Known allergies to medical adhesives or hydrogel.