Trial to Evaluate Acasunlimab and Pembrolizumab Combination Superiority Over Standard of Care Docetaxel in Non-Small Cell Lung Cancer (ABBIL1TY NSCLC-06)

The goal of this trial is to determine the efficacy and safety of acasunlimab (an experimental antibody also known as GEN1046 or DuoBody® PDL1x4-1BB) in combination with pembrolizumab (an antibody known as KEYTRUDA®) compared to that of docetaxel (a standard of care chemotherapy). During the trial, the participant's quality of life will also be evaluated using industry-standard scales of measurement. To be eligible, participants must have: 1. non-small cell lung cancer that are locally advanced, unresectable stage IIIB/C or has metastasized (spread) 2. tumors that are positive for the PD-L1 protein (a biomarker that may be predictive of response to therapy) 3. been previously treated with a PD-1/PD-L1-inhibitor and a platinum-containing cancer therapy administered in combination or sequentially (irrespective of the order). Other eligibility criteria will also apply. Participants will be assigned to 1 of 2 active therapies, also known as treatment arms, as follows: * Acasunlimab (100 milligrams \[mg\]) and pembrolizumab (400 mg) once every 6 weeks (Q6W), or * Docetaxel 75 milligrams per meter squared (mg/m\^2) once every 3 weeks (Q3W). The estimated trial duration for a participant will vary but may be up to 5 years, consisting of: * An optional 3-month pre-screening period * A 28-day screening period * Up to 2 years of treatment * A 90-day safety follow-up period * Post-treatment follow-up.