Pembrolizumab is effective as first-line therapy against advanced non-small cell lung cancer (NSCLC) in patients with programmed death ligand-1 (PD-L1) expression levels ≥50% [1]. However, it is not effective in all patients, and the factors predicting responses among this population remain unknown. | Prediction of patients with a tumor proportion score 50 who do not respond to first-line monotherapy with pembrolizumab