Real-world evidence from over 400 non-small-cell lung cancer patients shows that combining mistletoe with programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) inhibitors doubles median overall survival (6.8 to 13.8 months), with biomarker-selected populations experiencing up to a 91.2% reduction in death risk. The gene discussed is CD274; the disease is non-small cell lung carcinoma.