Dietel M, et al. - Given the association of tumor programmed death ligand 1 (PD-L1) expression with enhanced clinical benefit from immunotherapies targeting the PD-1 pathway, researchers investigated the real-world prevalence of tumor PD-L1 expression in patients with non-small cell lung cancer (NSCLC) via performing a global, multicenter, retrospective observational study to determine. From 45 centers across 18 countries, 2617 patients met inclusion criteria. Of these, 2368 (90%) had PD-L1 data; PD-L1 TPS (tumor proportion score) ≥ 50% was reported in 530 (22%) patients, PD-L1 TPS ≥ 1% was reported in 1232 (52%), and PD-L1 TPS < 1% was reported in 1136 (48%). Till date, this is identified as the largest real-world study in advanced NSCLC, assessing PD-L1 tumor expression employing the 22C3 pharmDx kit. Across a large number of centers, a low testing failure rate with local evaluation of PD-L1 TPS was observed. Patients with stage IIIB/IV NSCLC showed similar prevalence of PD-L1 TPS ≥ 50% and TPS ≥ 1% across geographic regions that was broadly consistent with central testing results from clinical trial screening populations.