Programmed Death-Ligand 1 Tumor Proportion Score and Overall Survival From First-Line Pembrolizumab in Patients With Nonsquamous Versus Squamous NSCLC

For patients with NSCLC receiving immune checkpoint inhibitors, programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) has been validated as a predictive biomarker for improved overall survival (OS). Nevertheless, its histology-specific predictive value in patients with advanced squamous versus nonsquamous cancers remains unclear. To evaluate the differential value of PD-L1 TPS as a predictive biomarker for OS after first-line pembrolizumab in patients with squamous versus nonsquamous NSCLC. Retrospective, observational study of patients diagnosed with having advanced NSCLC who were treated between October 2015 and April 2019 at community oncology clinics and academic medical centers in a deidentified electronic health record–derived database. Included patients were diagnosed with having advanced or metastatic NSCLC, received treatment with first-line, single-agent pembrolizumab, and had documentation of PD-L1 testing with a numeric result. Exclusion criteria included alterations in EGFR, ALK, and ROS1. The primary end point was OS from start of first-line pembrolizumab therapy by squamous or nonsquamous histology and PD-1 expression level measured by TPS (low,