LAUSR

BACKGROUND PD-L1 testing is feasible in a majority of specimens acquired using endobronchial ultrasound-guided needle aspiration (EBUS-TBNA). RESEARCH QUESTION Are the outcomes of patients with advanced NSCLC treated with immune checkpoint inhibitors (ICI) on the basis of PD-L1 expression in EBUS-TBNA samples significantly different from those of patients who are treated on the basis of PD-L1 expression in histological samples? STUDY DESIGN AND METHODS Patients treated with pembrolizumab or nivolumab between June 2016 and 2019 were included. Patient characteristics, PD-L1 expression, line of treatment, response (RECIST criteria) and vital status (14 May, 2020) were recorded. Progression-free survival (PFS) and overall survival (OS) were assessed, and hazard ratios (HR) estimated. RESULTS A total of 145 patients were treated with pembrolizumab or nivolumab on the basis of PD-L1 expression in EBUS-TBNA (31.7%) or histological (68.3%) samples. The majority had metastatic disease, with a predominance of adenocarcinomas (64.1%). First-line pembrolizumab was administered to 61 patients with tumor proportion score ≥ 50% in EBUS-TBNA (16) or histology samples (45). Median OS and PFS of patients who received first-line pembrolizumab on the basis of PD-L1 Results in EBUS-TBNA vs. histology samples were not significantly different (OS 25.8 months vs. not reached, respectively, HR 0.82 [95% CI, 0.34-1.95], p=0.651). Similarly, the median OS and PFS of patients who received subsequent lines of treatment on the basis of PD-L1 results in EBUS-TBNA vs. histological samples were not significantly different (including after adjustment for PD-L1 expression). INTERPRETATION These findings suggest that PD-L1 Results in EBUS-TBNA samples can guide ICI therapy, with treatment outcomes being comparable to those of patients in whom PD-L1 expression was assessed in histological specimens.