Real-World Outcomes of Patients With Advanced Non-small Cell Lung Cancer Treated With Anti-PD1 Therapy on the Basis of PD-L1 Results in EBUS-TBNA vs Histological Specimens

Abstract

Background: Programmed death-ligand 1 (PD-L1) testing is feasible in most specimens acquired using endobronchial ultrasound-guided needle aspiration (EBUS-TBNA). Research Question: Are the outcomes of patients with advanced non-small cell lung cancer (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 (Response Evaluation Criteria in Solid Tumors [RECIST] criteria), and vital status (May 14, 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. Most 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 (n = 16) or histology samples (n = 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 = .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.