PD-L1 Expression and Outcome in Patients with Metastatic Non-Small Cell Lung Cancer and EGFR Mutations Receiving EGFR-TKI as Frontline Treatment

Abstract

Background Epidermal growth factor receptor (EGFR) mutations are most common in Eastern Asia, and frequencies of 30–50% have been reported. EGFR-tyrosine kinase inhibitors (TKIs) are recommended as first-line therapeutic options for non-small cell lung cancer (NSCLC) with sensitizing EGFR mutations. Several immune checkpoint inhibitors have been successful in improving the outcomes of advanced lung cancer. The expression of programmed cell death-ligand 1 (PD-L1) on tumor cells plays an important role in predicting the efficacy of programmed cell death protein 1/PD-L1 inhibitors. The role of PD-L1 expression in tumors with EGFR mutation and its influence on clinical outcomes remain controversial. Methods Patients with newly diagnosed metastatic NSCLC with sensitizing EGFR mutations who received the standard treatment, ie, EGFR-TKIs for mutant adenocarcinoma as the first-line treatment, were enrolled in this retrospective study. EGFR mutations and PD-L1 expression levels were detected by Cobas RT-PCR and Dako 22C3 immunohistochemistry staining, respectively. Results From January 2011 to February 2019, 114 patients were enrolled. The average age was 62 years (range 34–92), and 45 (39.5%) patients were male. Among these patients, EGFR mutation analysis revealed exon 19 in-frame deletion in 55 (48.2%) patients, exon 21 L858R in 53 (46.5%) patients, and uncommon mutations in 6 (5.3%) patients. Among these patients with EGFR mutations, PD-L1 expression levels by tumor proportion score (TPS) were <1% in 54 (46.9%) patients, 1–49% in 50 (44.2%) patients, and ≥50% in 10 (8.8%) patients. All patients received EGFR-TKIs as first-line treatment, and in the Kaplan-Meier analysis, progression-free survival was not significantly different among groups with different PD-L1 expression status. Conclusion For patients with metastatic NSCLC and EGFR mutations, PD-L1 expression is not uncommon, but no significant influence on clinical outcomes was observed in patients receiving standard initial treatment.