Efficacy of anti-PD-1 antibodies in NSCLC patients with an EGFR mutation and high PD-L1 expression

Introduction Several studies have demonstrated that non-small cell lung cancer patients (NSCLCs) harboring epidermal growth factor receptor (EGFR) mutations have poor clinical outcomes in response to treatment with programmed death-1 (PD-1) inhibitors. However, it remains unclear whether EGFR-mutated NSCLCs with a high programmed death-ligand-1 (PD-L1) expression (tumor proportion score ≥ 50%) respond to PD-1 inhibitors. Methods We retrospectively investigated the NSCLCs who had received PD-1 inhibitors between January 2016 and December 2018 to assess the efficacy of PD-1 inhibitors in patients with an EGFR mutation and high PD-L1 expression. Results There were 153 patients with a high PD-L1 expression level, and the median progression-free survival (mPFS) was 5.3 months [95% confidence interval (CI) 1.3–12.4 months] in the patients with EGFR mutations (n = 17) and 8.3 months (95% CI 6.0–11.7 months) in those with wild-type EGFR (n = 136; hazard ratio (HR) 1.62; 95% CI 0.83–2.87). Among the 110 patients in the low PD-L1 expression group, the mPFS was 1.6 months (95% CI 1.3–5.9 months) in the patients with EGFR mutations (n = 18) and 3.8 months (95% CI 2.5–5.9 months) in those with wild-type EGFR (n = 92; HR 2.59; 95% CI 1.48–4.31). The HR for PFS in the group with EGFR mutations and high PD-L1 expression was 0.97 (95% CI 0.56–1.59) compared to the group with wild-type EGFR and low PD-L1 expression. Conclusions PD-1 inhibitors can serve as one of the treatment options for NSCLCs with an EGFR mutation and high PD-L1 expression.