Abstract
BACKGROUND: The safety of pembrolizumab monotherapy in treatment-naïve non-small cell lung cancer (NSCLC) patients with high programed death-ligand 1 (PD-L1) expression and pre-existing interstitial lung disease (ILD) has not yet been determined. Here, we aimed to evaluate the prognosis, efficacy and safety associated with pembrolizumab in such settings. METHODS: In this single-institution retrospective study conducted from May 2017 to October 2019, pembrolizumab was administered to 72 Japanese patients with treatment-naïve advanced NSCLC with PD-L1 tumor proportion score (TPS) ≥50%. Patients with ILD were assigned to the ILD group, and those without to the non-ILD group. Between-group comparisons were then performed. RESULTS: Of the 72 patients, 61 (84.7%) were male. The median age was 70 years. A total of 64 patients (88.9%) had a smoking history, median PD-L1 TPS status was 77.5%, and 10 of the 72 patients (13.9%) had ILD on pretreatment computed tomography. The objective response rate (ORR) was 45.8% and disease control rate (DCR) was 75.0%. The ORR was 70.0% and DCR was 90.0% in the ILD group, while the ORR was 41.9% and DCR was 72.6% in the non-ILD group. The median overall survival was 568 days; the value in the non-ILD group was 521 days, while in the ILD group was not reached. There was no significant difference between the two groups (log-lank, P = 0.73). CONCLUSIONS: Pembrolizumab was administered to patients with pre-existing ILD with no difference in prognosis compared to patients without ILD. In patients with ILD, physicians should consider the expected long-term prognosis and risk of adverse events.