Non‐small cell lung cancer with tumor proportion score > 90% could increase the risk of severe immune‐related adverse events in first‐line treatments with immune checkpoint inhibitors: A retrospective single‐center study

BACKGROUND: Since 2015, immune checkpoint inhibitors have been a clinical treatment strategy for patients with advanced or recurrent non‐small cell lung cancer (NSCLC). However, the relationship between immune‐related adverse event (irAE) risk factors and patient clinical characteristics is unclear. This study aimed to evaluate the relationship between irAE risk and the clinical characteristics of patients with NSCLC. METHODS: We included patients with advanced or recurrent NSCLC with known programmed death‐ligand 1 expression levels treated with immune checkpoint inhibitors. We retrospectively examined the medical records of 260 patients with NSCLC (March 2016–November 2020) and analyzed the relationship between the patient clinical characteristics and irAEs. RESULTS: Our retrospective analysis revealed that tumor proportion score (TPS) ≥ 90% and adenocarcinoma histology were independent risk factors for irAEs (odds ratio: 3.750 95% confidence interval [CI]: 1.58–8.89 and 0.424 95% CI: 0.19–0.97, respectively) in first‐line treatment. However, in patients receiving second‐ or later‐line treatments, no clinical characteristics were identified as risk factors for irAEs. Furthermore, no difference was observed in the response rates to first‐line treatments between the TPS ≥ 90% and TPS < 90% groups (74% vs. 71%, p = 0.83). In later‐line treatments, the TPS ≥ 90% group had a better response rate than the TPS < 90% group (55% vs. 17%, p < 0.05). However, no significant differences in overall survival were observed in either of the groups. CONCLUSIONS: TPS ≥ 90% and adenocarcinoma histology were independent risk factors for irAEs in previously untreated patients with advanced or recurrent NSCLC. Therefore, patients at high risk of irAEs require additional monitoring.