%0 Journal Article %A TOSHIHIRO SHIOZAWA %A TAKESHI NUMATA %A TOMOHIRO TAMURA %A TAKEO ENDO %A TAKAYUKI KABURAGI %A YUSUKE YAMAMOTO %A HIDEYASU YAMADA %A NORIHIRO KIKUCHI %A KAZUHITO SAITO %A MASAHARU INAGAKI %A KOICHI KURISHIMA %A YASUNORI FUNAYAMA %A KUNIHIKO MIYAZAKI %A NOBUYUKI KOYAMA %A KINYA FURUKAWA %A HIROYUKI NAKAMURA %A SHINJI KIKUCHI %A HIDEO ICHIMURA %A YUKIO SATO %A IKUO SEKINE %A HIROAKI SATOH %A NOBUYUKI HIZAWA %T Prognostic Implication of PD-L1 Expression on Osimertinib Treatment for EGFR-mutated Non-small Cell Lung Cancer %D 2022 %R 10.21873/anticanres.15736 %J Anticancer Research %P 2583-2590 %V 42 %N 5 %X Background/Aim: Real-world data on the clinical outcomes of first-line osimertinib treatment for non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations is lacking. This study aimed to reveal the treatment outcomes and prognostic factors of osimertinib as first-line therapy in clinical practice settings. Patients and Methods: We retrospectively evaluated clinical outcomes of patients with EGFR-mutated NSCLC treated with osimertinib as first-line therapy across 12 institutions in Japan between August 2018 and March 2020. Results: Among 158 enrolled patients, the objective response rate (ORR) was 68%, and the estimated median progression-free survival (PFS) was 17.1 months [95% confidence interval (CI)=14.5-19.7]. Subgroup analysis showed that PFS in the group with high programmed death-ligand 1 (PD-L1) expression was significantly shorter than that in groups with low or no PD-L1 expression (10.1 vs. 16.1 vs. 19.0 months; p=0.03). Univariate and multivariate analyses demonstrated that high PD-L1 expression was the only independent adverse prognostic factor of osimertinib outcome related to PFS (hazard ratio=2.71; 95%CI=1.26-5.84; p=0.01). In terms of anti-tumor response, there was no statistically significant correlation between PD-L1 expression and the ORR (67% vs. 76% vs. 65%; p=0.51). No significant correlation was also found between PD-L1 and the incidence of de novo resistance to osimertinib (p=0.39). Conclusion: Although PD-L1 expression was not associated with either the ORR or frequency of de novo resistance, high PD-L1 expression could be an independent adverse prognostic factor related to PFS in osimertinib treatment. %U https://ar.iiarjournals.org/content/anticanres/42/5/2583.full.pdf