Circulating Plasma Exosomal PD-L1 Predicts Prognosis of Head and Neck Squamous Cell Carcinoma After Radiation Therapy

Keisuke Tamari; Kazumasa Minami; Shotaro Tatekawa; Yuji Seo; Takahito Fukusumi; Hidenori Tanaka; Motoyuki Suzuki; Hirotaka Eguchi; Yukinori Takenaka; Takero Hirata; Kazuhiko Hayashi; Fumiaki Isohashi; Shinichi Shimizu; Masahiko Koizumi; Hidenori Inohara; Kazuhiko Ogawa

doi:10.1016/j.adro.2023.101353

Circulating Plasma Exosomal PD-L1 Predicts Prognosis of Head and Neck Squamous Cell Carcinoma After Radiation Therapy

Adv Radiat Oncol. 2023 Aug 15;9(2):101353. doi: 10.1016/j.adro.2023.101353. eCollection 2024 Feb.

Authors

Keisuke Tamari¹, Kazumasa Minami², Shotaro Tatekawa¹, Yuji Seo³, Takahito Fukusumi⁴, Hidenori Tanaka⁴, Motoyuki Suzuki⁴, Hirotaka Eguchi⁴, Yukinori Takenaka⁴, Takero Hirata¹, Kazuhiko Hayashi¹, Fumiaki Isohashi¹, Shinichi Shimizu³, Masahiko Koizumi², Hidenori Inohara⁴, Kazuhiko Ogawa¹

Affiliations

¹ Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
² Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
³ Department of Carbon Ion Radiotherapy, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
⁴ Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.

Abstract

Purpose: Radiation therapy is widely used to treat head and neck squamous cell carcinoma (HNSCC). This study evaluated the association between circulating plasma programmed death-ligand 1 (PD-L1) and the outcomes of patients with HNSCC after radiation therapy.

Methods and materials: In this retrospective observational study, plasma samples of 76 patients with HNSCC who underwent radiation therapy from June 2019 to August 2021 were analyzed. These plasma samples were obtained before radiation therapy. The median follow-up was 32.5 months. Total and exosomal PD-L1 was measured by enzyme-linked immunosorbent assay and retrospectively analyzed for association with overall survival (OS), progression-free survival (PFS), and local control (LC). Prognostic factors among patients' characteristics and circulating PD-L1 in plasma were evaluated by univariate (log-rank test) and multivariate (Cox proportional hazards model) analyses.

Results: The median concentration of total PD-L1 in plasma was 115.1 pg/mL (95% CI, 114.7-137.9 pg/mL), and the median concentration of exosomal PD-L1 was 2.8 pg/mL (95% CI, 6.0-13.0 pg/mL). Univariate and multivariate analyses showed exosomal PD-L1 as a prognostic factor for PFS and LC. Patients with high exosomal PD-L1 in plasma had poor PFS and LC compared with those with low exosomal PD-L1, indicating that 1-year PFS was 79.2% versus 33.3% (P < .001) and 1-year LC was 87.3% versus 50.0% (P < .001) in patients with high and low exosomal PD-L1, respectively. However, exosomal PD-L1 in plasma had no significant effect on OS. Total PD-L1 in plasma did not correlate with PFS, LC, and OS.

Conclusions: The pretreatment circulating exosomal PD-L1 in plasma of patients with HNSCC was a prognostic factor after radiation therapy.