Prognostic significance of exosomal programmed death-ligand 1 in advanced gastric cancer patients treated with first-line chemotherapy.

Abstract

Retraction The abstract by Shin et al entitled, “Prognostic significance of exosomal programmed death-ligand 1 in advanced gastric cancer patients treated with first-line chemotherapy,” ( Journal of Clinical Oncology 40, no. 4, suppl 665) published on February 1, 2022, has been retracted due to statistical errors that significantly changed the results and conclusion of the abstract. This abstract was retracted on November 4, 2022. 665 Background: Recent studies have found that exosomal PD-L1 could be associated with prognosis in several malignancies by its potential immunosuppressive role. Prognostic role of exosomal PD-L1 in advanced gastric cancer patients treated with systemic chemotherapy has not been well explored. The aim of the present study was to explore prognostic and predictive significance of exosomal PD-L1 in advanced gastric cancer patients. Methods: We prospectively collected plasma samples of patients with advanced gastric cancer receiving first-line chemotherapy at pre and post treatment. Combined ultracentrifugation with polymer-based precipitation was applied to isolate exosome and enzyme-linked immunosorbent assay(ELISA) was applied to measure exosomal PD-L1. The correlation between exosomal PD-L1 and circulating immune cells in the plasma was evaluated. Patients were divided into two groups according to pretreatment exosomal PD-L1 level. Survival analysis was performed using Kaplan-Meier method and multivariate analyses based on Cox-proportional hazards regression model. Results: A total of 99 patients were enrolled in the study, and serum samples collected at pre-treatment and post-treatment were pooled. Median value of the pre-treatment exosomal PD-L1 was 0.42 pg/ml (range 0.01 ̃3.75). Patients with pre-treatment exoPD-L1 < 0.42 pg/mL (exoPD-L1low) showed significantly better overall survival than those with exoPD-L1 ≥ 0.42 pg/mL(exoPD-L1high) (p = 0.033). Progression-free survival was not different between the groups (p = 0.754). exoPD-L1lowgroup showed significantly higher percentages of CD8+T cells than exoPD-L1high group. (p = 0.024). In multivariate analysis, pretreatment exosomal PD-L1, poorly differentiated tumors and No. of metastatic sites(≥2) were independent prognostic factors for overall survival. Conclusions: In summary, the level of pre-treatment exosomal PD-L1 could be used as a prognostic marker for patients with advanced gastric cancer receiving systemic chemotherapy.