Programmed Death Ligand-1 (PD-L1) Is an Independent Negative Prognosticator in Western-World Gallbladder Cancer

• Main Authors: Thomas Albrecht, Fritz Brinkmann, Michael Albrecht, Anke S. Lonsdorf, Arianeb Mehrabi, Katrin Hoffmann, Yakup Kulu, Alphonse Charbel, Monika N. Vogel, Christian Rupp, Bruno Köhler, Christoph Springfeld, Peter Schirmacher, Stephanie Roessler, Benjamin Goeppert
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Cancers
• Subjects: programmed cell death ligand-1; PD-L1; gallbladder cancer; biomarkers; tumor; gastrointestinal neoplasms
• Online Access: https://www.mdpi.com/2072-6694/13/7/1682

Inhibition of the programmed cell death protein-1/ligand-1 (PD-1/PD-L1) axis has opened a new era in the treatment of solid cancers. However, there is no data on the expression and relevance of PD-L1 in Western gallbladder cancer (GBC). We assessed PD-L1 immunohistochemically in 131 GBC patients as Tumor Proportion Score (TPS), Immune Cell Score (IC) and Combined Positivity Score (CPS). Tumor cells expressed PD-L1 in a subset of 14.7% GBC patients at a TPS cut-off of 1%. Higher PD-L1 levels above 10% and 25% TPS were reached in 4.7% and 3.1% of GBC cases, respectively. At a 10% cut-off, TPS was associated with distinct histomorphological subtypes and correlated with poor tumor differentiation. Survival analysis revealed a TPS above 10% to be a highly significant and independent negative prognosticator in GBC. PD-L1 expression was associated with increased CD4⁺, CD8⁺ and PD-1⁺ immune cell densities. In 14.8% of the cases, scattered immune cells expressed T-cell immunoreceptor with Ig and ITIM domains (TIGIT), which was correlated to tumoral expression of its ligand CD155. We here show that a high PD-L1 expression confers a negative prognostic value in Western-world GBC and highlight the TIGIT/CD155 immune checkpoint as a potential new target for GBC immunotherapy.