ICOS-L as a Potential Therapeutic Target for Cancer Immunotherapy

Author(s): Oliviero Marinelli, Massimo Nabissi*, Maria Beatrice Morelli, Luciana Torquati, Consuelo Amantini, Giorgio Santoni.

Journal Name: Current Protein & Peptide Science

Volume 19 , Issue 11 , 2018

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Abstract:

Background: The co-stimulatory B7 family members are cell-surface protein ligands, binding to receptors on lymphocytes to regulate immune responses. One of them is the inducible co-stimulatory molecule ligand (ICOS-L). This protein is expressed on professional antigen-presenting cells (APCs), including B cells, macrophages, and dendritic cells (DCs), but it can also be expressed by endothelial cells, lung epithelium and in tumour microenvironment cells. ICOS-L is important for memory and effector T cells during the specific humoral immune responses, but its role in cancer is not yet understood.

Objective: To discuss the role of ICOS/ICOS-L in cancer, given importance of identifying selective targets for cancer treatment, and knowing the mechanism of immune evasion by tumour.

Main Findings: ICOS/ICOS-L signal has opposite effects on the T-cell response. ICOS-L is activated in several types of cancers to maintain immunosuppressive CD4+ T cell subsets, such as regulatory T cells (Tregs). ICOS-L over-expression is associated with tumour progression and poor overall survival. In colon cancer, activation of this co-stimulatory signal is associated with improved survival suggesting a dualistic effect of the ICOS/ICOs-L signal pathway. Interestingly, following anti-cancer vaccine or anti- CTLA-4 treatment, ICOS+ T cells increased significantly in both the CD4+ and CD8+ population and the ratio Teff/Treg increased in tumour microenvironment. This suggests a potential role of ICOS/ICOS-L in improving effectiveness of cancer therapy.

Conclusion: ICOS/ICOS-L signal pathway has the potential to improve cancer treatment. However, studies in other models are needed to understand whether inhibition of ICOS expression or the blockage of its co-stimulation could be a potential therapeutic target or adjuvant treatment for immunotherapy.

Keywords: ICOS-L, ICOS, CD275, CD278, B7, Tregs, cancer.

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Article Details

VOLUME: 19
ISSUE: 11
Year: 2018
Page: [1107 - 1113]
Pages: 7
DOI: 10.2174/1389203719666180608093913
Price: $58

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