Immunoscore assay for the immune classification of solid tumors: Technical aspects, improvements and clinical perspectives

Abstract

The past two decades witnessed the appreciation of the importance of specific tumor-infiltrating immune cells in influencing tumor evolution. The discovery that a favorable immune contexture is linked to a prolonged patients' survival, and more specifically that intratumoral cytotoxic T lymphocytes hold powerful prognostic value, provided the foundations for the development of the Immunoscore. Immunoscore is a digital pathology, IHC-based immune assay measuring the densities of CD3⁺ and CD8⁺ T cells at different tumor locations, linking them with patients' clinical outcome. The present chapter provides a detailed overview of the assay development and procedure, from the bench to the data analysis, and of the internationally approved and validated guidelines to perform a consensus Immunoscore for colon cancer patients. Assay strengths and limitations are also discussed, as well as the clinical implications of its introduction in routine practice.

Keywords: Colon cancer; Digital pathology; Immune contexture; Immuno-histochemistry; Immunoscore; Prognostic value; Tumor classification; Tumor microenvironment (TME); Tumor-infiltrating immune cells.