Evolving role for eosinophils in cancer: from bench to bedside

Eosinophils are increasingly recognized as important immune cells in the tumor microenvironment (TME). Recent technological advancements reveal their heterogeneity and complex context-dependent activities including the ability to elicit pro- or anti-tumorigenic effects. For instance, they can mediate cytotoxicity via highly eosinophil-specific granule proteins and reactive oxygen species, and contribute to antitumor immunity by interacting with various cells including T cells. Clinically, eosinophilia is often observed following various treatments including immunotherapy, where they may be beneficial for therapy. This Review explores eosinophil recruitment, immune interactions, therapeutic potential and methods for studying their activity. Understanding the role of eosinophils in the TME may lead to new therapeutic strategies and position them as targets or biomarkers in precision oncology.