Subtypes of tumor-associated neutrophils and their roles in cancer immunotherapy

Neutrophils are essential components of the innate immune system. Tumor-associated neutrophils (TANs) are shaped by tumor microenvironment (TME), leading to significant heterogeneity in biological characteristics and functions. Recent advances in single-cell sequencing have revealed a wide array of TAN subtypes, while a comprehensive classification system is still lacking. This review aims to summarize the alterations observed in TAN subgroups following cancer immunotherapy, and identify the distinctions and commonalities between pro-tumor and anti-tumor subgroups. Current progress of preclinical and clinical studies is also highlighted, involving novel therapies targeting TANs.