Natural killer cell therapy targeting cancer stem cells: Old wine in a new bottle

A small proportion of cancer cells that have stem cell-like properties are known as cancer stem cells (CSCs). They can be used to identify malignant tumor phenotypes and patients with poor prognosis. Targeting these cells has been shown to improve the effectiveness of cancer therapies. Owing to the nature of CSCs, they are resistant to conventional treatment methods such as radio-and chemotherapy. Therefore, more effective anti-CSC therapies are required. Immunotherapy, including natural killer (NK) and T cell therapy, has demonstrated the ability to eliminate CSCs. NK cells have demonstrated superior anti-CSC capabilities compared to T cells in recognizing low levels of major histocompatibility complex (MHC) class I expression. However, CSC escape also occurs during NK cell therapy. It is important to determine CSC-specific immune evasion mechanisms and find out potential so-lutions to optimize NK cell function. Therefore, this review discusses promising strategies that can improve the efficiency of NK cell therapy in treating CSCs, and aims to provide a reference for future research.