Vitamin B6 competition in the tumor microenvironment hampers antitumor functions of NK cells.

Nutritional factors play crucial roles in immune responses. The tumor-caused nutritional deficiencies are known to affect anti-tumor immunity. Here, we demonstrate that pancreatic ductal adenocarcinoma (PDAC) cells can suppress NK cell cytotoxicity by restricting the accessibility of vitamin B6 (VB6). PDAC cells actively consume VB6 to support one-carbon metabolism, and thus tumor cell growth, causing VB6 deprivation in the tumor microenvironment. In comparison, NK cells require VB6 for intracellular glycogen breakdown, which serves as a critical energy source for NK cell activation. VB6 supplementation in combination with one-carbon metabolism blockage effectively diminishes tumor burden in vivo. Our results expand the understanding of the critical role of micronutrients in regulating cancer progression and anti-tumor immunity, and open new avenues for developing novel therapeutic strategies against PDAC.