Nicotinamide drives T cell activation in the mammary tumor microenvironment.

Nicotinamide (NAM, a variant of vitamin B) has recently been shown to accelerate the activation of human CD4 and CD8 T cells exposed to repeated CD3/CD28 agonism in vitro. Here, we demonstrate that T cells infiltrating mouse mammary carcinomas that are therapeutically controlled by NAM also express multiple markers of late-stage activation. Taken together, these findings lend additional support to the notion that the antineoplastic effects of NAM involve at least some degree of restored cancer immunosurveillance.