The aryl hydrocarbon receptor has key roles regulating the development and function of the immune system [95,99,163], and AhR has garnered significant attention in the fields of immunology and immuno-oncology for its role in immunosuppression downstream of its activation by tumor- and microenvironment-derived tryptophan metabolites such as kynurenine, quinolinic acid, and kynurenic acid, among others [164]. Here, AHR is linked to neoplasm.