They have also shown that AhR translocation activated by 5-HTP induces tumor-specific CD8+ T cell exhaustion accompanied by upregulation of programmed cell death protein 1 (PD-1), lymphocyte activating 3 (LAG3), and CD39, and downregulation of cytokines, and consequently causing T cells dysfunction in the TME [149]. The gene discussed is PDCD1; the disease is neoplasm.