Furthermore, kynurenine promotes cancer cell invasion, metastasis, and resistance to chemotherapy.[41] Studies have demonstrated that elevated IDO expression was detected in 56.7% of patients with OC, and this was correlated with reduced overall survival and progression-free survival.[42] Kynurenine induces T regulatory cell differentiation, leading to enhanced production of anti-inflammatory cytokines and suppression of T cell cytotoxic activity. This evidence concerns the gene IDO1 and cancer.