AHR antagonist 5, a potent and orally active aryl hydrocarbon receptor (AHR) antagonist extracted from patent WO2018195397, example 39, has an IC 50 of In Vivo Tumor growth inhibition is statistically significant with AHR antagonist 5 as single. AHR antagonist 5 (10 mg/kg; p.o.; every day for 3 weeks) combination with anti-PD-1 significantly inhibited tumor growth inhibition compared to the anti-PD-1 alone . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Balb/c Mice (Mouse Colorectal Cancer Model CT26) Dosage: 10 mg/kg (combination with anti-PD-1) Administration: P.o.; every day for 3 weeks Result: Significantly inhibited tumor growth inhibition. Form:Solid