(R)-N-(2-(5-fluoropyridin-3-yl)-8-isopropylpyrazolo[1,5-a][1,3,5]triazin-4-yl)-2,3,4,9-tetrahydro-1H-carbazol-3-amine

AHR antagonist 5, a potent and orally active aryl hydrocarbon receptor (AHR) antagonist extracted from patent WO2018195397, example 39, has an IC50 of < 0.5 μμ. AHR antagonist 5 significantly inhibits tumor growth combined with checkpoint inhibitor anti-PD-1[1]. 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[1].

[1]. Alfredo C. Castro, et al. Indole ahr inhibitors and uses thereof. WO2018195397A2.