The aryl hydrocarbon receptor (AhR) is a transcription factor that modulates the activity of tumor and immune cells, hence targeting AhR may represent a feasible option for cancer immunotherapy. Researchers from the Institute of Materia Medica of Beijing and collaborators recently reported on the discovery and synthesis of a novel series of AhR antagonists derived from Salvia miltiorrhiza Bunge intended to be used in cancer immunotherapy.