The leaf extract of R. officinalis L. and its substances CA, CS, and BA as antagonists of AhR inhibit its prolonged activation and could be useful candidates for the adjuvant treatment of melanoma (1) together with BRAFi and (2) together with immunotherapy drugs, such as monoclonal antibodies that bind PD-1 or PD-L1. The gene discussed is AHR; the disease is melanoma.