The HIF-1α inhibitor digoxin, which exerts anti-cancer effects by reducing the protein levels of HIF-1α and its target genes (GLUT1, HK, and VEGF [66]) is currently in phase II clinical trials to treat several cancers, including head and neck cancer, Kaposi’s sarcoma, and breast cancer [67]. The gene discussed is HIF1A; the disease is head and neck cancer.