Tissue clearing has been beneficial to evaluate therapy efficiency in various preclinical cancer models, such as HepG2 xenografts to assess the severing of the vasculature induced by antiangiogenic therapeutic siRNAs (52), and HER-2-expressing breast cancer xenografts treated with colony-stimulation factor 1 receptor inhibitor PLX3397, which reduced tumor burden without impairing the infiltration of macrophages (35). The gene discussed is ERBB2; the disease is breast cancer.