CD105, also termed endoglin, is highly expressed on cancer cells, and on peri- and intratumoral endothelial cells, which line tumor blood vessels.1,2 On the other hand, CD105 is expressed in varying degrees in the vasculature of normal tissues and on normal blood vessels, except for the umbilical cord of newborns.3 A phase II study of TRC105 in patients with hepatocellular carcinoma (HCC) or advanced/metastatic urothelial carcinoma were carried out by Tracon Pharma and several oncologists. Here, ENG is linked to hepatocellular carcinoma.