DXR is a widely used anticancer drug either in the free form or encapsulated in liposomes, like Doxil.[20] The liposomes were first tested in vitro against HER2+ (SKOV3, BT474, SKBR3) and HER2‐ (MDA‐MB‐231) cell lines, evaluating their activity and internalization, and then in vivo in different model organisms: 1) to confirm their toxicity and tumor targeting properties in a zebrafish‐based setup; 2) to assess their pharmacokinetic and toxicological profile in rats; 3) to evaluate their antitumor activity in an immunodeficient mouse xenografted with HER2‐positive ovarian cancer cells. The gene discussed is ERBB2; the disease is ovarian carcinoma.