Apratoxin S10, a Dual Inhibitor of Angiogenesis and Cancer Cell Growth To Treat Highly Vascularized Tumors

Renal, hepatocellular, and neuroendocrine carcinomas are known as highly vascularized tumors. Although vascular endothelial growth factor A (VEGF-A)-targeted therapies have shown efficacy in the treatment of these cancers, drug resistance is a major concern and might be mediated by interleukin 6 (IL-6). Furthermore, upon antiangiogenic drug exposure, tumor cells may adapt to survive in a vascular-independent manner. Apratoxins are potent marine-derived cytotoxic in vivo-active agents, preventing cotranslational translocation in the secretory pathway, and show promise to overcome resistance by targeting angiogenesis and tumor growth simultaneously. We designed and synthesized a novel apratoxin analogue, apratoxin S10, with a balanced potency and stability as well as synthetic accessibility and scalability. We showed that apratoxin S10 potently inhibits both angiogenesis in vitro and growth of cancer cells from vascularized tumors. Apratoxin S10 down-regulated vascular endothelial growth factor receptor 2 (VEGFR2) on endothelial cells and blocked the secretion of VEGF-A and IL-6 from cancer cells. It inhibited cancer cell growth through down-regulation of multiple receptor tyrosine kinases (RTKs) and compares favorably to currently approved RTK inhibitors in both angiogenesis and cancer cell growth.