New somatostatin-drug conjugates for effective targeting pancreatic cancer.

Pancreatic cancer poorly responds to available drugs, and finding novel approaches to target this cancer type is of high significance. Here, based on a common property of pancreatic cancer cells to express somatostatin receptors (SSTR), we designed drug conjugates with novel somatostatin-derived cyclic peptides (SSTp) with broad selectivity towards SSTR types to facilitate drug targeting of the pancreatic cancer cells specifically. Uptake of our newly designed SSTps was facilitated by SSTRs expressed in the pancreatic cancers, including SSTR2, SSTR3, SSTR4 and SSTR5. Three major drugs were conjugated to our best SSTps that served as delivery vehicles, including Camptothecin (CPT), Combretastatin-4A (COMB) and Azatoxin (AZA). All designed drug conjugates demonstrated penetration to pancreatic cancer cell lines, and significant toxicity towards them. Furthermore, the drug conjugates specifically accumulated in tumors in the animal xenograft model, though some accumulation was also seen in kidney. Overall these findings lay the basis for development of novel drug series that could target the fatal pancreatic cancer.

Discovery of potent molecular chimera (CM358) to treat human metastatic melanoma.

The resistance of cancer cells to chemotherapeutic agents, whether through intrinsic mechanisms or developed resistance, motivates the search for new chemotherapeutic strategies. In the present report, we demonstrate a facile synthetic strategy towards the discovery of new anti-cancer substances. This strategy is based on simple covalent coupling between known anti-cancer drugs, which results in novel 'chimeric' small molecules. One of these novel compounds, CM358, is the product of an amide bond formation between the known Topoisomerase II (Topo II) inhibitor amonafide (AM) and the known DNA mustard alkylator chlorambucil (CLB). It demonstrates significant enhanced cytotoxicity over an equimolar mixture of AM and CLB in various cancer cell lines and in a xenograft model of human metastatic melanoma. Topo II inhibition as well as in silico docking studies suggest that CM358 is a stronger Topo II binder than AM. This may be attributed, at least partially, to the placement of the CLB moiety in a favorable orientation with respect to DNA cross-linking with nearby guanines. In a human metastatic melanoma (WM 266-4) xenograft model, this compound was profoundly superior to a mixture of AM and CLB in reduction of tumor growth, maintenance of body weight and extension of overall survival.