A KDR-binding peptide (ST100,059) can block angiogenesis, melanoma tumor growth and metastasis in vitro and in vivo.

A major goal of treatment strategies for cancer is the development of agents which can block primary tumor growth and development as well as the progression of tumor metastasis without any treatment associated side effects. Using mini peptide display (MPD) technology, we generated peptides that can bind to the human vascular endothelial growth factor (VEGF) receptor KDR. These peptides were evaluated for their ability to block angiogenesis, tumor growth and metastasis in vitro and in vivo. A D-amino acid peptide with high serum stability (ST100,059) was found to have the most potent activity in vitro as indicated by inhibition of VEGF stimulation of endothelial cells. It was also found to be the most active of the series in blocking VEGF-mediated activity in vivo, as measured in Matrigel-filled angioreactors implanted in mice. ST100,059 blocks VEGF-induced MAPK phosphorylation, as well as inhibits VEGF-induced changes in gene expression in HUVEC cells. In in vivo studies, treatment of female C57BL/6 mice inoculated with B16 mouse melanoma cells with ST100,059 resulted in a dose-dependent decrease in tumor volume and lung metastasis as compared to control groups of animals receiving vehicle alone. These studies demonstrate that by using MPD, peptides can be identified with enhanced affinity relative to those discovered using phage display. Based on these studies we have identified one such peptide ST100,059 which can effectively block tumor growth and metastasis due to its anti-angiogenic effects and ability to block intracellular signaling pathways involved in tumor progression.

Discovery of antitumor indolocarbazoles: rebeccamycin, NSC 655649, and fluoroindolocarbazoles.

A fermentation directed product search for potential anticancer drugs conducted by Bristol-Myers in the 1970s and early 1980s resulted in the identification of a novel indolocarbazole (IC) rebeccamycin (RBM) as a potential drug development candidate. Subsequently, an analog program designed to impart distal site in vivo antitumor activity resulted in the discovery of diethylaminoethyl analog of RBM (DEAE-RBM), which is presently undergoing clinical evaluation as NSC 655649 and BMY-27557. Strong DNA intercalation is the primary mechanism of action of DEAE-RBM resulting in the potent catalytic inhibition of both topoisomerases I and II. Precursor feeding fermentation experiments with fluorine-substituted tryptophans yielded novel fluoroindolocarbazoles (FICs). These FICs were identified as targeting topoisomerase (topo) I in a mechanism-based screen and their action on topo I was confirmed by production of topo I-mediated single-strand breaks in DNA at sites essentially identical to those induced by camptothecin. Topo I dependent cytotoxicity was demonstrated for specific FICs using a P388 and camptothecin-resistant P388/CPT45 pair of cell lines, the latter expresses little or no functional topo I. For example, topo I selectivity was greatest with 3,9-difluoro substituted FIC and was least significant and least cytotoxic with 4,8-difluoro substituted FIC. The review focuses on the discovery of the rebeccamycin class of compounds and their structure-activity relationships leading to the development of the clinical candidate BMY-27557 (NSC 655649), as well as the lead identification of the fluoroindolocarbazole class of compounds.