title: Inhibition of vascular endothelial growth factor (VEGF) as a novel approach for cancer therapy.
abstract: Of the numerous growth factors and cytokines that have been shown to have angiogenic effects, vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), appears to be a key factor in pathological situations which involve neovascularization as well as enhanced vascular permeability. Our aim was to design a low molecular weight synthetic molecule that potently and selectively blocks the VEGF/VEGF receptor system after oral administration, suitable for the chronic therapy of VEGF-dependent pathological neovascularization. PTK787/ZK 222584 is a potent inhibitor of VEGF receptor tyrosine kinases, active in the submicromolar range. It also inhibits other class III kinases, like the PDGFR-beta tyrosine kinase, c-Kit and c-Fms, but at higher concentrations. It is not active against kinases from other receptor families such as EGFR, FGFR-1, c-Met and Tie-2 or intracellular kinases like c-Src, c-Abl, PKC-alpha. PTK787/ZK 222584 inhibits VEGF-induced autophosphorylation of KDR, and endothelial cell proliferation, migration and survival in the nanomolar range in cell based assays. In concentrations up to 1 microM, PTK787/ZK 222584 does not have any cytotoxic or anti-proliferative effect on cells that do not express VEGF receptors. After oral dosing (50 mg/kg) to mice, plasma concentrations of PTK787/ZK 222584 remain above 1 microM for more than 8 h. PTK787/ZK 222584 induces dose-dependent inhibition of VEGF- and PDGF-induced angiogenesis in a growth factor implant model, as well as a tumor cell-driven angiogenesis model after once daily oral dosing (25-100 mg/kg). In the same dose range, it also inhibits the growth of several human carcinomas, grown subcutaneously in nude mice, as well as a murine renal carcinoma and its metastases in syngeneic, orthotopic models. Histological examination of tumors reveals inhibition of microvessel formation in the interior of the tumor. PTK787/ZK 222584 also significantly inhibits ascites formation induced by a human ovarian carcinoma grown in the peritoneum of nude mice as well as pleural effusion induced by a human lung adenocarcinoma in nude mice. PTK787/ZK 222584 is very well tolerated and does not impair wound healing. It also does not have any significant effects on circulating blood cells or bone marrow leukocytes as a single agent, or impair hematopoetic recovery following concomitant cytotoxic anti-cancer agent challenge. These studies indicate that compounds that inhibit the effects of VEGF, such as PTK787/ZK 222584, have the potential to provide a novel, effective and well-tolerated therapy for the treatment of solid tumors. These agents may also provide a new therapeutic approach for the treatment of other diseases where angiogenesis plays an important role.
authors.affiliation: Oncology Research, Novartis Pharma AG, Basel, Switzerland. jeanette.wood@pharma.novartis.com
authors.forename: J M
authors.initials: JM
authors.lastname: Wood
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D004354:Drug Screening Assays, Antitumor; D016228:Endothelial Growth Factors / Q000037:antagonists & inhibitors*; D004730:Endothelium, Vascular / Q000187:drug effects; D006801:Humans; D008222:Lymphokines / Q000037:antagonists & inhibitors*; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000188:drug therapy*; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D010793:Phthalazines / Q000494:pharmacology*; D011725:Pyridines; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D017978:Receptors, Growth Factor / Q000037:antagonists & inhibitors*; D040262:Receptors, Vascular Endothelial Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D020533:Angiogenesis Inhibitors; D016228:Endothelial Growth Factors; D008222:Lymphokines; D010793:Phthalazines; D011725:Pyridines; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C404768:vatalanib; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor