ABSTRACT
Resistance to anti-angiogenic therapy can occur via several potential mechanisms. Unexpectedly, recent studies showed that short-term inhibition of either VEGF or VEGFR enhanced tumour invasiveness and metastatic spread in preclinical models. In an effort to evaluate the translational relevance of these findings, we examined the consequences of long-term anti-VEGF monoclonal antibody therapy in several well-validated genetically engineered mouse tumour models of either neuroendocrine or epithelial origin. Anti-VEGF therapy decreased tumour burden and increased overall survival, either as a single agent or in combination with chemotherapy, in all four models examined. Importantly, neither short- nor long-term exposure to anti-VEGF therapy altered the incidence of metastasis in any of these autochthonous models, consistent with retrospective analyses of clinical trials. In contrast, we observed that sunitinib treatment recapitulated previously reported effects on tumour invasiveness and metastasis in a pancreatic neuroendocrine tumour (PNET) model. Consistent with these results, sunitinib treatment resulted in an up-regulation of the hypoxia marker GLUT1 in PNETs, whereas anti-VEGF did not. These results indicate that anti-VEGF mediates anti-tumour effects and therapeutic benefits without a paradoxical increase in metastasis. Moreover, these data underscore the concept that drugs targeting VEGF ligands and receptors may affect tumour metastasis in a context-dependent manner and are mechanistically distinct from one another.
Subject(s)
Adenocarcinoma/drug therapy , Antibodies, Anti-Idiotypic/therapeutic use , Lung Neoplasms/drug therapy , Neoplasm Metastasis/drug therapy , Neuroendocrine Tumors/drug therapy , Pancreatic Neoplasms/drug therapy , Small Cell Lung Carcinoma/drug therapy , Vascular Endothelial Growth Factor A/immunology , Adenocarcinoma/genetics , Angiogenesis Inhibitors/therapeutic use , Animals , Disease Models, Animal , Drug Therapy, Combination , Genetic Engineering , Indoles/therapeutic use , Kaplan-Meier Estimate , Lung Neoplasms/genetics , Mice , Neuroendocrine Tumors/genetics , Pancreatic Neoplasms/genetics , Proto-Oncogene Proteins p21(ras)/genetics , Pyrroles/therapeutic use , Small Cell Lung Carcinoma/genetics , Sunitinib , Vascular Endothelial Growth Factor A/antagonists & inhibitorsABSTRACT
Aurora kinase inhibitors have attracted a great deal of interest as a new class of antimitotic agents. We report a novel class of Aurora inhibitors based on a pentacyclic scaffold. A prototype pentacyclic inhibitor 32 (AKI-001) derived from two early lead structures improves upon the best properties of each parent and compares favorably to a previously reported Aurora inhibitor, 39 (VX-680). The inhibitor exhibits low nanomolar potency against both Aurora A and Aurora B enzymes, excellent cellular potency (IC50 < 100 nM), and good oral bioavailability. Phenotypic cellular assays show that both Aurora A and Aurora B are inhibited at inhibitor concentrations sufficient to block proliferation. Importantly, the cellular activity translates to potent inhibition of tumor growth in vivo. An oral dose of 5 mg/kg QD is well tolerated and results in near stasis (92% TGI) in an HCT116 mouse xenograft model.
