Endothelial Growth Factor Receptor Inhibitor Research Articles

Association of hypertension with overall outcome in patients taking sorafenib in advanced hepatocellular carcinoma (HCC).

e14536 Background: Hypertension is a commonly reported side effect following administration of vascular endothelial growth factor receptor (VEGFR) inhibitors. There have been multiple studies in renal cell carcinoma which showed elevated blood pressure correlates with better outcome in patients these drugs. In this study we assessed the predictive effect of HTN in patients taking sorafenib for advanced HCC. Methods: We looked at 41 patients from 2007 to 2009 in patients who received sorafenib for advanced HCC. Blood pressure was monitored at baseline and every 4 weeks. Elevated BP was defined as 20% increase in systolic or diastolic pressure from baseline or > 140/90 if baseline BP was within normal limits. Logrank tests were used to compare Kaplan-Meier estimates of overall survival. Results: Out of 41 patients who received sorafenib, 38 patients had complete blood pressure assessment. 15 (38%) were on HTN meds at baseline. 27 (65.9%) patients were classified as Child-Pugh (CP) A, 11 (26.8%) CP B and 3 (...

In Vitro to In Vivo Comparison of the Substrate Characteristics of Sorafenib Tosylate toward P-Glycoprotein

Sorafenib (Nexavar) is a novel oral Raf kinase and vascular endothelial growth factor receptor inhibitor. Most anticancer drugs are substrates for ATP-binding cassette efflux pumps especially for P-glycoprotein (P-gp). To evaluate the influence of P-gp on the pharmacokinetics of sorafenib substrate properties for this transporter were investigated. Therefore, permeability of sorafenib across Caco-2 and P-gp-overexpressing cells was determined. To determine the in vivo relevance of these in vitro findings, pharmacokinetics of sorafenib in mdr1a/1b(-/-) and wild-type (WT) mice was studied. Sorafenib is highly permeable and exhibits a slight efflux across Caco-2 cells. In P-gp-overexpressing cells, a small concentration-dependent efflux was observed, which was completely blocked by the addition of ivermectin. In mdr1a/1b(-/-) and WT mice, unchanged compound represented by far the majority of radioactivity in plasma. After intravenous and oral administration, brain/plasma concentration ratios in mdr1a/1b(-/-) mice were 1.3- to 1.5-fold higher than those in WT mice. However, after intravenous or oral administration, plasma concentrations were similar in both mouse strains. In conclusion, sorafenib is highly permeable and a weak P-gp substrate in vitro. These findings were confirmed by the small factor of 1.3 to 1.5 observed for the brain/plasma ratios in mdr1a/1b(-/-) versus WT mice in vivo. Based on these in vitro and in vivo results, it is unlikely that P-gp has a major effect on the plasma concentrations of sorafenib in humans. Because of the high permeability and low P-gp-mediated transport, sorafenib might be able to cross the blood-brain barrier and target tumors within the brain.

Sequential Therapy of Transarterial Chemoembolisation and Sorafenib in Intermediate Stage Hepatocellular Carcinoma

Prolongation of median survival can be achieved for intermediate Barcelona Clinic Liver Cancer stage hepatocellular carcinoma (HCC) by transarterial chemoembolisation (TACE). TACE might induce induction of angiogenic factors, especially in patients not responding to TACE, which might result in further tumour progression with development of new satellite lesions. Here, we report a patient with intermediate stage HCC, who initially responded to TACE, but developed new satellite lesions. After careful discussion, TACE was stopped, and a sequential treatment with sorafenib, a vascular endothelial growth factor receptor and RAF tyrosinkinase inhibitor, was started, resulting in a progression-free survival of 10 months. The presented case demonstrates the feasibility of sequential TACE and sorafenib treatment. Results of ongoing controlled, clinical trials in this regard are awaited.

Abstract 3620: Efficacy of Vandetanib on EGFR mutant lung cancer cells with PTEN loss

Abstract Introduction EGFR gene is frequently mutated in non-small cell lung cancer (NSCLC) of never smokers, especially in Asian ethnicity. The mutations often predict dramatic response to EGFR-tyrosine kinase inhibitors (TKIs) like gefitinib. PTEN is a tumor-suppressor gene deactivating PI3K in downstream of EGFR signaling. Approximately 2% to 9% in NSCLC tumors were considered to be PTEN loss. PTEN loss and EGFR mutation co-occurred in 1 out of 24 EGFR mutant patients with lung adenocarcinoma (Sos, et al. Cancer Res 69, 2009). PTEN loss was considered to represent primary or acquired resistance to EGFR-TKIs. Therefore, a new strategy is needed to break through for the resistance due to PTEN loss. Objective We clarify the effectiveness of vandetanib, EGFR and vascular endothelial growth factor receptor (VEGFR) inhibitor, against lung cancer cell lines harboring EGFR mutations with PTEN loss. Materials and methods: Two EGFR mutant (deletion in exon19) NSCLC cell lines, PC-9 (PTEN wild type) and NCI-H1650 (PTEN loss) were used. Other two cell lines with PTEN loss, prostate cancer cell line (PC-3) and glioblastoma cell line (U-87MG) were also examined. We transfected intact PTEN gene into H1650 cells and knocked down PTEN expression in the PC-9 cells using shRNA. Antiproliferative activity was determined by MTT assay in terms of 50% inhibitory concentration (IC50) values. We also examined the effectiveness of the drugs (15 mg/kg/day) in xenograft model. Protein expression profile was examined by Western blotting. Expression of VEGFR mRNA levels was also assessed by RT-PCR. Results PC-9 cells were more resistant to vandetanib (IC50: 0.08 μM) than to gefitinib (IC50: 0.01 μM). However, mean IC50 values of vandetenib were significantly lower than those of gefitinib against H1650 cells (2 μM vs 25 μM), PC-3 cells (8 μM vs 25 μM), and U87MG cells (6 μM vs 28 μM) with PTEN loss. EGFR downstream signals including pAKT, pMAPK, and pSTAT3, and VEGFR were not different in the H1650 cells treated with vandetanib or gefitinib. In the xenograft model using H1650 cells, vandetanib was also more effective than gefitinib. Although PTEN transfected H1650 cells did not restore sensitiveness to gefitinib in vitro, the xenograft tumors responded to gefitinib as well as vandetanib. Knockdown of PTEN lead six times more resistance to gefitinib in PC-9 cells. Conclusion PTEN loss may play a role to determine the sensitivity to gefitinib in NSCLC with EGFR mutations. Vandetanib is more effective in NSCLC with EGFR mutation and PTEN loss. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3620.

Synthesis and biological activity of N4-phenylsubstituted-6-(2,4-dichloro phenylmethyl)-7 H-pyrrolo[2,3- d]pyrimidine-2,4-diamines as vascular endothelial growth factor receptor-2 inhibitors and antiangiogenic and antitumor agents

A series of eight N 4-phenylsubstituted-6-(2,4-dichlorophenylmethyl)-7 H-pyrrolo[2,3- d]pyrimidine-2,4-diamines 8– 15 were synthesized as vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors with varied substitutions in the phenyl ring of the 4-anilino moiety. In addition, five N 4-phenylsubstituted-6-phenylmethylsubstituted-7 H-pyrrolo[2,3- d]pyrimidin-4-amines 16– 20 were synthesized to evaluate the importance of the 2-NH 2 moiety for multiple receptor tyrosine kinase (RTK) inhibition. Cyclocondensation of α-halomethylbenzylketones with 2,6-diamino-4-hydroxypyrimidine afforded 2-amino-6-(2,4-dichlorophenylmethyl)-3,7-dihydro-4 H-pyrrolo[2,3- d]pyrimidin-4-one, 23 and reaction of α-bromomethylbenzylketones with ethylamidinoacetate followed by cyclocondensation with formamide afforded the 6-phenylmethylsubstituted-3,7-dihydro-4 H-pyrrolo[2,3- d]pyrimidin-4-ones, 40– 42, respectively. Chlorination of the 4-position and displacement with appropriate anilines afforded the target compounds 8– 20. Compounds 8, 10 and 14 were potent VEGFR-2 inhibitors and were 100-fold, 40-fold and 8-fold more potent than the standard semaxanib, respectively. Previously synthesized multiple RTK inhibitor, 5 and the VEGFR-2 inhibitor 8 from this study, were chosen for further evaluation in a mouse orthotopic model of melanoma and showed significant inhibition of tumor growth, angiogenesis and metastasis.

Simultaneously Optimized Support Vector Regression Combined With Genetic Algorithm for QSAR Analysis of KDR/VEGFR‐2 Inhibitors

Considering the fact that majority of support vector regression models have not been fully optimized in the realm of quantitative structure-activity relationship, an idea of simultaneous optimization has been proposed and evaluated on a set of novel kinase insert domain receptor/vascular endothelial growth factor receptor-2 inhibitors including naphthalene and indazole-based compounds in this study. After the powerful feature searching process using genetic algorithm, the final support vector regression model was constructed on an optimal set of six descriptors, based on which simultaneous optimization was carried out. Specifically, the global optimum is grid searched in the joint parametric space defined by cost (C), gamma and epsilon, where performance of support vector regression using each combination of (C, gamma, epsilon) is evaluated and recorded, resulting in bulky information. Based on the data decomposition strategies provided in the main paper, the best performance was achieved for C = 1.2, gamma = 0.15 and epsilon = 0.065. As a comparison, a linear model based on genetic algorithm-multiple linear regression has also been developed and compared. Performances of these models are rigorously validated using both leave-one-out cross-validation and also external validation. The significant higher R(2) (0.908, 0.837) and lower root-mean-square error (0.237, 0.311) for 45 training and 16 test samples compared to that of genetic algorithm-multiple linear regression (0.764, 0.700 and 0.402, 0.421) confirm the superior performance of genetic algorithm-support vector regression. Robustness and predictive ability of this model is further prudently evaluated. The resulting models introduced not only the idea of simultaneous optimization in support vector regression, but also an efficient strategy for estimating the vascular endothelial growth factor receptor-2 inhibitory activity of novel naphthalene and indazole-based compounds. Moreover, some insights into the structural features related to the biological activity of these compounds have also been provided, which might be of great help for further designing novel vascular endothelial growth factor receptor-2/kinase insert domain receptor inhibitors with potent activity.

Spontaneous bilateral pneumothorax in metastatic renal cell carcinoma on sunitinib therapy

Bilateral spontaneous pneumothorax is a rare occurrence in patients with both primary and metastatic lung cancer. Pneumothorax occurring as a complication of vascular endothelial growth factor receptor (VEGFR) inhibitor therapy has not been previously described in the medical literature. Sunitinib malate is a VEGFR inhibitor approved for the treatment of advanced renal cell carcinoma. We present a patient with metastatic renal cell carcinoma manifested as bilateral pulmonary nodules who developed a bilateral spontaneous pneumothorax 3 weeks after initiation of sunitinib therapy. We believe that sunitinib therapy resulted in necrosis of multiple pleural-based pulmonary nodules with central cavernization and ultimately rupture with bronchopleural fistula formation. Based on this experience, we advise that practitioners exercise caution when prescribing anti-VEGFR therapy in patients with pleural-based pulmonary metastases and recognize that the efficacy and toxicity of these agents may be closely linked.

Receptor and nonreceptor tyrosine kinases in vascular biology of hypertension

Extensive evidence indicates that receptor tyrosine kinases and nonreceptor tyrosine kinases underlie vascular damage in hypertension. However, recent clinical studies using vascular endothelial growth factor (VEGF) receptor inhibitors (bevacizumab, axitinib) revealed the unexpected finding of increased blood pressure. Whether this is a generalized receptor tyrosine kinase phenomenon or a VEGF receptor-specific effect is unclear. The present review focuses on current findings regarding the role of tyrosine kinases and signaling in vascular pathobiology of hypertension. Multiple complex and interacting signaling pathways activated by receptor and nonreceptor tyrosine kinases are upregulated and have been implicated in vascular alterations associated with high blood pressure. Experimental evidence suggests that receptor tyrosine kinase activation by direct ligand binding as well as by ligand-independent mechanisms through transactivation by G protein-coupled receptors plays a role in vascular signaling and cardiovascular diseases. Cellular mechanisms and signaling pathways mediated by tyrosine kinases involved in hypertensive vascular damage are currently the subject of intensive investigation. The unexpected finding of hypertension as a side effect in patients treated with VEGF receptor inhibitors suggests that some tyrosine kinases negatively regulate vascular function. Further characterization of these processes will provide greater understanding of the role of tyrosine kinases in vascular pathobiology in hypertension and should provide new insights on novel therapeutic targets.

Dependence on Phosphoinositide 3-Kinase and RAS-RAF Pathways Drive the Activity of RAF265, a Novel RAF/VEGFR2 Inhibitor, and RAD001 (Everolimus) in Combination

Activation of phosphatidylinositol-3-kinase (PI3K)-AKT and Kirsten rat sarcoma viral oncogene homologue (KRAS) can induce cellular immortalization, proliferation, and resistance to anticancer therapeutics such as epidermal growth factor receptor inhibitors or chemotherapy. This study assessed the consequences of inhibiting these two pathways in tumor cells with activation of KRAS, PI3K-AKT, or both. We investigated whether the combination of a novel RAF/vascular endothelial growth factor receptor inhibitor, RAF265, with a mammalian target of rapamycin (mTOR) inhibitor, RAD001 (everolimus), could lead to enhanced antitumoral effects in vitro and in vivo. To address this question, we used cell lines with different status regarding KRAS, PIK3CA, and BRAF mutations, using immunoblotting to evaluate the inhibitors, and MTT and clonogenic assays for effects on cell viability and proliferation. Subcutaneous xenografts were used to assess the activity of the combination in vivo. RAD001 inhibited mTOR downstream signaling in all cell lines, whereas RAF265 inhibited RAF downstream signaling only in BRAF mutant cells. In vitro, addition of RAF265 to RAD001 led to decreased AKT, S6, and Eukaryotic translation initiation factor 4E binding protein 1 phosphorylation in HCT116 cells. In vitro and in vivo, RAD001 addition enhanced the antitumoral effect of RAF265 in HCT116 and H460 cells (both KRAS mut, PIK3CA mut); in contrast, the combination of RAF265 and RAD001 yielded no additional activity in A549 and MDAMB231 cells. The combination of RAF and mTOR inhibitors is effective for enhancing antitumoral effects in cells with deregulation of both RAS-RAF and PI3K, possibly through the cross-inhibition of 4E binding protein 1 and S6 protein.

Rapid Development of Hypertension and Proteinuria with Cediranib, an Oral Vascular Endothelial Growth Factor Receptor Inhibitor

Hypertension and proteinuria are common but poorly understood renal toxicities of vascular endothelial growth factor (VEGF) receptor signaling pathway inhibitors. In this phase II study of cediranib (AZD2171) for recurrent epithelial ovarian cancer, the time course and severity of BP changes and proteinuria were characterized. 46 women ages 41 to 77 years were treated with cediranib. 26% had baseline hypertension. Twice-daily BP was recorded. Urinalyses were performed every 2 weeks, and in some patients proteinuria was further quantified. 31 women (67%) developed hypertension by day 3; 87% by the end of the study. 43% developed grade > or =3 hypertension. Mean systolic BP increase over 3 days was 18 mmHg. Women above the mean age (> or =57 years) had a larger rise in systolic BP by day 3 (15.9 versus 7.0 mmHg). 14 women developed proteinuria. There was a dose response (45 versus 30 mg daily). Proteinuria also developed rapidly, with 7 of 14 women developing proteinuria within 2 weeks. Only 7 of 20 women who developed grade 3 hypertension developed proteinuria. Cediranib induced a rapid but variable rise in BP within 3 days of initiation in most patients. Proteinuria was common and also developed rapidly. The rapid development of hypertension suggests that acute inhibition of VEGF-dependent vasodilation might explain the BP rise with VEGF inhibitors. Clinicians must be vigilant in early detection and management of toxicities of this expanding drug class, especially in older patients.

Stimulation of sphingosine 1-phosphate signaling as an alveolar cell survival strategy in emphysema.

Vascular endothelial growth factor receptor (VEGFR) inhibition increases ceramides in lung structural cells of the alveolus, initiating apoptosis and alveolar destruction morphologically resembling emphysema. The effects of increased endogenous ceramides could be offset by sphingosine 1-phosphate (S1P), a prosurvival by-product of ceramide metabolism. The aims of our work were to investigate the sphingosine-S1P-S1P receptor axis in the VEGFR inhibition model of emphysema and to determine whether stimulation of S1P signaling is sufficient to functionally antagonize alveolar space enlargement. Concurrent to VEGFR blockade in mice, S1P signaling augmentation was achieved via treatment with the S1P precursor sphingosine, S1P agonist FTY720, or S1P receptor-1 (S1PR1) agonist SEW2871. Outcomes included sphingosine kinase-1 RNA expression and activity, sphingolipid measurements by combined liquid chromatography-tandem mass spectrometry, immunoblotting for prosurvival signaling pathways, caspase-3 activity and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assays, and airspace morphometry. Consistent with previously reported de novo activation of ceramide synthesis, VEGFR inhibition triggered increases in lung ceramides, dihydroceramides, and dihydrosphingosine, but did not alter sphingosine kinase activity or S1P levels. Administration of sphingosine decreased the ceramide-to-S1P ratio in the lung and inhibited alveolar space enlargement, along with activation of prosurvival signaling pathways and decreased lung parenchyma cell apoptosis. Sphingosine significantly opposed ceramide-induced apoptosis in cultured lung endothelial cells, but not epithelial cells. FTY720 or SEW2871 recapitulated the protective effects of sphingosine on airspace enlargement concomitant with attenuation of VEGFR inhibitor-induced lung apoptosis. Strategies aimed at augmenting the S1P-S1PR1 signaling may be effective in ameliorating the apoptotic mechanisms of emphysema development.

Induction of E-Cadherin in Lung Cancer and Interaction with Growth Suppression by Histone Deacetylase Inhibition

Loss of E-cadherin confers a poor prognosis in lung cancer patients and is associated with in vitro resistance to endothelial growth factor receptor inhibitors. Zinc finger E box-binding homeobox (ZEB)-1, the predominant transcriptional suppressor of E-cadherin in lung tumor lines, recruits histone deacetylases (HDACs) as co-repressors. NSCLC cell lines were treated with HDAC inhibitors and analyzed for E-cadherin induction, growth inhibition and apoptosis. National Cancer Institute-H157 cells expressing ectopic E-cadherin were tested for tumorigenicity in murine xenografts. We found that treatment with MS-275, compared to vorinostat (SAHA), valproic acid or trichostatin A, was most effective in E-cadherin up-regulation and persistence in non-small cell lung cancers. As with other tumor types and HDAC inhibitors, MS-275 inhibited growth and induced apoptosis. Importantly, blocking E-cadherin induction by short hairpin RNA resulted in less inhibition by MS-275, implicating the epithelial to mesenchymal phenotype process as a contributing factor. In contrast to H460 and H661, H157 cells were resistant to E-cadherin up-regulation by HDAC inhibitors. However, E-cadherin was restored, in a synergistic manner, by combined knockdown of ZEB-1 and ZEB-2. In addition, H157 cells stably transfected with E-cadherin were markedly attenuated in their tumor forming ability. Lastly, combining MS-275 with the microtubule stabilizing agent, paclitaxel, or 17-(allylamino)-17-demethoxygeldanamycin, a heat shock protein 90 inhibitor, resulted in synergistic growth inhibition. Since MS-275 has no reported activity against HDAC6, which regulates both microtubule and heat shock protein 90 functions, other mechanisms of synergy are anticipated. These results support the role of ZEB proteins and HDAC inhibitors in the pathogenesis and treatment of lung cancer.

Sorafenib, a dual Raf kinase/vascular endothelial growth factor receptor inhibitor has significant anti-myeloma activity and synergizes with common anti-myeloma drugs

Multiple myeloma is characterized by increased bone marrow neovascularization driven in part by vascular endothelial growth factor (VEGF). In addition, the Ras/Raf/MEK/ERK pathway is critical for the proliferation of myeloma cells and is often upregulated. Sorafenib (Nexavar) is a novel multi-kinase inhibitor that acts predominantly through inhibition of Raf-kinase and VEGF receptor 2, offering the potential for targeting two important aspects of disease biology. In in vitro studies, sorafenib-induced cytotoxicity in MM cell lines as well as freshly isolated patient myeloma cells. It retained its activity against MM cells in co-culture with stromal cells or with interleukin-6, VEGF or IGF; conditions mimicking tumor microenvironment. Examination of cellular signaling pathways showed downregulation of Mcl1 as well as decreased phosphorylation of the STAT3 and MEK/ERK, as potential mechanisms of its anti-tumor effect. Sorafenib induces reciprocal upregulation of Akt phosphorylation; and simultaneous inhibition of downstream mTOR with rapamycin leads to synergistic effects. Sorafenib also synergizes with drugs such as proteasome inhibitors and steroids. In a human in vitro angiogenesis assay, sorafenib showed potent anti-angiogenic activity. Sorafenib, through multiple mechanisms exerts potent anti-myeloma activity and these results favor further clinical evaluation and development of novel sorafenib combinations.

3033 Health-related quality of life (HRQL) of family members and cancer patients undergoing chemotherapy – final results

Targeted anticancer therapies, unlike the traditional cytotoxic chemotherapies which lead to systemic toxicities, frequently cause cutaneous adverse events that are symptomatic and manifest in cosmetically sensitive areas. The most common dermatologic toxicities related to epidermal growth factor receptor (EGFR) inhibitors are papulopustular eruption, xerosis, pruritus and paronychia. Vascular endothelial growth factor receptor (VEGFR) inhibitors usually cause hand-foot skin reaction. Reports of dermatologic side effects such as abnormalities of hair growth and mucosal changes also increased.These events may contribute to poor adherence, dose interruption and discontinuation of the regimens. In addition, psychosocial discomfort causing reduction in the quality of life does occur. However, the presence and severity of cutaneous adverse events has shown to have positive correlation with treatment response.The management of these side effects can be categorized into prophylaxis and reactive treatment. Systemic antibiotics and topical corticosteroid could possibly prevent or alleviate symptoms caused by EGFR inhibitors. The prevention of sun exposure is recommended to all patients on targeted therapy, and emollients and lubricants can be used to relieve and improve the hand-foot skin reaction.

Syngeneic Bone Marrow Mononuclear Cells Improve Pulmonary Arterial Hypertension Through Vascular Endothelial Growth Factor Upregulation

We investigated the effects and possible mechanism of syngeneic bone marrow mononuclear cell (BM-MNC) transplantation on pulmonary arterial hypertension induced by monocrotaline. Monocrotaline (80 mg/kg body weight) was administrated to C57BL/6 mice, and pulmonary arterial hypertension was induced 4 weeks later. Bone marrow mononuclear cells harvested from syngeneic donor mice were injected intravenously into those mice 4 weeks after monocrotaline administration. The ratio of right ventricular to septum plus left ventricular weight, the number of small pulmonary arteries, and medial thickness of pulmonary arteries were measured. Western immunoblotting of the lung tissue was performed to observe vascular endothelial growth factor and its receptor expression 1 week after BM-MNC transplantation. Vascular endothelial growth factor receptor-2 inhibitor was administered to pulmonary arterial hypertension mice simultaneously with BM-MNC transplantation. The ratio of right ventricular to septum plus left ventricular weight increased, the number of pulmonary arteries decreased, and medial thickness increased significantly 4 weeks after monocrotaline injection compared with those of vehicle-injected mice. These indices of monocrotaline-injected mice improved significantly 4 weeks after BM-MNC transplantation compared with those of mice at 8 weeks after monocrotaline injection (0.22 +/- 0.02 versus 0.31 +/- 0.02; 17.1 +/- 2.6 versus 8.2 +/- 1.7; 7.7% +/- 2.2% versus 20% +/- 2.1%, respectively; p < 0.01). However, BM-MNCs were not incorporated into the lung at 1 week after transplantation, and significant vascular endothelial growth factor upregulation and without receptor expression was observed in lung tissue 1 week after transplantation. Improvement of pulmonary arterial hypertension was inhibited by simultaneous administration of vascular endothelial growth factor receptor-2 inhibitor with BM-MNC transplantation. These results indicate that syngeneic BM-MNC transplantation improves monocrotaline-induced pulmonary arterial hypertension by favorable pulmonary artery remodeling through vascular endothelial growth factor upregulation.

An open letter to the FDA and other regulatory agencies: Preclinical drug development must consider the impact on metastasis.

Recently, two landmark reports on antiangiogenic therapy were published: Paez-Ribes and colleagues (1) and Ebos and colleagues (2). The Board of the Metastasis Research Society (MRS) congratulates the authors for their informative articles (1, 2) that help to explain the puzzle of why antiangiogenic agents have had a relatively minor or no significant impact on patient survival. Using four model systems and several different strategies, these researchers showed that inhibition of angiogenesis reduced primary tumor growth and microvessel density in keeping with many earlier reports, but strikingly, accelerated invasion and metastasis.It is well known that the majority of cancer patients who succumb to their disease do so following development of incurable metastatic disease. However, the emphasis on preclinical testing of new compounds still rests on the responses of subcutaneous or orthotopic primary tumors from various mouse models over a relatively short time frame. The reports of both Ebos and colleagues (2) and Paez-Ribes and colleagues (1) elegantly reveal the limitations of this approach, at least with regard to targeting of angiogenesis.It is important to reflect on the fact that other drugs and preclinical compounds, when tested for both primary tumor size and metastasis, have exhibited discordant results. For example, cyclophosphamide inhibited primary lung adenocarcinoma but promoted metastasis to the lung and liver (3), and the Hsp90 inhibitor 17-AAG inhibited primary breast cancer but promoted metastasis to the bone (4). Vandetanib, a vascular endothelial growth factor receptor (VEGFR) inhibitor, reduced the growth of primary fibrosarcomas, but had no effect on their metastasis (5). Interestingly, a number of agents have been shown to exert no significant effects on primary tumor size, but still had the capacity to inhibit metastasis (6–13). Given the fact that primary tumors can often be controlled using conventional therapies, could agents that act specifically on the process of metastasis be more likely to increase long term patient survival?On the basis of these new reports and earlier data, we propose that preclinical drug development in general—and not only for antiangiogenic compounds—be required to show efficacy in at least one metastasis model, preferably incorporating metastasis from an orthotopic site. Robust models are available with relevant histology (i.e., similar to human) and imaging for quantification. The U.S. Food and Drug Administration (FDA), other regulatory agencies and their clients, and patients considering entrance into a clinical trial, currently have access to detailed information such as weight loss in mice exposed to a compound. In our opinion, it is just as important to reveal information on the capacity of a new compound to accelerate or inhibit invasion and tumor metastasis.No potential conflicts of interest were disclosed.

Dual epidermal growth factor receptor and vascular endothelial growth factor receptor inhibition with vandetanib sensitizes bladder cancer cells to cisplatin in a dose‐ and sequence‐dependent manner

To investigate the activity of the combination of vandetanib and cytotoxic agents using in vitro models of bladder cancer, as modern chemotherapy regimens are built around cisplatin, with gemcitabine or a taxane such as docetaxel also commonly added in combination for the treatment of advanced bladder cancer. Human bladder cancer cells HTB3, HT1376, J82, RT4, CRL1749, T24, SUP and HTB9 were cultured. The activity of gefitinib (ZD1839) and vandetanib (ZD6474) was assessed in these eight bladder cancer cell lines with a tetrazolium-based assay of cell viability. RT4 bladder cancer cells, determined to have moderate cisplatin resistance and also moderate sensitivity to vandetanib, were treated with vandetanib and cisplatin. RT4 and T24 cells were treated with six different regimens. The apoptosis and cell-cycle analysis were studied by flow cytometry. Expression of p21 and p27 was detected by Western blotting. Fluorescence in situ hybridization (FISH) analysis of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 was performed for all cell lines. At equal concentrations, vandetanib was a more potent inhibitor of cell viability, compared to gefitinib. At vandetanib concentrations of <or=2 microM, the combination with cisplatin was synergistic, especially in the treatment sequence of cisplatin followed by vandetanib, and additive with vandetanib followed by cisplatin. An analysis of the cell-cycle distribution showed that vandetanib treatment induced G1 arrest at high concentrations, but not at lower concentrations. High-concentration treatment was associated with increased levels of the cyclin-dependent kinase p27. FISH analysis showed that there was a low level of genomic gain, and no gene amplification. Mutational analysis of exons 18, 19, and 21 of EGFR in each cell line revealed no mutation. Vandetanib has synergistic activity when given at low concentration with cytotoxic chemotherapy. The addition of vandetanib to cisplatin-based chemotherapy regimens merits further study.

Angiogenesis inhibitor DC101 delays growth of intracerebral glioblastoma but induces morbidity when combined with irradiation

The combination of irradiation with angiogenic inhibition is increasingly being investigated for treatment of glioblastoma multiforme (GBM). We investigated whether vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitor DC101 affects morbidity and tumor growth in irradiated and non-irradiated intracerebral GBM-bearing mice, controlled with sham treatments. End-points were toxicity, morbidity and histology. Irradiation either or not combined, reduced tumor size strongly, whereas DC101 mono-treatment reduced tumor size by 64%. Irradiation delayed morbidity from 5.8 weeks in sham-treated mice to 10.3 weeks. Morbidity after combined treatment occurred after 5.9 weeks. Treatment with angiogenesis inhibitor DC101 delays tumor growth but it induces morbidity, by itself or combined with irradiation.

Vascular endothelial growth factor receptor inhibitor enhances dietary salt-induced hypertension in Sprague-Dawley rats

Clinical evidence links the inhibition of VEGF to hypertension. However, the mechanisms by which VEGF affects the pathogenesis of hypertension remain in question. We determined 1) whether administration of VEGF receptor inhibitor SU5416 enhances dietary salt-induced hypertension in Sprague-Dawley (SD) rats, and 2) whether VEGF or SU5416 directly affects proliferation of cultured human renal proximal tubular epithelial cells (HRPTEC) and endothelial nitric oxide synthase (eNOS) expression in cultured human glomerular microvessel endothelial cells (HGMEC). Ten 10-wk-old male SD rats received a high sodium diet (HS; 8%) and the other 10 SD rats received a normal sodium diet (NS; 0.5%) for 4 wks. After 2 wks of the dietary program, five rats were administered with SU5416 at 10 mg x kg(-1) x day(-1) ip or DMSO (vehicle) for 14 days in HS and NS groups. Mean arterial pressure was significantly higher in rats treated with SU5416, as opposed to those treated with DMSO and fed with HS for 4 wk (157.6 +/- 3.9 vs. 125.9 +/- 4.3 mmHg, P < 0.01). Increased proteinuria and albuminuria were associated with marked renal histological abnormalities in HS group with SU5416 administration, compared with those in the vehicle HS group. 3H-thymidine incorporation assay showed that SU5416 blocked the actions of both exogenous and endogenous VEGF on the proliferation of HRPTEC. VEGF (10 ng/ml) significantly increased eNOS protein levels by 29% in cultured HGMEC, but its action was completely abolished by SU5416. These results suggest that VEGF receptor inhibition enhances dietary salt-induced hypertension and kidney injury, possibly by direct damage on renal cells and decreasing NO production by eNOS.

Phase I pharmacokinetic study of the vascular endothelial growth factor receptor tyrosine kinase inhibitor vatalanib (PTK787) plus imatinib and hydroxyurea for malignant glioma

This study determined the maximum tolerated dose (MTD) and dose-limiting toxicities (DLT) of the oral vascular endothelial growth factor receptor (VEGFR) inhibitor, vatalanib, when administered with imatinib and hydroxyurea on a continuous daily schedule among recurrent malignant glioma patients. All patients received 500 mg of hydroxyurea twice daily. Imatinib was dosed at 400 mg per day for patients not taking enzyme-inducing antiepileptic drugs (EIAEDs; stratum A) and at 500 mg twice-a-day for patients taking EIAEDs (stratum B). Vatalanib was escalated from 500 mg to 1250 mg twice daily in successive cohorts, independently for each stratum. Pharmacokinetics of each drug were assessed. A total of 37 recurrent patients, 34 (92%) with glioblastoma and 3 (8%) with grade 3 malignant glioma, were enrolled. Nineteen patients (51%) were taking EIAEDs. The MTD of vatalanib for all patients was 1000 mg twice-a-day. DLTs were hematologic, gastrointestinal, renal, and hepatic. No patients developed intracranial hemorrhage. Concurrent administration of imatinib and hydroxyurea did not affect vatalanib exposure, but EIAEDs decreased vatalanib and imatinib plasma exposures. Vatalanib doses up to 1000 mg twice-a-day combined with imatinib and hydroxyurea were well tolerated. Strategies to target tumor blood vessel endothelial cells and pericytes by inhibiting VEGFR and platelet-derived growth factor, respectively, were safe among recurrent malignant glioma patients and may enhance antiangiogenesis activity.