Vatalanib

Vatalanib is a novel and potent inhibitor of VEGFR with IC50 value of 77 nM, 27 nM and 37 nM for VEGFR-1 (Flt-1), VEGFR-2 (FLK-1) and VEGFR-2 (KDR), respectively [1].
The vascular endothelial growth factor receptors (VEGFRs) are tyrosine kinases and are receptors for VEGF. VEGF acts as a key factor in pathological situations that involve in pathological situations that involve enhancing vascular permeability as well as neovascularization [1].
In CHO and HUVECs cells transfected with the KDR receptor, Vatalanib inhibited the VEGF-induced phosphorylation of KDR with an IC50 of 34 nM and 17 nM for the CHO and HUVECs cells, respectively. Also, Vatalanib inhibited thymidine incorporation induced by VEGF with IC50 value of 7.1 nM in HUVECs cells. Vatalanib inhibited VEGF-induced endothelial cell proliferation in a dose-dependant way [1].
In a growth factor implant mice model, Vatalanib (12.5, 25 or 50 mg/kg, 6 days) inhibited the angiogenic response around the implant induced by VEGF and PDGF [1]. In a xenograft mouse model, treatment mice with Vatalanib through gastric tube daily caused tumor inhibition rate of 76% [2].  
References:
[1]. Wood JM, Bold G, Buchdunger E, et al. PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration. Cancer Res, 2000, 60(8): 2178-2189.
[2]. Paesler J, Gehrke I, Gandhirajan RK, et al. The vascular endothelial growth factor receptor tyrosine kinase inhibitors vatalanib and pazopanib potently induce apoptosis in chronic lymphocytic leukemia cells in vitro and in vivo. Clin Cancer Res, 2010, 16(13): 3390-3398.

Combination of vatalanib and a 20-HETE synthesis inhibitor results in decreased tumor growth in an animal model of human glioma.[Pubmed:27022280]

Onco Targets Ther. 2016 Mar 9;9:1205-19.

BACKGROUND: Due to the hypervascular nature of glioblastoma (GBM), antiangiogenic treatments, such as Vatalanib, have been added as an adjuvant to control angiogenesis and tumor growth. However, evidence of progressive tumor growth and resistance to antiangiogenic treatment has been observed. To counter the unwanted effect of Vatalanib on GBM growth, we have added a new agent known as N-hydroxy-N'-(4-butyl-2 methylphenyl)formamidine (HET0016), which is a selective inhibitor of 20-hydroxyeicosatetraenoic acid (20-HETE) synthesis. The aims of the studies were to determine 1) whether the addition of HET0016 can attenuate the unwanted effect of Vatalanib on tumor growth and 2) whether the treatment schedule would have a crucial impact on controlling GBM. METHODS: U251 human glioma cells (4x10(5)) were implanted orthotopically. Two different treatment schedules were investigated. Treatment starting on day 8 (8-21 days treatment) of the tumor implantation was to mimic treatment following detection of tumor, where tumor would have hypoxic microenvironment and well-developed neovascularization. Drug treatment starting on the same day of tumor implantation (0-21 days treatment) was to mimic cases following radiation therapy or surgery. There were four different treatment groups: vehicle, Vatalanib (oral treatment 50 mg/kg/d), HET0016 (intraperitoneal treatment 10 mg/kg/d), and combined (Vatalanib and HET0016). Following scheduled treatments, all animals underwent magnetic resonance imaging on day 22, followed by euthanasia. Brain specimens were equally divided for immunohistochemistry and protein array analysis. RESULTS: Our results demonstrated a trend that HET0016, alone or in combination with Vatalanib, is capable of controlling the tumor growth compared with that of Vatalanib alone, indicating attenuation of the unwanted effect of Vatalanib. When both Vatalanib and HET0016 were administered together on the day of the tumor implantation (0-21 days treatment), tumor volume, tumor blood volume, permeability, extravascular and extracellular space volume, tumor cell proliferation, and cell migration were decreased compared with that of the vehicle-treated group. CONCLUSION: HET0016 is capable of controlling tumor growth and migration, but these effects are dependent on the timing of drug administration. The addition of HET0016 to Vatalanib may attenuate the unwanted effect of Vatalanib.

Vatalanib sensitizes ABCB1 and ABCG2-overexpressing multidrug resistant colon cancer cells to chemotherapy under hypoxia.[Pubmed:26206183]

Biochem Pharmacol. 2015 Sep 1;97(1):27-37.

Cancer microenvironment is characterized by significantly lower oxygen concentration. This hypoxic condition is known to reduce drug responsiveness to cancer chemotherapy via multiple mechanisms, among which the upregulation of the ATP-binding cassette (ABC) efflux transporters confers resistance to a wide variety of structurally unrelated anticancer drugs. Vatalanib (PTK787/ZK22584) is a multitargeted tyrosine kinase inhibitor for all isoforms of VEGFR, PDGFR and c-Kit, which exhibit potent anticancer activity in vitro and in vivo. We investigated the potentiation effect of Vatalanib on the anticancer activity of conventional cytotoxic drugs in colon cancer cell lines under both normoxic and hypoxic conditions. Mechanistically, Vatalanib was found to inhibit ABCG2 and ABCB1 efflux activity, presumably by acting as a competitive inhibitor and interfering with their ATPase activity. Under hypoxic growth condition, ABCG2 and ABCB1-overexpressing cells sorted out by FACS technique as side population (SP) were found to be significantly more responsive to SN-38 (ABCG2 and ABCB1 substrate anticancer drug) in the presence of Vatalanib. The anchorage independent soft agar colony formation capacity of the SP cells was remarkably reduced upon treatment with a combination of SN-38 and Vatalanib, compared to SN-38 alone. However, Vatalanib, at concentrations that produced the circumvention of the transporters-mediated resistance, did not appreciably alter ABCG2/ABCB1 mRNA or protein expression levels or the phosphorylation of Akt and extracellular signal-regulated kinase (ERK1/2). Our study thus advocates the further investigation of Vatalanib for use in combination chemotherapy to eradicate drug-resistant cancer cells under hypoxia.

2D and 3D similarity landscape analysis identifies PARP as a novel off-target for the drug Vatalanib.[Pubmed:26403354]

BMC Bioinformatics. 2015 Sep 24;16:308.

BACKGROUND: Searching for two-dimensional (2D) structural similarities is a useful tool to identify new active compounds in drug-discovery programs. However, as 2D similarity measures neglect important structural and functional features, similarity by 2D might be underestimated. In the present study, we used combined 2D and three-dimensional (3D) similarity comparisons to reveal possible new functions and/or side-effects of known bioactive compounds. RESULTS: We utilised more than 10,000 compounds from the SuperTarget database with known inhibition values for twelve different anti-cancer targets. We performed all-against-all comparisons resulting in 2D similarity landscapes. Among the regions with low 2D similarity scores are inhibitors of vascular endothelial growth factor receptor (VEGFR) and inhibitors of poly ADP-ribose polymerase (PARP). To demonstrate that 3D landscape comparison can identify similarities, which are untraceable in 2D similarity comparisons, we analysed this region in more detail. This 3D analysis showed the unexpected structural similarity between inhibitors of VEGFR and inhibitors of PARP. Among the VEGFR inhibitors that show similarities to PARP inhibitors was Vatalanib, an oral "multi-targeted" small molecule protein kinase inhibitor being studied in phase-III clinical trials in cancer therapy. An in silico docking simulation and an in vitro HT universal colorimetric PARP assay confirmed that the VEGFR inhibitor Vatalanib exhibits off-target activity as a PARP inhibitor, broadening its mode of action. CONCLUSION: In contrast to the 2D-similarity search, the 3D-similarity landscape comparison identifies new functions and side effects of the known VEGFR inhibitor Vatalanib.

Data showing the circumvention of oxaliplatin resistance by vatalanib in colon cancer.[Pubmed:27014726]

Data Brief. 2016 Mar 2;7:437-44.

We have recently reported that Vatalanib, an orally active small molecule multi-tyrosine kinase inhibitor (Hess-Stumpp et al., 2005 [1]), can sensitize multidrug resistant (MDR) colon cancer cells to chemotherapy under hypoxia by inhibiting two MDR transporters ABCB1 and ABCG2 (To et al., 2015 [2]). This data article describes the possible circumvention of resistance to specifically platinum (Pt)-based anticancer drugs by Vatalanib via inhibition of two other efflux transporters ABCC2 and ATP7A. Data from the flow cytometric transporter efflux assay showed specific inhibition of ABCC2 activity by Vatalanib in stable transfected cells and ABCC2-overexpressing oxaliplatin-resistant colon cancer cells HCT116/Oxa. We also performed the transporter ABCC2 ATPase assay and showed an increase in ATP hydrolysis by ABCC2 in the presence of Vatalanib. ATP7A mRNA expression was also shown to be upregulated in HCT116/Oxa cells. Vatalanib was shown to suppress this upregulated ATP7A expression. Data from the cellular Pt accumulation assay showed a lower Pt accumulation in HCT116/Oxa cells than the parental sensitive HCT116 cells. Vatalanib was shown to increase cellular Pt accumulation in a concentration-dependent manner. Combination of oxaliplatin and Vatalanib was shown to restore the suppressed apoptosis in HCT116/Oxa cells.