Tivozanib: current status and future directions in the treatment of solid tumors

Intuitive repositioning of an anti-depressant drug in combination with tivozanib: precision medicine for breast cancer therapy

Despite the existing therapies and lack of receptors such as HER-2, estrogen receptor and progesterone receptor, triple-negative breast cancer is one of the most aggressive subtypes of breast cancer. TNBCs are known for their highly aggressive metastatic behavior and typically migrate to brain and bone for secondary site propagation. Many diseases share similar molecular pathology exposing new avenues in molecular signaling for engendering innovative therapies. Generation of newer therapies and novel drugs are time consuming associated with very high resources. In order to provide personalized or precision medicine, drug repositioning will contribute in a cost-effective manner. In our study, we have repurposed and used a neoteric combination of two drug molecules namely, fluvoxamine and tivozanib, to target triple-negative breast cancer growth and progression. Our combination regime significantly targets two diverse but significant pathways in TNBCs. Subsequent analysis on migratory, invasive, and angiogenic properties showed the significance of our repurposed drug combination. Molecular array data resulted in identifying the specific and key players participating in cancer progression when the drug combination was used. The innovative combination of fluvoxamine and tivozanib reiterates the use of drug repositioning for precision medicine and subsequent companion diagnostic development.

Design, synthesis, and biological evaluation of polo-like kinase 1/eukaryotic elongation factor 2 kinase (PLK1/EEF2K) dual inhibitors for regulating breast cancer cells apoptosis and autophagy

Both PLK1 and EEF2K are serine⁄threonine kinases that play important roles in the proliferation and programmed cell death of various types of cancer. They are highly expressed in breast cancer tissues. Based on the multiple-complexes generated pharmacophore models of PLK1 and homology models of EEF2K, the integrated virtual screening is performed to discover novel PLK1/EEF2K dual inhibitors. The top ten hit compounds are selected and tested in vitro, and five of them display PLK1 and EEF2K inhibition in vitro. Based on the docking modes of the most potent hit compound, a series of derivatives are synthesized, characterized and biological assayed on the PLK1, EEF2K as well as breast cancer cell proliferation models. Compound 18i with satisfied inhibitory potency are shifted to molecular mechanism studies contained molecular dynamics simulations, cell cycles, apoptosis and autophagy assays. Our results suggested that these novel PLK1/EEF2K dual inhibitors can be used as lead compounds for further development breast cancer chemotherapy.

Targeted Therapies in Elderly Patients with Metastatic Colorectal Cancer: A Review of the Evidence

Metastatic colorectal cancer (mCRC) is the third leading cause of cancer deaths worldwide. As the population of the western world ages, the incidence of colorectal tumours among elderly patients is increasing and consequently so is the demand for treatments for elderly patients. Unfortunately, elderly patients (≥65 years) often go untreated and they are also under-represented in clinical trials. Yet there is some evidence suggesting that 'fit' elderly patients have similar outcomes and tolerance to chemotherapy treatment to their younger counterparts (although the definition of fitness in the elderly population is still a matter of debate). The evidence supporting the administration of new targeted therapies in patients older than 65 years is scarce and more research is needed. In this paper, we review all the available data concerning the use of targeted therapies for mCRC in patients older than 65 years of age and discuss the differences between this age subgroup and younger patients.

Biological evaluation, docking and molecular dynamic simulation of some novel diaryl urea derivatives bearing quinoxalindione moiety

In this study a series of diarylurea derivatives containing quinoxalindione group were biologically evaluated for their cytotoxic activities using MTT assay against MCF-7 and HepG2 cell lines. Antibacterial activities of these compounds were also evaluated by Microplate Alamar Blue Assay (MABA) against three Gram-negative (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi), three Gram-positive (Staphylococcus aureus, Bacillus subtilis and Listeria monocitogenes) and one yeast-like fungus (Candida albicans) strain. Furthermore, molecular docking was carried out to study the binding pattern of the compounds to the active site of B-RAF kinase (PDB code: 1UWH). Molecular dynamics simulation was performed on the best ligand (16e) to investigate the ligand binding dynamics in the physiological environment. Cytotoxic evaluation revealed the most prominent cytotoxicity for 6 compounds with IC₅₀ values of 10-18 μM against two mentioned cell lines. None of the synthesized compounds showed significant antimicrobial activity. The obtained results of the molecular docking study showed that all compounds fitted in the binding site of enzyme with binding energy range of -11.22 to -12.69 kcal/mol vs sorafenib binding energy -11.74 kcal/mol as the lead compound. Molecular dynamic simulation indicated that the binding of ligand (16e) was stable in the active site of B-RAF during the simulation.

BATON-CRC: A Phase II Randomized Trial Comparing Tivozanib Plus mFOLFOX6 with Bevacizumab Plus mFOLFOX6 in Stage IV Metastatic Colorectal Cancer

PURPOSE

Tivozanib, a selective inhibitor of VEGFR-1, -2, and -3, plus mFOLFOX6 in an advanced gastrointestinal cancer phase Ib study had encouraging antineoplastic activity and a tolerable safety profile. This randomized, open-label, phase II trial of tivozanib/mFOLFOX6 versus bevacizumab/mFOLFOX6 in patients with previously untreated metastatic colorectal cancer (mCRC) evaluated tivozanib activity versus bevacizumab.

EXPERIMENTAL DESIGN

Treatment-naïve patients received mFOLFOX6 every 2 weeks of each 28-day cycle plus either tivozanib orally 1.5 mg once daily for 21 days or bevacizumab intravenously 5 mg/kg every 2 weeks. Investigator-assessed progression-free survival (PFS) was the primary endpoint; some secondary endpoints included safety, overall survival, overall response rate (ORR), duration of response, time to treatment failure, and biomarker subgroup analyses.

RESULTS

A prespecified interim futility analysis demonstrated that the futility boundary for superiority of tivozanib/mFOLFOX6 over bevacizumab/mFOLFOX6 for PFS in the intent-to-treat population was crossed; median PFS was 9.4 versus 10.7 months [HR = 1.091; confidence interval (CI), 0.693-1.718; P = 0.706]. Tivozanib/mFOLFOX6 resulted in PFS and ORR comparable with bevacizumab/mFOLFOX6; interim analyses biomarker results revealed no significant PFS association. Post hoc final analyses demonstrated a potential difference in tivozanib-specific PFS in patients with low neuropilin-1 (NRP-1), but not in patients with high NRP-1. Tivozanib/mFOLFOX6 was tolerable and adverse events were comparable with both bevacizumab/mFOLFOX6 and previous tivozanib studies.

CONCLUSIONS

The efficacy of tivozanib/mFOLFOX6 was comparable with but not superior to bevacizumab/mFOLFOX6 in patients with previously untreated mCRC. Since data from the prespecified interim analysis did not demonstrate superiority, this resulted in discontinuation of the study. The safety and tolerability profile of tivozanib/mFOLFOX6 was consistent with other tivozanib trials. NRP-1 is a potential predictive biomarker for tivozanib activity, but these results require further validation. Clin Cancer Res; 22(20); 5058-67. ©2016 AACR.

Tivozanib: status of development

Tivozanib is a potent and highly specific orally available, tyrosine kinase inhibitor that targets vascular endothelial growth factor (VEGF) receptor-1, VEGF receptor-2, and VEGF receptor-3 at very low concentrations with a long half-life (4 days). After its promising activity in xenograft and preclinical models, tivozanib was evaluated in early phase clinical trials in various solid tumors. The phase III trial (TIVO-1) compared tivozanib with sorafenib in metastatic clear cell renal cell carcinoma (RCC). Because of detrimental overall survival (OS), Oncology Drug Advisory Committee (ODAC) voted against its approval in RCC. Tivozanib is also being evaluated in various other solid tumors like breast, gastrointestinal cancers, hepatocellular cancer, sarcomas, and gynecological cancer. In BATON-CRC trial, low-serum neuropilin-1 (NRP-1) levels were associated with better progression-free survival (PFS) in patients treated with tivozanib. The NRP-1 will be evaluated as a biomarker for tivozanib response in future clinical trials. Ongoing clinical trial will further characterize activity of tivozanib in hepatocellular carcinoma, sarcomas, and gynecologic cancers.

Comparison of effects of anti-angiogenic agents in the zebrafish efficacy-toxicity model for translational anti-angiogenic drug discovery

Background

Anti-angiogenic therapy in certain cancers has been associated with improved control of tumor growth and metastasis. Development of anti-angiogenic agents has, however, been saddled with higher attrition rate due to suboptimal efficacy, narrow therapeutic windows, or development of organ-specific toxicities. The aim of this study was to evaluate the translational ability of the zebrafish efficacy–toxicity model to stratify anti-angiogenic agents based on efficacy, therapeutic windows, and off-target effects to streamline the compound selection process in anti-angiogenic discovery.

Methods

The embryonic model of zebrafish was employed for studying angiogenesis and toxicity. The zebrafish were treated with anti-angiogenic compounds to evaluate their effects on angiogenesis and zebrafish-toxicity parameters. Angiogenesis was measured by scoring the development of subintestinal vessels. Toxicity was evaluated by calculating the median lethal concentration, the lowest observed effect concentration, and gross morphological changes. Results of efficacy and toxicity were used to predict the therapeutic window.

Results

In alignment with the clinical outcomes, the zebrafish assays demonstrated that vascular endothelial growth factor receptor (VEGFR) inhibitors are the most potent anti-angiogenic agents, followed by multikinase inhibitors and inhibitors of endothelial cell proliferation. The toxicity assays reported cardiac phenotype in zebrafish treated with VEGFR inhibitors and multikinase inhibitors with VEGFR activity suggestive of cardiotoxic potential of these compounds. Several other pathological features were reported for multikinase inhibitors suggestive of off-target effects. The predicted therapeutic window was translational with the clinical trial outcomes of the anti-angiogenic agents. The zebrafish efficacy–toxicity approach could stratify anti-angiogenic agents based on the mechanism of action and delineate chemical structure-driven biological activity of anti-angiogenic compounds.

Conclusion

The zebrafish efficacy–toxicity approach can be used as a predictive model for translational anti-angiogenic drug discovery to streamline compound selection, resulting in safer and efficacious anti-angiogenic agents entering the clinics.

Tivozanib reverses multidrug resistance mediated by ABCB1 (P-glycoprotein) and ABCG2 (BCRP)

AIM

This study aimed to investigate the mechanism of reversal of multidrug resistance mediated by ABC transporters with tivozanib (AV-951 and KRN-951). Tivozanib is a potent inhibitor of VEGF-1, -2 and -3 receptors.

MATERIALS & METHODS

ABCB1- and ABCG2-overexpressing cell lines were treated with respective substrate antineoplastic agents in the presence or absence of tivozanib.

RESULTS

The results indicate that tivozanib can significantly reverse ABCB1-mediated resistance to paclitaxel, vinblastine and colchicine, as well as ABCG2-mediated resistance to mitoxantrone, SN-38 and doxorubicin. Drug efflux assays showed that tivozanib increased the intracellular accumulation of substrates by inhibiting the ABCB1 and ABCG2 efflux activity. Furthermore, at a higher concentration, tivozanib inhibited the ATPase activity of both ABCB1 and ABCG2 and inhibited the photolabeling of ABCB1 or ABCG2.

CONCLUSION

We conclude that tivozanib at noncytotoxic concentrations has the previously unknown activity of reversing multidrug resistance mediated by ABCB1 and ABCG2 transporters.

A new age for vaccine therapy in renal cell carcinoma

Over the past several years, the dominant paradigm in drug development for metastatic renal cell carcinoma (mRCC) has been to more selectively and potently target moieties such as the vascular endothelial growth factor receptor. The effectiveness of this strategy appears to be nearing a plateau, however, underscoring the need for novel approaches. Vaccine-based therapies represent one such approach. Several distinct vaccines are currently being examined in mRCC, each using a distinct mechanism of action. For instance, the autologous dendritic cell vaccine AGS-003 uses patient-specific antigens derived from primary tumor tissue. In contrast, the poxvirus vaccine TG4010 produces an antigenic response to MUC1, a cell surface glycoprotein that reduces cell-cell interactions and thereby precludes contact inhibition. Other vaccines elicit a response to a broader spectrum of antigens-for instance, the vaccine IMA901 is based on 9 tumor-associated peptides identified from a novel biotechnology platform combining mass spectroscopy, microarray analysis of RNA expression, and immunogenicity assays. Herein, the current status of vaccine-based therapies for mRCC is described in detail. Furthermore, challenges to clinical implementation (eg, cost, optimal pairing with targeted agents, appropriate sequencing) are presented.

Tivozanib in the treatment of renal cell carcinoma

Renal cell carcinoma (RCC) is an aggressive malignancy compared to other urological malignancies and has been associated with poor responses to conventional cytotoxic chemotherapy. Interferon-α and interleukin-2 were previously utilized in a limited number of patients with good performance status due to toxicity and safety issues. Over the last decade, through advances in the understanding of the biology and pathology of RCC, the important role of vascular endothelial growth factor (VEGF) in RCC has been identified. Data from randomized trials have led to the approval of first-generation tyrosine kinase inhibitors (TKIs) sorafenib, sunitinib, and pazopanib; however, these agents inhibit a wide variety of kinase targets and are associated with a range of adverse effects. More recently, a new generation TKI, axitinib, has been approved by the US Food and Drug Administration. Tivozanib is a novel TKI, which is a potent inhibitor of VEGF-1, VEGF-2, VEGF-3, c-kit, and PDGR kinases, with a more restricted target spectrum. Phase II and III studies have demonstrated significant activity and a favorable safety profile as an initial targeted treatment for advanced RCC. This review examines the emerging data with tivozanib for the treatment of advanced RCC. Preclinical investigations as well as Phase I, II, and III data are examined; data on the comparative benefits of tivozanib are reviewed. Finally, we discuss the future potential of tivozanib in combination, biomarkers associated with tivozanib response, and acquisition of resistance and nonkidney cancer indications.