Phase Ib study of tivozanib (AV-951) in combination with temsirolimus in patients with renal cell carcinoma

The mTOR Signaling Pathway and mTOR Inhibitors in Cancer: Next-generation Inhibitors and Approaches

mTOR is a serine/threonine kinase that plays various roles in cell growth, proliferation, and metabolism. mTOR signaling in cancer becomes irregular. Therefore, drugs targeting mTOR have been developed. Although mTOR inhibitors rapamycin and rapamycin rapalogs (everolimus, rapamycin, temsirolimus, deforolimus, etc.) and new generation mTOR inhibitors (Rapalink, Dual PI3K/mTOR inhibitors, etc.) are used in cancer treatments, mTOR resistance mechanisms may inhibit the efficacy of these drugs. Therefore, new inhibition approaches are developed. Although these new inhibition approaches have not been widely investigated in cancer treatment, the use of nanoparticles has been evaluated as a new treatment option in a few types of cancer. This review outlines the functions of mTOR in the cancer process, its resistance mechanisms, and the efficiency of mTOR inhibitors in cancer treatment. Furthermore, it discusses the next-generation mTOR inhibitors and inhibition strategies created using nanoparticles. Since mTOR resistance mechanisms prevent the effects of mTOR inhibitors used in cancer treatments, new inhibition strategies should be developed. Inhibition approaches are created using nanoparticles, and one of them offers a promising treatment option with evidence supporting its effectiveness.

Etiology and Management of Dyslipidemia in Patients With Cancer

Patients with cancer are now living longer than ever before due to the growth and expansion of highly effective antineoplastic therapies. Many of these patients face additional health challenges, of which cardiovascular disease (CVD) is the leading contributor to morbidity and mortality. CVD and cancer share common biological mechanisms and risk factors, including lipid abnormalities. A better understanding of the relationship between lipid metabolism and cancer can reveal strategies for cancer prevention and CVD risk reduction. Several anticancer treatments adversely affect lipid levels, increasing triglycerides and/or LDL-cholesterol. The traditional CVD risk assessment tools do not include cancer-specific parameters and may underestimate the true long-term CVD risk in this patient population. Statins are the mainstay of therapy in both primary and secondary CVD prevention. The role of non-statin therapies, including ezetimibe, PCSK9 inhibitors, bempedoic acid and icosapent ethyl in the management of lipid disorders in patients with cancer remains largely unknown. A contemporary cancer patient needs a personalized comprehensive cardiovascular assessment, management of lipid abnormalities, and prevention of late CVD to achieve optimal overall outcomes.

Tivozanib, a highly potent and selective inhibitor of VEGF receptor tyrosine kinases, for the treatment of metastatic renal cell carcinoma

The VHL mutation-HIF upregulation-VEGF transcription sequence is the principal pathway in the development of renal cell carcinoma. Tyrosine kinase inhibitors target the VEGF receptors to inhibit further growth of renal cell carcinoma tumors. Tivozanib, originally named AV-951 and KRN-951, is a novel, orally bioavailable VEGF tyrosine kinase inhibitor that is selective for VEGF receptors 1, 2 and 3. Further, only picomolar concentrations of tivozanib are required to target these VEGF receptors and prevent phosphorylation; this potency prevents the debilitating side effects that occur with treatments whose mechanisms of action involve broad-spectrum tyrosine kinase inhibition. This review summarizes the growing body of evidence supporting tivozanib's efficacy and safety in the treatment of advanced renal cell carcinoma.

Tivozanib in renal cell carcinoma: a new approach to previously treated disease

Targeted therapies have been a mainstay of the renal cell carcinoma (RCC) treatment paradigm for the better part of two decades. Multikinase inhibitors of the vascular endothelial growth factor receptor tyrosine kinases (VEGF-TKIs) comprise nearly all targeted therapies in RCC, having been prospectively tested through large, multi-institutional phase III trials. Tivozanib is a VEGF-TKI with high selectivity for VEGF receptors 1–3. Tivozanib has been under investigation for nearly 15 years, with a robust portfolio of preclinical and clinical data. This review seeks to characterize tivozanib within the context of RCC by highlighting preclinical and early clinical trials alongside the phase III trials in RCC, TIVO-1, and TIVO-3. We also aim to explore further trials of tivozanib, whether in combination with other agents and/or in differing disease settings, while providing insight into the utility of tivozanib as a clinical tool for the management of RCC.

Tivozanib for the treatment of renal cell carcinoma: patient selection and perspectives

Tivozanib is an oral selective vascular endothelial growth factors receptor (VEGFR) tyrosine kinase inhibitor that is recently approved by the European Medicines Agency for the treatment of previously untreated patients with metastatic renal cell carcinoma (mRCC) as well as for those patients with disease progression during or after cytokine therapy. Nowadays, in first-line and second-line treatment of mRCC, there is an abundance of options, mainly consisting of VEGFR-directed tyrosinekinase inhibitors. This review focusses on the role of tivozanib with respect to patient selection and future perspectives in this fast-changing landscape.

mTOR Signaling in Cancer and mTOR Inhibitors in Solid Tumor Targeting Therapy

The mammalian or mechanistic target of rapamycin (mTOR) pathway plays a crucial role in regulation of cell survival, metabolism, growth and protein synthesis in response to upstream signals in both normal physiological and pathological conditions, especially in cancer. Aberrant mTOR signaling resulting from genetic alterations from different levels of the signal cascade is commonly observed in various types of cancers. Upon hyperactivation, mTOR signaling promotes cell proliferation and metabolism that contribute to tumor initiation and progression. In addition, mTOR also negatively regulates autophagy via different ways. We discuss mTOR signaling and its key upstream and downstream factors, the specific genetic changes in the mTOR pathway and the inhibitors of mTOR applied as therapeutic strategies in eight solid tumors. Although monotherapy and combination therapy with mTOR inhibitors have been extensively applied in preclinical and clinical trials in various cancer types, innovative therapies with better efficacy and less drug resistance are still in great need, and new biomarkers and deep sequencing technologies will facilitate these mTOR targeting drugs benefit the cancer patients in personalized therapy.

Tumor growth velocity: A modified tumor growth rate defining tumor progression during sorafenib treatment in patients with metastatic renal cell carcinoma

OBJECTIVES

To investigate the role of tumor growth velocity in defining tumor progression in metastatic renal cell carcinoma patients treated with the vascular endothelial growth factor tyrosine kinase inhibitor, sorafenib.

METHODS

A modified calculation for tumor growth velocity was introduced to evaluate the tumor growth velocity, before and after sorafenib withdrawal. Known prognostic factors together with tumor growth velocity before drug withdrawal and tumor growth velocity after drug withdrawal were compared using a χ² -test from a contingency table, and partial likelihood test from a Cox regression model for overall survival.

RESULTS

A total of 114 patients who reached progressive disease and withdrew from sorafenib were enrolled after a median follow-up period of 107.8 months. Tumor growth velocity before drug withdrawal was 7.347 ± 4.040, and tumor growth velocity after drug withdrawal was 11.647 ± 5.937 (P < 0.001). Higher tumor growth velocity before drug withdrawal was correlated with a higher risk Memorial Sloan Kettering Cancer Center score (P = 0.022), Karnofsky Performance Status <80 (P = 0.028), non-clear cell carcinoma (P = 0.037), higher tumor nucleus grade (P < 0.001) and best treatment response (P < 0.001). Patients with tumor growth velocity before drug withdrawal >5.0 had shorter overall survival (P < 0.001). On multivariate analysis, factors associated with overall survival were high/intermediate Memorial Sloan Kettering Cancer Center risk score (hazard ratio 2.119, P = 0.006), non-clear histological subtype (hazard ratio 1.900, P = 0.031), tumor growth velocity before drug withdrawal ≥5.0 (hazard ratio 2.758, P < 0.001) and progressive disease as best response (hazard ratio 2.069, P = 0.001).

CONCLUSIONS

Significantly faster tumor growth can be observed if sorafenib is discontinued in the case of disease progression. Thus, we suggest not to withdraw targeted agents until tumor growth velocity is >5.0.

Tivozanib for the treatment of renal cell carcinoma

INTRODUCTION

Renal cell carcinoma (RCC) represents a heterogeneous group of cancers with distinct histological features, molecular alterations, prognosis, and response to therapy. Target agents directed against vascular endothelial growth factor and its receptor and mammalian target of rapamycin (mTOR) inhibitors have completely changed the landscape of RCC. However, the rate of complete response is still low, thus supporting the research of novel therapeutic agents. Area covered: The authors describe the chemical features of tivozanib, its pharmacodynamic and pharmacokinetic properties, and the results obtained in human phase I-III clinical trials. Tivozanib received its first global approval in EU, Iceland, and Norway on 28 August 2017 for the first-line treatment of adult patients with advanced RCC and for adult patients who are VEGFR and mTOR inhibitor-naive following disease progression after one prior treatment with cytokines. Expert opinion: The US Food and Drug Administration did not approve tivozanib due to the lack of a significant advantage in terms of survival compared to sorafenib. To date, the role of tivozanib in the pharmaceutical landscape of mRCC appears to be very limited. However, ongoing trials on the association between tivozanib and immunotherapy may represent a promising strategy to be assessed in future clinical trials.

Therapeutic Strategies for Patients With Metastatic Renal Cell Carcinoma in Whom First-Line Vascular Endothelial Growth Factor Receptor-Directed Therapies Fail

Metastases are present in one third of renal cell carcinomas at diagnosis. The overall survival duration in metastatic renal cell carcinoma is approximately 22 months, which underlines the need for more effective systemic treatments. Therapies on the basis of antiangiogenic agents and inhibitors of the mammalian target of rapamycin have been approved for treatment of metastatic renal cell carcinoma, but only benefits for progression-free survival were demonstrated in the second-line setting. Fortunately, promising treatments are emerging, from new antiangiogenic agents to immune checkpoint inhibitors. For the first time, both an immune checkpoint inhibitor (nivolumab) and a dual inhibitor of the tyrosine kinases c-Met and vascular endothelial growth factor receptor-2 (cabozantinib) have demonstrated improvements in overall survival in the second-line setting. Finding the best sequence for these novel agents will be crucial to improving outcomes in patients with metastatic renal cell carcinoma. This article comprises both a systematic review of the literature and recommendations for second-line therapeutic strategies for patients with metastatic clear cell renal cell carcinoma in whom inhibitors of vascular endothelial growth factor have failed.

A phase II study of tivozanib in patients with metastatic and nonresectable soft-tissue sarcomas

Background

Soft tissue sarcomas (STSs) overexpress vascular endothelial growth factors (VEGF) and VEGF-receptors (VEGFR) activation have been associated with tumor aggressiveness. Tivozanib is a potent small molecule tyrosine kinase inhibitor against VEGFR1-3, with activity against PDGFRα/β and cKIT. The primary endpoint of this study was progression free survival (PFS) rate at 16 weeks. Secondary end points were overall survival (OS), response rate, safety and correlative studies.

Patients and methods

A Simon two-stage phase II trial was performed using tivozanib given orally at 1.5 mg daily, 3 week on 1 week off on a 28 day cycle until disease progression or intolerable toxicity.

Results

Fifty-eight patients were enrolled and treated with tivozanib. Leiomyosarcoma was the most common STS histological type in our cohort (47%) and 27 patients (46%) had received at least 3 lines of therapy prior to study entry. Up to 24 patients (41%) had prior VEGF targeted therapies. Partial response and stable disease were observed in 2 (3.6%) and 30 (54.5%) patients. The 16 week PFS rate was 36.4% [95% confidence interval (CI) 23.7-49.1] and a median PFS of 3.5 months (95% CI 1.8-3). Median OS observed was 12.2 months (95% CI 8.1-16.8). The most frequent all grade toxicities were fatigue (48.3%), hypertension (43.1%), nausea (31%) and diarrhea (27.6%). The most common grade three toxicity was hypertension (22.4%). Correlative studies demonstrate no correlation between the expression of VEGFR 1, 2 or 3, PDGFRα/β or FGF, and activity of tivozanib.

Conclusion

Tivozanib was well tolerated and showed antitumor activity with a promising median PFS and PFS rate at 4 months in a heavily pretreated population of metastatic STSs. Our results support further studies to assess the clinical efficacy of tivozanib in STS.

Clinical Trial Number

NCT01782313.

Lenvatinib for use in combination with everolimus for the treatment of patients with advanced renal cell carcinoma following one prior anti-angiogenic therapy

INTRODUCTION

In patients with mRCC options for second line therapies, following progression on anti-angiogenic agents, that demonstrate a survival advantage in clinical trials have been limited. Recently a number of agents have demonstrated efficacy in this setting. Here in we profile one such therapy, the combination of lenvatinib and everolimus, and discuss the expanded options for therapy available in this setting. Areas covered: In this review, we discuss current algorithms for treatment of mRCC in both the first-line and second-line setting. We discuss the recent addition of cabozantinib and nivolumab, in the second line setting, to the market. Lenvatinib's pharmacology, clinical efficacy and toxicity profile is discussed. A comprehensive literature review was performed using PUBMED. Expert commentary: The current treatment algorithms for mRCC will likely see significant change in the coming years. The addition of immunotherapy to our treatment options in mRCC is of particular importance. Future trials examining the use of immunotherapy, both as monotherapy and in combination with VEGF targeted therapy, will likely be a dominant influence in the therapeutic landscape of mRCC. Progress in terms of the rapid expansion of available active therapies in mRCC needs to be balanced with current deficiencies in terms of predictive biomarkers.

Pharmacokinetic Aspects of Vascular Endothelial Growth Factor Tyrosine Kinase Inhibitors

Scientists have identified the impact of angiogenesis on tumor growth and survival. Among other efficient drugs, several small-molecule tyrosine kinase inhibitors (TKIs) targeting the vascular endothelial growth factor receptor (VEGFR) have been developed and have already been integrated into the treatment of various advanced malignancies. This review provides a compilation of current knowledge on the pharmacokinetic aspects of all VEGFR-TKIs already approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) and of those still under investigation. Additional information on substance metabolism, potential for drug-drug interactions (DDIs), and the need for dose adaptation in patients with predominant renal and/or hepatic impairment has been included. All TKIs introduced in this review were administered orally, allowing for easy drug handling for healthcare professionals and patients. For almost all substances, the maximum plasma concentrations were reached within a short period of time. The majority of the substances showed a high plasma protein binding and their excretion occurred via the feces and, to a lesser extent, via the urine. In most cases, dose adaptation in patients with mild to moderate renal or hepatic impairment is not recommended. Cytochrome P450 (CYP) 3A4 was found to play a crucial role in the drug metabolic processes of many compounds. In order to prevent unwanted DDIs, co-administration of VEGFR TKIs together with CYP3A4 inhibitors or inducers should be avoided. Throughout all TKIs, the data indicate high inter-individual variability. The causes of this are still unclear and require further research to allow for individualization of treatment regimens.

Combination of mTOR and MAPK Inhibitors-A Potential Way to Treat Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common neoplasm that occurs in the kidney and is marked by a unique biology, with a long history of poor response to conventional cancer treatments. In the past few years, there have been significant advancements to understand the biology of RCC. This has led to the introduction of novel targeted therapies in the management of patients with metastatic disease. Patients treated with targeted therapies for RCC had shown positive impact on overall survival, however, no cure is possible and patients need to undergo treatment for long periods of time, which raises challenges to manage the associated adverse events. Moreover, many patients may not respond to it and even response may not last long enough in the responders. Many inhibitors of the Mammalian target of Rapamycin (mTOR) signaling pathway are currently being used in treatment of advanced RCC. Studies showed that inhibitions of mTOR pathways induce Mitogen-Activated Protein Kinase (MAPK) escape cell death and cells become resistant to mTOR inhibitors. Because of this, there is a need to inhibit both pathways with their inhibitors comparatively for a better outcome and treatment of patients with RCC.

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.

Phase 2 Study of Bevacizumab and Temsirolimus After VEGFR TKI in Metastatic Renal Cell Carcinoma

BACKGROUND

Inhibiting VEGF and mammalian target of rapamycin (mTOR) pathways are standard treatment approaches for patients with metastatic renal cell carcinoma (mRCC). Here we report the activity and safety of the VEGF ligand inhibitor bevacizumab and the mTOR inhibitor temsirolimus combination in patients with clear cell (CC) and non-clear cell (NCC) mRCC whose disease had failed to respond to prior VEGF blockade.

PATIENTS AND METHODS

In this phase 2 investigator-initiated multicenter study, patients received bevacizumab and temsirolimus. The primary end point was 4-month progression-free survival (PFS) rate. Secondary end points included overall response rate, median overall survival (OS), toxicity, and correlative studies of biomarkers downstream of mTOR.

RESULTS

Forty patients received at least 1 dose of therapy. Thirty-three (82.5%) had favorable/intermediate risk disease according to International Metastatic Renal Cell Carcinoma Database Consortium criteria, 13 (32.5%) with nccRCC histology. Nineteen (48.7%) had primary vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI)-refractory disease. The 4-month PFS rate was 65%. Overall median PFS and OS were 5.6 and 12.2 months. Median PFS and OS were 6.5 and 9.6 months in patients with primary VEGFR TKI-refractory disease, and 5.6 months and 13.1 months in patients with nccRCC. Dose reductions were needed in 80% of patients. Most frequent toxicities included fatigue, hypertension, dyslipidemia, and proteinuria. Dose discontinuation due to adverse events occurred in 27.5% of patients. Baseline tumor immunohistochemistry for phospho-S6 protein was not associated with clinical benefit.

CONCLUSION

Combining bevacizumab and temsirolimus in patients previously treated with VEGFR TKI was possible but with dose reductions and treatment discontinuations. This combination resulted in modest activity, including in patients with primary VEGF-refractory disease and NCC histology.

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.

Phase I combination of pazopanib and everolimus in PIK3CA mutation positive/PTEN loss patients with advanced solid tumors refractory to standard therapy

PURPOSE

Combining agents that block both the VEGF and PI3K/AKT/mTOR pathways may be synergistic. We explored a novel dosing schedule to assess safety, toxicity and activity in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients with refractory solid tumors were enrolled in a modified 3 + 3 Phase I dose escalation study to determine dose limiting toxicities (DLTs) and the maximum tolerated dose (MTD) of a combination of everolimus (mTOR inhibitor) and pazopanib (tyrosine kinase inhibitor with anti-VEGF activity). An expansion cohort selected for patients with molecular alterations in the PI3K/AKT/mTOR pathway.

RESULTS

Sixty-two patients were enrolled; median age was 60 years; 29 were women. The MTD was pazopanib 600 mg every other day (QOD) alternating with everolimus 10 mg PO QOD. DLTs were grade 3 thrombocytopenia and creatinine elevation. Most common toxicities of any grade were thrombocytopenia, transaminitis, leukopenia/neutropenia and lipid abnormalities. Among 52 patients evaluable for response, the clinical benefit rate (CBR) was 27 % (14/52) including four partial responses (PR), and 10 stable disease (SD) ≥6 months. 26 of 45 patients evaluated for molecular alterations had at least one alteration in the PI3K/AKT/mTOR pathway. CBR in patients with a matched alteration was 27 % (7/26) versus 26 % (5/19) for patients without an alteration (p = 0.764). However, 64% of those with CBR and molecular testing done for alteration in the PI3K/AKT/mTOR pathway were positive.

CONCLUSION

Combination treatment with pazopanib and everolimus was well tolerated and demonstrated activity in solid tumors. Further exploration of this combination and molecular correlation with treatment outcomes is warranted.

Current clinical regulation of PI3K/PTEN/Akt/mTOR signalling in treatment of human cancer

PURPOSE

PTEN is an essential tumour suppressor gene which encodes a phosphatase protein that antagonises the PI3K/Akt/mTOR antiapoptotic pathway. Impairment of this tumour suppressor pathway potentially becomes a causal factor for development of malignancies. This review aims to assess current understanding of mechanisms of dysfunction involving the PI3K/PTEN/Akt/mTOR pathway linked to tumorigenesis and evaluate the evidence for targeted therapy directed at this signalling axis.

METHODS

Relevant articles in scientific databases were identified using a combination of search terms, including "malignancies", "targeted therapy", "PTEN", and "combination therapy". These databases included Medline, Embase, Cochrane Review, Pubmed, and Scopus.

RESULTS

PI3K/PTEN expression is frequently deregulated in a majority of malignancies through genetic, epigenetic, and post-transcriptional modifications. This contributes to the upregulation of the PI3K/Akt/mTOR pathway which has been the focus of intense clinical studies. Targeted agents aimed at this pathway offer a novel treatment approach in a variety of haematologic malignancies and solid tumours. Compared to single-agent use, greater response rates were obtained in combination regimens, supporting further investigation of suitable drug combinations in a broad spectrum of malignancies.

CONCLUSION

Activation of the PI3K/PTEN/Akt/mTOR pathway is implicated both in the pathogenesis of malignancies and development of resistance to anticancer therapies. Therefore, PI3K/Akt/mTOR inhibitors are a promising therapeutic option, in association with systemic cytotoxic and biological therapies, to enable sustained clinical outcomes in cancer treatment. Therapeutic strategies could be tailored according to appropriate biomarkers and patient-specific mutation profiles to maximise benefit of combination therapies.

Effects of ketoconazole or rifampin on the pharmacokinetics of tivozanib hydrochloride, a vascular endothelial growth factor receptor tyrosine kinase inhibitor

The vascular endothelial growth factor (VEGF) pathway is associated with the promotion of endothelial cell proliferation, migration, and survival necessary for angiogenesis. VEGF and its three receptor isoforms are often overexpressed in many human solid tumors. Tivozanib is a potent, selective inhibitor of VEGF receptors 1, 2, and 3, with a long half-life. The purpose of these studies was to evaluate the effect of ketoconazole, a potent inhibitor of CYP3A4, and rifampin, a potent inducer of CYP3A4, on the pharmacokinetics of tivozanib. Two phase I, open-label, 2-period, single-sequence studies evaluated the effect of steady-state ketoconazole (NCT01363778) or rifampin (NCT01363804) on the pharmacokinetic profile, safety, and tolerability of a single oral 1.5-mg dose of tivozanib. Tivozanib was well tolerated in both studies. Steady-state ketoconazole did not cause a clinically significant change in the pharmacokinetics of a single dose of tivozanib; therefore, dosing of tivozanib with a CYP3A4 pathway inhibitor should not cause a clinically significant change in serum tivozanib levels. However, coadministration of tivozanib with rifampin caused a significant decrease in the area under the curve from 0 to infinity and half-life and an increase in clearance of tivozanib, which suggest increased clearance via the enhanced CYP3A4-mediated metabolism of tivozanib.

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.