A phase I study of axitinib (AG-013736) in combination with bevacizumab plus chemotherapy or chemotherapy alone in patients with metastatic colorectal cancer and other solid tumors

Risks of hypertension and thromboembolism in patients receiving bevacizumab with chemotherapy for colorectal cancer: A systematic review and meta-analysis

BACKGROUND

Guidelines show that for metastatic colorectal cancer (mCRC), a combination of three-drug regimens, fluorouracil, leucovorin, and oxaliplatin and bevacizumab (BVZ), is one of the first-line standard therapies. BVZ is generally well tolerated; however, it is associated with infrequent, life-threatening side effects such as severe hypertension (HTN) (5%-18%), Grade ≥3 arterial thromboembolism (ATE) (2.6%), Grade ≥3 hemorrhagic events (1.2%-4.6%), and gastrointestinal perforation (0.3%-2.4%). This meta-analysis aims to evaluate the additive risk of BVZ-induced severe HTN and thromboembolism when BVZ is combined with a standard chemotherapy regime in patients with mCRC.

METHODS

Our search was conducted from January 29, 2022, to February 22, 2022, through databases of PubMed, clinicaltrial.gov, EMBASE, Web of Science, and Cochrane Library. Data analysis from randomized controlled trials (RCTs) and clinical trials was conducted using Review Manager V.5.4, comparing BVZ-chemotherapy to chemotherapy only, focusing on cardiovascular AE such as HTN and arterial and venous thromboembolism.

RESULTS

The analysis from 26 clinical trials and RCTs showed that the odds of HTN were about four times higher, and ATE subgroup analysis of 11 studies showed over two times higher odds of ATE in patients being treated with BVZ compared to the chemotherapy-only group.

CONCLUSION

BVZ, when added to the standard chemotherapy regimen for mCRC, was associated with higher odds of developing HTN and thromboembolism, specifically ATE, than the chemotherapy-only group. Our findings are significant as they provide vital information in analyzing the risk-benefit ratio of adding BVZ to the standard chemotherapy regime in patients with mCRC, especially in patients with vascular comorbidities.

Colorectal cancer management: Strategies in drug delivery

INTRODUCTION

Colorectal cancer (CRC) is the third most common cancer leading to death worldwide following breast and lung cancer with the incidence rate of 10%. The treatment comprises of surgery, radiation, and ablation therapy depending upon the stage of cancer.

AREAS COVERED

The review focuses on various drug delivery strategies explored to circumvent the major constraints associated with the conventional drug delivery systems- poor bioavailability, intra- and inter individual variability, exposure of normal cells to antineoplastic agents, and presence of efflux pump. All these attributes impact the effective delivery of chemotherapeutic agents at the tumor site. The various target specific drug delivery systems developed for colorectal cancer include pH dependent, microbiologically triggered, time dependent, magnetically driven, pressure dependent, prodrug/polysaccharide based, osmotic and ligand mediated systems. This review enumerates novel target specific approaches developed and investigated for potential utility in CRC therapeutics.

EXPERT OPINION

The limitations of conventional delivery systems can be overcome by development of colon-specific targeted drug delivery systems that overcome the obstacles of nonspecific biodistribution, drug resistance and unwanted adverse effects of conventional drug delivery systems. In addition, nanotechnology approaches help to increase drug solubility, bioavailability, reduce side effects and provide superior drug response in CRC.

Cancer Chemotherapy-Induced Sinus Bradycardia: A Narrative Review of a Forgotten Adverse Effect of Cardiotoxicity

Cardiotoxicity is a common adverse effect of anticancer drugs (ACDs), including the so-called targeted drugs, and increases morbidity and mortality in patients with cancer. Attention has focused mainly on ACD-induced heart failure, myocardial ischemia, hypertension, thromboembolism, QT prolongation, and tachyarrhythmias. Yet, although an increasing number of ACDs can produce sinus bradycardia (SB), this proarrhythmic effect remains an underappreciated complication, probably because of its low incidence and severity since most patients are asymptomatic. However, SB merits our interest because its incidence increases with the aging of the population and cancer is an age-related disease and because SB represents a risk factor for QT prolongation. Indeed, several ACDs that produce SB also prolong the QT interval. We reviewed published reports on ACD-induced SB from January 1971 to November 2020 using the PubMed and EMBASE databases. Published reports from clinical trials, case reports, and recent reviews were considered. This review describes the associations between ACDs and SB, their clinical relevance, risk factors, and possible mechanisms of onset and treatment.

Neutralization of the induced VEGF-A potentiates the therapeutic effect of an anti-VEGFR2 antibody on gastric cancer in vivo

The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis is an essential regulator of angiogenesis and important therapeutic target in cancer. Ramucirumab is an anti-VEGFR2 monoclonal antibody used for the treatment of several cancers. Increased circulating VEGF-A levels after ramucirumab administration are associated with a worse prognosis, suggesting that excess VEGF-A induced by ramucirumab negatively affects treatment efficacy and that neutralizing VEGF-A may improve treatment outcomes. Here, we evaluated the effect of combination treatment with an anti-VEGFR2 antibody and anti-VEGF-A antibody on gastric tumor progression and normal tissues using a preclinical BALB/c-nu/nu mouse xenograft model. After anti-VEGFR2 antibody treatment in mice, a significant increase in plasma VEGF-A levels was observed, mirroring the clinical response. The elevated VEGF-A was host-derived. Anti-VEGF-A antibody co-administration enhanced the anti-tumor effect of the anti-VEGFR2-antibody without exacerbating the toxicity. Mechanistically, the combination treatment induced intra-tumor molecular changes closely related to angiogenesis inhibition and abolished the gene expression changes specifically induced by anti-VEGFR2 antibody treatment alone. We particularly identified the dual treatment-selective downregulation of ZEB1 expression, which was critical for gastric cancer cell proliferation. These data indicate that the dual blockade of VEGF-A and VEGFR2 is a rational strategy to ensure the anti-tumor effect of angiogenesis-targeting therapy.

Perivascular cell-derived extracellular vesicles stimulate colorectal cancer revascularization after withdrawal of antiangiogenic drugs

Antiangiogenic tyrosine kinase inhibitors (AA‐TKIs) have become a promising therapeutic strategy for colorectal cancer (CRC). In clinical practice, a significant proportion of cancer patients temporarily discontinue AA‐TKI treatment due to recurrent toxicities, economic burden or acquired resistance. However, AA‐TKI therapy withdrawal‐induced tumour revascularization frequently occurs, hampering the clinical application of AA‐TKIs. Here, this study demonstrates that tumour perivascular cells mediate tumour revascularization after withdrawal of AA‐TKI therapy. Pharmacological inhibition and genetic ablation of perivascular cells largely attenuate the rebound effect of CRC vascularization in the AA‐TKI cessation experimental settings. Mechanistically, tumour perivascular cell‐derived extracellular vehicles (TPC‐EVs) contain Gas6 that instigates the recruitment of endothelial progenitor cells (EPCs) for tumour revascularization via activating the Axl pathway. Gas6 silence and an Axl inhibitor markedly inhibit tumour revascularization by impairing EPC recruitment. Consequently, combination therapy of regorafenib with the Axl inhibitor improves overall survival in mice metastatic CRC model by inhibiting tumour growth. Together, these data shed new mechanistic insights into perivascular cells in off‐AA‐TKI‐induced tumour revascularization and indicate that blocking the Axl signalling may provide an attractive anticancer approach for sustaining long‐lasting angiostatic effects to improve the therapeutic outcomes of antiangiogenic drugs in CRC.

Transient Asymptomatic Sinus Bradycardia and Sinus Pauses with Bevacizumab: Case Report and Literature Review

Systemic side effects of anti-cancer therapy remain a major limiting factor for patients, even with targeted therapy. Bevacizumab is an example of targeted cancer therapy which targets the vascular endothelial growth factor receptor (VEGFR) that has been approved for the treatment of various cancers and has been evaluated in metastatic urothelial carcinoma (MUC). We report a case of MUC on bevacizumab containing regimen who developed temporary asymptomatic sinus bradycardia with sinus pauses. That adverse event was thought to be related to the bevacizumab in her cancer regimen. Her Holter monitoring recording for a total duration of 28 days and 14 h after discharge did not show recurrence of sinus pauses. This case indicates the necessity for observation for the cardiac conduction defects as side effects in patients receiving bevacizumab, especially since they might be asymptomatic and transient. 

Management of recurrent or refractory Ewing sarcoma: A systematic review of phase II clinical trials in the last 15 years

The aim of the present study was to evaluate the antitumor activity of drugs in phase II clinical trials for recurrent or refractory EWS. A systematic review was performed using clinical trials from four data sources: i) ClinicalTrials.gov; ii) PubMed; iii) Clinicaltrialsregister.eu; and iv) American Society of Clinical Oncology. The search terms included: '(Ewing sarcoma OR Ewing family of tumors) AND (phase II OR phase I/II)'. Overall, 465 trials were identified and 64 were included in the present study, of which, 37 had published results. The highest objective response rate came from irinotecan-based chemotherapy. Currently, the majority of targeted therapy has failed to demonstrate any activity except for regorafenib. Trials using anti-angiogenesis small molecular tyrosine kinase inhibitors (aaTKIs) are currently ongoing with promising early results. For immunotherapy, anti-insulin like growth factor 1 receptor antibody demonstrated disappointing activity. The best outcome came from irinotecan-based regimens. Targeted therapy with aaTKIs is worthy of further investigation, with immunotherapy is not recommended for off-label use.

Vascular endothelial growth factor (VEGF) antibody significantly increases the risk of hand-foot skin reaction to multikinase inhibitors (MKIs): A systematic literature review and meta-analysis

With the use of multikinase inhibitors (MKIs) having emerged in recent years, skin toxicities such as hand-foot skin reaction (HFSR) are primary side effects, and they lack effective prediction methods. Here, we updated a previous systematic review by establishing a meta-analysis of the risk of developing HFSR among patients receiving MKIs and antivascular endothelial growth factor antibody. Publications from PubMed and abstracts presented at the American Society of Clinical Oncology Annual Meeting up to February 5, 2015, were searched to identify relevant studies, and a total of 236 patients with metastatic tumours in nine trials were included for analysis. In the meta-analysis, the pooled incidence rates of all-grade and high-grade HFSR among patients who received the combination therapy were 56.9% [95% confidence interval (CI), 45%-71.1%] and 14.3% (95% CI, 9%-24.2%), respectively, with significant differences observed with MKI monotherapy (P < .05). Further subgroup analysis demonstrated that increasing the dosages of bevacizumab (77.8% vs 51.1%, P = .04) and MKIs (64.3% vs 52.6%, P = .02) significantly increased HFSR incidence. Moreover, combination with chemotherapy exerted a minimal effect on HFSR risk (61% vs 55.3%, P = .5). This updated review and meta-analysis confirm the increased risk of HFSR incidence due to the use of MKIs and antivascular endothelial growth factor antibody. Thus, using these therapies requires safety standards.

Pharmacodynamic and Pharmacokinetic Markers For Anti-angiogenic Cancer Therapy: Implications for Dosing and Selection of Patients

Angiogenesis is integral to tumour growth and invasion, and is a key target for cancer therapeutics. However, for many of the licensed indications, only a modest clinical benefit has been observed for both monoclonal antibody and small-molecule tyrosine kinase inhibitor anti-angiogenic therapy. Pre-clinical and clinical studies have attempted to evaluate circulating, imaging, genomic, pharmacokinetic, and pharmacodynamic markers that may aid both the selection of patients for treatment and define dosing. Correct dosing is likely to be critical in the context of vascular normalization to allow better delivery of concomitant anti-cancer therapy and novel imaging techniques hold much promise in the early evaluation of pharmacodynamic response to improve efficacy.

A Phase-2 Trial of Single Agent Axitinib as Maintenance Therapy Following First-Line Treatment With Modified FOLFOX/Bevacizumab in Patients With Metastatic Colorectal Cancer

This phase-2 trial evaluated the efficacy of axitinib as maintenance therapy for patients with metastatic colorectal cancer (mCRC) following first-line treatment with FOLFOX/bevacizumab. Patients with mCRC received mFOLFOX/bevacizumab followed by axitinib maintenance after four cycles. The primary endpoint was progression-free survival (PFS). Seventy patients were enrolled. Common treatment-related toxicities were fatigue, nausea, diarrhea, and peripheral neuropathy during FOLFOX/bevacizumab treatment; and fatigue, hypertension, diarrhea, and peripheral neuropathy during axitinib treatment. Median PFS was 8.3 months. Treatment with FOLFOX/bevacizumab followed by maintenance axitinib as first-line treatment for mCRC produced a median PFS consistent with historical controls of other first-line regimens.

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.

Clinical and Translational Assessment of VEGFR1 as a Mediator of the Premetastatic Niche in High-Risk Localized Prostate Cancer

Preclinical studies have suggested that VEGFR1-positive cells potentially foster the development of metastases by establishing a "premetastatic niche." We sought to test this hypothesis in high-risk localized prostate cancer and assess potential niche modulation by the VEGFR1-targeting drug axitinib. Formalin-fixed, paraffin-embedded tissue derived from benign lymph nodes was collected and VEGFR1-positive cell clustering was assessed in benign lymph nodes via IHC. Recursive partitioning was used to define a threshold for VEGFR1 clustering that could segregate patients based on time to biochemical recurrence (TTBR). Multivariate analyses were used to determine whether VEGFR1 clustering, age, pathologic T-stage, Gleason score, or baseline PSA could independently predict TTBR. A randomized, phase II clinical trial comparing axitinib for 28 days followed by radical prostatectomy and pelvic lymph node dissection (RP/PLND) to RP/LND alone was then conducted, with the primary endpoint of demonstrating downregulation of VEGFR1-positve cell clustering in benign lymph nodes. Our retrospective analysis assessed a cohort of 46 patients. A threshold of 1.65 VEGFR1-positive cells per high power field was identified, below which TTBR was delayed. VEGFR1 clustering was an independent predictor of TTBR in a multivariate analysis. Only 11 out of the planned 44 patients were accrued to the phase II trial. While preoperative axitinib was safe and well tolerated, there was no sign of clinical activity or VEGFR1 downregulation. Our results validate previous findings that suggest VEGFR1-positive cells in benign lymph nodes can predict clinical outcome. Further work is needed to develop a viable clinical strategy for modulating VEGFR1 in these tissues.

Receptor tyrosine kinase inhibitors: Are they real tumor killers?

Inhibiting tumor growth by targeting the tumor vasculature was first proposed by Judah Folkman almost 40 years ago. Since then, different approaches and numerous drugs and agents have been developed to achieve this goal, either with the aim of inhibiting tumor neoangiogenesis or normalizing the tumor vasculature. Among the most promising therapeutic targets are receptor tyrosine kinases (RTKs), some of which are predominantly expressed on tumor endothelial cells, although they are sometimes also present on tumor cells. The majority of RTK inhibitors investigated over the past two decades competes with ATP at the active site of the kinase and therefore block the phosphorylation of intracellular targets. Some of these drugs have been approved for therapy, whereas others are still in clinical trials. Here, we discuss the scientific basis, current status, problems and future prospects of RTK inhibition in anti-tumor therapy.

A phase Ib study of the VEGF receptor tyrosine kinase inhibitor tivozanib and modified FOLFOX-6 in patients with advanced gastrointestinal malignancies

BACKGROUND

Tivozanib hydrochloride (tivozanib) is a potent and selective tyrosine kinase inhibitor of all 3 vascular endothelial growth factor receptors with antitumor activity additive to 5-fluorouracil in preclinical models. This study was conducted to determine maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), pharmacokinetics (PKs), and antitumor activity of escalating doses of tivozanib with a modified (m)FOLFOX-6 (leucovorin, 5-fluorouracil [5-FU], and 85 mg/kg(2) oxaliplatin) regimen in patients with advanced gastrointestinal tumors.

PATIENTS AND METHODS

Tivozanib was administered orally once daily for 21 days in 28-day cycles, with mFOLFOX-6 administered every 14 days. Patients were allowed to continue tivozanib after discontinuation of mFOLFOX-6.

RESULTS

Thirty patients were assigned to tivozanib 0.5 mg (n = 9), 1.0 mg (n = 3), or 1.5 mg (n = 18) with mFOLFOX-6. Patients received a median of 5.2 (range, 0.03-26.9) months of tivozanib. DLTs were observed in 2 patients: Grade 3/4 transaminase level increases with tivozanib 0.5 mg, and Grade 3 dizziness with tivozanib 1.5 mg. Other Grade 3/4 adverse events included hypertension (n = 8), fatigue (n = 8), and neutropenia (n = 6). MTD for tivozanib with mFOLFOX-6 was confirmed as 1.5 mg. No PK interactions between tivozanib and mFOLFOX-6 were observed. One patient had an ongoing clinical complete response, 10 had a partial response, and 11 obtained prolonged stable disease.

CONCLUSION

Tivozanib and mFOLFOX-6 is feasible and appears to be safe. The recommended dose for tivozanib with mFOLFOX-6 is 1.5 mg/d. Observed clinical activity merits further exploration in gastrointestinal tumors.

Safety of bevacizumab in treating metastatic colorectal cancer: a systematic review and meta-analysis of all randomized clinical trials

BACKGROUND AND OBJECTIVE

The incidence rates of colorectal cancer (CRC) are increasing in a number of different regions, and recent studies have indicated that addition of bevacizumab to CRC therapy is beneficial. To better understand the relative risk (RR) of adverse events associated with use of bevacizumab, we systematically reviewed published clinical trials that studied use of bevacizumab in treatment of patients affected by metastatic CRC (mCRC).

METHODS

The National Library of Medicine PubMed, MEDLINE, Ovid, Cochrane Library and Chinese Biomedicine databases were searched. The RR and number needed to harm (NNH) values for major side effects with 95% confidence intervals (CIs) were calculated in a fixed-effects model and a random-effects model, where appropriate.

RESULTS

Fifteen controlled trials totalling 6,937 patients were eligible for this analysis. Compared with the control group, the bevacizumab treatment group had a slightly higher risk of any severe adverse event (pooled RR 1.07 [95% CI 1.02-1.12]). The pooled risk difference was 5% [95% CI 2-9%], with an NNH of 20 treated patients. Analyses showed a statistically significantly higher risk of secondary endpoints, including the discovery that bevacizumab was associated with a threefold higher risk of hypertension (pooled RR 3.06 [95% CI 2.45-3.83]), a twofold higher risk of gastrointestinal haemorrhage/perforation and a lower risk of neutropenia (pooled RR 0.75 [95% CI 0.26-2.19]).

CONCLUSION

Bevacizumab has efficacy in all treatment regimens for advanced CRC. However, our meta-analysis raises safety concerns regarding an increased risk of serious adverse events associated with use of bevacizumab among patients with mCRC. Our findings warrant cautious use of bevacizumab in clinical oncology.

Axitinib alone or in combination with chemotherapeutic drugs exerts potent antitumor activity against human gastric cancer cells in vitro and in vivo

OBJECTIVE

As the new oral selective VEGFR tyrosine kinase inhibitor, axitinib (AG-013736) exerts powerful antitumor activity in multiple solid tumors, while its' effect was unclear in gastric cancer. We aimed to investigate the antitumor activity of axitinib alone or combined with chemotherapeutic drugs against human gastric cancer cells in vitro and in vivo.

METHODS

The IC50 values of drugs were determined by MTS assay. The median effect of Chou-Talalay was used to assess the synergistic effect of two drugs. Flow cytometry was employed to analyze cell cycle and cell apoptosis. Cell senescence and microvessel density were evaluated by SA-β-gal staining and CD34 staining, respectively. BGC-823-derived xenografts in nude mice were established to investigate the effects of drugs in vivo.

RESULTS

Axitinib alone could inhibit cell proliferation and retard tumor growth through inducing cell cycle arrest at G2/M phase, cell senescence, cell apoptosis, and antiangiogenesis in vitro and in vivo. Axitinib combined with 5-fluorouracil (5-FU) had synergistic inhibitory effect compared to axitinib or 5-FU alone. However, the highest inhibitory effect was found between axitinib and cisplatin (inhibitory ratio >80 % compared to control), which was significantly higher than any single drug (inhibitory ratio for single 5-FU, cisplatin, and axitinib >10, >40, and >40 %, respectively, compared to control) or axitinib combined with 5-FU (inhibitory ratio >50 % compared to control).

CONCLUSION

We highlighted for the first time that axitinib alone or in combination with 5-fluorouracil or cisplatin has potent antitumor activity against human gastric cancer in vitro and in vivo, which provided solid evidence for future clinical trial.

Clinical pharmacology of axitinib

Axitinib is a potent and selective second-generation inhibitor of vascular endothelial growth factor receptors 1, 2, and 3 that is approved in the US and several other countries for treatment of patients with advanced renal cell carcinoma after failure of one prior systemic therapy. The recommended clinical starting dose of axitinib is 5 mg twice daily, taken with or without food. Dose increase (up to a maximum of 10 mg twice daily) or reduction is permitted based on individual tolerability. Axitinib pharmacokinetics are dose-proportional within 1-20 mg twice daily, which includes the clinical dose range. Axitinib has a short effective plasma half-life (range 2.5-6.1 h), and the plasma accumulation of axitinib is in agreement with what is expected based on the plasma half-life of the drug. Axitinib is absorbed relatively rapidly, reaching maximum observed plasma concentrations (C max) within 4 h of oral administration. The mean absolute bioavailability of axitinib is 58 %. Axitinib is highly (>99 %) bound to human plasma proteins with preferential binding to albumin and moderate binding to α1-acid glycoprotein. In patients with advanced renal cell carcinoma, at the 5-mg twice-daily dose in the fed state, the geometric mean (% coefficient of variation) C max and area under the plasma concentration-time curve (AUC) from time 0-24 h (AUC24) were 27.8 ng/mL (79 %) and 265 ng·h/mL (77 %), respectively. Axitinib is metabolized primarily in the liver by cytochrome P450 (CYP) 3A4/5 and, to a lesser extent (<10 % each), by CYP1A2, CYP2C19, and uridine diphosphate glucuronosyltransferase (UGT) 1A1. The two major human plasma metabolites, M12 (sulfoxide product) and M7 (glucuronide product), are considered pharmacologically inactive. Axitinib is eliminated via hepatobiliary excretion with negligible urinary excretion. Although mild hepatic impairment does not affect axitinib plasma exposures compared with subjects with normal hepatic function, there was a 2-fold increase in AUC from time zero to infinity (AUC∞) following a single 5-mg dose in subjects with moderate hepatic impairment. In the presence of ketoconazole, a strong CYP3A4/5 inhibitor, axitinib C max and AUC∞ increased by 1.5- and 2-fold, respectively, whereas co-administration of rifampin, a strong CYP3A4/5 inducer, resulted in a 71 and 79 % decrease in the C max and AUC∞, respectively. Axitinib does not inhibit CYP3A4/5, CYP1A2, CYP2C8, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, or UGT1A1 at concentrations obtained with the clinical doses and is not expected to have major interactions with drugs that are metabolized by these enzymes. Axitinib is an inhibitor of the efflux transporter P-glycoprotein (P-gp) in vitro, but is not expected to inhibit P-gp at therapeutic plasma concentrations. A two-compartment population pharmacokinetic model with first-order absorption and lag time was used to describe axitinib pharmacokinetics. No clinically relevant effects of age, sex, body weight, race, renal function, UGT1A1 genotype, or CYP2C19 inferred phenotype on the clearance of axitinib were identified.

Intermittent dosing of axitinib combined with chemotherapy is supported by (18)FLT-PET in gastrointestinal tumours

Background:

We evaluated week-on/week-off axitinib dosing plus chemotherapy in patients with gastrointestinal tumours, including tumour thymidine uptake by fluorine-18 3′-deoxy-3′-fluorothymidine positron emission tomography (¹⁸FLT-PET).

Methods:

During a lead-in period, patients received twice daily (b.i.d.) axitinib 7 mg (n=3) or 10 mg (n=18) for 7 days followed by a 7-day dosing interruption; serial ¹⁸FLT-PET scans were performed before day 1 and on days 7, 10, and 14. Axitinib plus FOLFIRI or FOLFOX was then administered in 2-week cycles; axitinib was interrupted on day 10 of each cycle for 7 days.

Results:

The maximum tolerated dose of axitinib was 10 mg b.i.d., in a week-on/week-off schedule, combined with FOLFIRI or FOLFOX. Common all-causality grade 3 adverse events were neutropenia (38%), hypertension (33%), and fatigue (29%). Of 21 patients, 2 (10%) had a partial response and 12 (57%) had stable disease. Following 7 days of continuous axitinib dosing, tumour ¹⁸FLT uptake decreased –49% from baseline and recovered to –28% and –17% from baseline, respectively, after 3 and 7 days of axitinib interruption.

Conclusion:

Axitinib administered in a week-on/week-off schedule combined with FOLFIRI or FOLFOX is supported by ¹⁸FLT-PET data and was well tolerated in patients with gastrointestinal tumours.

Regorafenib: from bench to bedside in colorectal cancer

Colorectal cancer (CRC) remains the third cause of cancer-related mortality in the USA. Despite the advances in screening, many patients present with incurable metastatic disease. Chemotherapy forms the basis of treatment for patients with advanced disease. Angiogenesis is an important step in developing metastases and, therefore, blocking the VEGF pathway seems promising. The development of bevacizumab as a monoclonal antibody targeting the VEGF pathway improved progression-free survival and overall survival in the metastatic settings, with no improvement in disease-free or overall survival in the adjuvant settings. Small molecules such as tyrosine-kinase inhibitors have been long evaluated in metastatic CRC with disappointing results in improving outcome. Most recently, the CORRECT study has resulted in improved outcome in patients with metastatic CRC who were heavily pretreated when they received regorafenib.

Combination therapy in metastatic renal cell cancer

The standard strategy in metastatic renal cell carcinoma (mRCC) is to use sequential treatment. Different pathways are known to be involved in the pathogenesis of mRCC and in the development of resistance to targeted drugs. Combinations of targeted drugs could theoretically achieve better inhibition of a given pathway, inhibition of different pathways, or inhibition of a pathway involved in the resistance to a given drug. However, there is as yet no clear evidence that combination therapy is of clinical benefit and excess toxicity has been observed. In mRCC the majority of studies have explored combinations of vascular endothelial growth factor (VEGF) inhibitors and mammalian target of rapamycin (mTOR) inhibitors. A new generation of VEGF tyrosine kinase inhibitors (TKIs) seems to be more tolerable, and therefore potentially easier to combine with other agents. Trials with PI3K/akt/mTORC1/2 inhibitor combinations and with other new targeted drugs are also ongoing.

Sunitinib combined with pemetrexed and carboplatin in patients with advanced solid malignancies--results of a phase I dose-escalation study

Objectives The maximum tolerated dose (MTD) and overall safety of sunitinib plus pemetrexed and carboplatin was determined in patients with advanced solid malignancies. Methods In this phase I dose-escalation study, patients received oral sunitinib on a continuous daily dosing (CDD) schedule (37.5 mg/day) or Schedule 2/1 (2 weeks on treatment, 1 week off treatment; 37.5 or 50 mg/day). Pemetrexed (400–500 mg/m² IV) and carboplatin (AUC = 5 mg·min/ml IV) were administered q3w. At the MTD for the chosen schedule, a cohort of patients with non-small cell lung cancer (NSCLC) or mesothelioma was further evaluated. Results Twenty-one patients were enrolled on Schedule 2/1 (expansion cohort included) and 3 patients on the CDD schedule. The MTD on Schedule 2/1 was sunitinib 37.5 mg/day with pemetrexed 500 mg/m² and carboplatin AUC = 5 mg·min/ml; MTD on the CDD schedule was not established. Dose-limiting toxicities included grade 3/4 neutropenia, grade 3 thrombocytopenia, and grade 3 hand–foot syndrome. The most common grade 3/4 drug-related non-hematologic adverse events at Schedule 2/1 MTD were fatigue/asthenia and diarrhea (both n = 4). Grade 3/4 hematologic abnormalities included neutropenia (83 %) and leukopenia (83 %). Pharmacokinetic data revealed no clinically significant drug–drug interactions. Best response at the Schedule 2/1 MTD was stable disease ≥8 weeks in 3/5 evaluable patients (60 %). Conclusions With this combination, in patients with advanced solid malignancies, sunitinib MTD on Schedule 2/1 was 37.5 mg/day. Sunitinib plus pemetrexed and carboplatin were tolerable at the MTD, although sunitinib dose delays and reductions were often required due to myelosuppression.

Role of bevacizumab in colorectal cancer growth and its adverse effects: A review

Angiogenesis affects both wound healing and malignant cell growth through nutrients and oxygen. Vascular endothelial growth factor (VEGF) is the most important element involved in this complex process. Inhibition of VEGF influences angiogenesis and may restrict tumor growth and metastatic ability. Modern anti-angiogenic therapy is based on this theory. Bevacizumab is a recombinant humanized monoclonal antibody (immunoglobulin G1) which binds with VEGF-A forming a large molecule. It can not be bound with VEGF tyrosine kinase receptors preventing VEGF-A incorporation; thus its activity is inhibited inducing blockage of VEGF-mediated angiogenesis. Bevacizumab, in combination with chemotherapy or other novel targeted therapeutic agents, is currently used more frequently in clinical practice, mainly for managing advanced colorectal cancer. It is also used for managing other malignancies, such as breast cancer, pancreatic cancer, prostate cancer, non small-cell lung cancer, metastatic renal carcinoma and ovarian tumors. Although it is generally considered a safe treatment, there are reports of some rare side effects which should be taken into account. Recent experiments in rats and mice show promising results with a wider therapeutic range.

Real time dynamic imaging and current targeted therapies in the war on cancer: a new paradigm

In biology, as every science student is made to learn, ontology recapitulates phylogeny. In medicine, however, oncology recapitulates polemology, the science of warfare: The medical establishment is transitioning from highly toxic poisons that kill rapidly dividing normal and malignant cells with little specificity to tailored therapies that target the tumors with the lethality of the therapeutic warhead. From the advent of the information age with the incorporation of high-tech intelligence, reconnaissance, and surveillance has resulted in "data fusion" where a wide range of information collected in near real-time can be used to redesign most of the treatment strategies currently used in the clinic. The medical community has begun to transition from the 'black box' of tumor therapy based solely on the clinical response to the 'glass box' of dynamic imaging designed to bring transparency to the clinical battlefield during treatment, thereby informing the therapeutic decision to 'retreat or repeat'. The tumor microenvironment is dynamic, constantly changing in response to therapeutic intervention, and therefore the therapeutic assessment must map to this variable and ever-changing landscape with dynamic and non-static imaging capabilities. The path to personalized medicine will require incorporation and integration of dynamic imaging at the bedside into clinical practice for real-time, interactive assessment of response to targeted therapies. The application of advanced real time imaging techniques along with current molecularly targeted anticancer therapies which alter cellular homeostasis and microenvironment can enhance therapeutic interventions in cancer patients and further improve the current status in clinical management of patients with advanced cancers.

Reduced immunosuppressive properties of axitinib in comparison with other tyrosine kinase inhibitors

The multikinase inhibitors sunitinib, sorafenib, and axitinib have an impact not only on tumor growth and angiogenesis, but also on the activity and function of immune effector cells. In this study, a comparative analysis of the growth inhibitory properties and apoptosis induction potentials of tyrosine kinase inhibitors on T cells was performed. Tyrosine kinase inhibitor treatment resulted in a dramatic decrease in T cell proliferation along with distinct impacts on the cell cycle progression. This was at least partially associated with an enhanced induction of apoptosis although triggered by distinct apoptotic mechanisms. In contrast to sunitinib and sorafenib, axitinib did not affect the mitochondrial membrane potential (Δψm) but resulted in an induction or stabilization of the induced myeloid leukemia cell differentiation protein (Mcl-1), leading to an irreversible arrest in the G2/M cell cycle phase and delayed apoptosis. Furthermore, the sorafenib-mediated suppression of immune effector cells, in particular the reduction of the CD8(+) T cell subset along with the down-regulation of key immune cell markers such as chemokine CC motif receptor 7 (CCR7), CD26, CD69, CD25, and CXCR3, was not observed in axitinib-treated immune effector cells. Therefore, axitinib rather than sorafenib seems to be suitable for implementation in complex treatment regimens of cancer patients including immunotherapy.

Axitinib and/or bevacizumab with modified FOLFOX-6 as first-line therapy for metastatic colorectal cancer: a randomized phase 2 study

BACKGROUND

In this multicenter, open-label, randomized phase 2 trial, the authors evaluated the vascular endothelial growth factor receptor inhibitor axitinib, bevacizumab, or both in combination with chemotherapy as first-line treatment of metastatic colorectal cancer (mCRC).

METHODS

Patients with previously untreated mCRC were randomized 1:1:1 to receive continuous axitinib 5 mg twice daily, bevacizumab 5 mg/kg every 2 weeks, or axitinib 5 mg twice daily plus bevacizumab 2 mg/kg every 2 weeks, each in combination with modified 5-fluorouracil/leucovorin/oxaliplatin (FOLFOX-6). The primary endpoint was the objective response rate (ORR).

RESULTS

In all, 126 patients were enrolled from August 2007 to September 2008. The ORR was numerically inferior in the axitinib arm (n = 42) versus the bevacizumab arm (n = 43; 28.6% vs 48.8%; 1-sided P = .97). Progression-free survival (PFS) (11.0 months vs 15.9 months; 1-sided P = .57) and overall survival (OS) (18.1 months vs 21.6 months; 1-sided P = .69) also were numerically inferior in the axitinib arm. Similarly, efficacy endpoints for the axitinib/bevacizumab arm (n = 41) were numerically inferior (ORR, 39%; PFS, 12.5 months; OS, 19.7 months). The patients who received axitinib had fewer treatment cycles compared with other arms. Common all-grade adverse events across all 3 treatment arms were fatigue, diarrhea, and nausea (all ≥49%). Hypertension and headache were more frequent in the patients who received axitinib. Patients in the bevacizumab arm had the longest treatment exposures and the highest rates of peripheral neuropathy.

CONCLUSIONS

Neither the addition of continuous axitinib nor the axitinib/bevacizumab combination to FOLFOX-6 improved ORR, PFS, or OS compared with bevacizumab as first-line treatment of mCRC.

Anti-tumour and anti-vascular effects of cediranib (AZD2171) alone and in combination with other anti-tumour therapies

PURPOSE

Cediranib (AZD2171) is a highly potent inhibitor of all three vascular endothelial growth factor receptors. The aim of this preclinical study was to examine the effect of combining cediranib with mechanistically distinct anti-tumour therapies.

METHODS

Cediranib (1.5 or 3 mg/kg/day) was evaluated alone and in combination with either gefitinib, imatinib, ZD6126, saracatinib, selumetinib, bevacizumab, 5-fluorouracil (5-FU), docetaxel, oxaliplatin, gemcitabine, pemetrexed, irinotecan or cisplatin in human tumour xenograft models. Anti-tumour activity was measured by assessing the change in tumour volume following treatment compared with vehicle-treated time-matched controls.

RESULTS

In all cases, the combination regimens, at tolerated doses and schedules, inhibited tumour growth to a greater extent than the corresponding monotherapy treatments. Compared with cediranib alone, statistically significant enhancements in anti-tumour activity were observed with all combination regimens. Notably, after 14 days of treatment, the combination of cediranib with ZD6126 induced substantial tumour regression (60 % compared with pre-treatment volume), whilst treatment with each agent alone led only to partial growth inhibition. A combination of cediranib with gefitinib also induced tumour regressions, and cediranib combined with either gemcitabine or irinotecan was found to inhibit tumour growth profoundly (by 99 and 98 %, respectively).

CONCLUSIONS

Combining cediranib with selected cytotoxic or targeted agents proved efficacious in a range of human tumour xenograft models.

Phase I study of axitinib combined with paclitaxel, docetaxel or capecitabine in patients with advanced solid tumours

Background:

Axitinib, a potent and selective second-generation inhibitor of vascular endothelial growth factor receptors, enhanced the efficacy of chemotherapy in human xenograft tumour models. This phase I study investigated the safety, tolerability, pharmacokinetics and antitumour activity of axitinib combined with chemotherapy.

Methods:

A total of 42 patients with advanced solid tumours received a continuous axitinib starting dose of 5 mg twice daily (b.i.d.) plus paclitaxel (90 mg m^–2 weekly), docetaxel (100 mg m^–2 every 3 weeks) or capecitabine (1000 or 1250 mg m^–2 b.i.d., days 1–14).

Results:

Common treatment-related adverse events across all cohorts were nausea (45.2%), hypertension (45.2%), fatigue (42.9%), diarrhoea (38.1%), decreased appetite (33.3%) and hand–foot syndrome (31.0%). There was one complete response, nine partial responses and seven patients with stable disease. Ten patients (23.8%) remained on therapy for >8 months. Paclitaxel and capecitabine pharmacokinetics were similar in the absence or presence of axitinib, but docetaxel exposure was increased in the presence of axitinib. Axitinib pharmacokinetics were similar in the absence or presence of co-administered agents.

Conclusions:

Axitinib combined with paclitaxel or capecitabine was well tolerated; no additive increase in toxicities was observed. Antitumour activity was observed for each treatment regimen and across multiple tumour types.

Phase I trial of axitinib combined with platinum doublets in patients with advanced non-small cell lung cancer and other solid tumours

Background:

This phase I dose-finding trial evaluated safety, efficacy and pharmacokinetics of axitinib, a potent and selective second-generation inhibitor of vascular endothelial growth factor receptors, combined with platinum doublets in patients with advanced non-small cell lung cancer (NSCLC) and other solid tumours.

Methods:

In all, 49 patients received axitinib 5 mg twice daily (b.i.d.) with paclitaxel/carboplatin or gemcitabine/cisplatin in 3-week cycles. Following determination of the maximum tolerated dose, a squamous cell NSCLC expansion cohort was enroled and received axitinib 5 mg b.i.d. with paclitaxel/carboplatin.

Results:

Two patients experienced dose-limiting toxicities: febrile neutropenia (n=1) in the paclitaxel/carboplatin cohort and fatigue (n=1) in the gemcitabine/cisplatin cohort. Common nonhaematologic treatment-related adverse events were hypertension (36.7%), diarrhoea (34.7%) and fatigue (28.6%). No grade⩾3 haemoptysis occurred among 12 patients with squamous cell NSCLC. The objective response rate was 37.0% for patients receiving axitinib/paclitaxel/carboplatin (n=27) and 23.8% for patients receiving axitinib/gemcitabine/cisplatin (n=21). Pharmacokinetics of axitinib and chemotherapeutic agents were similar when administered alone or in combination.

Conclusion:

Axitinib 5 mg b.i.d. may be combined with standard paclitaxel/carboplatin or gemcitabine/cisplatin regimens without evidence of overt drug–drug interactions. Both combinations demonstrated clinical efficacy and were well tolerated.

Combined vaccine+axitinib therapy yields superior antitumor efficacy in a murine melanoma model

Axitinib, a tyrosine kinase inhibitor of vascular endothelial growth factor receptors, has demonstrated modest efficacy when applied as a single agent in the setting of advanced-stage melanoma. On the basis of the reported ability of axitinib to 'normalize' the tumor vasculature, we hypothesize that combination therapy using axitinib plus specific peptide-based vaccination would promote superior activation and recruitment of protective T cells into the melanoma microenvironment, leading to enhanced treatment benefit. Using a subcutaneous M05 (B16.OVA) melanoma model, we observed that a treatment regimen consisting of a 7-day course of axitinib (0.5 mg/day provided orally) combined with a subcutaneous vaccine [ovalbumin (OVA) peptide-pulsed syngenic dendritic cells adenovirally engineered to produce IL-12p70] yielded superior protection against melanoma growth and extended overall survival when compared with animals receiving either single modality therapy. Treatment benefits were associated with: (a) a reduction in suppressor cell (myeloid-derived suppressor cells and Treg) populations in the tumor, (b) activation of tumor vascular endothelial cells, and (c) activation and recruitment of type-1, vaccine-induced CD8 T cells into tumors. These results support the therapeutic superiority of combined vaccine+axitinib immunotherapy and the translation of such approaches into the clinic for the treatment of patients with advanced-stage melanoma.

Combining antiangiogenics to overcome resistance: rationale and clinical experience

Antiangiogenic therapies are now well established in oncology clinical practice; however, despite initial optimism, the results of late-phase trials, especially in the adjuvant setting, have largely proved disappointing. In the context of metastatic disease, resistance to antiangiogenic agents arises through a range of mechanisms, including the development of alternative angiogenic pathways. One of the proposed strategies to overcome this resistance is to combine antiangiogenic agents with different mechanisms of action. Early-phase clinical trials assessing the tolerability and efficacy of different combinations of antiangiogenic drugs, including those that target the VEGF pathway or the angiopoietins, as well as vascular disrupting agents, are increasing in number. An example of this strategy is the combination of sorafenib and bevacizumab, which has elicited major responses in different tumor types, including ovarian carcinoma and glioblastoma. However, overlapping and cumulative toxicities pose a real challenge. This review summarizes the preclinical rationale for this approach and current clinical experience in combining antiangiogenic therapies.

Irinotecan synergistically enhances the antiproliferative and proapoptotic effects of axitinib in vitro and improves its anticancer activity in vivo

AIMS

To demonstrate the synergistic antiproliferative and proapoptotic activity of irinotecan and axitinib in vitro and the improvement of the in vivo effects on angiogenesis and pancreatic cancer.

METHODS

Proliferation and apoptotic assays were performed on human dermal microvascular endothelial cells and pancreas cancer (MIAPaCa-2, Capan-1) cell lines exposed to SN-38, the active metabolite of irinotecan, axitinib, or their simultaneous combination for 72 hours. ERK1/2 and Akt phosphorylation, the vascular endothelial growth factor (VEGF), VEGF receptor-2, and thrombospondin-1 (TSP-1) concentration were measured by ELISAs. ATP7A and ABCG2 gene expression was performed with real-time polymerase chain reaction and SN-38 intracellular concentrations were measured by high-performance liquid chromatography. Capan-1 xenografts in nude mice were treated with irinotecan and axitinib alone or in simultaneous combination.

RESULTS

A strong synergistic effect on antiproliferative and proapoptotic activity was found with the axitinib/SN-38 combination on endothelial and cancer cells. ERK1/2 and Akt phosphorylation were significantly inhibited by lower concentrations of the combined drugs in all the cell lines. Axitinib and SN-38 combined treatment greatly inhibited the expression of the ATP7A and ABCG2 genes in endothelial and cancer cells, increasing the SN-38 intracellular concentration. Moreover, TSP-1 secretion was increased in cells treated with both drugs, whereas VEGFR-2 levels significantly decreased. In vivo administration of the simultaneous combination determined an almost complete regression of tumors and tumor neovascularization.

CONCLUSIONS

In vitro results show the highly synergistic properties of simultaneous combination of irinotecan and axitinib on endothelial and pancreas cancer cells, suggesting a possible translation of this schedule into the clinics.

A drug interaction study evaluating the pharmacokinetics and toxicity of sorafenib in combination with capecitabine

PURPOSE

To address tolerability and a possible pharmacologic interaction of capecitabine with sorafenib.

METHODS

Patients with advanced solid tumors (ECOG PS 0-1) were included. Cohort A received capecitabine 750 mg/m(2) BID and Cohort B received capecitabine 1,000 mg/m(2) BID, both for 14 days of a 21-day cycle. Steady-state PK was obtained for capecitabine alone, sorafenib alone, and in combination. Cohort C explored an alternate schedule of 7-day on/7-day off flat dose capecitabine 1,000 mg BID with continuous dosing of sorafenib 400 mg BID.

RESULTS

A total of 32 patients were enrolled between February 08 and April 09. Hand-foot skin reaction (HFSR) was the primary toxicity with 16 (50%) of the 32 patients experiencing grade 3 events (75% occurring during cycles 1-2). Grade 3 HFSR defined the maximum tolerated dose (MTD) of Cohort C at 1,000 mg BID flat dose of capecitabine. Other grade 3/4 toxicities were rare (diarrhea 6%, mucositis 3%, and fatigue 3%). Capecitabine did not change the C (max) or AUC((0-12)) of sorafenib. Co-administration of sorafenib with capecitabine 750 mg/m(2) (n = 6 patients) increased capecitabine AUC((0-12)) 15% and produced no change in the 5FU AUC((0-12)). At the capecitabine 1,000 mg/m(2) dose level (n = 12 pts), there was a 16% increase in capecitabine AUC((0-12)) and an 8% increase in 5FU AUC((0-12)). However, these trends were not statistically significant.

CONCLUSIONS

Co-administration of sorafenib resulted in a mild increase in capecitabine AUC, although not statistically significant. Capecitabine did not affect the exposure of sorafenib. The rate of grade 3 HFSR is concerning and limits the feasibility of prolonged dosing of sorafenib with capecitabine 1,000 mg/m(2) on the 21-day schedule.

Integration of biologic agents with cytotoxic chemotherapy in metastatic colorectal cancer

Colorectal cancer (CRC) remains a leading cause of cancer death in the developed world. Metastatic disease eventually develops in nearly 50% of patients with CRC. Chemotherapy is the mainstay of treatment in metastatic CRC (mCRC); however the majority of patients remain incurable with current therapeutic options. Progress made in the field of surgery, locoregional treatment for low-volume metastatic disease, and systemic chemotherapy has created new treatment paradigms and improved survival in mCRC. Development of new cytotoxic drugs and the advent of targeted agents over the past decade have seen the median overall survival (OS) for mCRC increase from 9 months to > 2 years. Data from trials integrating targeted therapies appear to indicate that not all have efficacy as single agents and the choice of chemotherapy used in combination with these agents may impact results. Ongoing research is leading to identification of new biomarkers of response, further defining the subpopulations who achieve greatest benefit. Hence optimizing treatment for this group of patients has become increasingly complex, requiring a multidisciplinary approach not only to identify those who are curable with resectable disease but also to determine when it is best to incorporate targeted drugs, with which chemotherapy, and in whom. Currently bevacizumab, cetuximab, and panitumumab are the only approved biologic agents for use in mCRC. In this article we discuss the evidence supporting the use of biologic agents with chemotherapy and suggested strategies for their integration into the treatment armamentarium of mCRC.

Does axitinib (AG-01376) have a future role in metastatic renal cell carcinoma and other malignancies?

Axitinib (Pfizer Inc., UK) is an oral small-molecule receptor tyrosine kinase inhibitor that targets angiogenesis. Axitinib has greater affinity and is a more selective inhibitor of VEGF receptor 1, -2 and -3, PDGFR and c-KIT than both sunitinib and sorafenib. It has encouraging efficacy and safety data in Phase II trials for metastatic renal cell carcinoma and advanced thyroid cancer patients. It is now being investigated in two Phase III trials in metastatic renal cell carcinoma and in Phase II trials in a range of tumor types. These trials will determine whether axitinib is an effective and safe antiangiogenic therapy.

Development of second-generation VEGFR tyrosine kinase inhibitors: current status

The vascular endothelial growth factor (VEGF) signaling pathway appears to be the dominant pathway involved in tumor angiogenesis, providing a rationale for targeting the VEGF receptors (VEGFR-1, -2, and -3) in the treatment of cancers. In particular, VEGF signaling is thought to be important in renal cell carcinoma (RCC) because of the deregulation of the pathway through nearly uniform loss of the von Hippel Lindau protein. The tyrosine kinase inhibitors (TKIs) sorafenib, sunitinib, and pazopanib are approved by the US Food and Drug Administration for the treatment of advanced RCC; however, these multitargeted agents inhibit a wide range of kinase targets in addition to the VEGFRs, resulting in a range of adverse effects unrelated to efficient VEGF blockade. This article reviews recent advances in the development of the second-generation VEGFR TKIs, including the more selective VEGFR TKIs tivozanib and axitinib, and focuses on the potential benefits of novel inhibitors with improved potency and selectivity.

Intra-Laboratory Pre-Validation of a Human Cell Based in vitro Angiogenesis Assay for Testing Angiogenesis Modulators

The developed standardized human cell based in vitro angiogenesis assay was intra-laboratory pre-validated to verify that the method is reliable and relevant for routine testing of modulators of angiogenesis, e.g., pharmaceuticals and industrial chemicals. This assay is based on the earlier published method but it was improved and shown to be more sensitive and rapid than the previous assay. The performance of the assay was assessed by using six reference chemicals, which are widely used pharmaceuticals that inhibit angiogenesis: acetyl salicylic acid, erlotinib, 2-methoxyestradiol, levamisole, thalidomide, and anti-vascular endothelial growth factor. In the intra-laboratory pre-validation, the sensitivity of the assay (upper and lower limits of detection and linearity of response in tubule formation), batch to batch variation in tubule formation between different Master cell bank batches, and precision as well as the reliability of the assay (reproducibility and repeatability) were tested. The pre-set acceptance criteria for the intra-laboratory pre-validation study were met. The relevance of the assay in man was investigated by comparing the effects of reference chemicals and their concentrations to the published human data. The comparison showed a good concordance, which indicates that this human cell based angiogenesis model predicts well the effects in man and has the potential to be used to supplement and/or replace of animal tests.

Axitinib for the management of metastatic renal cell carcinoma

In recent years, targeted agents have changed the treatment landscape for patients with advanced renal cell carcinoma (RCC), greatly improving treatment outcomes. Several targeted agents are now licensed for the treatment of metastatic RCC (mRCC), and a number of new agents are under investigation. Axitinib, a small molecule indazole derivative is an oral, potent multitargeted tyrosine kinase receptor inhibitor, which selectively inhibits vascular endothelial growth factor receptors (VEGFR)-1, -2, and -3 at subnanomolar concentrations, in vitro. In various nonclinical models, axitinib has demonstrated in vivo target modulation and antiangiogenesis. In pharmacokinetic studies, axitinib administered orally with food at the proposed regimen of 5 mg twice daily continuous daily dosing, is rapidly absorbed, reaching peak concentrations within 2-6 hours. Axitinib is metabolized primarily in the liver via the cytochrome P450 (CYP) system with less than 1% of the administered drug passing unchanged in the urine. The pharmacokinetics of axitinib do not appear to be altered by coadministered chemotherapies, and antacids do not have a clinically significant effect. However, coadministration with CYP3A4 and 1A2 inducers is contraindicated. In addition, proton pump inhibitors reduce the rate of axitinib absorption. Increased axitinib exposure is associated with higher efficacy indicated by decreased tumor perfusion and volume. In three phase II clinical trials in patients with advanced RCC previously treated with cytokines, chemotherapy or targeted agents, axitinib has demonstrated antitumor activity with a favorable non-cumulative toxicity profile. In one study of Western patients with cytokine-refractory mRCC, an objective response rate (ORR) of 44.2% (95% CI 30.5, 58.7) was achieved. The median time to progression was 15.7 months (95% CI 8.4, 23.4) and the median overall survival (OS) was 29.9 months (95% CI 20.3, not estimable). In the second study of patients with sorafenib-refractory mRCC, ORR was 22.6% (95% CI 12.9, 35.0). The median progression-free survival (PFS) was 7.4 months (95% CI 6.7, 11.0) and a median OS of 13.6 months (95% CI 8.4, 18.8) was achieved. Results from the third study in Japanese patients with cytokine-refractory mRCC reported an ORR of 55% and median PFS of 12.9 months (95% CI 9.8, 15.6). In the three studies, the most common adverse events reported were fatigue, hypertension, hand-foot syndrome (HFS), and gastrointestinal toxicity, which were generally manageable with standard medical intervention. Of note, the incidence of HFS and proteinuria in the Japanese study was higher than that reported in the Western study in cytokine-refractory mRCC patients. An observed association between diastolic blood pressure ≥90 mmHg and increased efficacy suggests potential use as a prognostic biomarker. However, this requires further investigation. Two randomized phase III clinical trials are ongoing to determine the efficacy of axitinib in patients with mRCC in the first- and second-line setting. These results will help to determine the place of axitinib in the mRCC treatment algorithm.

A Phase Ib pharmacokinetic study of the anti-angiogenic agent CKD-732 used in combination with capecitabine and oxaliplatin (XELOX) in metastatic colorectal cancer patients who progressed on irinotecan-based chemotherapy

BACKGROUND

We conducted a Phase I clinical trial to evaluate the safety, tolerability, and pharmacokinetics (PK) of CKD-732 [6-O-(4-dimethylaminoethoxy) cinnamoyl fumagillol hemioxalate] in combination with capecitabine and oxaliplatin (XELOX) in nine metastatic colorectal cancer patients who had progressed on irinotecan-based chemotherapy.

METHODS

Using a dose-escalation schedule, CKD-732 doses of 2, 5, or 10 mg/m(2)/d were administered twice weekly for 2 weeks, followed by a 1-week rest. Oxaliplatin (130 mg/m(2)) was administered on day 1, and capecitabine (1,000 mg/m(2) twice a day) was orally administered for 14 days of a 3-week cycle.

RESULTS

In the group given the 10 mg/m(2)/d dose, two patients experienced dose limiting toxicities (one had grade 3 nausea, insomnia, and fatigue; the other had grade 3 insomnia). The maximum tolerated dose was 10 mg/m(2)/d, and the clinically recommended dose was 5 mg/m(2)/d for CKD-732 in combination with XELOX. Frequently encountered non-hematological grade 3/4 adverse events included insomnia (22.2%), fatigue (11.1%), sensory neuropathy (11.1%), hyperbilirubinemia (11.1%), and dyspnea (11.1%). The area under the concentration-time curve and maximum concentration of CKD-732 increased in a dose-dependent manner. There were no notable effects of CKD-732 on the PK of capecitabine and oxaliplatin-derived platinum.

CONCLUSION

The Phase II recommended dose of CKD-732 was determined to be 5 mg/m(2)/d, and this dose was safely combined with a conventional dose of capecitabine and oxaliplatin in this patient population. Further studies on the effects of CKD-732 in combination with XELOX and other chemotherapies using a larger study population are warranted.

Antiangiogenesis agents in colorectal cancer

PURPOSE OF REVIEW

The vascular endothelial growth factor (VEGF) system is a critical regulator of angiogenesis and known to promote tumor growth and invasion in colorectal cancer (CRC). Bevacizumab is currently the only VEGF inhibitor with clear proof of efficacy in CRC, but optimal use of this agent at various stages of the disease is still under investigation. Additionally, there are numerous other angiogenesis agents targeting VEGF and other proangiogenic systems in clinical development.

RECENT FINDINGS

Although bevacizumab has been shown to improve outcomes in terms of progression-free and overall survival in the setting of metastatic CRC (mCRC), it does not appear to provide long-term benefit in the adjuvant setting. The combination of VEGF inhibition with epidermal growth factor inhibition with chemotherapy does not improve survival for patients with mCRC, and may potentially be harmful in the first-line setting. Tyrosine kinase inhibitors in combination with other therapies show promise in early clinical trials in mCRC.

SUMMARY

Current evidence suggests that the benefit of VEGF inhibition with bevacizumab in CRC is limited to the metastatic setting. Dual antibody therapy with bevacizumab and an epidermal growth factor inhibitor (cetuximab or panitumumab) should not be used in mCRC. Results of ongoing trials involving tyrosine kinase inhibitors may result in an expansion of treatment options for patients with CRC.