Antitumor activity and biomarker analysis of sunitinib in patients with bevacizumab-refractory metastatic renal cell carcinoma

The current status of tailor-made medicine with molecular biomarkers for patients with clear cell renal cell carcinoma

Appropriate use of multiple reliable molecular biomarkers in the right context will play a role in tailormade medicine of clear cell renal cell carcinoma (RCC) patients in the future. A total of 11,056 patients from 53 studies were included in this review. The article numbers of the each evidence levels, using the grading system defined by the Oxford Centre for Evidence-based Medicine, in 1b, 2a, 2b, and 3b were 5 (9%), 18 (34%), 29 (55%), and 1 (2%), respectively. The main goal of using biomarkers is to refine predictions of tumor progression, pharmacotherapy responsiveness, and cancer-specific and/or overall survival. Currently, carbonic anhydrase (CA9) and vascular endothelial growth factor (VEGF) in peripheral blood and p53 in tumor tissues are measured to predict metastasis, while VEGF-related proteins in peripheral blood are used to assess pharmacotherapy responsiveness with sunitinib. Furthermore, interleukin 8, osteopontin, hepatocyte growth factor, and tissue inhibitors of metalloproteinases-1 in peripheral blood enable assessment of responsiveness to pazopanib treatment. Other reliable molecular biomarkers include von Hippel–Lindau gene alteration, hypoxia-inducible factor-1a, CA9, and survivin in tumor tissues and VEGF in peripheral blood for predicting cancer-specific survival. In the future, studies should undergo external validation for developing tailored management of clear cell RCC with molecular biomarkers, since individual institutional studies lack the generalization and consistency required to maintain accuracy among different patient series.

Exogenous norepinephrine attenuates the efficacy of sunitinib in a mouse cancer model

Background

Sunitinib alone exhibits satisfactory efficacy in several mouse homografts and xenografts but unsatisfactory efficacy in many kinds of solid tumors in clinic. Different from animals, receiving a diagnosis of cancer impacts chronic stress on patients. Here, we examine whether norepinephrine (NE), one of the most potent stress related hormones, leads to the difference in the efficacy of sunitinib between clinical and preclinical trials.

Methods

The influence of NE on mouse melanoma B16F1 cells under sunitinib was evaluated in vitro and in vivo. The β-AR/cAMP/PKA (β-adrenoceptor/cyclic adenosine monophosphate/protein kinase A) signaling pathway was also evaluated in human lung adenocarcinoma cells.

Results

We found that NE upregulated the expression of VEGF, IL-8 and IL-6 in vitro and stimulated tumor growth in vivo, which was mediated by β-AR/cAMP/PKA signaling pathway and could be inhibited by propranolol, a β-blocker for hypertension for decades.

Conclusions

This research indicates exogenous norepinephrine attenuates the efficacy of sunitinib, and a combination of sunitinib and propranolol might be suggested as a new strategy in solid tumor in clinic.

Epigenetic control of hypoxia inducible factor-1α-dependent expression of placental growth factor in hypoxic conditions

Hypoxia plays a crucial role in the angiogenic switch, modulating a large set of genes mainly through the activation of hypoxia-inducible factor (HIF) transcriptional complex. Endothelial cells play a central role in new vessels formation and express placental growth factor (PlGF), a member of vascular endothelial growth factor (VEGF) family, mainly involved in pathological angiogenesis. Despite several observations suggest a hypoxia-mediated positive modulation of PlGF, the molecular mechanism governing this regulation has not been fully elucidated. We decided to investigate if epigenetic modifications are involved in hypoxia-induced PlGF expression. We report that PlGF expression was induced in cultured human and mouse endothelial cells exposed to hypoxia (1% O 2), although DNA methylation at the Plgf CpG-island remains unchanged. Remarkably, robust hyperacetylation of histones H3 and H4 was observed in the second intron of Plgf, where hypoxia responsive elements (HREs), never described before, are located. HIF-1α, but not HIF-2α, binds to identified HREs. Noteworthy, only HIF-1α silencing fully inhibited PlGF upregulation. These results formally demonstrate a direct involvement of HIF-1α in the upregulation of PlGF expression in hypoxia through chromatin remodeling of HREs sites. Therefore, PlGF may be considered one of the putative targets of anti-HIF therapeutic applications.

Optimal management of metastatic renal cell carcinoma: current status

The armamentarium for the systemic therapy of advanced renal cell carcinoma (RCC) has undergone dramatic changes over the past 6 years. While high-dose interleukin (IL)-2 remains an option for highly selected good and intermediate risk patients with clear-cell histology because of durable complete responses in a small fraction of patients, cytokine-based therapy including interferon (IFN) has been supplanted by vascular-endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) inhibitors. Treatment decision is initially based on prognostication of the disease. As metastatic RCC (mRCC) is commonly an indolent disease, a period of observation should always been considered. For good and intermediate risk disease, pazopanib, sunitinib or the combination of bevacizumab plus IFN are considered. Notably, recent data suggest non-inferiority for the efficacy of pazopanib compared to sunitinib coupled with a better toxicity profile. A novel VEGF receptor inhibitor, tivozanib, is expected to be approved based on improvement in PFS when compared to sorafenib in the first-line setting. The use of temsirolimus for poor risk disease is supported by a phase III trial dedicated to this group of patients. The role of cytoreductive nephrectomy in the context of VEGF and mTOR inhibitors is being studied in randomized trials. Selected patients with solitary or oligometastatic disease may be eligible for metastatectomy. Following first-line VEGF inhibitors, second-line therapy with everolimus and axitinib have demonstrated benefits in progression-free survival (PFS). One phase III trial comparing sorafenib and temsirolimus in the post-sunitinib setting showed no difference in PFS, the primary endpoint, but did show a superior overall survival for sorafenib. Sorafenib, pazopanib and axitinib have all demonstrated clinical benefit following cytokines. Therapy following first-line mTOR inhibitors remains undefined, although VEGF inhibitors have demonstrated activity in this setting. Optimal sequencing of agents and individualized therapy based on biomarkers is undergoing investigation. Today, the choice of therapy is based on patient and physician decision, which is a function of comorbidities, toxicity profiles and costs. Clinical trials evaluating novel agents and combinations should be preferred when available since agents in the current therapeutic arsenal have not yielded cures despite extending median survival to greater than 2 years. One noteworthy new class of agents that has yielded durable responses is programmed death (PD)-1 inhibitors, which target a T-lymphocyte checkpoint and are heralding a resurgence of immunotherapy. Finally, optimal therapy for non-clear cell RCC remains to be delineated, although sunitinib, everolimus and other VEGFR-TKI or mTOR inhibitors have all demonstrated modest benefit.

Renal carcinoma pharmacogenomics and predictors of response: Steps toward treatment individualization

Molecular knowledge has deeply affected the treatment and outcome of kidney cancer in recent years, and several therapeutic options have become available. However, there are no validated biomarkers to select the best drug for each patient. Already published studies and ongoing investigations could change this scenario in the near future. Regarding antiangiogenic drugs, several works on single nucleotide polymorphisms have achieved promising results, with some SNPs predicting resistance to sunitinib and pazopanib being validated. If more evidence is gained, it could prompt prospective studies exploring a molecularly driven selection of treatment. Another relevant line of investigation for antiangiogenic drugs is the cytokines and antiangiogenic factors. Different studies have found that cytokines and antiangiogenic factors are able to predict the outcome of patients treated with sunitinib, pazopanib, or sorafenib. Issues regarding the thresholds of normality and the best time for assessment are pending, but the communicated results are encouraging. Less evidence is available for mammalian target of rapamycin inhibitors but recent data support a key role of the phosphoinositide 3-kinase/Akt pathway in clear cell renal cell carcinoma and points toward poor response to angiogenic drugs when the pathway is activated. Whether modern phosphoinositide 3-kinase inhibitors could be the best option for these patients is a question that should be addressed. Additionally, a new class of immunomodulators, like anti-programmed death 1 drugs, has demonstrated to achieve long-lasting stabilizations even in some patients with no radiological response or early progression. This is a singular situation where the identification of reliable predictors of efficacy will be key in the development of these drugs in renal cell carcinoma. Finally, germline mutations of the c-Met gene have been proposed as the first predictor of response to targeted therapies in papillary renal cell carcinoma. As a conclusion, translational research will be a cornerstone to move a next step forward in kidney cancer.

Anti-angiogenic therapy for cancer: current progress, unresolved questions and future directions

Tumours require a vascular supply to grow and can achieve this via the expression of pro-angiogenic growth factors, including members of the vascular endothelial growth factor (VEGF) family of ligands. Since one or more of the VEGF ligand family is overexpressed in most solid cancers, there was great optimism that inhibition of the VEGF pathway would represent an effective anti-angiogenic therapy for most tumour types. Encouragingly, VEGF pathway targeted drugs such as bevacizumab, sunitinib and aflibercept have shown activity in certain settings. However, inhibition of VEGF signalling is not effective in all cancers, prompting the need to further understand how the vasculature can be effectively targeted in tumours. Here we present a succinct review of the progress with VEGF-targeted therapy and the unresolved questions that exist in the field: including its use in different disease stages (metastatic, adjuvant, neoadjuvant), interactions with chemotherapy, duration and scheduling of therapy, potential predictive biomarkers and proposed mechanisms of resistance, including paradoxical effects such as enhanced tumour aggressiveness. In terms of future directions, we discuss the need to delineate further the complexities of tumour vascularisation if we are to develop more effective and personalised anti-angiogenic therapies.

Management of metastatic kidney cancer in the era of personalized medicine

Patients with localized renal cell cancer (RCC) are often cured following surgical resection. However, a significant proportion of patients will experience recurrence or present with metastatic disease at distant sites and may be deemed incurable. The worldwide incidence of RCC is rising, affecting more than 271,000 people and resulting in 116,000 deaths each year. Unfortunately, advanced RCC is typically resistant to classical chemotherapy and radiotherapy. Previously, non-specific immunotherapies such as interleukin-2 and interferon were used in hopes of improving cancer immunity, leading to rare but durable responses. However, enthusiasm for these immunotherapies has waned due to limited patient responses, their excessive toxicities, and the emergence of alternative targeted therapies that have resulted in improved clinical endpoints for patients with metastatic RCC (mRCC). Strides in targeted treatment can be attributed to an improved understanding of the molecular underpinnings that cause and drive the progression of renal cell cancers. More recently, interest in immunotherapies has resurfaced, as agents inhibiting specific checkpoints involved in cancer immune evasion have demonstrated promising activity in patients with mRCC. Here we review the novel targeted agents, biomarkers and immunotherapies that promise to change the clinical outcomes for patients with advanced RCC.

Circulating proteins as potential biomarkers of sunitinib and interferon-α efficacy in treatment-naïve patients with metastatic renal cell carcinoma

PURPOSE

We investigated potential biomarkers of efficacy in a phase III trial of sunitinib versus interferon-alpha (IFN-α), first-line in metastatic renal cell carcinoma (mRCC), by analyzing plasma levels of vascular endothelial growth factor (VEGF)-A, VEGF-C, soluble VEGF receptor-3 (sVEGFR-3) and interleukin (IL)-8.

METHODS

Seven hundred and fifty mRCC patients were randomized to oral sunitinib 50 mg/day in repeated cycles of a 4-week on/2-week off schedule or IFN-α 9 million units subcutaneously thrice weekly. Plasma samples collected from a subset of 63 patients on days 1 and 28 of cycles 1-4 and at end of treatment were analyzed by ELISA.

RESULTS

Baseline characteristics of biomarker-evaluated patients in sunitinib (N = 33) and IFN-α (N = 30) arms were comparable to their respective intent-to-treat populations. By univariate Cox regression analysis, low baseline soluble protein levels were associated with lower risk of progression/death (all P < 0.05): in both treatment arms, baseline VEGF-A and IL-8 were associated with overall survival (OS) and baseline VEGF-C with progression-free survival (PFS); in the sunitinib arm, baseline VEGF-A was associated with PFS and baseline sVEGFR-3 with PFS and OS; in the IFN-α arm, baseline IL-8 was associated with PFS. In multivariate analysis, baseline sVEGFR-3 and IL-8 remained independent predictors of OS in the sunitinib arm, while no independent predictors of outcome remained in the IFN-α arm. Pharmacodynamic changes were not associated with PFS or OS for any plasma protein investigated.

CONCLUSIONS

Our findings suggest that, in mRCC, baseline VEGF-A and IL-8 may have prognostic value, while baseline sVEGFR-3 may predict sunitinib efficacy.

Association of matrix metalloproteinase 2 plasma level with response and survival in patients treated with bevacizumab for recurrent high-grade glioma

BACKGROUND

A predictive marker of bevacizumab activity is an unmet medical need. We evaluated the predictive value of selected circulating prebiomarkers involved in neoangiogenesis and invasion on patient outcome in recurrent high-grade glioma treated with bevacizumab.

METHODS

Analyzed in plasma were a set of 11 prebiomakers of interest (vascular endothelial growth factor receptor [VEGF]; VEGF receptor 2; basic fibroblast growth factor; stromal cell derived factor 1; placenta growth factor; urokinase-type plasminogen activator; plasminogen activator inhibitor 1; matrix metalloproteinases 2, 7, and 9; and adrenomedulline), using ELISA, at baseline and 2 weeks after bevacizumab initiation in a prospective cohort of 26 patients (Cohort 1). Correlations were validated in a separate retrospective cohort (Cohort 2; n = 50) and tested in cohort patients treated with cytotoxic agents without bevacizumab (Cohort 3; n = 34). Dosages were correlated to objective response, progression-free survival (PFS), and overall survival (OS).

RESULTS

In Cohort 1, high MMP2 baseline level was associated with a probability of objective response of 83.3% versus 15.4% for low MMP2 level (P = .001). In multivariate analysis, baseline level of MMP2 correlated with PFS (hazard ratio, 3.92; 95% confidence interval [CI]:1.46-10.52; P = .007) and OS (hazard ratio, 4.62; 95% CI: 1.58-13.53; P = .005), as decrease of VEGF (P = .038 for PFS and P = .013 for OS) and MMP9 (P = .016 for PFS and P = .025 for OS). In Cohort 2, MMP2, but not MMP9, confirmed its predictive significance. In Cohort 3, no association was found between MMP2, MMP9, and outcome.

CONCLUSION

In patients with recurrent high-grade glioma treated with bevacizumab, but not with cytotoxic agent, high MMP2 plasma levels are associated with prolonged tumor control and survival. MMP2 should be tested in randomized clinical trials that evaluate bevacizumab efficacy, and its biological role reassessed.

A systematic review of predictive and prognostic biomarkers for VEGF-targeted therapy in renal cell carcinoma

BACKGROUND

Vascular endothelial growth factor (VEGF)-targeted therapy is the currently standard treatment for advanced and metastatic renal cell carcinoma (RCC). Multiple candidate predictive and prognostic biomarkers have been evaluated. We performed a systematic review and graded the available evidence on the biomarkers for VEGF-targeted therapy in RCC.

METHODS

We conducted an independent review of PubMed and ASCO databases up to August 2013. Studies were included if biomarkers obtained from metastatic clear-cell RCC patients treated with the FDA-approved VEGF-targeted therapy were assessed for their correlation with clinical outcomes. We graded the studies and determined the Level-of-evidence for each biomarker using a previously published framework.

RESULTS

A total of 50 articles were selected for this review. Seven studies assessed the predictive value of biomarkers using the archived specimens from randomized controlled trials. Five predictive biomarkers, such as VEGF, interleukin (IL)-6, hepatocyte growth factor (HGF), osteopontin, single nucleotide polymorphisms in IL-8, satisfied Level II evidence. IL-6 is the most corroborated predictive biomarker based on its consistent predictive value in two different trials. The prognostic value of biomarkers was assessed in 48 studies using the archived specimens from clinical trials, prospective and retrospective observational registries. Three biomarkers, including IL-8, HGF and osteopontin, satisfied Level I evidence for PFS.

CONCLUSION

Though several promising predictive biomarkers for VEGF-targeted therapy have been found, none of them has satisfied the determination of Level I evidence. A more focused development of biomarkers with prospective assessment in clinical trials and clear intent of use in clinical practice is needed.

Correlation of bevacizumab-induced hypertension and outcomes of metastatic colorectal cancer patients treated with bevacizumab: a systematic review and meta-analysis

BACKGROUND

With the wide application of targeted drug therapies, the relevance of prognostic and predictive markers in patient selection has become increasingly important. Bevacizumab is commonly used in combination with chemotherapy in the treatment of metastatic colorectal cancer. However, there are currently no predictive or prognostic biomarkers for bevacizumab. Several clinical studies have evaluated bevacizumab-induced hypertension in patients with metastatic colorectal cancer. This meta-analysis was performed to better determine the association of bevacizumab-induced hypertension with outcome in patients with metastatic colorectal cancer, and to assess whether bevacizumab-induced hypertension can be used as a prognostic factor in these patients.

METHODS

We performed a systematic review and meta-analysis on seven published studies to investigate the relationship between hypertension and outcome of patients with metastatic colorectal cancer treated with bevacizumab. Our primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS) and overall response rate (ORR). Hazard ratios (HRs) for PFS and OS were extracted from each trial, and the log of the relative risk ratio (RR) was estimated for ORR.

RESULTS

The occurrence of bevacizumab-induced hypertension in patients was highly associated with improvements in PFS (HR = 0.57, 95% CI: 0.46-0.72; P <0.001), OS (HR = 0.50; 95% CI: 0.37-0.68; P <0.001), and ORR (RR = 1.57, 95% CI: 1.07-2.30, P <0.05), as compared to patients without hypertension.

CONCLUSIONS

Bevacizumab-induced hypertension may represent a prognostic factor in patients with metastatic colorectal cancer.

A phase I, open-label study of trebananib combined with sorafenib or sunitinib in patients with advanced renal cell carcinoma

BACKGROUND

Trebananib, an investigational peptibody, binds to angiopoietin 1 and 2, thereby blocking their interaction with Tie2.

PATIENTS AND METHODS

This open-label phase I study examined trebananib 3 mg/kg or 10 mg/kg intravenous (I.V.) once weekly plus sorafenib 400 mg twice per day or sunitinib 50 mg once per day in advanced RCC. Primary end points were adverse event incidence and pharmacokinetics.

RESULTS

Thirty-seven patients were enrolled. During trebananib plus sorafenib administration (n = 17), the most common treatment-related adverse events (TRAEs) included rash (n = 12; 71%), diarrhea (n = 12; 71%), hypertension (n = 11; 65%), and fatigue (n = 11; 65%); grade ≥ 3 TRAEs (n = 7; 41%); and 2 patients (12%) had peripheral edema. During trebananib plus sunitinib administration (n = 19), the most common TRAEs included diarrhea (n = 14; 74%), fatigue (n = 13; 68%), hypertension (n = 11; 58%), and decreased appetite (n = 11; 58%); grade ≥ 3 TRAEs (n = 13; 68%); and 8 (42%) patients had peripheral edema. Trebananib did not appear to alter the pharmacokinetics of sorafenib or sunitinib. No patient developed anti-trebananib antibodies. Objective response rates were 29% (trebananib plus sorafenib) and 53% (trebananib plus sunitinib).

CONCLUSION

The toxicities of trebananib 3 mg/kg or 10 mg/kg I.V. plus sorafenib or sunitinib in RCC were similar to those of sorafenib or sunitinib monotherapy, with peripheral edema being likely specific to the combinations. Antitumor activity was observed.

Combined blockade of HER2 and VEGF exerts greater growth inhibition of HER2-overexpressing gastric cancer xenografts than individual blockade

Gastric cancer overexpressing the human epidermal growth factor 2 (HER2) protein has a poor outcome, although a combination of chemotherapy and the anti-HER2 antibody trastuzumab has been approved for the treatment of advanced gastric cancer. Vascular endothelial growth factor (VEGF) expression in gastric cancer is correlated with recurrence and poor prognosis; however, the anti-VEGF antibody bevacizumab has shown limited efficacy against gastric cancer in clinical trials. In this study, we evaluated the antitumor effects of trastuzumab; VEGF-Trap binding to VEGF-A, VEGF-B and placental growth factor (PlGF); and a combination of trastuzumab and VEGF-Trap in a gastric cancer xenograft model. Although trastuzumab and VEGF-Trap each moderately inhibited tumor growth, the combination of these agents exerted greater inhibition compared with either agent alone. Immunohistochemical analyses indicated that the reduction in tumor growth was associated with decreased proliferation and increased apoptosis of tumor cells and decreased tumor vascular density. The combined treatment resulted in fewer proliferating tumor cells, more apoptotic cells and reduced tumor vascular density compared with treatment with trastuzumab or VEGF-Trap alone, indicating that trastuzumab and VEGF-Trap had additive inhibitory effects on the tumor growth and angiogenesis of the gastric cancer xenografts. These data suggest that trastuzumab in combination with VEGF-Trap may represent an effective approach to treating HER2-overexpressing gastric cancer.

Molecularly targeted drugs for metastatic colorectal cancer

The survival rate of patients with metastatic colorectal cancer (mCRC) has significantly improved with applications of molecularly targeted drugs, such as bevacizumab, and led to a substantial improvement in the overall survival rate. These drugs are capable of specifically targeting the inherent abnormal pathways in cancer cells, which are potentially less toxic than traditional nonselective chemotherapeutics. In this review, the recent clinical information about molecularly targeted therapy for mCRC is summarized, with specific focus on several of the US Food and Drug Administration-approved molecularly targeted drugs for the treatment of mCRC in the clinic. Progression-free and overall survival in patients with mCRC was improved greatly by the addition of bevacizumab and/or cetuximab to standard chemotherapy, in either first- or second-line treatment. Aflibercept has been used in combination with folinic acid (leucovorin)-fluorouracil-irinotecan (FOLFIRI) chemotherapy in mCRC patients and among patients with mCRC with wild-type KRAS, the outcomes were significantly improved by panitumumab in combination with folinic acid (leucovorin)-fluorouracil-oxaliplatin (FOLFOX) or FOLFIRI. Because of the new preliminary studies, it has been recommended that regorafenib be used with FOLFOX or FOLFIRI as first- or second-line treatment of mCRC chemotherapy. In summary, an era of new opportunities has been opened for treatment of mCRC and/or other malignancies, resulting from the discovery of new selective targeting drugs.

Pharmacokinetics, clinical indications, and resistance mechanisms in molecular targeted therapies in cancer

The strategy for discovery and development of new cancer drugs has shifted the field from cytotoxic agents to therapies that selectively target oncogenic drivers. In the last decade, a number of targeted cancer therapies have been discovered and proven effective in a variety of hematological and solid malignancies. In this article, we review clinical pharmacokinetic characteristics of the U.S. Food and Drug Administration-approved targeted therapies and provide an overview of key clinical trials that led to approval of these drugs. The major limiting factor of targeted treatment is the development of resistance. We describe general principles of resistance and specific, clinically confirmed mechanisms of resistance to several therapies in different malignancies.

Analyses of potential predictive markers and survival data for a response to sunitinib in patients with metastatic renal cell carcinoma

BACKGROUND

Patients with metastatic clear cell renal cell carcinoma (ccRCC) are frequently treated with tyrosine kinase inhibitors (TKI) such as sunitinib. It inhibits angiogenic pathways by mainly targeting the receptors of VEGF and PDGF. In ccRCC, angiogenesis is characterized by the inactivation of the von Hippel-Lindau gene (VHL) which in turn leads to the induction of HIF1α target genes such as CA9 and VEGF. Furthermore, the angiogenic phenotype of ccRCC is also reflected by endothelial markers (CD31, CD34) or other tumor-promoting factors like Ki67 or survivin.

METHODS

Tissue microarrays from primary tumor specimens of 42 patients with metastatic ccRCC under sunitinib therapy were immunohistochemically stained for selected markers related to angiogenesis. The prognostic and predictive potential of theses markers was assessed on the basis of the objective response rate which was evaluated according to the RECIST criteria after 3, 6, 9 months and after last report (12-54 months) of sunitinib treatment. Additionally, VHL copy number and mutation analyses were performed on DNA from cryo-preserved tumor tissues of 20 ccRCC patients.

RESULTS

Immunostaining of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β was significantly associated with the sunitinib response after 6 and 9 months as well as last report under therapy. Furthermore, HIF-1α, CA9, CD34, VEGFR1 and -3 and PDGRFα showed significant associations with progression-free survival (PFS) and overall survival (OS). In multivariate Cox proportional hazards regression analyses high CA9 membrane staining and a response after 9 months were independent prognostic factors for longer OS. Frequently observed copy number loss and mutation of VHL gene lead to altered expression of VHL, HIF-1α, CA9, and VEGF.

CONCLUSIONS

Immunoexpression of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β in the primary tumors of metastatic ccRCC patients might support the prediction of a good response to sunitinib treatment.

The potential of sunitinib as a therapy in ovarian cancer

INTRODUCTION

Sunitinib malate (SU11248; Sutent®; Pfizer, Inc., New York) is a multi-kinase inhibitor currently approved for use in advanced renal cell carcinoma (RCC), imatinib-resistant/-intolerant gastrointestinal stromal tumours and progressive, well-differentiated pancreatic neuroendocrine tumours in patients with unresectable, locally advanced or metastatic disease.

AREAS COVERED

This article describes the mechanism of action and of the pharmacokinetics of sunitinib; further, it summarizes Phase I and II trials on the clinical efficacy, tolerability and safety of this agent in the setting of ovarian cancer (OC) treatment.

EXPERT OPINION

On the basis of the current literature, sunitinib has shown modest antitumour activity and acceptable toxicity. Studies investigating the impact of horizontal and vertical combinations should represent a priority of future research. Although clinical Phase II trials on the use of sunitinib in the treatment of OC demonstrated an acceptable profile of AEs, a greater comprehension of the toxicity of this compound is recommended.

Differential regulation of sunitinib targets predicts its tumor-type-specific effect on endothelial and/or tumor cell apoptosis

PURPOSE

Sunitinib is an inhibitor of tyrosine-kinase receptors, and no biomarker predictive of sunitinib response is available. The purpose of this preclinical study was to show whether sunitinib molecular targets could be used as biomarkers to assess tumor response to sunitinib in human cancer cell line xenografts of three different tumor types.

METHODS

Using mice xenografted with liver, breast and renal carcinoma cell lines, we sequentially analyzed the effect of 7-day sunitinib treatment on tumor and vascular compartments.

RESULTS

In all xenografts, microvessel damage occurred from Day 1. Tumor damage also occurred in liver, breast, but not in renal xenografts. Using specific human and mouse probes for genes encoding sunitinib targets, we showed a significant relation between apoptotic tumor cell numbers and human PDGFRΒ and RET mRNA expression in liver cancer and to human VEGFR2 expression in breast cancer xenografts. In contrast, in renal cancer xenografts, vascular effect evaluated by measuring endothelial cell apoptosis was related to mouse Vegfr1, Vegfr2 and Vegfa-164 expression.

CONCLUSION

This study identifies sunitinib vascular and tumor effects according to different tumor types and shows that sunitinib molecular targets used as biomarkers enable assessment of therapeutic response.

A randomized, double-blind, phase II study of erlotinib with or without sunitinib for the second-line treatment of metastatic non-small-cell lung cancer (NSCLC)

BACKGROUND

Combined inhibition of vascular, platelet-derived, and epidermal growth factor receptor (EGFR) pathways may overcome refractoriness to single agents in platinum-pretreated non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

This randomized, double-blind, multicenter, phase II trial evaluated sunitinib 37.5 mg/day plus erlotinib 150 mg/day versus placebo plus erlotinib continuously in 4-week cycles. Eligible patients had histologically confirmed stage IIIB or IV NSCLC previously treated with one or two chemotherapy regimens, including one platinum-based regimen. The primary end point was progression-free survival (PFS) by an independent central review.

RESULTS

One hundred and thirty-two patients were randomly assigned, and the median duration of follow-up was 17.7 months. The median PFS was 2.8 versus 2.0 months for the combination versus erlotinib alone (HR 0.898, P = 0.321). The median overall survival (OS) was 8.2 versus 7.6 months (HR 1.066, P = 0.617). Objective response rates (ORRs) were 4.6% and 3.0%, respectively. Sunitinib plus erlotinib was fairly well tolerated although most treatment-related adverse events (AEs) were more frequent than with erlotinib alone: diarrhea (55% versus 33%), rash (41% versus 30%), fatigue (31% versus 25%), decreased appetite (30% versus 13%), nausea (28% versus 14%), and thrombocytopenia (13% versus 0%).

CONCLUSIONS

The addition of sunitinib to erlotinib did not significantly improve PFS in patients with advanced, platinum-pretreated NSCLC.

Molecular targets on the horizon for kidney and urothelial cancer

As whole-genome sequencing technology rapidly advances, the insights gained from deciphering cancer genomes are shifting the paradigm in the diagnosis and treatment of cancer with the promise of individualized treatment for each patient. Information gained in this way is extensive for certain cancers, but fairly limited in renal cell carcinomas and urothelial carcinoma. Mutations in multiple, potentially druggable genes have been identified in urothelial carcinomas; however, the association between molecular alterations and clinical outcome has not yet been robustly demonstrated. Data in this area are emerging in renal cell carcinoma, leading to the development of targeted agents that have improved overall survival. Unfortunately, these treatments rarely yield complete responses, are not curative, and development of resistance ensues. This Review will focus on the biology of non-hormonally driven urological cancers. We discuss how approaches using whole-genome sequencing can facilitate the discovery of biomarkers of drug sensitivity in both renal cell carcinomas and urothelial carcinomas. For renal cell carcinomas, we will describe how genomic and epigenomic mining has uncovered novel genes and pathways involved in tumorigenesis, tumour classification and mechanisms of resistance in the various subsets of this disease and the potential for exploiting these discoveries in the clinic.

Monoclonal antibodies and other targeted therapies for pancreatic cancer

Pancreatic cancer continues to be a challenging disease to treat because of its aggressive nature, advanced stage at the time of diagnosis, and limited treatment options that are available. Traditional cytotoxic chemotherapy provides modest benefit to patients with pancreatic adenocarcinoma. Recently, a FOLFIRINOX regimen revealed improved response in overall and progression-free survival over single-agent gemcitabine in metastatic pancreatic cancer, but there is still much needed advancement in the systemic treatment of pancreatic cancer. There is a growing interest in the development of novel agents, while our understanding of molecular pathogenesis of pancreatic adenocarcinoma continues to expand. With identification of various molecular pathways in pancreatic cancer tumorigenesis, potential targets for drug development have been pursued with the use of monoclonal antibodies and small-molecule inhibitors. Although preclinical studies with multiple targeted therapies demonstrated encouraging results in pancreatic cancer, only erlotinib, an epidermal growth factor receptor inhibitor, showed a marginal survival benefit in a phase III clinical trial, when combined with gemcitabine. As further signaling pathways and their importance in pancreatic cancer tumorigenesis are better understood, further clinical trials will need to be designed to study these targeted agents as single agents, in combination with other novel agents or in combination with cytotoxic chemotherapy. In this review, we present the current knowledge on targeted therapy in pancreatic adenocarcinoma and its application in clinical practice.

Prognostic biomarkers for patients with advanced renal cell carcinoma treated with VEGF-targeted tyrosine kinase inhibitors

Tyrosine kinase inhibitors with activity against vascular endothelial growth factor receptor 2 are now standard treatment for the majority of patients with advanced renal cell carcinoma. The clinical development of these agents followed by their broad clinical utilization has allowed the creation of large databases to facilitate the identification of prognostic biomarkers and development of prognostic models. While several clinical prognostic models have been created, work continues on identifying novel biomarkers which might be used in conjunction with or even in place of these clinical models. In this review, we discuss the progress thus far in improving on current prognostic models and speculate on possible developments in the near future.

Update on antiangiogenic therapy in colorectal cancer: aflibercept and regorafenib

Angiogenesis plays an important role in colorectal carcinogenesis and approaches targeting the vascular growth factor receptor (VEGF) signaling such as bevacizumab yielded significant survival improvement for metastatic colorectal cancer patients. Recent evidence demonstrated the benefit of continuing angiogenic suppression after first-progression following bevacizumab-containing cytotoxic regimen though no benefit was observed with the use of bevacizumab in adjuvant setting. Aflibercept, a soluble fusion protein with high affinity for VEGF-A, -B and PlGF, administered in combination with irinotecan-containing regimen improved the survival of metastatic colorectal cancer patients in second-line setting (VELOUR trial). Regorafenib, a small molecule multikinase inhibitor against various pro-angiogenic and -proliferation targets, improved the survival of metastatic colorectal cancer patients who had progressed on all standard therapy. These developments had renewed enthusiasm in the field and the role of aflibercept and regorafenib in other treatment settings will continue to be defined by on-going and future clinical trials. As other anti-angiogenic approaches are being tested clinically, other novel non-angiogenic targets deserve to be evaluated in our effort to improve the outcome of colorectal cancer patients.

Placental growth factor supports neuroendocrine tumor growth and predicts disease prognosis in patients

Placental growth factor (PlGF), a VEGF-homolog implicated in tumor angiogenesis and adaptation to antiangiogenic therapy, is emerging as candidate target in malignancies. Here, we addressed the expression, function, and prognostic value of PlGF in neuroendocrine tumors (NETs). PlGF was determined in NET patients' sera collected retrospectively (n=88) and prospectively (n=87) using Roche-Elecsys and correlated with clinicopathological data. Tumoral PlGF was evaluated by immunohistochemistry, effects of PlGF on proliferation and migration in vitro were assessed using different NET cell lines and effects on tumor growth in vivo in orthotopic xenografts. Circulating and tumoral PlGF was elevated in patients with pancreatic NETs (pNETs) compared with control sera and respective healthy tissue. De novo PlGF expression occurred primarily in the tumor stroma, suggesting paracrine stimulatory circuits. Indeed, PlGF enhanced NET proliferation and migration in vitro and, conversely, neutralizing antibodies to PlGF reduced tumor growth in vivo. Elevated circulating PlGF levels in NET patients correlated with advanced tumor grading and were associated with reduced tumor-related survival in pNETs. Subsequent determinations confirmed and extended our observation of elevated PlGF levels in a prospective cohort of grade 1 and grade 2 pNETs (n=30) and intestinal NETs (n=57). In low-grade pNETs, normal circulating PlGF levels were associated with better survival. In intestinal NETs, circulating PlGF above median emerged as an independent prognostic factor for shorter time-to-progression in multivariate analyses. These data assign to PlGF a novel function in the pathobiology of NETs and propose PlGF as a prognostic parameter and therapeutic target.

Pazopanib as second-line treatment after sunitinib or bevacizumab in patients with advanced renal cell carcinoma: a Sarah Cannon Oncology Research Consortium Phase II Trial

BACKGROUND

This phase II trial examined the activity and toxicity of second-line treatment with pazopanib after failure of first-line single-agent treatment with sunitinib or bevacizumab in patients with advanced clear cell renal carcinoma.

PATIENTS AND METHODS

Fifty-five patients with metastatic clear cell renal carcinoma who had previously received first-line treatment with sunitinib (39 patients) or bevacizumab (16 patients) were enrolled. Patients received pazopanib 800 mg orally daily and were evaluated for response after 8 weeks of treatment. Responses were measured using Response Evaluation Criteria in Solid Tumors (RECIST), version 1.0, and confirmed with repeated scans after 8 weeks. Patients with objective response or stable disease continued treatment until disease progression or unacceptable toxicity occurred.

RESULTS

Fifteen of 55 patients (27%) had objective response to pazopanib. An additional 27 patients (49%) had stable disease, for a disease control rate of 76%. After a median follow-up of 16.7 months, the median progression-free survival for the entire group was 7.5 months (95% confidence interval, 5.4-9.4 months). Similar progression-free survival was observed regardless of whether previous treatment was with sunitinib or bevacizumab. The estimated overall survival rate for the entire group at 24 months was 43%.

CONCLUSION

Pazopanib is an active agent for the treatment of advanced clear cell renal carcinoma, even after failure of sunitinib or bevacizumab. Treatment with pazopanib should be considered early in the sequence of therapy for patients with advanced renal cell carcinoma.

Risk of hypothyroidism in patients with cancer treated with sunitinib: a systematic review and meta-analysis

BACKGROUND

The multitargeted tyrosine kinase inhibitor sunitinib is used in various cancers. Clinical studies have reported a substantial variation in the incidence of hypothyroidism associated with sunitinib, without a systemic attempt to synthesize these data.

METHODS

We searched Medline databases for relevant clinical trials published up to May 2012. Phase II and III trials and expanded access programs of sunitinib in patients with any type of cancer that reported occurrence of hypothyroidism were eligible. The summary incidence, relative risk (RR) and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models based on the heterogeneity of included studies.

RESULTS

Incidence analysis was performed using 6678 sunitinib-treated patients from all 24 eligible trials. The incidence of all- and high-grade hypothyroidism was 9.8% (95% CI 7.3-12.4%) and 0.4% (95% CI 0.3-0.5%), respectively. A meta-analysis of seven randomized trials with 2787 subjects revealed a RR of all- and high-grade hypothyroidism of 13.95 (95% CI 6.91-28.15; p < 0.00001) and 4.78 (95% CI 1.09-20.84; p = 0.04), respectively. Subgroup analysis revealed a significantly higher incidence of all-grade hypothyroidism in patients receiving sunitinib for longer duration than in patients receiving sunitinib for shorter duration (p = 0.02).

CONCLUSIONS

This meta-analysis of data available from clinical trials demonstrates that sunitinib is associated with a significant risk of developing all- and high-grade hypothyroidism. These data provide further evidence to recommend monitoring for hypothyroidism in patients receiving sunitinib.

Opportunities and challenges for successful use of bevacizumab in pediatrics

Bevacizumab (Avastin) has rapidly gained status as a broadly active agent for malignancies of several different histologies in adults. This activity has spawned a range of uses in pediatrics for both oncologic and non-oncologic indications. Early analyses indicate that pediatric cancers exhibit a spectrum of responses to bevacizumab that suggest its activity may be more limited than in adult oncology. Most exciting, is that for low-grade tumors that threaten vision and hearing, there is not only evidence for objective tumor response but for recovery of lost function as well. In addition to oncological indications, there is a range of uses for non-oncologic disease for which bevacizumab has clear activity. Finally, a number of mechanisms have been identified as contributing to bevacizumab resistance in cancer. Elucidating these mechanisms will guide the development of future clinical trials of bevacizumab in pediatric oncology.

An evidence-based guide to the selection of sequential therapies in metastatic renal cell carcinoma

Targeted therapies have introduced a paradigm shift in the management of metastatic renal cell carcinoma. Currently, four molecules (sunitinib, pazopanib, bevacizumab plus interferon, temsirolimus) are considered in first-line therapy, and three other molecules for second, or subsequent lines of therapy (everolimus, axitinib, sorafenib). In addition, other molecules and sequencing schemes are being tested in ongoing phase II/III studies. We conducted a systematic review using PubMed and several other databases up to December 2011 of prospective and retrospective studies on treatment management of metastatic renal cell carcinoma using targeted therapies, with a special focus on use of sequential treatment. Based on phase III data, the optimal sequencing scheme for patients with clear cell or even non-clear cell histological subtype appears to consist of sunitinib, followed by axitinib, followed by everolimus. Subsequent treatment options rely on lower evidence studies and could consist of fourth-line sorafenib or sunitinib rechallenge. Such therapies would qualify as last recourse options. In another context, temsirolimus may be used in patients who fulfill the Memorial Sloan-Kettering Cancer Center poor risk criteria or who have poor performance status. We conclude that in the current setting, sequential therapy represents the cornerstone of effective management of metastatic renal cell carcinoma.

A comprehensive overview of targeted therapy in metastatic renal cell carcinoma

Chemotherapy and immunotherapy failed to deliver decisive results in the systemic treatment of metastatic renal cell carcinoma. Agents representing the current standards operate on members of the RAS signal transduction pathway. Sunitinib (targeting vascular endothelial growth factor), temsirolimus (an inhibitor of the mammalian target of rapamycin - mTOR) and pazopanib (a multi-targeted receptor tyrosine kinase inhibitor) are used in the first line of recurrent disease. A combination of bevacizumab (inhibition of angiogenesis) plus interferon α is also first-line therapy. Second line options include everolimus (another mTOR inhibitor) as well as tyrosine kinase inhibitors for patients who previously received cytokine. We review the results of clinical investigations focusing on survival benefit for these agents. Additionally, trials focusing on new agents, including the kinase inhibitors axitinib, tivozanib, dovitinib and cediranib and monoclonal antibodies including velociximab are also discussed. In addition to published outcomes we also include follow-up and interim results of ongoing clinical trials. In summary, we give a comprehensive overview of current advances in the systemic treatment of metastatic renal cell carcinoma.

Sorafenib or placebo with either gemcitabine or capecitabine in patients with HER-2-negative advanced breast cancer that progressed during or after bevacizumab

PURPOSE

We assessed adding the multikinase inhibitor sorafenib to gemcitabine or capecitabine in patients with advanced breast cancer whose disease progressed during/after bevacizumab.

EXPERIMENTAL DESIGN

This double-blind, randomized, placebo-controlled phase IIb study (ClinicalTrials.gov NCT00493636) enrolled patients with locally advanced or metastatic human epidermal growth factor receptor 2 (HER2)-negative breast cancer and prior bevacizumab treatment. Patients were randomized to chemotherapy with sorafenib (400 mg, twice daily) or matching placebo. Initially, chemotherapy was gemcitabine (1,000 mg/m(2) i.v., days 1, 8/21), but later, capecitabine (1,000 mg/m(2) orally twice daily, days 1-14/21) was allowed as an alternative. The primary endpoint was progression-free survival (PFS).

RESULTS

One hundred and sixty patients were randomized. More patients received gemcitabine (82.5%) than capecitabine (17.5%). Sorafenib plus gemcitabine/capecitabine was associated with a statistically significant prolongation in PFS versus placebo plus gemcitabine/capecitabine [3.4 vs. 2.7 months; HR = 0.65; 95% confidence interval (CI): 0.45-0.95; P = 0.02], time to progression was increased (median, 3.6 vs. 2.7 months; HR = 0.64; 95% CI: 0.44-0.93; P = 0.02), and overall response rate was 19.8% versus 12.7% (P = 0.23). Median survival was 13.4 versus 11.4 months for sorafenib versus placebo (HR = 1.01; 95% CI: 0.71-1.44; P = 0.95). Addition of sorafenib versus placebo increased grade 3/4 hand-foot skin reaction (39% vs. 5%), stomatitis (10% vs. 0%), fatigue (18% vs. 9%), and dose reductions that were more frequent (51.9% vs. 7.8%).

CONCLUSION

The addition of sorafenib to gemcitabine/capecitabine provided a clinically small but statistically significant PFS benefit in HER2-negative advanced breast cancer patients whose disease progressed during/after bevacizumab. Combination treatment was associated with manageable toxicities but frequently required dose reductions.

The evolving role of VEGF-targeted therapies in the treatment of metastatic colorectal cancer

Therapies that target angiogenesis and the VEGF pathway are a component of treatment for patients with metastatic colorectal cancer (mCRC). Bevacizumab is a humanized monoclonal antibody that binds to VEGFA. Chemotherapy plus bevacizumab has led to improved outcomes for mCRC patients. Despite these benefits, progressive disease invariably ensues. Multiple members of the VEGF family can potentially contribute to tumor angiogenesis and/or evasion of antiangiogenic therapy if one pathway should be inhibited. Aflibercept, a new biological agent, is a multiple angiogenic factor trap that prevents not only VEGFA, but also VEGFB and PlGF from activating their native receptors. Key clinical data for bevacizumab and aflibercept for treatment of mCRC, clinical evidence for use of these agents beyond progression, and the search for angiogenic biomarkers to better define patients most likely to benefit from these interventions will be reviewed.

The use of reverse phase protein arrays (RPPA) to explore protein expression variation within individual renal cell cancers

Currently there is no curative treatment for metastatic clear cell renal cell cancer, the commonest variant of the disease. A key factor in this treatment resistance is thought to be the molecular complexity of the disease. Targeted therapy such as the tyrosine kinase inhibitor (TKI)-sunitinib have been utilized, but only 40% of patients will respond, with the overwhelming majority of these patients relapsing within 1 year. As such the question of intrinsic and acquired resistance in renal cell cancer patients is highly relevant. In order to study resistance to TKIs, with the ultimate goal of developing effective, personalized treatments, sequential tissue after a specific period of targeted therapy is required, an approach which had proved successful in chronic myeloid leukaemia. However the application of such a strategy in renal cell carcinoma is complicated by the high level of both inter- and intratumoral heterogeneity, which is a feature of renal cell carcinoma as well as other solid tumors. Intertumoral heterogeneity due to transcriptomic and genetic differences is well established even in patients with similar presentation, stage and grade of tumor. In addition it is clear that there is great morphological (intratumoral) heterogeneity in RCC, which is likely to represent even greater molecular heterogeneity. Detailed mapping and categorization of RCC tumors by combined morphological analysis and Fuhrman grading allows the selection of representative areas for proteomic analysis. Protein based analysis of RCC is attractive due to its widespread availability in pathology laboratories; however, its application can be problematic due to the limited availability of specific antibodies. Due to the dot blot nature of the Reverse Phase Protein Arrays (RPPA), antibody specificity must be pre-validated; as such strict quality control of antibodies used is of paramount importance. Despite this limitation the dot blot format does allow assay miniaturization, allowing for the printing of hundreds of samples onto a single nitrocellulose slide. Printed slides can then be analyzed in a similar fashion to Western analysis with the use of target specific primary antibodies and fluorescently labelled secondary antibodies, allowing for multiplexing. Differential protein expression across all the samples on a slide can then be analyzed simultaneously by comparing the relative level of fluorescence in a more cost-effective and high-throughput manner.

Therapeutic challenges in advanced renal cell carcinoma

The therapeutic landscape of advanced renal cell carcinoma has grown increasingly more complex with the recent approval of several molecularly targeted agents. While researchers focus on developing predictive algorithms and identifying novel therapeutic targets and agents, clinical practitioners continue to face many practical challenges when determining therapeutic strategies for individual patients. This review will discuss several of these challenges including patient selection strategies, sequential therapy, optimal dose and schedule of various drugs, and therapeutic options for patients with nonclear-cell renal cell carcinoma.

A randomized phase II study of gemcitabine and carboplatin with or without cediranib as first-line therapy in advanced non-small-cell lung cancer: North Central Cancer Treatment Group Study N0528

INTRODUCTION

The purpose of this study was to assess the safety and efficacy of gemcitabine and carboplatin with (arm A) or without (arm B) daily oral cediranib as first-line therapy for advanced non-small-cell lung cancer.

METHODS

A lead-in phase to determine the tolerability of gemcitabine 1000 mg/m on days 1 and 8, and carboplatin on day 1 at area under curve 5 administered every 21 days with cediranib 45 mg once daily was followed by a 2 (A):1 (B) randomized phase II study. The primary end point was confirmed overall response rate (ORR) with 6-month progression-free survival (PFS6) rate in arm A as secondary end point. Polymorphisms in genes encoding cediranib targets and transport were correlated with treatment outcome.

RESULTS

On the basis of the safety assessment, cediranib 30 mg daily was used in the phase II portion. A total of 58 and 29 evaluable patients were accrued to arms A and B. Patients in A experienced more grade 3+ nonhematologic adverse events, 71% versus 45% (p = 0.01). The ORR was 19% (A) versus 20% (B) (p = 1.0). PFS6 in A was 48% (95% confidence interval: 35%-62%), thus meeting the protocol-specified threshold of at least 40%. The median overall survival was 12.0 versus 9.9 months (p = 0.10). FGFR1 rs7012413, FGFR2 rs2912791, and VEGFR3 rs11748431 polymorphisms were significantly associated with decreased overall survival (hazard ratio 2.78-5.01, p = 0.0002-0.0095).

CONCLUSIONS

The trial did not meet its primary end point of ORR but met its secondary end point of PFS6. The combination with cediranib 30 mg daily resulted in increased toxicity. Pharmacogenetic analysis revealed an association of FGFR and VEGFR variants with survival.

Affinity improvement of a VEGF aptamer by in silico maturation for a sensitive VEGF-detection system

Systematic evolution of ligands by exponential enrichment (SELEX) is an efficient method to identify aptamers; however, it sometimes fails to identify aptamers that bind to their target with high affinity. Thus, post-SELEX optimization of aptamers is required to improve aptamer binding affinity. We developed in silico maturation based on a genetic algorithm (1) as an efficient mutagenesis method to improve aptamer binding affinity. In silico maturation was performed to improve a VEGF-binding DNA aptamer (VEap121). The VEap121 aptamer is considered to fold into a G-quadruplex structure and this structure may be important for VEGF recognition. Using in silico maturation, VEap121 was mutated with the exception of the guanine tracts that are considered to form the G-quartet. As a result, four aptamers were obtained that showed higher affinity compared with VEap121. The dissociation constant (K(d)) of the most improved aptamer (3R02) was 300 pM. The affinity of 3R02 was 16-fold higher than that of VEap121. Moreover, a bivalent aptamer was constructed by connecting two identical 3R02s through a 10-mer thymine linker for further improvement of affinity. The bivalent aptamer (3R02 Bivalent) bound to VEGF with a K(d) value of 30 pM. Finally, by constructing a VEGF-detection system using a VEGF antibody as the capture molecule and monovalent 3R02 as the detection molecule, a more sensitive assay was developed compared with the system using VEap121. These results indicate that in silico maturation could be an efficient method to improve aptamer affinity for construction of sensitive detection systems.

Sequential therapy in metastatic renal cell carcinoma: pre-clinical and clinical rationale for selecting a second- or subsequent-line therapy with a different mechanism of action

Few types of cancer have had their treatment evolve as rapidly as metastatic renal cell carcinoma (mRCC). Since 2005, six new targeted therapies with proven efficacy have been approved for the treatment of mRCC. The downside is that our knowledge about the mechanisms of action of these therapies and the intrinsic and extrinsic mechanism of resistance has not evolved equally fast, and many questions remain unanswered. The only approved agent to date in the European Union for patients who progress on sunitinib or sorafenib is everolimus. The results of the phase III trial comparing axitinib vs. sorafenib after failure on sunitinib, bevacizumab, temsirolimus, or cytokines have recently been published, and axitinib has recently been licensed by the Food and Drugs Administration. Other phase III trials that are being conducted include a comparison between everolimus plus bevacizumab and everolimus after failure on tyrosine kinase inhibitors, and between temsirolimus and sorafenib after failure on sunitinib. In this article, we will review the available evidence from clinical studies on sequential therapy for mRCC, including those that are still in progress. In addition, information on the mechanism of resistance or tolerance to first-line therapy, recommendations of the main practice guidelines for second-line treatment, potential therapies for third or successive treatment lines, and the major reasons why patients who progress may benefit from a change of mechanism of action will also be discussed.