Vascular endothelial growth factor-targeted therapies in advanced renal cell carcinoma

Emerging Strategies in Adjuvant Immunotherapy: A Comparative Review of Bladder Cancer and Renal Cell Carcinoma Treatments

Recent progress in adjuvant immunotherapy offers hope for improving disease-free survival in high-risk bladder cancer (BC) and renal cell carcinoma (RCC). This review focuses on key trials such as CheckMate 274 and KEYNOTE-564, which show promising results with nivolumab in BC and pembrolizumab in RCC, including a 30% reduction in progression risk. Pembrolizumab also demonstrated overall survival (OS) benefit in RCC. The review also explores the potential of circulating tumor DNA (ctDNA) as a biomarker for better therapy selection and patient stratification. It emphasizes the need for ongoing research to establish survival benefits and suggests integrating biomarkers and risk stratification to optimize adjuvant immunotherapy in BC and RCC.

Belzutifan: a novel therapeutic for the management of von Hippel-Lindau disease and beyond

The identification of the VHL gene and its role in regulating the hypoxia-inducible factor signaling pathway has helped to revolutionize the treatment of renal cell carcinoma (RCC). Belzutifan is a novel small-molecule inhibitor of hypoxia-inducible factor 2α which has demonstrated efficacy in treating von Hippel-Lindau (VHL) disease, earning regulatory approvals for this indication. There is also early evidence for efficacy in sporadic RCC. Belzutifan has a favorable safety profile. Several clinical trials are currently ongoing, which should help in identifying this promising drug's role in RCC and beyond. This review summarizes the history, pharmacology and clinical evidence for belzutifan use to date, and also explores unanswered questions as they relate to this novel therapeutic agent.

Tumor-to-Tumor Metastasis of Lung Cancer to Kidney Cancer: A Review of the Literature and Our Experience

Tumor-to-tumor metastasis (TTM) is a rare phenomenon documented in patients with multiple primary cancers. This condition is defined as a metastasis between two true primary tumors. The most frequently reported recipient tumor is renal cell carcinoma (RCC), and the lung carcinomas are the most common metastatic tumor donors. Therefore, this paper attempts to address the current gap in knowledge about this rare phenomenon. The first part of this review outlines the recently proposed models and mechanisms involved in the TTM process. The second part then summarizes and analyzes previous case reports in the literature. We also present our experience with the case of lung cancer that metastasized into RCC. Given the sporadic incidence of TTM, no specific management guidelines exist. Therefore, considering TTM in patients with multiple primary tumors is important as it could potentially modify the oncological management offered.

Cost-effectiveness and budget impact of pembrolizumab+axitinib versus sunitinib in patients with advanced clear-cell renal cell carcinoma in the Netherlands

Background

The phase 3 clinical trial KEYNOTE-426 suggested a higher efficacy regarding overall survival (OS) and progression-free survival (PFS) of pembrolizumab+axitinib compared to sunitinib as a first-line treatment for patients with advanced renal cell carcinoma. In this analysis, the potential cost-effectiveness of this combination treatment versus sunitinib for patients with advanced clear-cell renal cell carcinoma (accRCC) was examined from the societal perspective in the Netherlands.

Methods

For this analysis, a partitioned survival model was constructed. Clinical data were obtained from the published KEYNOTE-426 trial reports; data on costs and (dis-)utilities were derived from published literature. Costs outside of the healthcare sector included treatment-related travel, informal care and productivity loss. Next to a probabilistic scenario analysis, various scenario analyses were performed that aimed at survival extrapolation, different utility values, treatment duration and drug pricing, as well as restricting the cohort to patients with an intermediate or poor prognosis. Further, a budget impact analysis over three years was conducted, in which a sensitivity analysis concerning ranges in costs and the number of patients was applied. Moreover, a scenario concerning increasing market penetration of pembrolizumab+axitinib up to a market share of 80% in the third year was analyzed.

Results

The incremental cost-effectiveness ratio (ICER) of pembrolizumab+axitinib was estimated at €368,396/quality-adjusted life year (QALY) gained, with an incremental QALY gain of 0.55 over sunitinib. The probability of cost-effectiveness at a willingness-to-pay threshold of €80,000/QALY was estimated at 0%, a 50% probability was estimated at €340,000/QALY. Cost-effectiveness was not achieved in any of the applied scenarios. The budget impact over three years amounted to €417.3 million upon instantaneous and full replacement of sunitinib, and to €214.9 million with increasing market penetration.

Conclusion

Pembrolizumab+axitinib was not estimated to be cost-effective compared to sunitinib as a first-line treatment for patients with accRCC in the Netherlands from a societal perspective. In none of the analyzed scenarios, cost-effectiveness was achieved. However, price reductions and shorter treatment durations might lead to a more favorable ICER.

Variations in the Profiles of Vascular-Related Factors Among Different Sub-Types of Polycystic Ovarian Syndrome in Northern China

Recently, a growing body of evidence has suggested that abnormal ovarian angiogenesis, secondary to the imbalance between various angiogenic markers, is involved in the pathogenesis of PCOS, and this has led to the use of various interventions (such as Diane-35) to restore the normal ovarian angiogenesis. Therefore, we conducted the current investigation to determine the role of such markers (endothelial growth factor (VEGF), endostatin (ES), and thrombospondin-1 (TSP-1)) in the pathogenesis of PCOS along with the associated changes in ovarian blood flow in patients with PCOS compared to healthy controls, both before and after a course of oral contraception. A total of 381 patients with PCOS and 98 healthy females of childbearing age were recruited from July 2014 to June 2017 at the Reproductive Center of the Second Affiliated Hospital of Harbin Medical University. The serum levels of VEGF, ES, and TSP-1 were determined by enzyme-linked immunosorbent assay, while ovarian perfusion was measured by the pulsatility index (PI) and resistance index (RI) by using transvaginal color Doppler ultrasound. Repeated analyses were carried out after 3 months of Diane-35 treatment. Post-treatment serum levels of luteinizing hormone (LH)/follicle stimulating hormone (FSH) ratio of patients with PCOS decreased significantly (P <0.05). The RI values of most PCOS patients increased after treatment (P<0.05), while PI was significantly increased in all patients (P<0.05). However, variable changes in the serum levels of TSP-1, VEGF, and ES after treatment were observed. Serum VEGF levels showed a negative correlation with serum LH/FSH ratio, T concentration, and ES (P <0.05), while ES levels were negatively correlated with serum T concentrations only (P<0.05). The markers of angiogenesis (VEGF, ES, and TSP-1) were expressed differently among PCOS patients, who also responded differently to the same course of Diane-35 treatment. This field still warrants further investigation to reach a more definitive conclusion.

The Role of Artificial Intelligence in the Diagnosis and Prognosis of Renal Cell Tumors

The increasing availability of molecular data provided by next-generation sequencing (NGS) techniques is allowing improvement in the possibilities of diagnosis and prognosis in renal cancer. Reliable and accurate predictors based on selected gene panels are urgently needed for better stratification of renal cell carcinoma (RCC) patients in order to define a personalized treatment plan. Artificial intelligence (AI) algorithms are currently in development for this purpose. Here, we reviewed studies that developed predictors based on AI algorithms for diagnosis and prognosis in renal cancer and we compared them with non-AI-based predictors. Comparing study results, it emerges that the AI prediction performance is good and slightly better than non-AI-based ones. However, there have been only minor improvements in AI predictors in terms of accuracy and the area under the receiver operating curve (AUC) over the last decade and the number of genes used had little influence on these indices. Furthermore, we highlight that different studies having the same goal obtain similar performance despite the fact they use different discriminating genes. This is surprising because genes related to the diagnosis or prognosis are expected to be tumor-specific and independent of selection methods and algorithms. The performance of these predictors will be better with the improvement in the learning methods, as the number of cases increases and by using different types of input data (e.g., non-coding RNAs, proteomic and metabolic). This will allow for more precise identification, classification and staging of cancerous lesions which will be less affected by interpathologist variability.

Survival Benefits of Second-line Axitinib Versus Everolimus After First Line Sunitinib Treatment in Metastatic Renal Cell Carcinoma

Background

Targeted therapies significantly improve clinical outcomes among patients with metastatic renal cell carcinoma (mRCC). Several new agents have been approved for first- and second-line use. However, there is a lack of compelling evidence comparing sequencing strategies, and available comparative data regarding the real-world effectiveness of different therapeutic sequences are limited.

Materials and Methods

We identified mRCC patients who initiated targeted therapy between January 1, 2008 and May 31, 2017 from the National Health Insurance Fund (NHIF) database of Hungary. Overall survival (OS) and duration of first-line treatment (DFT) were obtained for patients receiving sunitinib-everolimus, sunitinib-axitinib, or pazopanib-everolimus treatment sequences. OS of sunitinib-everolimus and sunitinib-axitinib sequences was also determined for patients having better or worse response to sunitinib first-line therapy.

Results

Median OS was significantly longer among patients treated with sunitinib-axitinib compared to those receiving sunitinib-everolimus. Median DFT was also significantly longer in the sunitinib-axitinib vs. sunitinib-everolimus group. Sunitinib-axitinib was associated with significantly longer median OS compared to sunitinib-everolimus in patients with better response to first-line sunitinib in the pooled sunitinib population. In patients with worse response to sunitinib, sunitinib-axitinib was associated with a trend towards greater OS compared to sunitinib-everolimus, but the difference did not reach statistical significance.

Conclusions

In this nationwide database analysis, mRCC patients treated with the sunitinib-axitinib sequence had significantly longer OS compared to those receiving sunitinib-everolimus therapy. The OS benefits of second-line axitinib were consistent among patients with better response to sunitinib defined by DFT values.

Texture analysis and machine learning algorithms accurately predict histologic grade in small (< 4 cm) clear cell renal cell carcinomas: a pilot study

PURPOSE

To predict the histologic grade of small clear cell renal cell carcinomas (ccRCCs) using texture analysis and machine learning algorithms.

METHODS

Fifty-two noncontrast (NC), 26 corticomedullary (CM) phase, and 35 nephrographic (NG) phase CTs of small (< 4 cm) surgically resected ccRCCs were retrospectively identified. Surgical pathology classified the tumors as low- or high-Fuhrman histologic grade. The axial image with the largest cross-sectional tumor area was exported and segmented. Six histogram and 31 texture (gray-level co-occurrences (GLC) and gray-level run-lengths (GLRL)) features were calculated for each tumor in each phase. T testing compared feature values in low- and high-grade ccRCCs, with a (Benjamini-Hochberg) false discovery rate of 10%. Area under the receiver operating curve (AUC) was calculated for each feature to assess prediction of low- and high-grade ccRCCs in each phase. Histogram, texture, and combined histogram and texture data sets were used to train and test four algorithms (k-nearest neighbor (KNN), support vector machine (SVM), random forests, and decision tree) with tenfold cross-validation; AUCs were calculated for each algorithm in each phase to assess prediction of low- and high-grade ccRCCs.

RESULTS

Zero, 23, and 0 features in the NC, CM, and NG phases had statistically significant differences between low and high-grade ccRCCs. CM histogram skewness and GLRL short run emphasis had the highest AUCs (0.82) in predicting histologic grade. All four algorithms had the highest AUCs (0.97) predicting histologic grade using CM histogram features. The algorithms' AUCs decreased using histogram or texture features from NC or NG phases.

CONCLUSION

The histologic grade of small ccRCCs can be accurately predicted with machine learning algorithms using CM histogram features, which outperform NC and NG phase image data.

Optimizing treatment of renal cell carcinoma with VEGFR-TKIs: a comparison of clinical pharmacology and drug-drug interactions of anti-angiogenic drugs

Anti-angiogenic treatment is an important option that has changed the therapeutic landscape in various tumors, particularly in patients affected by renal cell carcinoma (RCC). Agents that block signaling pathways governing tumor angiogenesis have raised high expectations among clinicians. Vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) comprise a heterogeneous class of drugs with distinct pharmacological profiles, including potency, selectivity, pharmacokinetics and drug-drug interactions. Among them, tivozanib is one of the last TKIs introduced in the clinical practice; this drug selectively targets VEGFRs, it is characterized by a favorable pharmacokinetics and safety profile and has been approved as first-line treatment for patients with metastatic RCC (mRCC). In this article, we describe the clinical pharmacology of selected VEGFR-TKIs used for the treatment of mRCC, highlighting the relevant differences; moreover we aim to define the main pharmacologic characteristics of these drug.

Targeting the Tumor Microenvironment in Renal Cell Cancer Biology and Therapy

Renal cell cancer (RCC) is a highly vascularized and immunogenic tumor type. The inhibition of vessel formation by anti-angiogenic therapies, as well as the stimulation of the immune system by immunotherapy has revolutionized the therapeutic landscape of RCC in recent years. Nevertheless, both therapies are associated with therapy resistance due to a highly dynamic, adaptive and heterogeneous tumor microenvironment (TME). The aim of this short review article is to provide an overview of the components of the RCC TME as well as to discuss their contribution to disease progression. In addition, we report on preclinical and clinical findings and how the different TME components can be modulated to impede treatment progression as well as to overcome therapy resistance to anti-angiogenic or immunomodulating therapy concepts. Furthermore, we discuss the predictive and prognostic role of the TME in RCC therapy. We also report on the concept of combinational targeting of anti-angiogenic therapies and immune checkpoint inhibitor therapy, also including the latest results of clinical studies discussed at recent oncological meetings. Finally, promising new therapeutic targets within the TME are mentioned.

Patterns, predictors and subsequent outcomes of disease progression in metastatic renal cell carcinoma patients treated with nivolumab

Background

Nivolumab is approved for the treatment of refractory metastatic renal cell carcinoma. Patterns and predictors of progressive disease (PD) on nivolumab, and outcomes in such patients are lacking.

Methods

A retrospective analysis of patients (pts) with metastatic clear cell renal cell carcinoma (ccRCC) who received nivolumab at Cleveland Clinic (2015–2017) was performed. PD was defined per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 or clinical progression as per treating physician. Univariate analyses (UVA) and multivariate analyses (MVA) were used to identify clinical and laboratory markers as potential predictors of progression-free survival (PFS).

Results

Ninety patients with mean age of 65, 74% men, and 83% good or intermediate International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk group were included. Median number of prior systemic treatments was 2 (range, 1–6). Median overall survival (OS) and PFS were 15.8 and 4.4 months, respectively. Fifty-seven patients (63%) had PD and 44% of patients with radiographic PD had new organ sites of metastases with brain (8/23, 35%) being the most common. Twelve patients received treatment beyond progression (TBP), and among 6 patients with available data, 3 (50%) had any tumor shrinkage (2 pts. with 17% shrinkage, one pt. with 29% shrinkage). Of 57 patients with PD, 28 patients (49%) were able to initiate subsequent treatment, mainly with axitinib and cabozantinib, while 40% of patients were transitioned to hospice after PD. In MVA, a higher baseline Neutrophil-to-Lymphocyte ratio (NLR) (HR, 1.86; 95% CI, 1.05–3.29; p = 0.033) was associated with an increased risk of progression, whereas higher (> 0.1 k/uL) baseline eosinophil count was associated with a lower risk of progression (HR, 0.54; 95% CI, 0.30–0.98; p = 0.042).

Conclusion

Brain was the most common site of PD in patients treated with nivolumab, and only half of patients progressing on nivolumab were able to initiate subsequent treatment. The risk of PD increased with a higher baseline NLR and reduced with a higher baseline eosinophil count.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0425-8) contains supplementary material, which is available to authorized users.

Vascular endothelial growth factor gene polymorphisms and the risk of renal cell carcinoma: Evidence from eight case-control studies

Background

Vascular endothelial growth factor (VEGF) protein plays important role in renal cell carcinoma (RCC) development and progression. VEGF gene polymorphisms can alter the protein concentrations and might be associated with renal cell carcinoma risk. However, the results of studies investigating the association between VEGF polymorphisms and renal cell carcinoma risk are inconsistent. Thus, a meta-analysis was performed.

Methods

We selected eligible studies via electronic searches. Only high-quality studies were included based on specific inclusion criteria and the Newcastle-Ottawa Scale (NOS).

Results

Eight studies primarily focusing on seven polymorphisms were included in our meta-analysis. Our results showed dramatically high risks for renal cell carcinoma were found regarding most genetic models and alleles of the +936C/T polymorphism (except CT vs. CC). In addition, significant increased renal cell carcinoma risks were found regarding all genetic models and alleles of the -2578C/A polymorphism. However, no significant associations were found between renal cell carcinoma risk and the +1612G/A, -460T/C, -634G/C, -405G/C or -1154G/A polymorphisms.

Conclusions

Our meta-analysis indicates that the +936C/T and -2578C/A polymorphisms of VEGF are associated with an increased risk for renal cell carcinoma. Additional rigorous analytical studies are needed to confirm our results.

Ovarian angiogenesis in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine pathology among women in reproductive age. Its main symptoms are oligo or amenorrhea, hyperandrogenism and the presence of ovarian cysts. It is also associated with infertility, obesity and insulin resistance. Mainly due to its heterogeneity, PCOS treatments are directed to manage its symptoms and to prevent associated diseases. The correct formation and regression of blood vessels during each ovarian cycle is indispensable for proper follicular development, ovulation and corpus luteum formation. The importance of these processes opened a new and promising field: ovarian angiogenesis. Vascular alterations characterize numerous pathologies, either with increased, decreased or abnormal angiogenesis. In the last years, several anomalies of ovarian angiogenesis have been described in women with PCOS. Therefore, it has been suggested that these alterations may be associated with the decreased - or lack of - ovulation rates and for the formation of cysts in the PCOS ovaries. Restoration of a proper vessel formation in the ovaries may lead to improved follicular development and ovulation in these patients. In the present review, we attempt to summarize the alterations in ovarian angiogenesis that have been described in women with PCOS. We also discuss the therapeutic approaches aimed to correct these alterations and their beneficial effects on the treatment of infertility in PCOS.

Heterogeneous response and progression patterns reveal phenotypic heterogeneity of tyrosine kinase inhibitor response in metastatic renal cell carcinoma

BACKGROUND

Molecular intratumour heterogeneity (ITH) is common in clear cell renal carcinomas (ccRCCs). However, it remains unknown whether this is mirrored by heterogeneity of drug responses between metastases in the same patient.

METHODS

We performed a retrospective central radiological analysis of patients with treatment-naïve metastatic ccRCC receiving anti-angiogenic tyrosine kinase inhibitors (TKIs) (sunitinib or pazopanib) within three similar phase II trials. Treatment was briefly interrupted for cytoreductive nephrectomy. All patients had multiple metastases that were measured by regular computed tomography scans from baseline until Response Evaluation Criteria In Solid Tumours (RECIST)-defined progression. Each metastasis was categorised as responding, stable or progressing. Patients were classed as having a homogeneous response if all lesions were of the same response category and a heterogeneous response if they differed.

RESULTS

A total of 115 metastases were assessed longitudinally in 27 patients. Of these patients, 56% had a heterogeneous response. Progression occurred through the appearance of new metastases in 67%, through progression of existing lesions in 11% and by both in 22% of patients. Despite RECIST-defined progression, 57% of existing metastases remained controlled. The sum of controlled lesions was greater than that of uncontrolled lesions in 47% of patients who progressed only with measurable new lesions.

CONCLUSIONS

We identified frequent ITH of anti-angiogenic TKI responses, with subsets of metastases responding and progressing within individual patients. This mirrors molecular ITH and may indicate that anti-angiogenic drug resistance is confined to subclones and not encoded on the trunk of the tumours' phylogenetic trees. This is clinically important, as patients with small-volume progression may benefit from drug continuation. Predominant progression with new rather than in existing metastases supports a change in disease biology through anti-angiogenics. The results highlight limitations of RECIST in heterogeneous cancers, which may influence clinical trial data validity. This analysis requires prospective confirmation.

TRIAL REGISTRATION

European Clinical Trials Database(EudraCT): 2009-016675-29 , registered 17 March 2010; EudraCT: 2006-004511-21 , registered 09 March 2007; EudraCT: 2006-006491-38 , registered 22 December 2006.

Cellular Adaptation to VEGF-Targeted Antiangiogenic Therapy Induces Evasive Resistance by Overproduction of Alternative Endothelial Cell Growth Factors in Renal Cell Carcinoma

Vascular endothelial growth factor (VEGF)–targeted antiangiogenic therapy significantly inhibits the growth of clear cell renal cell carcinoma (RCC). Eventually, therapy resistance develops in even the most responsive cases, but the mechanisms of resistance remain unclear. Herein, we developed two tumor models derived from an RCC cell line by conditioning the parental cells to two different stresses caused by VEGF-targeted therapy (sunitinib exposure and hypoxia) to investigate the mechanism of resistance to such therapy in RCC. Sunitinib-conditioned Caki-1 cells in vitro did not show resistance to sunitinib compared with parental cells, but when tested in vivo, these cells appeared to be highly resistant to sunitinib treatment. Hypoxia-conditioned Caki-1 cells are more resistant to hypoxia and have increased vascularity due to the upregulation of VEGF production; however, they did not develop sunitinib resistance either in vitro or in vivo. Human endothelial cells were more proliferative and showed increased tube formation in conditioned media from sunitinib-conditioned Caki-1 cells compared with parental cells. Gene expression profiling using RNA microarrays revealed that several genes related to tissue development and remodeling, including the development and migration of endothelial cells, were upregulated in sunitinib-conditioned Caki-1 cells compared with parental and hypoxia-conditioned cells. These findings suggest that evasive resistance to VEGF-targeted therapy is acquired by activation of VEGF-independent angiogenesis pathways induced through interactions with VEGF-targeted drugs, but not by hypoxia. These results emphasize that increased inhibition of tumor angiogenesis is required to delay the development of resistance to antiangiogenic therapy and maintain the therapeutic response in RCC.

FTY720 (Fingolimod) Inhibits HIF1 and HIF2 Signaling, Promotes Vascular Remodeling, and Chemosensitizes in Renal Cell Carcinoma Animal Model

Clear cell renal cell carcinoma (ccRCC) is characterized by intratumoral hypoxia and chemoresistance. The hypoxia-inducible factors HIF1α and HIF2α play a crucial role in ccRCC initiation and progression. We previously identified the sphingosine kinase 1/sphingosine 1-phosphate (SphK1/S1P) pathway as a new modulator of HIF1α and HIF2α under hypoxia in various cancer cell models. Here, we report that FTY720, an inhibitor of the S1P signaling pathway, inhibits both HIF1α and HIF2α accumulation in several human cancer cell lines. In a ccRCC heterotopic xenograft model, we show that FTY720 transiently decreases HIF1α and HIF2α intratumoral level and modifies tumor vessel architecture within 5 days of treatment, suggesting a vascular normalization. In mice bearing subcutaneous ccRCC tumor, FTY720 and a gemcitabine-based chemotherapy alone display a limited effect, whereas, in combination, there is a significant effect on tumor size without toxicity. Noteworthy, administration of FTY720 for 5 days before chemotherapy is not associated with a more effective tumor control, suggesting a mode of action mainly independent of the vascular remodeling. In conclusion, these findings demonstrate that FTY720 could successfully sensitize ccRCC to chemotherapy and establish this molecule as a potent therapeutic agent for ccRCC treatment, independently of drug scheduling. Mol Cancer Ther; 15(10); 2465-74. ©2016 AACR.

TM4SF1 Promotes Proliferation, Invasion, and Metastasis in Human Liver Cancer Cells

Transmembrane 4 superfamily member 1 (TM4SF1) is a member of tetraspanin family, which mediates signal transduction events regulating cell development, activation, growth and motility. Our previous studies showed that TM4SF1 is highly expressed in liver cancer. HepG2 cells were transfected with TM4SFl siRNA and TM4SF1-expressing plasmids and their biological functions were analyzed in vitro and in vivo. HepG2 cells overexpressing TM4SF1 showed reduced apoptosis and increased cell migration in vitro and enhanced tumor growth and metastasis in vivo, whereas siRNA-mediated silencing of TM4SF1 had the opposite effect. TM4SF1 exerts its effect by regulating a few apoptosis- and migration-related genes including caspase-3, caspase-9, MMP-2, MMP-9 and VEGF. These results indicate that TM4SF1 is associated with liver tumor growth and progression, suggesting that TM4SF1 may be a potential target for treatment of liver cancer in future.

Axitinib for the treatment of metastatic renal cell carcinoma

Renal cell carcinoma is a cancer that results from a genetic inactivation of the VHL tumor suppressor gene leading to an upregulation of VEGF. Targeted therapies against VEGF receptors have piqued substantial interest among clinicians and researchers, and these drugs are now the standard of care in the treatment of advanced renal cell carcinoma. One of these VEGF receptor inhibitors, axitinib, has been shown to be a superior second-line therapy when compared with sorafenib. Although axitinib has clinical activity and a manageable safety profile in patients with treatment-naive metastatic renal cell carcinoma, utility in the front-line setting is area of ongoing investigation. Another area of ongoing research is dose titration of axitinib to achieve the maximum clinical benefit. Interestingly, the axitinib-related side effect of hypertension has shown to be associated with more favorable clinical outcomes. This article describes the development of axitinib and discusses the current indications for clinical use in the management of metastatic renal cell carcinoma.

RNAi-mediated knockdown of vascular endothelial growth factor inhibits vascularization and tumor growth in renal cell carcinoma

In the present study, we aimed to examine the effects of the knockdown of vascular endothelial growth factor (VEGF) by RNA interference (RNAi) on vascularization and tumor growth in renal cell carcinoma (RCC). For this purpose, a lentiviral vector expressing VEGF-shRNA was constructed and transfected into 293T cells. The efficiency of RNAi was determined by infecting human 786-O RCC cells with viral particles and measuring the VEGF mRNA levels by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The effect of transfection with VEGF‑shRNA on the secreted VEGF levels was also examined and the inhibitory effects on vascularization were also examined using a chick chorioallantoic membrane (CAM) assay. An RCC xenograft model was established in nude mice by implanting 786-O cells to form subcutaneous tumors. VEGF expression was observed by immunohistochemical (IHC) staining of the xenograft tumors. The tumor volume and tumor inhibition rate were also recorded. The apoptosis of the cancer cells was measured by TUNEL assay and the efficiency of tumor inhibition was estimated. The interference rate of VEGF‑shRNA was 72.2% in the 786-O cells. Our results revealed that VEGF mRNA expression, the secreted VEGF level in the 786-O cells and the total vessel length were markedly reduced in the VEGF‑shRNA-transfected cells compared with the controls (all P<0.05). Compared with the controls, injections of lentivirus expressing VEGF-shRNA significantly inhibited tumor growth, and reduced tumor mass and VEGF expression in the tumor tissue (all P<0.05). The apoptotic index in the treatment group was significantly higher than that in the controls (both P<0.05). Thus, our data indicate that the inhibition of VEGF expression by RNAi reduces VEGF mRNA levels, and inhibits angiogenesis and tumor growth in RCC, providing a future treatment option for RCC.

MicroRNA-185 inhibits cell proliferation and induces cell apoptosis by targeting VEGFA directly in von Hippel-Lindau-inactivated clear cell renal cell carcinoma

OBJECTIVES

The von Hippel-Lindau (VHL) gene acts as a tumor suppressor in most clear cell renal cell carcinomas (ccRCCs). Tumor growth in ccRCCs relies on many factors that result from the loss of VHL. This study aims to identify new microRNAs with therapeutic potential for VHL-inactivated ccRCCs.

MATERIALS AND METHODS

We used 786O, A498 (VHL inactivated), and Caki-1 (VHL intact) ccRCC cell lines and 40 ccRCC samples and their adjacent nontumor tissues to measure the expression of microRNA-185 (miR-185) by real-time quantitative polymerase chain reaction. Overexpression or knockdown of VEGFA expression in renal cancer cells was fulfilled by transfecting expression plasmids or small interfering RNAs. Overexpression of miR-185 in ccRCC cell lines was fulfilled by transfecting chemically synthesized miR-185 mimics. The effects of miR-185 on ccRCC cell lines were detected by MTS assay, colony formation assay, and flow cytometric analysis.

RESULTS

Compared with adjacent nontumor renal tissues, miR-185 expression levels decreased significantly in ccRCC tissues. The expression of miR-185 had a negative correlation with tumor size, Fuhrman grade, and TNM staging. Luciferase assay showed that VEGFA was a direct target gene of miR-185. The overexpression of miR-185 significantly inhibited cell proliferation and induced cell apoptosis by down-regulating VEGFA expression in VHL-inactivated ccRCC cells.

CONCLUSIONS

Our results suggest that the miR-185, as a tumor suppressor, plays a pivotal role by inhibiting VEGFA in VHL-inactivated ccRCC.

Signalling pathways involved in antitumoral effects of VIP in human renal cell carcinoma A498 cells: VIP induction of p53 expression

Vasoactive intestinal peptide (VIP) decreases cell proliferation through PI3K signalling and prevents tumour progression in clear renal cell carcinoma (RCC). Here we analyzed the signalling pathways that mediate such VIP effects by using human RCC A498 cells. The effects of treatment with 1 μM VIP and/or specific protein kinase inhibitors such as H89, Wortmannin and PD98059 were studied by cell adhesion assay, ELISA of VEGF165 and ROS production assays. Semiquantitative RT-PCR and western blot were performed to study p53 expression. VIP increased cell adhesion and ROS production, and decreased VEGF165 secretion through PI3K signalling. Moreover, VIP increased nuclear expression of tumour suppressor p53. VIP effects could be blocked by cell incubation with a specific p53 inhibitor, cyclin pifithrin-α hydrobromide (CPFT-αH). In conclusion, this study provides a p53-dependent mechanism by which VIP regulates cell proliferation in RCC development. It supports a potential usefulness of VIP in new therapies of RCC.

Validation of housekeeping gene and impact on normalized gene expression in clear cell renal cell carcinoma: critical reassessment of YBX3/ZONAB/CSDA expression

Background

YBX3/ZONAB/CSDA is an epithelial-specific transcription factor acting in the density-based switch between proliferation and differentiation. Our laboratory reported overexpression of YBX3 in clear cell renal cell arcinoma (ccRCC), as part of a wide study of YBX3 regulation in vitro and in vivo. The preliminary data was limited to 5 cases, of which only 3 could be compared to paired normal tissue, and beta-Actin was used as sole reference to normalize gene expression. We thus decided to re-evaluate YBX3 expression by real-time-PCR in a larger panel of ccRCC samples, and their paired healthy tissue, with special attention on experimental biases such as inter-individual variations, primer specificity, and reference gene for normalization.

Results

Gene expression was measured by RT-qPCR in 16 ccRCC samples, each compared to corresponding healthy tissue to minimize inter-individual variations. Eight potential housekeeping genes were evaluated for expression level and stability among the 16-paired samples. Among tested housekeeping genes, PPIA and RPS13, especially in combination, proved best suitable to normalize gene expression in ccRCC tissues as compared to classical reference genes such as beta-Actin, GAPDH, 18S or B2M. Using this pair as reference, YBX3 expression level among a collection of 16 ccRCC tumors was not significantly increased as compared to normal adjacent tissues. However, stratification according to Fuhrman grade disclosed higher YBX3 expression levels in low-grade tumors and lower in high-grade tumors. Immunoperoxidase confirmed homogeneous nuclear staining for YBX3 in low-grade but revealed nuclear heterogeneity in high-grade tumors.

Conclusions

This paper underlines that special attention to reference gene products in the design of real-time PCR analysis of tumoral tissue is crucial to avoid misleading conclusions.

Furthermore, we found that global YBX3/ZONAB/CSDA mRNA expression level may be considered within a “signature” of RCC grading.

Tumoral CD105 is a novel independent prognostic marker for prognosis in clear-cell renal cell carcinoma

Background:

Angiogenesis is essential for tumour growth and metastasis. There are conflicting reports as to whether microvessel density (MVD) using the endothelial marker CD105 (cluster of differentiation molecule 105) in clear-cell renal cell carcinomas (ccRCC) is associated with prognosis. Recently, CD105 has been described as a RCC cancer stem cell marker.

Methods:

A total of 102 ccRCC were analysed. Representative tumour sections were stained for CD105. Vascularity (endothelial CD105) was quantified by MVD. The immunohistochemistry analysis detected positive (if present) or negative (if absent) CD105 tumoral staining. This retrospective population-based study was evaluated using Kaplan–Meier method, t-test and Cox proportional hazard model.

Results:

We found that the expression of endothelial CD105 (MVD) negatively correlated with nuclear grade (P<0.001), tumour stage (P<0.001) and Leibovitch score (P<0.001), whereas the expression of tumoral CD105 positively correlated with these three clinicopathological factors (P<0.001). In multivariate analysis, tumoral CD105 was found to be an independent predictor of poor overall survival (P=0.002).

Conclusions:

We have shown for the first time that tumoral CD105 is an independent predictive marker for death risk and unfavourable prognosis in patients with ccRCC after curative resection.

Recommendations for the clinical and radiological evaluation of response to treatment in metastatic renal cell cancer

The evaluation of response to treatment is a critical step for determining the effectiveness of oncology drugs. Targeted therapies such as tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors are active drugs in patients with metastatic renal cell carcinoma (mRCC). However, treatment with this type of drugs may not result in significant reductions in tumor size, so standard evaluation criteria based on tumor size, such as Response Evaluation Criteria in Solid Tumors (RECIST), may be inappropriate for evaluating response to treatment in patients with mRCC. In fact, targeted therapies apparently yield low response rates that do not reflect increased disease control they may cause and, consequently, the benefit in terms of time to progression. To improve the clinical and radiological evaluation of response to treatment in patients with mRCC treated with targeted drugs, a group of 32 experts in this field have reviewed different aspects related to this issue and have put together a series of recommendations with the intention of providing guidance to clinicians on this matter.

New agents in renal cell carcinoma

Prior to 2005, the treatment options for metastatic renal cell carcinoma (mRCC) were limited. There has been a proliferation of agents since the introduction of sorafenib, sunitinib, and becavicumab for clinical use in advanced renal cell carcinoma. Recently, four new agents have been approved by the US Food and Drug Administration (FDA) for use in mRCC. These agents come from two unique targeted pathways for RCC, tyrosine kinase inhibitors (TKIs) of vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) inhibitors. This review examines the investigational evolution, phases of development, adverse event profiles, and future directions of pazopanib, axitinib, everolimus, and temsirolimus as well as new novel agents being explored in clinical trials for these targeted pathways.

Prognostic scoring systems for spinal metastases in the era of anti-VEGF therapies

STUDY DESIGN

Spine Update on prognostic scoring systems for spinal metastases in the era of anti-vascular endothelial growth factor (VEGF) therapies.

OBJECTIVE

To review and discuss the strengths and weaknesses of available scoring systems since the introduction of molecular targeted anticancer agents.

SUMMARY OF BACKGROUND DATA

Molecular targeted anticancer agents have dramatically improved survival of patients in various cancers, including renal cancer.

METHODS

Using prognostic scoring systems for spinal metastases and recent survival data of patients with cancers treated with anti-VEGF agents, a review was undertaken, evaluating the strengths and weaknesses of available prognostic scoring systems designed in the 1990s and early 2000s among patients treated with recent agents (available from 2005).

RESULTS

All available prognostic scoring systems for spinal metastases include the primary tumor as a key variable. The estimation of life expectancy with these systems is inaccurate in view of recent survival data, as illustrated in renal cancer. The underestimation of life expectancy and subsequent inadequate treatment of spinal metastases may lead to dramatic alteration of the quality of life.

CONCLUSION

The assessment of the available scores in recent cohorts of patients is mandatory to test their current validity and evidence the need for aggressive surgical management. New scoring systems taking into account the gain in survival induced by recent anticancer agents will likely be warranted in a close future.

Genitourinary imaging: part 2, role of imaging in medical management of advanced renal cell carcinoma

OBJECTIVE

Renal cell carcinoma (RCC) comprises 80-85% of all primary renal neoplasms. Knowledge of the genetic and molecular features of RCC and the advent of molecular targeted therapy have revolutionized the treatment of RCC in the past decade. This article will review the changing role of the radiologist in the management of advanced RCC, especially in terms of the new relevance of RCC subtypes, treatment-related changes on imaging, new tumor response criteria, and commonly encountered molecular targeted therapy-related toxicities.

CONCLUSION

In this era of personalized cancer treatment, imaging has assumed a central role in treatment selection and follow-up of advanced RCC.

Evaluation of acute locoregional toxicity in patients with breast cancer treated with adjuvant radiotherapy in combination with pazopanib

Purpose. The purpose of this study was to analyze acute locoregional toxicity in patients with breast cancer receiving concurrent pazopanib and RT. Materials and Methods. Patients with breast cancer who received pazopanib in combination with radiation were identified and matched (2 : 1) to patients with breast cancer who did not receive pazopanib by use of chemotherapy, radiation field design, and radiation dose. Toxicity was scored by the Common Terminology Criteria for Adverse Events and statistical analysis was performed. Results. Grade 1 or 2 radiation dermatitis was seen in 100% and 84% of pazopanib and RT patients and matched controls respectively (P = NS). None of the patients receiving pazopanib and RT experienced ≥ grade 3 toxicity within the irradiated volume; three (16%) matched patients experienced a grade 3 skin reaction (P = 0.05). Interestingly, grade 1 or 2 hyperpigmentation was seen in 17% of pazopanib and RT patients and 60% of matched controls (P = 0.005). Conclusion. The addition of concurrent pazopanib and RT when treating the intact breast, chest wall, and associated nodal regions in breast cancer seems to be safe and well tolerated.

Axitinib in Metastatic Renal Cell Carcinoma

Targeted agents have revolutionized the management of metastatic renal cell carcinoma (RCC). Axitinib, an inhibitor of vascular endothelial growth factor receptor (VEGFR), has been an important addition to currently available therapies for advanced RCC. Its ability to inhibit VEGFRs at nanomolar concentrations distinguishes it as a potent tyrosine kinase inhibitor, with increased selectivity for VEGFR-1, 2, and 3 at clinically applicable concentrations. The phase 3 AXIS trial has established its superiority in prolonging progression-free survival (PFS) in previously treated RCC patients (median PFS 6.7 months for axitinib vs. 4.7 months for sorafenib). Common toxicities of axitinib include hypertension, diarrhea, nausea, hand-foot syndrome, fatigue, and hypothyroidism. Axitinib-induced diastolic blood pressure elevation may be associated with improved clinical outcome, likely reflecting the “on-target” effect of axitinib. Dose escalation to achieve therapeutic plasma drug levels is of considerable clinical interest. Although axitinib has established efficacy in patients treated with one previous agent, its use in the frontline setting is currently the subject of ongoing research.

VEGF polymorphisms are not associated with an increased risk of developing renal cell carcinoma in Spanish population

PURPOSE

Vascular endothelial growth factor (VEGF) plays a central role in promoting angiogenesis and is over-expressed in renal cell cancer (RCC). Published data on the association between polymorphisms of vascular endothelial growth factor (e.g., -2578C/A [rs699947], -460T/C [rs833061], +405C/G [rs2010963], and +936C/T [rs3025039]) and the risk of renal cell carcinoma are ambiguous and controversial. The aim of this investigation was to investigate this relationship in a series of Caucasian Spanish patients.

MATERIALS AND METHODS

A case-control study was performed with 216 cases and 280 controls, genotyping subjects for VEGF polymorphisms using the predesigned TaqMan single nucleotide polymorphism (SNP) genotyping assay (Applied Biosystems, Foster City, CA, USA). The combined effect of the four gene polymorphisms on overall survival was studied by haplotype analysis.

RESULTS

The overall results suggest that polymorphisms or haplotypes in the VEGF gene do not modify the risk of RCC. We were unable to replicate the association of the -460T/C (rs833061) polymorphism with renal cancer risk. Data were also gathered on clinical-pathological results, tumor size, clinical stage, histological grade, and survival.

CONCLUSIONS

According to our analysis of their contribution to prognostic factors, VEGF polymorphisms do not appear to exert a significant influence on RCC progression or prognosis. This finding might be explained by the tumor biology and pathogenesis of clear cell RCC. Additional studies with larger sample sizes are needed in different ethnic groups to further assess this association.

Tumor stroma as targets for cancer therapy

Cancer is not only composed malignant epithelial component but also stromal components such as fibroblasts, endothelial cells, and inflammatory cells, by which an appropriate tumor microenvironment (TME) is formed to promote tumorigenesis, progression, and metastasis. As the most abundant component in the TME, cancer-associated fibroblasts (CAFs) are involved in multifaceted mechanistic details including remodeling the extracellular matrix, suppressing immune responses, and secreting growth factors and cytokines that mediate signaling pathways to extensively affect tumor cell growth and invasiveness, differentiation, angiogenesis, and chronic inflammatory milieu. Today, more and more therapeutic strategies are purposefully designed to target the TME as well as tumor cells. This review will focus on the role of CAFs in tumor development and the novel strategies to target this component to inhibit the tumor growth.

Molecular conformations, interactions, and properties associated with drug efficiency and clinical performance among VEGFR TK inhibitors

Analyses of compounds in clinical development have shown that ligand efficient-molecules with privileged physical properties and low dose are less likely to fail in the various stages of clinical testing, have fewer postapproval withdrawals, and are less likely to receive black box safety warnings. However, detailed side-by-side examination of molecular interactions and properties within single drug classes are lacking. As a class, VEGF receptor tyrosine kinase inhibitors (VEGFR TKIs) have changed the landscape of how cancer is treated, particularly in clear cell renal cell carcinoma, which is molecularly linked to the VEGF signaling axis. Despite the clear role of the molecular target, member molecules of this validated drug class exhibit distinct clinical efficacy and safety profiles in comparable renal cell carcinoma clinical studies. The first head-to-head randomized phase III comparative study between active VEGFR TKIs has confirmed significant differences in clinical performance [Rini BI, et al. (2011) Lancet 378:193-1939]. To elucidate how fundamental drug potency-efficiency is achieved and impacts differentiation within the VEGFR TKI class, we determined potencies, time dependence, selectivities, and X-ray structures of the drug-kinase complexes using a VEGFR2 TK construct inclusive of the important juxtamembrane domain. Collectively, the studies elucidate unique drug-kinase interactions that are dependent on distinct juxtamembrane domain conformations, resulting in significant potency and ligand efficiency differences. The identified structural trends are consistent with in vitro measurements, which translate well to clinical performance, underscoring a principle that may be broadly applicable to prospective drug design for optimal in vivo performance.

Angiopoietins/TIE2 system and VEGF are involved in ovarian function in a DHEA rat model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrinological pathology among women of reproductive age. It is characterized by anovulation, oligo- or amenorrhea, hyperandrogenism, obesity, and insulin resistance. PCOS patients present with elevated levels of vascular endothelial growth factor (VEGF) in serum and follicular fluid. In this study, we examined the ovarian expression of angiopoietins (ANGPT) and their receptor tyrosine kinase receptor (TIE2), involved in the stabilization of blood vessels, in a rat model of dehydroepiandrosterone-induced PCOS. We also analyzed the effect of ovarian VEGF inhibition on ANGPT/TIE2, follicular development, and vascular stability. VEGF levels were increased in the PCOS ovaries, whereas the levels of its receptor fetal liver kinase-1 were decreased. In addition, the periendothelial cell area and the ANGPT1 to ANGPT2 ratio in the ovary were increased in the PCOS group. Percentage of primary follicles was increased and the percentage of preantral follicles and corpora lutea was decreased in the PCOS group. VEGF inhibition decreased the percentage of primary follicles close to control values. Interestingly, despite the presence of cysts in the ovaries from VEGF inhibitor-treated PCOS rats, its percentage was lower than the PCOS group without treatment. In summary, this study describes an alteration not only in the VEGF/fetal liver kinase-1 system but also in the ANGPT/TIE2 system in a dehydroepiandrosterone-induced PCOS rat model. This leads to an increase in periendothelial cell recruitment. We also demonstrated that ovarian VEGF inhibition can partially restore the accumulation of small follicles in PCOS rats and reduces cyst formation, improving ovulation and follicular development. Therefore, the inhibition of VEGF could be considered, in addition to other currently applied treatments, as a new strategy to be studied in PCOS patients to restore ovarian function.

Conditional survival in patients treated with vascular endothelial growth factor-targeted therapy for advanced renal cell carcinoma

PURPOSE

Conditional survival (CS) offers more relevant prognostic information for patients once they have survived for some time. The objective of this study was to determine the CS for advanced renal cell carcinoma (RCC) patients treated with vascular endothelial growth factor-targeted therapy.

METHODS

A total of 345 patients treated between 2006 and 2011 fulfilled the inclusion criteria and were reviewed for analyses. The 1-year conditional and actual survival rates were calculated for survivors from treatment to month 24. Subgroup-specific CS rates were generated after adjustment of the covariate influence. The Cox proportional hazard models were used to assess the prognostic factors at baseline and 1-year landmark.

RESULTS

The probabilities of surviving an additional year given survival to 6, 12, 18, and 24 months were 72.2, 76.3, 78.2, and 78.6 %, respectively. Remarkable increase in CS was observed in patients initially classified as intermediate or poor risk according to Heng risk groups. For patients survived 24 months after treatment, the adjusted CS for the following year was over 80 % regardless of initial risk attribution. Compared to baseline analysis, Heng risk groups were less predictive of survivorship after surviving 1 year. The addition of disease control status to multifactorial model significantly improved survival estimation for 1-year survivors (p < 0.01).

CONCLUSIONS

CS provides useful information regarding life expectancy for survivors of advanced RCC treated with targeted therapy. Furthermore, disease control status within a specific period of time is critical to the prediction of subsequent survival.

Determination of pazopanib (GW-786034) in mouse plasma and brain tissue by liquid chromatography-tandem mass spectrometry (LC/MS-MS)

A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC/MS-MS) method has been developed and validated for the quantitative determination of pazopanib in mouse plasma and brain tissue homogenate. Single liquid-liquid extraction step with ethyl acetate was employed for analysis of pazopanib and the internal standard (IS); vandetanib. HPLC separation was performed on an XTerra(®) MS C18 column 50 mm × 4.6 mm, 5.0 μm. The mobile phase consisted of 70% acetonitrile and 30% water with 0.1% formic acid, pumped at a flow rate of 0.25 ml/min. Analysis time was 3.5 min per run and both the analyte and IS eluted within 1.8-2.0 min. Multiple reactions monitoring (MRM) mode was utilized to detect the compounds of interest. The mass spectrometer was operated in the positive ion mode for detection. The precursor to product ions (Q1→Q3) selected for pazopanib and internal standard during quantitative optimization were (m/z) 438.1→357.2 and 475.0→112.2 respectively. The calibration curves were linear over the range of 3.9-1000 ng/ml in both biological matrices. Lower limit of quantification (LLOQ) for mouse plasma and brain tissue was 3.9 ng/ml. The values for inter and intra day precision and accuracy were well within the ranges acceptable for analytical assessment (<15%). This method was applied to determine brain to plasma concentration ratio and relevant pharmacokinetic parameters of pazopanib after a single intravenous dose of 5 mg/kg in FVB wild type mice.

Von Hippel-Lindau: how a rare disease illuminates cancer biology

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant syndrome (1/36,000 live births) with highly penetrance that predispose to the development of a panel of highly vascularized tumors (model of tumoral angiogenesis). Main manifestations include central nervous system (CNS) and retinal haemangioblastomas, endolymphatic sac tumors, clear-cell renal cell carcinomas (RCC), phaeochromocytomas and pancreatic neuroendocrine tumors. RCC has become the first potential cause of mortality and VHL disease is the main cause of inherited RCC. The disease is caused by germline mutations in the VHL tumor-suppressor gene that plays a major role in regulation of the oxygen-sensing pathway by targeting the hypoxia-inducible factor HIF for degradation in proteasome. VHL has also major HIF-independent functions, specially in regulation of primary cilium, extracellular matrix and apoptosis. Somatic inactivation of the VHL gene is the main molecular event in most sporadic RCC and the treatment of advanced RCC has been revolutionized by targeted therapy with drugs that block angiogenesis. These drugs are now in first line in metastatic sporadic RCC and have shown promising results for RCC, pancreatic neuroendocrine tumors and malignant pheochromocytomas in VHL patients.

The biology of personalized cancer medicine: facing individual complexities underlying hallmark capabilities

It is a time of great promise and expectation for the applications of knowledge about mechanisms of cancer toward more effective and enduring therapies for human disease. Conceptualizations such as the hallmarks of cancer are providing an organizing principle with which to distill and rationalize the abject complexities of cancer phenotypes and genotypes across the spectrum of the human disease. A countervailing reality, however, involves the variable and often transitory responses to most mechanism-based targeted therapies, returning full circle to the complexity, arguing that the unique biology and genetics of a patient's tumor will in the future necessarily need to be incorporated into the decisions about optimal treatment strategies, the frontier of personalized cancer medicine. This perspective highlights considerations, metrics, and methods that may prove instrumental in charting the landscape of evaluating individual tumors so to better inform diagnosis, prognosis, and therapy. Integral to the consideration is remarkable heterogeneity and variability, evidently embedded in cancer cells, but likely also in the cell types composing the supportive and interactive stroma of the tumor microenvironment (e.g., leukocytes and fibroblasts), whose diversity in form, regulation, function, and abundance may prove to rival that of the cancer cells themselves. By comprehensively interrogating both parenchyma and stroma of patients' cancers with a suite of parametric tools, the promise of mechanism-based therapy may truly be realized.

High dose intermittent sorafenib shows improved efficacy over conventional continuous dose in renal cell carcinoma

BACKGROUND

Renal cell carcinoma (RCC) responds to agents that inhibit vascular endothelial growth factor (VEGF) pathway. Sorafenib, a multikinase inhibitor of VEGF receptor, is effective at producing tumor responses and delaying median progression free survival in patients with cytokine refractory RCC. However, resistance to therapy develops at a median of 5 months. In an effort to increase efficacy, we studied the effects of increased sorafenib dose and intermittent scheduling in a murine RCC xenograft model.

METHODS

Mice bearing xenografts derived from the 786-O RCC cell line were treated with sorafenib according to multiple doses and schedules: 1) Conventional dose (CD) continuous therapy; 2) high dose (HD) intermittent therapy, 3) CD intermittent therapy and 4) HD continuous therapy. Tumor diameter was measured daily. Microvessel density was assessed after 3 days to determine the early effects of therapy, and tumor perfusion was assessed serially by arterial spin labeled (ASL) MRI at day 0, 3, 7 and 10.

RESULTS

Tumors that were treated with HD sorafenib exhibited slowed tumor growth as compared to CD using either schedule. HD intermittent therapy was superior to CD continous therapy, even though the total dose of sorafenib was essentially equivalent, and not significantly different than HD continuous therapy. The tumors exposed to HD sorafenib had lower microvessel density than the untreated or the CD groups. ASL MRI showed that tumor perfusion was reduced to a greater extent with the HD sorafenib at day 3 and at all time points thereafter relative to CD therapy. Further the intermittent schedule appeared to maintain RCC sensitivity to sorafenib as determined by changes in tumor perfusion.

CONCLUSIONS

A modification of the sorafenib dosing schedule involving higher dose intermittent treatment appeared to improve its efficacy in this xenograft model relative to conventional dosing. MRI perfusion imaging and histologic analysis suggest that this benefit is related to enhanced and protracted antiangiogenic activity. Thus, better understanding of dosing and schedule issues may lead to improved therapeutic effectiveness of VEGF directed therapy in RCC and possibly other tumors.