Update on targeted therapies for clear cell renal cell carcinoma

Combining the Tyrosine Kinase Inhibitor Cabozantinib and the mTORC1/2 Inhibitor Sapanisertib Blocks ERK Pathway Activity and Suppresses Tumor Growth in Renal Cell Carcinoma

Current treatment approaches for renal cell carcinoma (RCC) face challenges in achieving durable tumor responses due to tumor heterogeneity and drug resistance. Combination therapies that leverage tumor molecular profiles could offer an avenue for enhancing treatment efficacy and addressing the limitations of current therapies. To identify effective strategies for treating RCC, we selected ten drugs guided by tumor biology to test in six RCC patient-derived xenograft (PDX) models. The multitargeted tyrosine kinase inhibitor (TKI) cabozantinib and mTORC1/2 inhibitor sapanisertib emerged as the most effective drugs, particularly when combined. The combination demonstrated favorable tolerability and inhibited tumor growth or induced tumor regression in all models, including two from patients who experienced treatment failure with FDA-approved TKI and immunotherapy combinations. In cabozantinib-treated samples, imaging analysis revealed a significant reduction in vascular density, and single-nucleus RNA sequencing (snRNA-seq) analysis indicated a decreased proportion of endothelial cells in the tumors. SnRNA-seq data further identified a tumor subpopulation enriched with cell-cycle activity that exhibited heightened sensitivity to the cabozantinib and sapanisertib combination. Conversely, activation of the epithelial-mesenchymal transition pathway, detected at the protein level, was associated with drug resistance in residual tumors following combination treatment. The combination effectively restrained ERK phosphorylation and reduced expression of ERK downstream transcription factors and their target genes implicated in cell-cycle control and apoptosis. This study highlights the potential of the cabozantinib plus sapanisertib combination as a promising treatment approach for patients with RCC, particularly those whose tumors progressed on immune checkpoint inhibitors and other TKIs.

SIGNIFICANCE

The molecular-guided therapeutic strategy of combining cabozantinib and sapanisertib restrains ERK activity to effectively suppress growth of renal cell carcinomas, including those unresponsive to immune checkpoint inhibitors.

Downstream Targets of VHL/HIF-α Signaling in Renal Clear Cell Carcinoma Progression: Mechanisms and Therapeutic Relevance

The clear cell variant of renal cell carcinoma (ccRCC) is the most common renal epithelial malignancy and responsible for most of the deaths from kidney cancer. Patients carrying inactivating mutations in the Von Hippel-Lindau (VHL) gene have an increased proclivity to develop several types of tumors including ccRCC. Normally, the Hypoxia Inducible Factor alpha (HIF-α) subunits of the HIF heterodimeric transcription factor complex are regulated by oxygen-dependent prolyl-hydroxylation, VHL-mediated ubiquitination and proteasomal degradation. Loss of pVHL function results in elevated levels of HIF-α due to increased stability, leading to RCC progression. While HIF-1α acts as a tumor suppressor, HIF-2α promotes oncogenic potential by driving tumor progression and metastasis through activation of hypoxia-sensitive signaling pathways and overexpression of HIF-2α target genes. One strategy to suppress ccRCC aggressiveness is directed at inhibition of HIF-2α and the associated molecular pathways leading to cell proliferation, angiogenesis, and metastasis. Indeed, clinical and pre-clinical data demonstrated the effectiveness of HIF-2α targeted therapy in attenuating ccRCC progression. This review focuses on the signaling pathways and the involved genes (cyclin D, c-Myc, VEGF-a, EGFR, TGF-α, GLUT-1) that confer oncogenic potential downstream of the VHL-HIF-2α signaling axis in ccRCC. Discussed as well are current treatment options (including receptor tyrosine kinase inhibitors such as sunitinib), the medical challenges (high prevalence of metastasis at the time of diagnosis, refractory nature of advanced disease to current treatment options), scientific challenges and future directions.

Pyroptosis-Related Gene Signature Predicts the Prognosis of ccRCC Using TCGA and Single-Cell RNA Seq Database

Clear cell renal cell carcinoma (ccRCC) is the most prevalent type of renal carcinoma, which is not sensitive to both radiotherapy and chemotherapy. The objective response rate of metastatic renal cancer to targeted drugs and immunotherapy is unsatisfactory. Pyroptosis, proven as an inflammatory form of programmed cell death, could be activated by some inflammasomes, while could create a tumor-suppressing environment by releasing inflammatory factors in the tumor. To explore indicators predicting the prognosis of ccRCC and the effect of antitumor therapy, we constructed a pyroptosis risk model containing 4 genes after 11 pyroptosis-related genes of 516 ccRCC cases in the TCGA database were scanned. Based on the risk score, 516 ccRCC cases were divided into two groups for functional enrichment analysis and immune profile to seek functional pathways and potential therapeutic targets. Besides, those results were verified in GSE29609 and single-cell transcriptomic data. The study suggests that the conducted pyroptosis model could predict the prognosis of ccRCC and reflect the immune microenvironment, which may help in immune checkpoint inhibitor treatment.

Circular RNA circPPP6R3 upregulates CD44 to promote the progression of clear cell renal cell carcinoma via sponging miR-1238-3p

Circular RNAs (circRNAs) are a type of covalently closed circular-formed RNAs and play crucial roles in the oncogenesis and progression of various human cancers. Here we identified a novel circRNA, circPPP6R3, to be highly expressed both in clear cell renal cell carcinoma (ccRCC) tissues and cell lines based on analyzing high-throughput sequencing data and qRT-PCR analysis. Highly expressed circPPP6R3 was positively correlated with higher histological grade, T stage, and M stage as well as advanced clinical stage of ccRCC patients. Functionally, knockdown of circPPP6R3 attenuated the proliferation, migration, and invasion of ccRCC cells whereas overexpression had the reverse effects. Mechanistically, the biotin-labeled pull-down assay and dual-luciferase reporter assay revealed that circPPP6R3 directly interacted with miR-1238-3p. miR-1238-3p inhibitors had a rescue effect on the proliferative and metastatic capacities by knockdown of circPPP6R3. Moreover, RNA-sequencing analysis and dual-luciferase reporter assay indicated that circPPP6R3 upregulated CD44, a cell-surface glycoprotein contributed to the cell adhesion and metastasis, via sponging to miR-1238-3p. Further investigation revealed that MMP9 and Vimentin were regulated by CD44 in ccRCC. Our study thus provided evidence that the regulatory network involving circPPP6R3/miR-1238-3p/CD44 axis might provide promising biomarkers as well as a therapeutic approach for ccRCC.

Comprehensive analysis of pyroptosis regulators and tumor immune microenvironment in clear cell renal cell carcinoma

Background

Increasing evidence has indicated that pyroptosis could regulate the tumor immune microenvironment (TIME) to affect the tumor development. As a highly immunogenic tumor, clear cell renal cell carcinoma (ccRCC) can benefit from immunotherapy, but related research on pyroptosis in the TIME of ccRCC is still deficient.

Methods

Available data derived from TCGA and GEO databases were analyzed to identify the different expression profiles of pyroptosis in ccRCC and normal tissues, and the correlation of pyroptosis regulators with TIME was evaluated in ccRCC.

Results

According to consensus clustering analysis, two differential expression levels of subtypes were identified to affect patient prognosis, and were related to histological tumor stage and grade. Immune cells were calculated by the CIBERSORT algorithm. Higher infiltrated levels of B cells naive, T cells CD4 memory resting, NK cells resting, monocytes, macrophages were observed in Cluster 1, while higher infiltrated levels of CD8⁺ T cells, T follicular helper cells, and Tregs were observed in Cluster 2. Gene set enrichment analysis indicated that Cluster 2 was enriched in multiple immune-related pathways, including the JAK-STAT signaling pathway. Moreover, overexpression of eight immune checkpoints was related to ccRCC development, especially in Cluster 2. As four potentially key pyroptosis regulators, AIM2, CASP5, NOD2, and GZMB were confirmed to be upregulated in ccRCC by RT-qPCR analysis and further verified by the HPA database. Further pan-cancer analysis suggested that these four pyroptosis regulators were differentially expressed and related to the TIME in multiple cancers.

Conclusion

The present study provided a comprehensive view of pyroptosis regulators in the TIME of ccRCC, which may provide potential value for immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02384-y.

Improved cancer biomarkers identification using network-constrained infinite latent feature selection

Identifying biomarkers that are associated with different types of cancer is an important goal in the field of bioinformatics. Different researcher groups have analyzed the expression profiles of many genes and found some certain genetic patterns that can promote the improvement of targeted therapies, but the significance of some genes is still ambiguous. More reliable and effective biomarkers identification methods are then needed to detect candidate cancer-related genes. In this paper, we proposed a novel method that combines the infinite latent feature selection (ILFS) method with the functional interaction (FIs) network to rank the biomarkers. We applied the proposed method to the expression data of five cancer types. The experiments indicated that our network-constrained ILFS (NCILFS) provides an improved prediction of the diagnosis of the samples and locates many more known oncogenes than the original ILFS and some other existing methods. We also performed functional enrichment analysis by inspecting the over-represented gene ontology (GO) biological process (BP) terms and applying the gene set enrichment analysis (GSEA) method on selected biomarkers for each feature selection method. The enrichments analysis reports show that our network-constraint ILFS can produce more biologically significant gene sets than other methods. The results suggest that network-constrained ILFS can identify cancer-related genes with a higher discriminative power and biological significance.

Neoadjuvant and adjuvant immunotherapy in renal cell carcinoma

OBJECTIVE

The treatment landscape for renal cell carcinoma (RCC) is rapidly evolving. The aim of this review is to summarize the randomized-controlled trials evaluating the role of immunotherapy in neoadjuvant or adjuvant setting.

MATERIALS AND METHODS

We searched PubMed, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies including neoadjuvant or adjuvant immunotherapy, and provided a brief overview of the pharmacodynamics of immunotherapy for RCC.

RESULTS

Several drugs are currently under investigation. In the neoadjuvant setting, four studies are evaluating the role of single-agent immunotherapy, one of dual-agent immunotherapy, and four studies the role of immunotherapy in combination with tyrosine kinase inhibitors or anti-interleukin-1 beta. In the adjuvant setting, two studies are evaluating the role of single-agent immunotherapy and two of dual-agent immunotherapy.

CONCLUSIONS

The approval of immune checkpoint inhibition as a front-line therapeutic strategy for advanced RCC has also ultimately led to the investigation of these agents first in the adjuvant and then in the neoadjuvant setting. Currently, there are nine studies aimed to evaluate the role of immunotherapy in the neoadjuvant setting and four studies in the adjuvant setting.

Silibinin inhibits epithelial‑mesenchymal transition of renal cell carcinoma through autophagy‑dependent Wnt/β‑catenin signaling

Silibinin is a flavonoid extracted from milk thistle seeds which has been widely used as a hepatoprotective and antioxidant agent. Recently, accumulating evidence has demonstrated the anti-cancer effects of silibinin in various cancer models. It was previously reported that silibinin induced apoptosis and decreased metastasis by activating autophagy in renal cell carcinoma (RCC). However, the underlying molecular mechanisms by which silibinin regulates autophagy remain largely unknown. The aim of the present study was to investigate the effects of silibinin on RCC metastasis in vitro and in vivo, with a focus on autophagy-dependent Wnt/β-catenin signaling. Human RCC 786-O and ACHN cell lines were used as the model system in vitro and RCC xenografts of nude mice were used for in vivo studies. Silibinin inhibited metastasis and epithelial-mesenchymal transition (EMT) of RCC in vitro and in vivo, by regulating the Wnt/β-catenin signaling pathway. Furthermore, silibinin inhibited the Wnt/β-catenin signaling pathway in an autophagy-dependent manner. Autophagic degradation of β-catenin induced by silibinin was associated with the anti-metastatic effects of silibinin against RCC. These findings identify a novel mechanism by which silibinin inhibits EMT and metastasis of RCC, highlighting a potential novel strategy for treating metastatic RCC.

Metastatic renal cell carcinoma to the pancreas and subcutaneous tissue 10 years after radical nephrectomy: a case report

Background

Synchronous renal cell carcinoma metastasizing to the pancreas and subcutaneous tissue is very rare. Unusual metastatic sites require attention during follow-up of renal cell carcinoma. It is extremely rare for renal cell carcinoma to metastasize to the pancreas; it is also very rare for it to metastasize to the subcutaneous tissue and extremely rare for it to synchronously metastasize to the pancreas and subcutaneous tissue almost a decade after radical nephrectomy. It is well known that most pancreatic tumors are primary pancreatic adenocarcinoma. However, the pancreas can also be an uncommon site for metastasis. We present a rare case of synchronous metastasis of renal cell carcinoma to the pancreas and subcutaneous tissue; we believe it to be only the second such case reported to date.

Case presentation

We describe a case of a 74-year-old Chinese man who was diagnosed with metastatic renal cell carcinoma to the pancreas and subcutaneous tissue at the same time, 10 years after left radical nephrectomy. He received distal pancreatectomy with spleen preservation plus resection of the subcutaneous tissue lesions on the left side of the anterior abdominal wall and right waist. Pathology showed that all resected metastatic tumors were of the clear cell type. The patient was seen in regular follow-up afterward.

Conclusion

Synchronous metastatic renal cell carcinoma to the pancreas and subcutaneous tissue is very rare, and it might occur after primary tumor resection. Patients must undergo lifelong monitoring and follow-up with regular examination so that any possible metastasis can be detected early. The optimal resection strategy should involve adequate resection margins and maximal tissue preservation of the pancreas, because renal cell carcinoma metastasizing to the pancreas and subcutaneous tissue has a good prognosis with long-term survival.

The failure of DAC to induce OCT2 expression and its remission by hemoglobin-based nanocarriers under hypoxia in renal cell carcinoma

Background: Human organic cation transporter 2 (OCT2) is the most abundant and important uptake transporter involved in the renal excretion of cationic drugs. Abnormal hypermethylation- mediated silencing of OCT2 results in oxaliplatin resistance in renal cell carcinoma (RCC). The epigenetic activation of OCT2 by decitabine (DAC) reversed this resistance in normoxic conditions. Given the hypoxic characteristic of RCC, it is still unclear whether hypoxia promotes DAC resistance and is involved in the regulation of OCT2. Methods: The mRNA and protein expression of OCT2 was determined by qRT-PCR and Western blotting. MSRE-qPCR and BSP were used to examine methylation modifications at the OCT2 promoter. The ChIP-qPCR analysis was performed to detect the abundance of histone modification and HIF-1α. The accumulation of DAC and 5-mC were detected using LC-MS, and the amount of 5-hmC was determined by dot blot analysis. To understand the role of hypoxia in the regulation of equilibrative nucleoside transporter 1 (ENT1) expression, the HIF-1α KO cell model was constructed. The re-emulsion method was used for the construction of H-NPs, an oxygen nanocarrier based on hemoglobin, to alleviate the drug resistance of DAC under hypoxia. Results: DAC was unable to upregulate OCT2 expression in hypoxic conditions because of the hypermethylation and low H3K4me3 modification in its promoter region. Hypoxia-mediated repression of human ENT1, which was markedly suppressed in RCC, resulted in a decrease in the cellular accumulation of DAC. Besides, hypoxia-induced upregulation of histone deacetylase HDAC9, which impaired the enrichment of H3K27ac modification in the OCT2 promoter, led to the transcriptional repression of OCT2. H-NPs could attenuate the hypoxia-induced loss of DAC activity and sensitize RCC cells to the sequential combination therapy of DAC and oxaliplatin. Conclusions: Hypoxia-mediated repression of ENT1 led to the inability of DAC to upregulate the expression of OCT2 under hypoxia. H-NPs could alleviate resistance to oxaliplatin and DAC in RCC cells under hypoxia and may have potential clinical applications.

Limited utility of qPCR-based detection of tumor-specific circulating mRNAs in whole blood from clear cell renal cell carcinoma patients

Background

RNA sequencing data is providing abundant information about the levels of dysregulation of genes in various tumors. These data, as well as data based on older microarray technologies have enabled the identification of many genes which are upregulated in clear cell renal cell carcinoma (ccRCC) compared to matched normal tissue. Here we use RNA sequencing data in order to construct a panel of highly overexpressed genes in ccRCC so as to evaluate their RNA levels in whole blood and determine any diagnostic potential of these levels for renal cell carcinoma patients.

Methods

A bioinformatics analysis with Python was performed using TCGA, GEO and other databases to identify genes which are upregulated in ccRCC while being absent in the blood of healthy individuals. Quantitative Real Time PCR (RT-qPCR) was subsequently used to measure the levels of candidate genes in whole blood (PAX gene) of 16 ccRCC patients versus 11 healthy individuals. PCR results were processed in qBase and GraphPadPrism and statistics was done with Mann-Whitney U test.

Results

While most analyzed genes were either undetectable or did not show any dysregulated expression, two genes, CDK18 and CCND1, were paradoxically downregulated in the blood of ccRCC patients compared to healthy controls. Furthermore, LOX showed a tendency towards upregulation in metastatic ccRCC samples compared to non-metastatic.

Conclusions

This analysis illustrates the difficulty of detecting tumor regulated genes in blood and the possible influence of interference from expression in blood cells even for genes conditionally absent in normal blood. Testing in plasma samples indicated that tumor specific mRNAs were not detectable. While CDK18, CCND1 and LOX mRNAs might carry biomarker potential, this would require validation in an independent, larger patient cohort.

Upregulation of miR-489-3p and miR-630 inhibits oxaliplatin uptake in renal cell carcinoma by targeting OCT2

Renal cell carcinoma (RCC) is one of the most common malignant tumors affecting the urogenital system, accounting for 90% of renal malignancies. Traditional chemotherapy options are often the front-line choice of regimen in the treatment of patients with RCC, but responses may be modest or limited due to resistance of the tumor to anticarcinogen. Downregulated expression of organic cation transporter OCT2 is a possible mechanism underlying oxaliplatin resistance in RCC treatment. In this study, we observed that miR-489-3p and miR-630 suppress OCT2 expression by directly binding to the OCT2 3'-UTR. Meanwhile, via 786-O-OCT2-miRNAs stable expression cell models, we found that miRNAs could repress the classic substrate 1-methyl-4-phenylpyridinium (MPP⁺), fluorogenic substrate N,N-dimethyl-4-(2-pyridin-4-ylethenyl) aniline (ASP⁺), and oxaliplatin uptake by OCT2 both in vitro and in xenografts. In 33 clinical samples, miR-489-3p and miR-630 were significantly upregulated in RCC, negatively correlating with the OCT2 expression level compared to that in adjacent normal tissues, using tissue microarray analysis and qPCR validation. The increased binding of c-Myc to the promoter of pri-miR-630, responsible for the upregulation of miR-630 in RCC, was further evidenced by chromatin immunoprecipitation and dual-luciferase reporter assay. Overall, this study indicated that miR-489-3p and miR-630 function as oncotherapy-obstructing microRNAs by directly targeting OCT2 in RCC.

Current Status of Immunotherapy for Localized and Locally Advanced Renal Cell Carcinoma

Systemic therapy strategies in the setting of localized and locally advanced renal cell carcinoma (RCC) have continued to evolve in two directions: as adjuvant therapy (to reduce risk of recurrence or progression in high risk localized groups), or as neoadjuvant therapy as a strategy to render primary renal tumors amenable to planned surgical resection in settings where radical resection or nephron-sparing surgery was not thought to be safe or feasible. In the realm of adjuvant therapy, the results of phase III randomized clinical trials have been mixed and contradictory; nonetheless based on the findings of the landmark S-TRAC study, the tyrosine kinase inhibitor Sunitinib has been approved as an adjuvant agent in the United States. In the realm of neoadjuvant therapy, presurgical tumor reduction has been demonstrated in a number of phase II studies utilizing targeted molecular agents. The advent of immunomodulation through checkpoint inhibition as first line therapy for metastatic RCC represents an exciting horizon for adjuvant and neoadjuvant strategies. This article reviews the current status and future prospects of adjuvant and neoadjuvant immunotherapy in localized and locally advanced RCC.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

MicroRNAs Associated with Von Hippel-Lindau Pathway in Renal Cell Carcinoma: A Comprehensive Review

Renal cell carcinoma (RCC) are the most common renal neoplasia and can be divided into three main histologic subtypes, among which clear cell RCC is by far the most common form of kidney cancer. Despite substantial advances over the last decade in the understanding of RCC biology, surgical treatments, and targeted and immuno-therapies in the metastatic setting, the prognosis for advanced RCC patients remains poor. One of the major problems with RCC treatment strategies is inherent or acquired resistance towards therapeutic agents over time. The discovery of microRNAs (miRNAs), a class of small, non-coding, single-stranded RNAs that play a crucial role in post-transcriptional regulation, has added new dimensions to the development of novel diagnostic and treatment tools. Because of an association between Von Hippel–Lindau (VHL) genes with chromosomal loss in 3p25-26 and clear cell RCC, miRNAs have attracted considerable scientific interest over the last years. The loss of VHL function leads to constitutional activation of the hypoxia inducible factor (HIF) pathway and to consequent expression of numerous angiogenic and carcinogenic factors. Since miRNAs represent key players of carcinogenesis, tumor cell invasion, angiogenesis, as well as in development of metastases in RCC, they might serve as potential therapeutic targets. Several miRNAs are already known to be dysregulated in RCC and have been linked to biological processes involved in tumor angiogenesis and response to anti-cancer therapies. This review summarizes the role of different miRNAs in RCC angiogenesis and their association with the VHL gene, highlighting their potential role as novel drug targets.

miR-122 promotes metastasis of clear-cell renal cell carcinoma by downregulating Dicer

Although overall downregulation of microRNAs (miRNAs) is a general feature of clear-cell renal cell carcinoma (ccRCC), several miRNAs are consistently upregulated, among which miR-122 was markedly increased in ccRCC tissues. Our study aims to determine the functional importance and underlying mechanism of miR-122 in ccRCC metastasis. Here, we demonstrate that the expression of miR-122 increased in ccRCC tissues, and higher miR-122 expression was found in ccRCC tissues with metastatic disease than in those without metastasis. The increased miR-122 levels were associated with poor metastasis-free survival in ccRCC patients with localized disease. Dicer was validated as a direct functional target of miR-122. Overexpression of miR-122 promoted migration and invasion of ccRCC cells in vitro and metastatic behavior of ccRCC cells in vivo. Inhibition of miR-122 attenuated this metastatic phenotype in vitro. Importantly, miR-122 exerted its pro-metastatic properties in ccRCC cells by downregulating Dicer and its downstream effector, the miR-200 family, thereby inducing epithelial-mesenchymal transition (EMT). Our results suggest an important role of the miR-122/Dicer/miR-200s/EMT pathway in ccRCC metastasis. Furthermore, miR-122 may serve as a biomarker for discriminating ccRCC with metastatic potential.

Axitinib in metastatic renal cell carcinoma: beyond the second-line setting

Treatment options for advanced and metastatic renal cell carcinoma have advanced considerably in the past decade with the approval of several targeted agents, including axitinib. Axitinib is a potent and selective inhibitor of VEGFRs 1-3, and is well established as second-line treatment. This article summarizes factors to be considered when administering axitinib, such as individualized dose titration and axitinib-associated adverse events, in order to retain patients longer on treatment, which would likely lead to improved efficacy outcomes. In addition, potential clinical perspectives for axitinib beyond the second-line setting, including its role in the first-line setting, sequential therapy, neoadjuvant and adjuvant therapies, and combination therapy with immunotherapy, in particular, immune checkpoint inhibitors, are discussed.

Expression of lactate dehydrogenase C correlates with poor prognosis in renal cell carcinoma

Lactate dehydrogenase C is an isoenzyme of lactate dehydrogenase and a member of the cancer-testis antigens family. In this study, we aimed to investigate the expression and functional role of lactate dehydrogenase C and its basic mechanisms in renal cell carcinoma. First, a total of 133 cases of renal cell carcinoma samples were analysed in a tissue microarray, and Kaplan-Meier survival curve analyses were performed to investigate the correlation between lactate dehydrogenase C expression and renal cell carcinoma progression. Lactate dehydrogenase C protein levels and messenger RNA levels were significantly upregulated in renal cell carcinoma tissues, and the patients with positive lactate dehydrogenase C expression had a shorter progression-free survival, indicating the oncogenic role of lactate dehydrogenase C in renal cell carcinoma. In addition, further cytological experiments demonstrated that lactate dehydrogenase C could prompt renal cell carcinoma cells to produce lactate, and increase metastatic and invasive potential of renal cell carcinoma cells. Furthermore, lactate dehydrogenase C could induce the epithelial-mesenchymal transition process and matrix metalloproteinase-9 expression. In summary, these findings showed lactate dehydrogenase C was associated with poor prognosis in renal cell carcinoma and played a pivotal role in the migration and invasion of renal cell carcinoma cells. Lactate dehydrogenase C may act as a novel biomarker for renal cell carcinoma progression and a potential therapeutic target for the treatment of renal cell carcinoma.

Englerin A induces an acute inflammatory response and reveals lipid metabolism and ER stress as targetable vulnerabilities in renal cell carcinoma

Renal cell carcinoma (RCC) is among the top ten most common forms of cancer and is the most common malignancy of the kidney. Clear cell renal carcinoma (cc-RCC), the most common type of RCC, is one of the most refractory cancers with an incidence that is on the rise. Screening of plant extracts in search of new anti-cancer agents resulted in the discovery of englerin A, a guaiane sesquiterpene with potent cytotoxicity against renal cancer cells and a small subset of other cancer cells. Though a few cellular targets have been identified for englerin A, it is still not clear what mechanisms account for the cytotoxicity of englerin A in RCC, which occurs at concentrations well below those used to engage the targets previously identified. Unlike any prior study, the current study used a systems biology approach to explore the mechanism(s) of action of englerin A. Metabolomics analyses indicated that englerin A profoundly altered lipid metabolism by 24 h in cc-RCC cell lines and generated significant levels of ceramides that were highly toxic to these cells. Microarray analyses determined that englerin A induced ER stress signaling and an acute inflammatory response, which was confirmed by quantitative PCR and Western Blot analyses. Additionally, fluorescence confocal microscopy revealed that englerin A at 25 nM disrupted the morphology of the ER confirming the deleterious effect of englerin A on the ER. Collectively, our findings suggest that cc-RCC is highly sensitive to disruptions in lipid metabolism and ER stress and that these vulnerabilities can be targeted for the treatment of cc-RCC and possibly other lipid storing cancers. Furthermore, our results suggest that ceramides may be a mediator of some of the actions of englerin A. Lastly, the acute inflammatory response induced by englerin A may mediate anti-tumor immunity.

Dicer suppresses the malignant phenotype in VHL-deficient clear cell renal cell carcinoma by inhibiting HIF-2α

Both the von Hippel-Lindau (VHL)/hypoxia-inducible factor (HIF) pathway and microRNA (miRNA) regulation are important mechanisms underlying the development and progression of clear cell renal cell carcinoma (ccRCC). Here we demonstrate that VHL deficiency leads to downregulation of Dicer and, in turn, defects in the miRNA biogenesis machinery in ccRCCs. Dicer inhibited expression of HIF-2α, which was a direct target of Dicer-dependent miR-182-5p in VHL-deficient ccRCCs. Ectopic Dicer expression in VHL-deficient ccRCCs suppressed tumor growth and angiogenesis by inhibiting HIF-2α both in vitro and in vivo. Reduced Dicer mRNA levels served as an independent prognostic factor for poor survival in patients with VHL-deficient ccRCC. Our results indicate that downregulation of Dicer in VHL-deficient ccRCCs contributes to high levels of HIF-2α and a malignant phenotype, which suggests Dicer could be a useful therapeutic target for managing this disease.

Establishment and characterization of a highly immunogenic human renal carcinoma cell line

Renal cell carcinoma (RCC) is the most common kidney cancer, and accounts for ~3% of all adult malignancies. RCC has proven refractory to conventional treatment modalities but appears to be the only histological form that shows any consistent response to immunotherapeutic approaches. The development of a clinically effective vaccine remains a major strategic target for devising active specific immunotherapy in RCC. We aimed to identify a highly immunogenic antigenic format for immunotherapeutic approaches, so as to boost immune responses in RCC patients. We established and cloned an immunogenic cell line, RCC85#21 named Elthem, which was derived from a non-aggressive and non-metastatic clear cell carcinoma. The cell line characterization was performed by genomics (real-time PCR, genome instability), proteomics (two dimensional electrophoresis, mass spectro-metry) and immunological analysis (mixed lymphocytes tumor cell cultures). Real-time PCR confirmed the RCC85#21 cell expression of tumor antigens and cytokine genes. No difference in microsatellite instability (MSI) in RCC85#21 cell line was found as compared to control, loss of heterozygosity was observed in the RCC85#21 clone, but not in the renal cancer cell lines from which it was generated. The image analysis of RCC85#21 by two-dimensional gels showed 700±26 spots and 119 spots were identified by mass spectrometry analysis. RCC85#21 promoted a significant RCC-specific T cells activation by exhibiting a cytotoxic phenotype after mixed lymphocyte and tumor cell cultures. CD8+ T cells isolated from RCC patients displayed an elevated reactivity against RCC85#21 and efficiently lysed the RCC85#21 clone. The RCC85#21 immunogenic cell line will be suitable for immune stimulation. The identification of novel tumor associated antigens will allow the evaluation of the immune response in vitro and, subsequently, in vivo paving the way for new immunotherapeutic strategies in the RCC setting.

Improving our understanding of papillary renal cell carcinoma with integrative genomic analysis

Papillary renal cell carcinoma (pRCC) is a heterogeneous and incompletely understood histologic subtype of kidney cancer. Recently, authors from The Cancer Genome Atlas Research Network performed a comprehensive molecular characterization of pRCC. Using multiple analytic methods, they identified 4 subgroups of pRCC with varied genotypic anomalies and probabilities of overall survival. This analysis elucidated the differences between type 1 and type 2 pRCC. Furthermore, type 2 pRCC was found to be heterogeneous itself, with at least 3 subtypes with distinct molecular features. This improved characterization and insight about potential driver mutations and altered pathways may lead to the development of more targeted agents and better patient stratification in clinical trials for pRCC.

Synchronous renal cell carcinoma metastasis to the contralateral adrenal gland and pancreas: A case report with 7-year follow-up subsequent to surgical therapy

Metastatic renal cell carcinoma (RCC) disseminates to a number of organ sites and few patients demonstrate long-term survival following surgery. However, synchronous metastasis of RCC to the contralateral adrenal gland and pancreas is rare. In the present report, a case of synchronous RCC metastasis to the contralateral adrenal gland and pancreas in a 55-year-old patient, with an 116×92×61 mm right renal tumor and a 96×79×57 mm left adrenal lesion, is described. In April 2007, right nephrectomy was performed to treat the RCC, left adrenalectomy was performed to treat the adrenal tumor and the pancreatic metastases were resected. The patient remained alive at the 7-year follow-up appointment.

von Hippel-Lindau Disease: Review of Genetics and Imaging

von Hippel-Lindau (VHL) disease is an autosomal-dominant, hereditary, multisystem neoplasia syndrome with increased susceptibility to several benign and malignant tumors. VHL occurs in about 1 in 36,000 live births and is associated with germline mutation of the VHL tumor suppressor gene on the short arm of chromosome 3. VHL disease exhibits diverse genotype and phenotype correlations, exhibits variable intrafamilial and interfamilial expressivity, and can manifest with benign and malignant tumors of the central nervous system, kidneys, adrenals, pancreas, and reproductive organs. Imaging and management of this entity are therefore multidisciplinary. An overview of VHL disease is presented.

The anticancer gene ORCTL3 targets stearoyl-CoA desaturase-1 for tumour-specific apoptosis

ORCTL3 is a member of a group of genes, the so-called anticancer genes, that cause tumour-specific cell death. We show that this activity is triggered in isogenic renal cells upon their transformation independently of the cells' proliferation status. For its cell death effect ORCTL3 targets the enzyme stearoyl-CoA desaturase-1 (SCD1) in fatty acid metabolism. This is caused by transmembrane domains 3 and 4, which are more efficacious in vitro than a low molecular weight drug against SCD1, and critically depend on their expression level. SCD1 is found upregulated upon renal cell transformation indicating that its activity, while not impacting proliferation, represents a critical bottleneck for tumourigenesis. An adenovirus expressing ORCTL3 leads to growth inhibition of renal tumours in vivo and to substantial destruction of patients' kidney tumour cells ex vivo. Our results indicate fatty acid metabolism as a target for tumour-specific apoptosis in renal tumours and suggest ORCTL3 as a means to accomplish this.

Relationship between tumour angiogenesis and expression of cyclo-oxygenase-2 and vascular endothelial growth factor-A in human renal cell carcinoma

OBJECTIVE

*These authors contributed equally to this work. To study the relationship between tumour angiogenesis and expression of cyclo-oxygenase (COX)-2 and vascular endothelial growth factor (VEGF)-A in human renal cell carcinoma.

METHODS

Archival samples of primary human renal cell carcinoma tissue and surrounding normal renal tissue (control samples) obtained from patients diagnosed with renal cell carcinoma were analysed for COX-2 and VEGF-A expression by immunohistochemistry using specific monoclonal antibodies. Tumour microvasculature was examined using factor VIII-related antigen antibody staining.

RESULTS

A total of 33 renal cell carcinoma and 12 control renal tissue specimens were included. COX-2 and VEGF-A genes were overexpressed in tumour specimens compared with normal epithelia. A significant correlation was found between COX-2 and VEGF-A expression. Microvessel density was found to be increased in tumour tissues that expressed COX-2 and VEGF-A.

CONCLUSION

Microvessel density was increased in tumour tissues that expressed COX-2 and VEGF-A, suggesting that COX-2 and VEGF-A are related to tumour angiogenesis in human renal cell carcinoma.

Relationships between the Effect of Sunitinib and Immature Blood Vessels in Metastatic Renal Cell Cancer

Introduction: This study was conducted to investigate the relationships between the effect of sunitinib and immature microvessels which are not covered by pericytes. Materials and Methods: This study involved 29 patients with clear-cell renal cell carcinoma (RCC) who took sunitinib after radical nephrectomy or biopsy due to metastatic RCC. Associations among clinicopathological factors, responses to sunitinib, and patient survival were reviewed. CD31 was used to stain endothelial cells, and anti-α-smooth muscle actin was used to stain pericytes. Immature vessels were defined as vessels that were positive only for CD31 staining. A high pericyte coverage was defined as a rate of pericyte coverage above 40%. Results: Partial responses, disease stabilization, and disease progression constituted 51.7, 10.4, and 37.9% of cases, respectively. Nine cases had a low pericyte coverage (31.0%). In the high-pericyte-coverage group, the number of metastatic sites was smaller (p = 0.003). The overall response rate to sunitinib was greater in the high-pericyte-coverage group than in the low-pericyte-coverage group (p = 0.027). The median overall survival and the median progression-free survival were not significantly different between the high- and low-pericyte-coverage groups. Conclusion: In the high-pericyte-coverage group, the overall response rates to sunitinib were higher, and the numbers of metastatic sites were smaller.

NADPH oxidase NOX4 supports renal tumorigenesis by promoting the expression and nuclear accumulation of HIF2α

Most sporadically occurring renal tumors include a functional loss of the tumor suppressor von Hippel Lindau (VHL). Development of VHL-deficient renal cell carcinoma (RCC) relies upon activation of the hypoxia-inducible factor-2α (HIF2α), a master transcriptional regulator of genes that drive diverse processes, including angiogenesis, proliferation, and anaerobic metabolism. In determining the critical functions for HIF2α expression in RCC cells, the NADPH oxidase NOX4 has been identified, but the pathogenic contributions of NOX4 to RCC have not been evaluated directly. Here, we report that NOX4 silencing in VHL-deficient RCC cells abrogates cell branching, invasion, colony formation, and growth in a murine xenograft model RCC. These alterations were phenocopied by treatment of the superoxide scavenger, TEMPOL, or by overexpression of manganese superoxide dismutase or catalase. Notably, NOX4 silencing or superoxide scavenging was sufficient to block nuclear accumulation of HIF2α in RCC cells. Our results offer direct evidence that NOX4 is critical for renal tumorigenesis and they show how NOX4 suppression and VHL re-expression in VHL-deficient RCC cells are genetically synonymous, supporting development of therapeutic regimens aimed at NOX4 blockade.

Critical appraisal of sorafenib in the treatment of Chinese patients with renal cell carcinoma

Renal cell carcinoma (RCC) accounts for 3% of all malignancies, and is the most aggressive cancer of the genitourinary system. Metastatic RCC is naturally resistant to chemotherapy and radiotherapy, and immunotherapy is of little benefit. In recent years, the emergence of molecular-targeted therapies has largely changed the therapeutic approach to metastatic RCC. These novel multikinase inhibitors have now become first-choice therapy because of their activity in inhibiting both cell proliferation and tumor angiogenesis. Sorafenib is the first tyrosine kinase inhibitor found to be effective in treating patients with metastatic RCC. Due to its good efficacy and safety, this agent is recommended as both first-line and second-line therapy for metastatic RCC in the People's Republic of China. Sorafenib seems to be more effective in patients of Chinese ethnicity than in western patients, and is well tolerated with a manageable toxicity profile, even at higher dosages and when used in combination with other anticancer agents. Novel biomarkers for predicting the efficacy of sorafenib have potential clinical value for guiding individualized targeted therapy.

Renal cell carcinoma: molecular biology and targeted therapy

PURPOSE OF REVIEW

Renal cell carcinoma (RCC) continues to be the subject of vigorous clinical and translational investigation. Advances in systemic targeted therapies, new molecular pathways and immunotherapy approaches will be discussed.

RECENT FINDINGS

Agents targeting the vascular endothelial growth factor (VEGF) and/or the mammalian target of rapamycin (mTOR) pathways continue to be the mainstay for treating metastatic RCC (mRCC). Although enhanced target specificity has improved the toxicity profile associated with newer VEGF-pathway antagonists, durable complete responses remain the exception. Identification of novel pathways/agents, as well as the optimal sequencing and combination of existing targeted agents, remain areas of active study. In addition, emerging data from early clinical trials have reinvigorated interest in immunomodulatory agents.

SUMMARY

The therapeutic armamentarium available to genitourinary oncologists continues to grow, but much work remains to be done to fully realize the potential of pathway-specific targeted strategies and immune-based approaches for mRCC.

Comparative outcomes of everolimus, temsirolimus and sorafenib as second targeted therapies for metastatic renal cell carcinoma: a US medical record review

OBJECTIVE

To compare outcomes of metastatic renal cell carcinoma (mRCC) patients treated with everolimus, temsirolimus, and sorafenib following initial treatment with a tyrosine kinase inhibitor (TKI) in community and academic practices throughout the US.

RESEARCH DESIGN AND METHODS

Medical records of mRCC patients who received everolimus, temsirolimus or sorafenib as their second therapy following a TKI were retrospectively reviewed from a nationally representative panel of oncologists. Overall survival (OS) and progression-free survival (PFS) of second targeted therapies were compared using multivariable Cox proportional hazard models, with adjustment for demographics, disease severity and prior treatments.

RESULTS

A total of 233, 178, and 123 mRCC patients receiving everolimus, temsirolimus, and sorafenib, respectively, as second targeted therapies were included. Eighty-six percent used sunitinib and the remainder used sorafenib or pazopanib as their initial TKI. After adjusting for baseline characteristics, everolimus was associated with significantly prolonged OS (hazard ratio [HR] 0.60; CI 0.42-0.85; p = 0.004) and PFS (HR 0.73; CI 0.54-0.97; p = 0.032) compared to temsirolimus. Everolimus was associated with significantly longer OS (HR 0.66; CI 0.44-0.99; p = 0.045) and numerically longer PFS compared to sorafenib. No significant differences were observed between temsirolimus and sorafenib.

LIMITATIONS

Despite adjustment for multiple patient characteristics, comparisons between treatment groups may be confounded by unobserved factors in this retrospective observational study. Tolerability outcomes were not collected.

CONCLUSIONS

In this retrospective, non-randomized study of mRCC patients with prior TKI treatment, everolimus was associated with significantly prolonged OS and PFS compared to temsirolimus and significantly prolonged OS compared to sorafenib.

Renal cancer-selective Englerin A induces multiple mechanisms of cell death and autophagy

Renal cell carcinoma (RCC), the most common malignancy of the kidney, is refractory to standard therapy and has an incidence that continues to rise. Screening of plant extracts in search of new agents to treat RCC resulted in the discovery of englerin A (EA), a natural product exhibiting potent selective cytotoxicity against renal cancer cells. Despite the establishment of synthetic routes to the synthesis of EA, very little is known about its mechanism of action. The results of the current study demonstrate for the first time that EA induces apoptosis in A498 renal cancer cells in addition to necrosis. The induction of apoptosis by EA required at least 24 h and was caspase independent. In addition, EA induced increased levels of autophagic vesicles in A498 cells which could be inhibited by nonessential amino acids (NEAA), known inhibitors of autophagy. Interestingly, inhibition of autophagy by NEAA did not diminish cell death suggesting that autophagy is not a cell death mechanism and likely represents a cell survival mechanism which ultimately fails. Apart from cell death, our results demonstrated that cells treated with EA accumulated in the G2 phase of the cell cycle indicating a block in G2/M transition. Moreover, our results determined that EA inhibited the activation of both AKT and ERK, kinases which are activated in cancer and implicated in unrestricted cell proliferation and induction of autophagy. The phosphorylation status of the cellular energy sensor, AMPK, appeared unaffected by EA. The high renal cancer selectivity of EA combined with its ability to induce multiple mechanisms of cell death while inhibiting pathways driving cell proliferation, suggest that EA is a highly unique agent with great potential as a therapeutic lead for the treatment of RCC.

Rare case of renal cell carcinoma with mandibular swelling as primary presentation

Introduction. Renal cell carcinoma accounts for approximately 3% of adult malignancies and 90–95% of neoplasms arising from the kidney. This disease is characterized by a lack of early warning signs, diverse clinical manifestations, and resistance to radiation and chemotherapy. Approximately one-third of patients with renal cell carcinoma have metastatic disease at initial presentation. Fifteen percent of patients with renal cell carcinoma are said to present with metastases in the head and neck region. Most of the metastases from RCC to the head and neck involve the thyroid gland. The head and neck are unusual sites for metastases, but skin, skeletal muscle, thyroid gland, nasal cavity and paranasal sinus metastases have been reported. Case Report. The following report describes a rare case where the patient presented with mandibular swelling of short duration as the primary complaint without any symptom or sign pertaining to urinary tract and was found to have renal cell carcinoma on further workup. Conclusion. Metastatic renal cell carcinoma is a diagnostic dilemma especially when there is no pointer historically towards renal cell carcinoma as was in our case. An unusual vascular osteolytic lesion in head and neck in a middle-aged person should be dealt with high index of suspicion with renal cell carcinoma at the back of the mind.

Evolving therapeutic targets in renal cell carcinoma

PURPOSE OF REVIEW

Recent developments in the treatment of advanced renal cell carcinoma (RCC) will be discussed, with emphasis on data published over the past year. The genetics and molecular biology of the various histologic subtypes of kidney cancer will be reviewed, as these subtle yet important genomic and metabolic alterations provide the opportunity for rational drug development and personalized treatment regimens.

RECENT FINDINGS

Additional targeted agents continue to be added to the uro-oncologist's armamentarium in the fight against metastatic kidney cancer. Targeting the vascular endothelial growth factor and its receptor, or the mammalian target of rapamycin complex, remains the foundation of systemic treatment. In clear cell RCC, increased emphasis is being placed on target selectivity and affinity in a bid to diminish off-target toxicity without compromising efficacy. Combination strategies targeting multiple pathways simultaneously continue to be explored. Histology-specific protocols testing later generation and novel agents in nonclear cell RCC should be made a priority, as there is still not a single drug approved specifically for a nonclear cell indication.

SUMMARY

The number of approved treatments for advanced RCC continues to grow, but additional work is needed to further delineate the optimal drug, combination of agents, or sequence best suited to each subtype of RCC.

Endothelial follicle stimulating hormone receptor in primary kidney cancer correlates with subsequent response to sunitinib

Sunitinib is an anti-angiogenic receptor tyrosine kinase inhibitor used to treat advanced metastatic renal cell carcinoma and other types of cancer. Sutent is effective in only approximately 70% of clear cell renal cell carcinoma (CCRCC) patients, has significant adverse side effects and no method is available to predict which patients will not respond. Our purpose was to explore the possibility of introducing an effective prediction method based on a marker of the tumour vasculature, the follicle stimulating hormone receptor (FSHR). Fifty patients diagnosed with advanced metastatic CCRCC have been subjected to surgery for removal of the primary tumour and were subsequently treated with sunitinib. After three months of therapy the patients were categorized as 'responsive', 'stable' or 'non-responsive' based on the RECIST guidelines. The blood vessel density and the percentage of FSHR-positive vessels were determined by immunofluorescence on sections from the primary tumours removed by surgery, prior to the sunitinib treatment. The percentage of FSHR-stained vessels was on average fivefold higher for the patients who responded to the treatment in comparison with the stable group and almost eightfold higher than in the non-responsive group. The percentage allowed the detection of responders with 87-100% sensitivity and specificity. No significant differences were detected in the total density of vessels among the three groups. The data suggest that FSHR expression levels in the blood vessels of CCRCC primary tumours can be used to predict, with high sensitivity and specificity, the patients who will respond to sunitinib therapy.

Interleukin-1β mediates metalloproteinase-dependent renal cell carcinoma tumor cell invasion through the activation of CCAAT enhancer binding protein β

Effective treatment of metastatic renal cell carcinoma (RCC) remains a major medical concern, as these tumors are refractory to standard therapies and prognosis is poor. Although molecularly targeted therapies have shown some promise in the treatment of this disease, advanced RCC tumors often develop resistance to these drugs. Dissecting the molecular mechanisms underlying the progression to advanced disease is necessary to design alternative and improved treatment strategies. Tumor-associated macrophages (TAMs) found in aggressive RCC tumors produce a variety of inflammatory cytokines, including interleukin-1β (IL-1β). Moreover, the presence of TAMs and high serum levels of IL-1β in RCC patients correlate with advanced disease. We hypothesized that IL-1β in the tumor microenvironment promotes the development of aggressive RCC tumors by directing affecting tumor epithelial cells. To address this, we investigated the role of IL-1β in mediating RCC tumor cell invasion as a measure of tumor progression. We report that IL-1β induced tumor cell invasion of RCC cells through a process that was dependent on the activity of matrix metalloproteinases (MMPs) and was independent of migration rate. Specifically, IL-1β induced the expression of MMP-1, MMP-3, MMP-10, and MT1-MMP in a mechanism dependent on IL-1β activation of the transcription factor CCAAT enhancer binding protein β (CEBPβ). Consistent with its role in MMP gene expression, CEBPβ knockdown significantly reduced invasion, but not migration, of RCC tumor cells. These results identify the IL-1β /CEBPβ/MMP pathway as a putative target in the design of anti-metastatic therapies for the treatment of advanced RCC.

Targeted therapeutic strategies for the management of renal cell carcinoma

PURPOSE OF REVIEW

This article reviews recent developments in the use of systemic targeted therapies for the treatment of advanced clear and nonclear cell renal cell carcinoma (RCC). The genetic/molecular basis of each form of RCC is discussed and current treatments and clinical trials are described.

RECENT FINDINGS

The treatment of advanced RCC continues to be a major challenge for uro-oncologists. The rapid growth in therapeutic options has brought much needed improvements in overall and progression-free survival, although durable complete responses remain elusive. The recent identification of mutations in genes involved in chromatin remodeling will likely lead to the investigation of whether components of this critical process can also be valid therapeutic targets in clear cell RCC. Similarly, efforts to decipher the molecular mechanisms underlying nonclear cell variants of RCC are beginning to engender novel therapeutic strategies directed against these rarer forms of kidney cancer. Despite the availability of multiple treatment options, several challenges remain: selecting the best first-line or subsequent therapy for a given patient, the optimal sequencing of the various agents available, designing trials with appropriate comparison arms and endpoints, and identifying well tolerated and effective drug combinations.

SUMMARY

Agents targeting the vascular endothelial growth factor and mammalian target of rapamycin pathways remain the mainstay in the management of metastatic RCC. Ongoing and future studies are expected to facilitate the development of therapeutic regimens that incorporate agents with improved tolerability and enhanced efficacy by continuing to capitalize on the strides made by basic and translational scientists in uncovering the mechanisms underlying the various forms of RCC.

Current status of targeted therapy for advanced renal cell carcinoma

The treatment of metastatic renal cell carcinoma (mRCC) has recently evolved from being predominantly cytokine-based treatment to the use of targeted agents, which include sorafenib, sunitinib, bevacizumab (plus interferon alpha [IFN-α]), temsirolimus, everolimus, pazopanib, and most recently, axitinib. Improved understanding of the molecular pathways implicated in the pathogenesis of RCC has led to the development of specific targeted therapies for treating the disease. In Korea, it has been 5 years since targeted therapy became available for mRCC. Thus, we now have broader and better therapeutic options at hand, leading to a significantly improved prognosis for patients with mRCC. However, the treatment of mRCC remains a challenge and a major health problem. Many questions remain on the efficacy of combination treatments and on the best methods for achieving complete remission. Additional studies are needed to optimize the use of these agents by identifying those patients who would most benefit and by elucidating the best means of delivering these agents, either in combination or as sequential single agents. Furthermore, numerous ongoing research activities aim at improving the benefits of the new compounds in the metastatic situation or their application in the early phase of the disease. This review introduces what is currently known regarding the fundamental biology that underlies clear cell RCC, summarizes the clinical evidence supporting the benefits of targeted agents in mRCC treatment, discusses survival endpoints used in pivotal clinical trials, and outlines future research directions.

Familial renal cancer: molecular genetics and surgical management

Familial renal cancer (FRC) is a heterogeneous disorder comprised of a variety of subtypes. Each subtype is known to have unique histologic features, genetic alterations, and response to therapy. Through the study of families affected by hereditary forms of kidney cancer, insights into the genetic basis of this disease have been identified. This has resulted in the elucidation of a number of kidney cancer gene pathways. Study of these pathways has led to the development of novel targeted molecular treatments for patients affected by systemic disease. As a result, the treatments for families affected by von Hippel-Lindau (VHL), hereditary papillary renal carcinoma (HPRC), hereditary leiomyomatosis renal cell carcinoma (HLRCC), and Birt-Hogg-Dubé (BHD) are rapidly changing. We review the genetics and contemporary surgical management of familial forms of kidney cancer.