Kinase targets in renal-cell carcinomas: reassessing the old and discovering the new

Potential new therapy of Rapalink-1, a new generation mammalian target of rapamycin inhibitor, against sunitinib-resistant renal cell carcinoma

Sunitinib, a multitargeted receptor tyrosine kinase inhibitor including vascular endothelial growth factor, has been widely used as a first-line treatment against metastatic renal cell carcinoma (mRCC). However, mRCC often acquires resistance to sunitinib, rendering it difficult to treat with this agent. Recently, Rapalink-1, a drug that links rapamycin and the mTOR kinase inhibitor MLN0128, has been developed with excellent therapeutic effects against breast cancer cells carrying mTOR resistance mutations. The aim of the present study was to evaluate the in vitro and in vivo therapeutic efficacy of Rapalink-1 against renal cell carcinoma (RCC) compared to temsirolimus, which is commonly used as a small molecule inhibitor of mTOR and is a derivative of rapamycin. In comparison with temsirolimus, Rapalink-1 showed significantly greater effects against proliferation, migration, invasion and cFolony formation in sunitinib-naïve RCC cells. Inhibition was achieved through suppression of the phosphorylation of substrates in the mTOR signal pathway, such as p70S6K, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and AKT. In addition, Rapalink-1 had greater tumor suppressive effects than temsirolimus against the sunitinib-resistant 786-o cell line (SU-R 786-o), which we had previously established, as well as 3 additional SU-R cell lines established here. RNA sequencing showed that Rapalink-1 suppressed not only the mTOR signaling pathway but also a part of the MAPK signaling pathway, the ErbB signaling pathway and ABC transporters that were associated with resistance to several drugs. Our study suggests the possibility of a new treatment option for patients with RCC that is either sunitinib-sensitive or sunitinib-resistant.

Prognostic Value of SETD2 Expression in Patients with Metastatic Renal Cell Carcinoma Treated with Tyrosine Kinase Inhibitors

PURPOSE

Mutations of SETD2 occur in 3% to 16% of clear cell renal cell carcinoma cases. Previous studies identified an association between SETD2 mutation and prognosis of patients with nonmetastatic clear cell renal cell carcinoma. In this study we explored the prognostic and predictive value of SETD2 expression in patients with metastatic renal cell carcinoma treated with targeted therapy.

MATERIALS AND METHODS

We retrospectively enrolled 138 patients with metastatic renal cell carcinoma treated with sunitinib or sorafenib at a single institution from 2007 to 2014. SETD2 expression was assessed by immunohistochemistry on tissue microarrays.

RESULTS

After excluding those patients with loss of followup or unavailable tissue samples, 111 were included in the study. Low SETD2 expression was associated with reduced overall survival (p <0.001) and progression-free survival (p=0.001). After adjustment for histological type, Heng risk group and drugs used for targeted therapy, SETD2 was defined as an independent prognostic marker for overall survival (HR 2.535 [95% CI 1.429-4.497], p=0.001) and progression-free survival (HR 1.755 [95% CI 1.031-2.988], p=0.038). Its prognostic value for overall survival was more predominant in patients with clear cell renal cell carcinoma (p <0.001) or patients in the intermediate risk group of Heng risk criteria (p <0.001), while its predictive value for progression-free survival was more predominant in patients treated with sorafenib (p <0.001). SETD2 could also be combined with the Heng risk model for better overall survival prediction.

CONCLUSIONS

SETD2 is a potential prognostic biomarker for overall survival and progression-free survival prediction in patients with metastatic renal cell carcinoma receiving targeted therapy. However, it remains to be seen whether this is generalizable to other ethnicities and prospective external validation is required.

Decreased Expression of SETD2 Predicts Unfavorable Prognosis in Patients With Nonmetastatic Clear-Cell Renal Cell Carcinoma

DNA sequencing revealed that mutations in SETD2 occur in 3% to 12% of clear-cell renal cell carcinoma (ccRCC) cases and are associated with poor clinical outcome. In this study, we used an immunohistochemistry (IHC) assay to evaluate the impact of SETD2 loss, with expression of H3K36me3, a nonredundantly histone modification by SETD2, on recurrence and survival of nonmetastatic ccRCC patients after nephrectomy.SETD2 and H3K36me3 were assessed in 192 nonmetastatic ccRCC patients enrolled retrospectively from a single institution. Kaplan-Meier and Cox regression analysis were used to associate prespecified SETD2/H3K36me3 score with overall survival (OS) and recurrence-free survival (RFS). And a nomogram was constructed to predict OS at 10 years.Patients with low expression of SETD2 were prone to possess large tumor size and advanced pT stage. And low H3K36me3 expression was associated with larger tumor size. A prespecified combined score based on SETD2 and H3K36me3 expression remained an independent prognosticator for OS and RFS, which was associated with tumor size, pT stage, and sarcomatoid. Furthermore, using prespecified SETD2/H3K36me3 score could stratify nonmetastatic ccRCC patients into different risk subgroups, especially in patients dichotomized by pT stage and Fuhrman grade, respectively. Finally, the C-index for predicting OS increased from 0.727 to 0.747, after adding SETD2/H3K36me3 score to pT stage and Fuhrman grade.The combined score based on expression of SETD2 and H3K36me3 using IHC could predict poor clinical outcomes in nonmetastatic ccRCC patients, and it may benefit preoperative risk stratification and guide treatment planning in the future.

GALNT4 predicts clinical outcome in patients with clear cell renal cell carcinoma

PURPOSE

We investigated the clinical significance of GALNT4 expression in patients with clear cell renal cell carcinoma.

MATERIALS AND METHODS

Enrolled in this study were 104 patients treated with curative nephrectomy at Zhongshan Hospital, Shanghai during 2004. Of the cohort 23 patients died of disease, 33 experienced recurrence and 3 died of another cause. GALNT4 density was assessed by immunohistochemistry in patient specimens. Univariate and multivariate Cox models, and ROC analysis were used to analyze the impact of prognostic factors on overall and relapse-free survival. Kaplan-Meier analysis with the log rank test was done to compare clinical outcomes between subgroups.

RESULTS

Intratumor GALNT4 expression was significantly lower than peritumor expression. Low GALNT4 expression was associated with poor overall and relapse-free survival (p = 0.001 and 0.004, respectively). Intratumor GALNT4 expression, which negatively correlated with tumor size (p = 0.032), necrosis (p = 0.013) and TNM stage (p = 0.017), was an independent prognostic indicator for overall and relapse-free survival (HR 3.088, p = 0.020 and 2.173, p = 0.047, respectively). Extending the TNM staging system according to GALNT4 expression showed a better prognostic value for overall and relapse-free survival (AUC 0.786, p = 0.029 and 0.761, p = 0.040, respectively).

CONCLUSIONS

Intratumor GALNT4 expression is a potential independent prognostic factor for overall and relapse-free survival in patients with clear cell renal cell carcinoma. Further external validation and functional analysis should be performed to assess its potential prognostic and therapeutic value in patients with clear cell renal cell carcinoma.

The relationship of kinase insert domain receptor gene polymorphisms and clinical outcome in advanced hepatocellular carcinoma patients treated with sorafenib

Kinase insert domain receptor (KDR) is the principal receptor that promotes the pro-angiogenic action of vascular endothelial growth factor and has been the principal target of anti-angiogenic therapies. Our aim was to determine whether single-nucleotide polymorphisms (SNPs) in KDR gene are associated with clinical outcomes after first-line sorafenib therapy in advanced hepatocellular carcinoma (HCC). The SNPs in KDR were tested in 78 advanced HCC patients receiving first-line sorafenib. Correlations with clinicopathological features and survival were analyzed. Patients with AA genotype of rs1870377 and AA genotype of rs2305948 were significantly associated with a better response and longer time to progression (TTP) (5.8 vs 4.0 months, P=0.001; 5.8 vs 4.5 months, P=0.016, respectively). Patients harboring AA genotype in rs1870377 and TT/TC genotype in rs2071559 had a longer overall survival (OS) (15.0 vs 9.6 months, P=0.001; 13.0 vs 9.0 months, P=0.007, respectively). At multivariate analysis, major vascular invasion and rs1870377 were independent factors in TTP and performance status, rs1870377, and rs2071559 were independent factors in OS. Our results suggest that SNPs in KDR gene can predict clinical outcome in advanced HCC patients receiving first-line sorafenib.

Total synthesis of (+/-)-4-demethylenglerin A

Racemic 4-demethylenglerin A (1'), a simplified analog of the guaiane-type sesquiterpene englerin A (1), has been synthesized. The cyclic hydrocarbon core structure was built through modified Metz approach using epoxynitrile cyclization and direct Aldol reaction to prepare the precursor of RCM. The primary cytotoxicity test summarized that C4 methyl has marked impacts on the bioactivity.

RASSF6 promotes p21(Cip1/Waf1)-dependent cell cycle arrest and apoptosis through activation of the JNK/SAPK pathway in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a highly aggressive and common pathological subtype of renal cancer. This cancer is characterized by biallelic inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene, which leads to the accumulation of hypoxia-inducible factors (HIFs). Although therapies targeted at HIFs can significantly improve survival, nearly all patients with advanced ccRCC eventually succumb to the disease. Thus, additional oncogenic events are thought to be involved in the development of ccRCC tumors. In this study, we investigated the role of RASSF6 in ccRCC. Downregulation of RASSF6 was commonly observed in primary tumors relative to matched adjacent normal tissues. Moreover, functional studies established that ectopic re-expression of RASSF6 in ccRCC cells inhibited cell proliferation, clonogenicity, and tumor growth in mice, whereas silencing of RASSF6 dramatically enhanced cell proliferation in vitro and in vivo. Mechanistic investigation suggested that RASSF6 triggers p21(Cip1/Waf1) accumulation to induce G 1 cell cycle arrest and promote apoptosis upon exposure to pro-apoptotic agents, and both of these mechanisms appear to be mediated by activated JNK signaling. Together, these findings suggest that RASSF6 may play a tumor suppressor role in the progression of ccRCC.

Prognostic value of EZH2 expression and activity in renal cell carcinoma: a prospective study

Increased expression of EZH2 correlates with aggressive clinical behavior in various malignancies. In this study, we aim to investigate the clinical and prognostic values of EZH2 expression and activity in tumor tissues and improve the risk stratification in patients with renal cell carcinoma after surgery. We analyzed EZH2 expression and its activity as indicated by H3K27me3 levels comprising 373 patients with renal cell carcinoma in our institute. Outcome was assessed as overall survival and disease free survival using Kaplan-Meier analysis. Prognostic values of EZH2 and H3K27me3 expression for clinical outcomes were evaluated by Cox regression analysis. We used receiver operating characteristic to calculate diagnostic accuracy. High EZH2 expression correlates with poor overall survival in all patients, especially in advanced RCC, which is an independent prognostic factor in disease free survival and overall survival. Compared with EZH2, H3K27me3 expression is not an independent prognostic factor. The expressions of H3K27me3 and EZH2 are not completely consistent, which might be due to complicated interaction of Polycomb Repressor Complex 2. A combination of EZH2 expression and TNM stage could have better prognostic value than do TNM stage or EZH2 expression alone in both sets for disease free survival and overall survival. These results imply that evaluating intratumoral EZH2 density might improve prognostic value to the TNM staging system and inform treatment decisions for patients with late-stage renal cell carcinoma.

PKCα is involved in the progression of kidney carcinoma through regulating netrin-1/UNC5B signaling pathway

With a special interest towards a better understanding of signal pathways, we attempted to discover a safer and more effective therapeutic strategy for kidney carcinoma. Recent studies had suggested a role mediated by PKCα for netrin-1 and its receptors in the initiation and progression of tumors. Real-time PCR and western blotting were used to determine the expression levels of netrin-1 and UNC5B. We made use of the agonist of PKCα (phorbol-12-myristate 13-acetate-PMA) and the inhibitor of PKCα (calphostin C) to treat renal cell carcinoma (RCC) cells, and MTT assays were used to measure cell proliferation. By immunofluorescence, we identified the localization of netrin-1 and UNC5B in RCC cell lines 769-P and ACHN. The expression of UNC5B in tumor tissues was significantly downregulated compared to the corresponding normal tissues in which netrin-1 was upregulated. In low grade tumors, UNC5B expression was more prominent while netrin-1 expression was the opposite when compared with high grade ones. Proliferation of ACHN cells was concentration dependent in the presence of PMA and calphostin C. Netrin-1 and UNC5B expressions were upregulated in cells treated with PMA while calphostin C reversed this upregulation. By immunofluorescence, we identified that netrin-1 was highly expressed in the nuclear but none of UNC5B. Our data highly suggested that PMA-induced upregulation and calphostin C-induced reversion of netrin-1 and UNC5B in kidney carcinoma were accompanied by the activation of the netrin-1/UNC5B pathways.

A comparison of Ku0063794, a dual mTORC1 and mTORC2 inhibitor, and temsirolimus in preclinical renal cell carcinoma models

Rapamycin analogs, temsirolimus and everolimus, are approved for the treatment of advance renal cell carcinoma (RCC). Currently approved agents inhibit mechanistic target of rapamycin (mTOR) complex 1 (mTORC1). However, the mTOR kinase exists in two distinct multiprotein complexes, mTORC1 and mTORC2, and both complexes may be critical regulators of cell metabolism, growth and proliferation. Furthermore, it has been proposed that drug resistance develops due to compensatory activation of mTORC2 signaling during treatment with temsirolimus or everolimus. We evaluated Ku0063794, which is a small molecule that inhibits both mTOR complexes. Ku0063794 was compared to temsirolimus in preclinical models for renal cell carcinoma. Ku0063794 was effective in inhibiting the phosphorylation of signaling proteins downstream of both mTORC1 and mTORC2, including p70 S6K, 4E-BP1 and Akt. Ku0063794 was more effective than temsirolimus in decreasing the viability and growth of RCC cell lines, Caki-1 and 786-O, in vitro by inducing cell cycle arrest and autophagy, but not apoptosis. However, in a xenograft model there was no difference in the inhibition of tumor growth by Ku0063794 or temsirolimus. A potential explanation is that temsirolimus has additional effects on the tumor microenvironment. Consistent with this possibility, temsirolimus, but not Ku0063794, decreased tumor angiogenesis in vivo, and decreased the viability of HUVEC (Human Umbilical Vein Endothelial Cells) cells in vitro at pharmacologically relevant concentrations. Furthermore, expression levels of VEGF and PDGF were lower in Caki-1 and 786-O cells treated with temsirolimus than cells treated with Ku0063794.

Clinical application of development of nonantibiotic macrolides that correct inflammation-driven immune dysfunction in inflammatory skin diseases

BACKGROUND

Inflammation-driven immune dysfunction supports the development of several chronic human disorders including skin diseases. Nonantibiotic macrolides have anti-inflammatory and/or immunomodulatory activity that suggests the exploitation of these in the treatment of skin diseases characterized by inflammatory disorders.

MATERIALS AND METHODS

We performed an extensive review of the nonantibiotic macrolide literature published between 2005 and 2012, including cross-references of any retrieved articles. We also included some data from our own experience.

RESULTS

Calcineurin antagonists such as tacrolimus and ascomycins (e.g., pimecrolimus) act by inhibiting the activation of the nuclear factor for activated T cells (NFAT). There are new applications for these macrolides that have been available for several years and have been applied to skin and hair disorders such as atopic dermatitis, oral lichen planus, vitiligo, chronic autoimmune urticaria, rosacea, alopecia areata, pyoderma gangrenosum, Behcet's disease, neutrophilic dermatosis, and lupus erythematosus. We also reviewed new macrolides, like rapamycin, everolimus, and temsirolimus. In addition to the literature review, we report a novel class of nonantibiotic 14-member macrocycle with anti-inflammatory and immunomodulatory effects.

CONCLUSIONS

This paper summarizes the most important clinical studies and case reports dealing with the potential benefits of nonantibiotic macrolides which have opened new avenues in the development of anti-inflammatory strategies in the treatment of cutaneous disorders.

Constitutional genetic variants as predictors of antiangiogenic therapy outcome in renal cell carcinoma

The development of specific angiogenesis inhibitors has drastically improved renal cancer treatment in recent years. Currently, four VEGF receptor inhibitors (sorafenib, sunitinib, pazopanib and axitinib), one anti-VEGF monoclonal antibody (bevacizumab) and two inhibitors of the mTOR pathway (temsirolimus and everolimus) have been approved to treat renal cell carcinoma (RCC), and several other molecules are under investigation. However, lack of response to antiangiogenic drugs and adverse drug reactions leading to treatment suspension are critical clinical problems that need to be solved. Because antiangiogenic drugs act on nonmalignant endothelial cells, the genetic background of the patient may play a crucial role determining the efficacy of these drugs. This article focuses on the identification of polymorphisms associated with antiangiogenic drugs outcome in RCC patients. It reviews and summarizes our current knowledge on this area and discusses future strategies to identify new biomarkers that could be used to personalize RCC management.

VEGF pathway genetic variants as biomarkers of treatment outcome with bevacizumab: an analysis of data from the AViTA and AVOREN randomised trials

BACKGROUND

No biomarkers that could guide patient selection for treatment with the anti-VEGF monoclonal antibody bevacizumab have been identified. We assessed whether genetic variants in the VEGF pathway could act as biomarkers for bevacizumab treatment outcome.

METHODS

We investigated DNA from white patients from two phase 3 randomised studies. In AViTA, patients with metastatic pancreatic adenocarcinoma were randomly assigned to receive gemcitabine and erlotinib plus either bevacizumab or placebo. In AVOREN, patients with metastatic renal-cell carcinoma were randomly assigned to receive interferon alfa-2a plus either bevacizumab or placebo. We assessed the correlation of 138 SNPs in the VEGF pathway with progression-free survival and overall survival in a subpopulation of patients from AViTA. Significant findings were confirmed in a subpopulation of patients from AVOREN and functionally studied at the molecular level.

FINDINGS

We investigated DNA of 154 patients from AViTA, of whom 77 received bevacizumab, and 110 patients from AVOREN, of whom 59 received bevacizumab. Only rs9582036, a SNP in VEGF receptor 1 (VEGFR1 or FLT1), was significantly associated with overall survival in the bevacizumab group of AViTA after correction for multiplicity (per-allele hazard ratio [HR] 2·1, 95% CI 1·45-3·06, p=0·00014). This SNP was also associated with progression-free survival (per-allele HR 1·89, 1·31-2·71, p=0·00081) in bevacizumab-treated patients from AViTA. AC and CC carriers of this SNP exhibited HRs for overall survival of 2·0 (1·19-3·36; p=0·0091) and 4·72 (2·08-10·68; p=0·0002) relative to AA carriers. No effects were seen in placebo-treated patients and a significant genotype by treatment interaction (p=0·041) was recorded, indicating that the VEGFR1 locus containing this SNP serves as a predictive marker for bevacizumab treatment outcome in AViTA. Fine-mapping experiments of this locus identified rs7993418, a synonymous SNP affecting tyrosine 1213 in the VEGFR1 tyrosine-kinase domain, as the functional variant underlying the association. This SNP causes a shift in codon usage, leading to increased VEGFR1 expression and downstream VEGFR1 signalling. This VEGFR1 locus correlated significantly with progression-free survival (HR 1·81, 1·08-3·05; p=0·033) but not overall survival (HR 0·91, 0·45-1·82, p=0·78) in the bevacizumab group in AVOREN.

INTERPRETATION

A locus in VEGFR1 correlates with increased VEGFR1 expression and poor outcome of bevacizumab treatment. Prospective assessment is underway to validate the predictive value of this novel biomarker.

FUNDING

F Hoffmann-La Roche.

New Perspectives in Advanced Genitourinary Malignancies

The management of advanced genitourinary malignancies has undergone a major transformation with the advent of novel drugs and targeted therapies in recent years. Assessment of the treatment risks and benefits is required for each patient and therefore better knowledge of the different clinical and molecular aspects of these diseases is warranted. The results of further studies and biomarker validations are expected to provide more treatment options and improve outcomes in the future management of genitourinary malignancies.

A review on various targeted anticancer therapies

Translational oncology aims to translate laboratory research into new anticancer therapies. Contrary to conventional surgery, chemotherapy, and radiotherapy, targeted anticancer therapy (TAT) refers to systemic administration of drugs with particular mechanisms that specifically act on well-defined targets or biologic pathways that, when activated or inactivated, may cause regression or destruction of the malignant process, meanwhile with minimized adverse effects on healthy tissues. In this article, we intend to first give a brief review on various known TAT approaches that are deemed promising for clinical applications in the current trend of personalized medicine, and then we will introduce our newly developed approach namely small molecular sequential dual targeting theragnostic strategy as a generalized class of TAT for the management of most solid malignancies, which, after optimization, is expected to help improve overall cancer treatability and curability.

Chronic inflammation and immunologic-based constraints in malignant disease

Acute inflammatory reactions benefit the host by supporting the effective clearance of pathogens and fostering wound healing, in addition to other self-preservative processes. However, when the inflammatory program is not resolved, becoming chronic in nature, it creates an environment conducive to cancer development and progression. Therefore, minimizing exposure to risk factors that contribute to chronic inflammation and reconditioning the host towards a state of (at least locoregional) acute inflammation would meaningfully impact cancer incidence and its treatment, respectively. Regarding cancer therapy, combinational treatments that both disrupt chronic inflammation and install specific adaptive type I immunity are predicted to enhance quality of life and extend the overall survival of patients.

Patients rank toxicity against progression free survival in second-line treatment of advanced renal cell carcinoma

BACKGROUND

The aims of this study were to quantify and contrast patient preferences between second-line advanced renal cell carcinoma (RCC) medication profiles and their associated benefits and toxicities, and to help frame the doctor-patient discussion about selecting appropriate RCC therapies.

RESEARCH DESIGN AND METHODS

Adult residents of the US with a diagnosis of RCC completed a Web-enabled choice-format conjoint survey consisting of a series of 10 treatment-choice questions, each of which included a pair of hypothetical RCC medication profiles. Each profile was described by various medication attributes (features or outcomes) with varying levels. The attributes included efficacy (progression-free survival [PFS]), tolerability (fatigue, stomach problems, mucositis or stomatitis, hand-foot syndrome [HFS]), serious but rare adverse events (pneumonitis, hepatic impairment), and mode of administration. Treatment-choice questions were based on an experimental design with known statistical properties. Random-parameters logit regression was used to estimate relative preference weights for each attribute level. Benefit equivalent measures (additional months of PFS in exchange for toxicities) were also calculated.

RESULTS

Of the 272 patients who completed the survey, the majority were female (53%), white (92%), and had at least a college degree (66%). The mean age was 57 years (standard deviation: 10 years). Over the range of attributes and attribute levels included in the survey, PFS was the most important attribute, followed by fatigue, stomach problems, hepatic impairment, mucositis or stomatitis, HFS, pneumonitis, and mode of administration. To reduce severe fatigue to mild-to-moderate fatigue, patients on average would be willing to forego 4.4 months of PFS. To reduce hepatic impairment risk from 0.5% to 0.0%, patients on average would be willing to forego 1.0 month of PFS. The main study limitation was that patients answered hypothetical treatment-choice questions.

CONCLUSIONS

This study provides information to physicians about patient priorities when reviewing and selecting RCC therapies with patients.

[The pathologist's role in the neoadjuvant strategy of renal-cell carcinoma]

The medical treatment of renal-cell carcinoma, and of its most frequent histologic subtype, the clear cell renal-cell carcinoma, has been changed by the emergence of targeted therapies. The development of these drugs has been made possible by more precise knowledge of molecular mechanisms involved in the carcinogenesis of these tumors. Three molecular pathways may be involved in clear cell renal-cell carcinoma: VHL/HIF/VEGF, PI3K/AKT/mTOR and MAPKinases pathways. These antiangiogenic therapies are approved for the treatment of advanced and metastatic clear cell renal-cell carcinoma. In metastatic disease, pathologists have significant and different implications: 1) in tumor biopsy, only the diagnosis of clear cell renal-cell carcinoma implies the prescription of antiangiogenic drugs, and 2) after targeted therapies, pathologists must evaluate the therapeutic effects on tumor. Consensus on macroscopic and histologic reports are needed by pathologists.

Combined gene expression profiling and RNAi screening in clear cell renal cell carcinoma identify PLK1 and other therapeutic kinase targets

In recent years, several molecularly targeted therapies have been approved for clear cell renal cell carcinoma (ccRCC), a highly aggressive cancer. Although these therapies significantly extend overall survival, nearly all patients with advanced ccRCC eventually succumb to the disease. To identify other molecular targets, we profiled gene expression in 90 ccRCC patient specimens for which tumor grade information was available. Gene set enrichment analysis indicated that cell-cycle-related genes, in particular, Polo-like kinase 1 (PLK1), were associated with disease aggressiveness. We also carried out RNAi screening to identify kinases and phosphatases that when inhibited could prevent cell proliferation. As expected, RNAi-mediated knockdown of PLK1 and other cell-cycle kinases was sufficient to suppress ccRCC cell proliferation. The association of PLK1 in both disease aggression and in vitro growth prompted us to examine the effects of a small-molecule inhibitor of PLK1, BI 2536, in ccRCC cell lines. BI 2536 inhibited the proliferation of ccRCC cell lines at concentrations required to inhibit PLK1 kinase activity, and sustained inhibition of PLK1 by BI 2536 led to dramatic regression of ccRCC xenograft tumors in vivo. Taken together, these findings highlight PLK1 as a rational therapeutic target for ccRCC.

MicroRNAs as regulators of signal transduction in urological tumors

BACKGROUND

MicroRNAs (miRNAs) are short noncoding RNAs that have been shown to play pivotal roles in carcinogenesis. In the past decade, miRNAs have been the focus of much research in oncology, and there are great expectations for their utility as cancer biomarkers and therapeutic targets.

CONTENT

In this review we examine how miRNAs can regulate signal transduction pathways in urological tumors. We performed in silico target prediction using TargetScan 5.1 to identify the signal transduction targets of miRNA, and we summarize the experimental evidence detailing miRNA regulation of pathways analyzed herein.

SUMMARY

miRNAs, which have been shown to be dysregulated in bladder, prostate, and renal cell cancer, are predicted to target key proteins in signal transduction. Because androgen receptor signaling is a major regulator of prostate cancer growth, its regulation by miRNAs has been well described. In addition, members of the phosphatidylinositol 3-kinase/Akt (RAC-alpha serine/threonine-protein kinase) signaling pathway have been shown to be susceptible to miRNA regulation. In contrast, there are very few studies on the impact of miRNA regulation on signaling by VHL (von Hippel-Lindau tumor suppressor) and vascular endothelial growth factor in renal cell carcinoma or by fibroblast growth factor receptor 3 and p53 in bladder cancer. Many miRNAs are predicted to target important signaling pathways in urological tumors and are dysregulated in their respective cancer types; a systematic overview of miRNA regulation of signal transduction in urological tumors is pending. The identification of these regulatory networks might lead to novel targeted cancer therapies. In general, the targeting of miRNAs is a valuable approach to cancer therapy, as has been shown recently for various types of cancer.

Impact of genetics on the diagnosis and treatment of renal cancer

Kidney cancer is a heterogeneous disease comprised of a number of histologic subtypes, each associated with unique genetic mutations, clinical features, and sensitivity to treatment. By examining families affected with the hereditary kidney cancer syndromes von Hippel-Lindau, hereditary papillary renal cell carcinoma, hereditary leiomyomatosis and renal cell carcinoma, and Birt-Hogg-Dubé, researchers have been able to identify the genes responsible for these syndromes. This work has revealed that kidney cancer is fundamentally a metabolic disorder, and as such, novel targeted therapies specific to their molecular biology have been developed and employed in both the hereditary and sporadic forms of renal cell carcinoma.

Targeted therapies for non-clear renal cell carcinoma

The treatment of advanced and metastatic kidney cancer has been revolutionized by the development of targeted systemic therapies. Despite the growing number of available agents approved for use against clear cell renal cell carcinoma, patients with non-clear histologies, constituting approximately 1 in 4 cases of kidney cancer, have not received the same attention. The majority of clinical trials testing novel targeted therapies have excluded non-clear subtypes, providing limited therapeutic options for patients with these diagnoses and their oncologists. This review will focus on the use of targeted therapies against the non-clear histologic subtypes of renal cell carcinoma: papillary I and II, chromophobe, and collecting duct. The unique genetic and molecular profiles of each distinct non-clear kidney cancer subtype will be described, as these differences are integral to the development and effectiveness of the novel agents used to treat them. Trials focusing on non-clear kidney cancer, or those that treated clear cell tumors along with significant numbers of non-clear subtypes, will be discussed. The role of cytoreductive nephrectomy and the use of neoadjuvant and adjuvant targeted therapy will be reviewed. Lastly, areas of future research will be highlighted.

Targeted therapy for advanced renal cell carcinoma

BACKGROUND

Advanced renal cell carcinoma has been resistant to drug therapy of different types and new types of drug therapy are needed. Targeted agents inhibit known molecular pathways involved in cellular proliferation and neoangiogenesis, the induction by the tumour of host microvascular networks. Angiogenesis is of special interest in the clear cell histologic subtype of renal cancer because of its vascularity and constitutively activated hypoxia-inducible path in the majority of tumours.

OBJECTIVES

1) To provide a systematic review of studies testing targeted agents.2) To identify the type and degree of clinical benefit, if any, of targeted agents over the prior standard of care, particularly any impact on overall survival.

SEARCH STRATEGY

1) Electronic search of CENTRAL, MEDLINE and EMBASE databases.2) Hand search of international cancer meeting abstract and other sources specified in the protocol.

SELECTION CRITERIA

Randomized controlled studies of targeted agents in patients with advanced renal cell cancer reporting major remission rate or overall survival by allocation. Progression-free survival (PFS) was adopted as an additional outcome because PFS was a commonly chosen primary outcome, and because several pivotal studies allowed crossover from the control to the investigational arm after closure to accrual thereby making overall survival a problematic endpoint.

DATA COLLECTION AND ANALYSIS

Nineteen fully eligible studies tested ten different targeted agents (Table 04). One additional study was excluded because no outcome data by allocation have been reported (Hutson 2007). For purposes of comparison, the studies were divided into three groups: Group 1 studies compared different doses of the same agents; Group 2 studies examined the impact of targeted agents in patients who had received prior cytokine or other systemic therapy; and Group 3 studies tested targeted agents in systemically naive patients, either against standard interferon-alfa or against another control therapy. Meta-analysis was not utilized because there were very few situations where the same agents had been tested in the same group in more than one study.

MAIN RESULTS

In systemically untreated patients in studies using subcutaneous interferon-alfa as control therapy, the major findings were: 1) An improvement in overall survival has been demonstrated only with the use of weekly intravenous temsirolimus in patients with unselected renal cancer histology and adverse prognostic features (median survival 10.9 months versus 7.3 months for temsirolimus or interferon-alfa respectively, HR 0.73, P = 0.008 log rank, Hudes 2007). However, the chance of major remission was low and not improved with temsirolimus. 2) In patients with mostly good or intermediate prognostic risk with clear cell renal cancer, oral sunitinib improves the chance of major remission, the probability of symptomatic improvement, and freedom from disease progression (Motzer 2007); in a similar setting, the addition of biweekly intravenous bevacizumab to interferon-alfa also improved the chance of major remission and prolonged progression-free survival (Escudier 2007b); overall survival had not changed at the time of interim reporting of either study. In patients with clear cell renal cancers who had failed prior cytokine therapy, oral sorafenib gives a better quality of life than placebo as well as improved chance of being free of disease progression; overall survival may have improved but is hard to evaluate because of crossover of placebo-assigned patients after the study closed to accrual (Escudier 2007a).

AUTHORS' CONCLUSIONS

Based on less than a decade of experience, some targeted agents with specified molecular targets have demonstrated clinically useful benefits over the previous standard of care for patients with advanced renal cancer. Much more research is required to fully establish the role of targeted agents in this condition.