Renal Cell Carcinoma Therapeutics Research Articles

Immunotherapy Applications for Thymine Dimers and WT1 Antigen in Renal Cancers: A Comparative Statistical Analysis.

Renal cell carcinoma (RCC) remains incurable in advanced stages. Biomarkers have proven to be quite useful in cancer therapeutics. Herein, we provide a comparative/integrative statistical analysis of seminal immunohistochemistry (IHC) findings for Wilms' Tumor 1 antigen (WT1) and thymine dimers (TDs), emerging as atypical, yet promising, potential biomarkers for RCCs. We assessed WT1/TD reactivity in adult RCC tumor cells, tumor microenvironment (TME), and tumor-adjacent healthy renal tissue (HRT). WT1 positivity was scarce and strictly nuclear in tumor cells, whereas TD-reactive tumor tissues were prevalent. We report statistically significant positive correlations between the density of reactive RCC cellularity and the intensity of nuclear staining for both biomarkers (WT1 - rho = 0.341, p-value = 0.036; TDs - rho = 0.379, p-value = 0.002). RCC stromal TME TD-positivity was much more frequent than WT1 reactivity, apparently proportional to that of the proper RCC cellularity and facilitated by extensive RCC inflammatory infiltration. TDs exhibited nuclear reactivity for most TME cell lines, while RCC TME WT1 expression was rare and inconsistent. In HRTs, TDs were entirely restricted to renal tubular cells, the likely cellular progenitor of most conventional RCC subtypes. In lieu of proper validation, these early findings have significant implications regarding the origins/biology of RCCs and may inform RCC therapeutics, both accounting for the high frequency of immunotherapy-permissive frameshift indels in RCCs, but also hinting at novel predictive clinical tools for WT1-targeted immunotherapy. Overall, the current study represents a meek yet hopefully significant step towards understanding the molecular biology and potential therapeutic targets of RCCs.

Biomarkers in renal cell carcinoma and their targeted therapies: a review.

Renal cell carcinoma (RCC) is one of the most life-threatening urinary malignancies displaying poor response to radiotherapy and chemotherapy. Although in the recent past there have been tremendous advancements in using targeted therapies for RCC, despite that it remains the most lethal urogenital cancer with a 5-year survival rate of roughly 76%. Timely diagnosis is still the key to prevent the progression of RCC into metastatic stages as well as to treat it. But due to the lack of definitive and specific diagnostic biomarkers for RCC and its asymptomatic nature in its early stages, it becomes very difficult to diagnose it. Reliable and distinct molecular markers can not only refine the diagnosis but also classifies the tumors into thier sub-types which can escort subsequent management and possible treatment for patients. Potential biomarkers can permit a greater degree of stratification of patients affected by RCC and help tailor novel targeted therapies. The review summarizes the most promising epigenetic [DNA methylation, microRNA (miRNA; miR), and long noncoding RNA (lncRNA)] and protein biomarkers that have been known to be specifically involved in diagnosis, cancer progression, and metastasis of RCC, thereby highlighting their utilization as non-invasive molecular markers in RCC. Also, the rationale and development of novel molecular targeted drugs and immunotherapy drugs [such as tyrosine kinase inhibitors and immune checkpoint inhibitors (ICIs)] as potential RCC therapeutics along with the proposed implication of these biomarkers in predicting response to targeted therapies will be discussed.

MiR-4284 Functions as a Tumor Suppressor in Renal Cell Carcinoma Cells by Targeting Glutamate Decarboxylase 1.

MicroRNAs (miRNAs) play a crucial role as oncogenic or tumor suppressors in the pathogenesis and progression of tumors. However, few studies have investigated the exact role of miR-4284 in renal cell carcinoma (RCC). We aimed to investigate the role of miR-4284 as a tumor suppressor in renal cancer cell lines. A498 and Caki-1 were transfected with miR-4284. The Cell Counting Kit-8, colony formation, apoptosis assays, and quantitative reverse transcription-polymerase chain reaction were used to evaluate tumor growth-inhibiting functions. The wound-healing, transwell, and sphere-formation assays were conducted to investigate tumorigenic characteristics. The potential target genes of miR-4284 were predicted and experimentally verified. A xenograft experiment was performed to estimate the tumor-growth-suppressive function of miR-4284. miR-4284 overexpression suppressed proliferation, induced apoptosis, and suppressed tumorigenic features of renal cancer cells. Glutamate decarboxylase 1 (GAD1) was directly targeted by miR-4284. A xenograft mouse model injected with Caki-1 cells transfected with miR-4284 showed significantly decreased tumor growth rate and volume. miR-4284 affected tumor growth, metastasis, and apoptosis of renal cancer cells in vitro and in vivo. These findings highlight the potential of miR-4284 as a target for anticancer miRNA therapeutics in RCC.

Adjuvant therapy options in renal cell carcinoma - targeting the metastatic cascade.

Localized renal cell carcinoma (RCC) is primarily managed with nephrectomy, which is performed with curative intent. However, disease recurs in ~20% of patients. Treatment with adjuvant therapies is used after surgery with the intention of curing additional patients by disrupting the establishment, maturation or survival of micrometastases, processes collectively referred to as the metastatic cascade. Immune checkpoint inhibitors and vascular endothelial growth factor receptor (VEGFR)-targeting tyrosine kinase inhibitors (TKIs) have shown efficacy in the treatment of metastatic RCC, increasing the interest in the utility of these agents in the adjuvant setting. Pembrolizumab, an inhibitor of the immune checkpoint PD1, is now approved by the FDA and is under review by European regulatory agencies for the adjuvant treatment of patients with localized resected clear cell RCC based on the results of the KEYNOTE-564 trial. However, the optimal use of immunotherapy and VEGFR-targeting TKIs for adjuvant treatment of RCC is not completely understood. These agents disrupt the metastatic cascade at multiple steps, providing biological rationale for further investigating the applications of these therapeutics in the adjuvant setting. Clinical trials to evaluate adjuvant therapeutics in RCC are ongoing, and clinical considerations must guide the practical use of immunotherapy and TKI agents for the adjuvant treatment of localized resected RCC.

The value measurement of emerging therapeutics in renal cell carcinoma: ASCO value framework and ESMO-MCBS

PurposeRapid development of novel therapeutics in renal cell carcinoma (RCC) has led to financial burden for patients and society. Value including clinical benefit, toxicity affecting quality of life and cost-effectiveness are a concern, prompting the need for tools to facilitate value assessment of therapeutics. This study reviews the value assessment tools, and evaluates the value of emerging therapeutics in RCC.Materials and methodsTwo medical oncologists used American Society of Clinical Oncology value framework (ASCO VF) v2.0 and European Society for Medical Oncology-magnitude of clinical benefit scale (ESMO-MCBS) v1.1 to phase 3 trials evaluating first-line therapy in patients with metastatic RCC. Follow-up (FU) reports and extended survival data were included. Equivocal aspects and limitations of the tools were discussed.ResultsSix trials (COMPARZ, CheckMate 214, JAVELIN renal 101, Keynote 426, CLEAR, and CheckMate 9ER) were assessed. The control arm was standard-of-care sunitinib in all trials. ASCO VF’s net health benefit, calculated as clinical benefit, toxicity and other bonus point was 11 in pazopanib, 41.9 in nivolumab plus ipilimumab, 22.4 in axitinib plus avelumab, 48.7 in axitinib plus pembrolizumab, 35.2 in lenvatinib plus pembrolizumab, and 50.8 in cabozantinib plus nivolumab. A higher score means a greater treatment benefit. ESMO-MCBS gave grade 5 to nivolumab plus ipilimumab, 4 to pazopanib, lenvatinib plus pembrolizumab and cabozantinib plus nivolumab, 3 to axitinib plus avelumab or pembrolizumab. Both tools had unclear aspects to be applied to clinical practice, and should be more clearly defined, such as endpoint for determining survival benefits or how to standardize quality of life and toxicity.ConclusionsASCO VF and ESMO-MCBS were applied to evaluate the newly emerging drugs in RCC and assessed their value. In-depth discussion by experts in various fields is required for appropriate clinical application in a real-world setting.

The Antidiabetic Agent Acarbose Improves Anti-PD-1 and Rapamycin Efficacy in Preclinical Renal Cancer.

Simple SummaryAlthough immune-stimulatory and targeted therapies benefit many patients with metastatic kidney cancer, a sizeable proportion of patients fail to respond. Recent studies in mice demonstrate that nutrient-limiting dietary interventions can improve responses to chemotherapy. However, these studies did not investigate effects on metastasis, and the impact of these interventions on the response to immunotherapy or targeted therapies in kidney cancer is unknown. We therefore studied the effects of a glucose-limiting drug called acarbose, which is used to treat type 2 diabetes, in a spontaneously-metastasizing mouse model of kidney cancer. We found that acarbose slowed kidney cancer growth and promoted protective immune responses. In combination with either an immunotherapy or a targeted therapy used clinically to treat kidney cancer, acarbose led to improved treatment outcomes and reduced lung metastases. Our findings contribute to the emerging idea of using nutrition-based interventions to enhance responses to cancer treatments. Although immune checkpoint inhibitors and targeted therapeutics have changed the landscape of treatment for renal cell carcinoma (RCC), most patients do not experience significant clinical benefits. Emerging preclinical studies report that nutrition-based interventions and glucose-regulating agents can improve therapeutic efficacy. However, the impact of such agents on therapeutic efficacy in metastatic kidney cancer remains unclear. Here, we examined acarbose, an alpha-glucosidase inhibitor and antidiabetic agent, in a preclinical model of metastatic kidney cancer. We found that acarbose blunted postprandial blood glucose elevations in lean, nondiabetic mice and impeded the growth of orthotopic renal tumors, an outcome that was reversed by exogenous glucose administration. Delayed renal tumor outgrowth in mice on acarbose occurred in a CD8 T cell-dependent manner. Tumors from these mice exhibited increased frequencies of CD8 T cells that retained production of IFNγ, TNFα, perforin, and granzyme B. Combining acarbose with either anti-PD-1 or the mammalian target of rapamycin inhibitor, rapamycin, significantly reduced lung metastases relative to control mice on the same therapies. Our findings in mice suggest that combining acarbose with current RCC therapeutics may improve outcomes, warranting further study to determine whether acarbose can achieve similar responses in advanced RCC patients in a safe and likely cost-effective manner.

Therapeutic Targeting of Autophagy for Renal Cell Carcinoma Therapy.

Kidney cancer is the 7th most prevalent form of cancer in the United States with the vast majority of cases being classified as renal cell carcinoma (RCC). Multiple targeted therapies have been developed to treat RCC, but efficacy and resistance remain a challenge. In recent years, the modulation of autophagy has been shown to augment the cytotoxicity of approved RCC therapeutics and overcome drug resistance. Inhibition of autophagy blocks a key nutrient recycling process that cancer cells utilize for cell survival following periods of stress including chemotherapeutic treatment. Classic autophagy inhibitors such as chloroquine and hydroxychloroquine have been introduced into phase I/II clinical trials, while more experimental compounds are moving forward in preclinical development. Here we examine the current state and future directions of targeting autophagy to improve the efficacy of RCC therapeutics.

Identification of mutations associated with acquired resistance to sunitinib in renal cell cancer.

Sunitinib is one of the most widely used targeted therapeutics for renal cell carcinoma (RCC), but acquired resistance against targeted therapies remains a major clinical challenge. To dissect mechanisms of acquired resistance and unravel reliable predictive biomarkers for sunitinib in RCC, we sequenced the exons of 409 tumor-suppressor genes and oncogenes in paired tumor samples from an RCC patient, obtained at baseline and after development of acquired resistance to sunitinib. From newly arising mutations, we selected, using in silico prediction models, six predicted to be deleterious, located in G6PD, LRP1B, SETD2, TET2, SYNE1, and DCC. Consistently, immunoblotting analysis of lysates derived from sunitinib-desensitized RCC cells and their parental counterparts showed marked differences in the levels and expression pattern of the proteins encoded by these genes. Our further analysis demonstrates essential roles for these proteins in mediating sunitinib cytotoxicity and shows that their loss of function renders tumor cells resistant to sunitinib in vitro and in vivo. Finally, sunitinib resistance induced by continuous exposure or by inhibition of the six proteins was overcome by treatment with cabozantinib or a low-dose combination of lenvatinib and everolimus. Collectively, our results unravel novel markers of acquired resistance to sunitinib and clinically relevant approaches for overcoming this resistance in RCC.

CIP2A Promotes Proliferation, Invasion and Chemoresistance to Cisplatin in Renal Cell Carcinoma.

CIP2A is a well-known oncoprotein whose expression is elevated in multiple human solid tumor types. However, its role in renal cell carcinoma (RCC) development is poorly understood. Thus, in our present study, we used the renal cancer cell lines 786-O, A498 and CAKI-1 and the renal epithelial cell line HK-2 to clarify the function of CIP2A in RCC. We found that CIP2A expression is much higher in the RCC cells than in the normal renal epithelial cell. Lentivirus covered coding region CIP2A cDNA sequence and CIP2A siRNA were used to up and down regulate CIP2A expression in vitro. We found that overexpression of CIP2A promoted G1/S transition and cell proliferation. In addition, up-regulation of CIP2A significantly enhanced the invasion and migration capabilities of the cells. Furthermore, CIP2A promoted epithelial-mesenchymal transformation (EMT) and chemoresistance to cisplatin in RCC cells. Taken together, our findings demonstrate that CIP2A plays an important role in proliferation, invasion and chemoresistance to cisplatin in RCC cells. CIP2A may serve as an ideal molecular target for RCC therapeutics.

Kidney cancer in 2016: RCC - advances in targeted therapeutics and genomics.

Recent advances have been exciting in the genomics of and targeted therapeutics for renal cell carcinoma (RCC). New agents have been approved for advanced RCC, a novel agent targeting hypoxia-inducible factor 2α has shown considerable promise and molecular characterization of papillary RCC provides the foundation for development of targeted therapeutic approaches for this disease.

Wnt Signaling in Renal Cell Carcinoma.

Renal cell carcinoma (RCC) accounts for 90% of all kidney cancers. Due to poor diagnosis, high resistance to the systemic therapies and the fact that most RCC cases occur sporadically, current research switched its focus on studying the molecular mechanisms underlying RCC. The aim is the discovery of new effective and less toxic anti-cancer drugs and novel diagnostic markers. Besides the PI3K/Akt/mTOR, HGF/Met and VHL/hypoxia cellular signaling pathways, the involvement of the Wnt/β-catenin pathway in RCC is commonly studied. Wnt signaling and its targeted genes are known to actively participate in different biological processes during embryonic development and renal cancer. Recently, studies have shown that targeting this pathway by alternating/inhibiting its intracellular signal transduction can reduce cancer cells viability and inhibit their growth. The targets and drugs identified show promising potential to serve as novel RCC therapeutics and prognostic markers. This review aims to summarize the current status quo regarding recent research on RCC focusing on the involvement of the Wnt/β-catenin pathway and how its understanding could facilitate the identification of potential therapeutic targets, new drugs and diagnostic biomarkers.

Abstract A36: Unveiling biomarker and mechanism of drug resistance to molecular targeted therapeutics in renal cell carcinoma

Abstract Introduction and Objective: Renal cell carcinoma (RCC) is the most lethal of the urologic malignancies and it is largely incurable when it becomes metastatic. Recent development of molecular targeted agents such as tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors have provided some survival benefit for a subset of RCC patients. Overall, only 30% patients exhibit a response to these agents, however, almost all patients eventually develop drug resistance. Currently, there is no reliable biomarker(s) for predicting drug response for individual patients and the mechanism(s) of drug resistance is largely unknown. It is known that DAB2IP, a novel member of the Ras GTPase-activating protein gene family, is associated with cell proliferation, apoptosis, metastasis and chemo- or radio-resistance in several cancer types. In the present study, we decided to investigate the association between DAB2IP expression and therapeutic response to molecular targeted agents in RCC patients and explored the possible mechanism of DAB2IP in regulating drug response of RCC cells. Methods: DAB2IP expression was evaluated by immunohistochemistry (IHC) in a cohort of RCC patients who had received targeted therapies. Correlation between DAB2IP expression and patients' survival was analyzed. The effect of DAB2IP on RCC cells was examined using a panel of knockdown (KD) or overexpression cells generated by gene transfection and also determined for their in vitro and in vivo (xenograft model) responses to targeted agents treatment. The mechanism of drug resistance was delineated by signaling cascade profiling with a variety of molecular biologic techniques such as cDNA array, ChIP, reporter gene assay, real-time PCR and Western blot. Results: The levels of DAB2IP expression in RCC specimens determined by IHC positively correlate with the survival of patients receiving targeted therapies. DAB2IP KD RCC cells exhibit drug resistance to mTOR inhibitor Temsirolimus (Tem) treatment compared with the control from both in vitro and in vivo experiments. In contrast, increased DAB2IP in RCC cells by gene transfection can sensitize their response to Tem. Mechanistically, loss of DAB2IP was able to activate both the PI3K/mTOR pathway and the ERK/RSK1 pathway that further led to increased expression of hypoxia-inducible factor (HIF)-2α protein. Inhibitor(s) of either the mTOR pathway or the ERK pathway only partially suppressed growth of DAB2IP KD cells. However, the combination of both inhibitors achieved a synergistic growth inhibition in resistant cells. In this event, HIF-2α, but not HIF-1α, appeared to be a key converging factor and we further demonstrated that silencing of HIF-2α expression with specific shRNA was able to reverse the resistant phenotype in DAB2IP KD cells. Conclusions: DAB2IP represents a new predictive biomarker for the therapeutic response of RCC patients to targeted therapy. Most importantly, its functional role in RCC provides new therapeutic strategies in combating this lethal disease. Citation Format: Jiancheng Zhou, Kaijie Wu, Eunjin Yun, Payal Kapur, Rey-Chen Pong, Dalin He, Jer-Tsong Hsieh. Unveiling biomarker and mechanism of drug resistance to molecular targeted therapeutics in renal cell carcinoma. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A36.

Abstract 5305: Phosphoproteomics analysis reveals differential signaling pathways among clear cell and papillary renal cell carcinoma tumors

Abstract Introduction: The use of kinase inhibitors with targets such as VEGFR has heralded a new era of treatment for metastatic renal cell carcinoma (RCC) patients. However, patients develop resistance with time. Therefore, novel targets must be identified and a systems level description of RCC produced. To this end, we used mass spectrometry based phosphoproteomics to nominate targets as well as compare RCC subtypes. Methods: We developed an integrative strategy combining RCC phosphoproteomics and functional interrogation using drug screening. Tyrosine phosphorylated peptide immunoprecipitation and purification was performed in clear cell RCC (ccRCC) and normal renal cortex cell lines and analyzed via nano-liquid chromatography/tandem mass spectrometry interfaced with an electrospray hybrid ion-trap mass spectrometer. Eight ccRCC and five papillary RCC (pRCC) tumor tissues were also analyzed. We assembled a library of 180 small molecules, including 60 tyrosine kinase inhibitors (TKIs), and screened them at multiple concentrations in 10 clear cell RCC (ccRCC) cell lines. Results: Among the ccRCC cell lines, 153 phosphosites (114 proteins) were identified. Receptor tyrosine kinases included EGFR, MET, ERBB4, and EPHB2 and nonreceptor tyrosine kinases included ABL2, JAK2, KALRN, and PTK2. Serine/threonine kinases were the most abundant kinases and included, among others, several CDK and MAPK members. Other frequently observed phosphosites corresponded to cytoskeleton (10%) and cell adhesion (6%) proteins. Among the ccRCC tumors, 119 phosphosites (99 proteins) were identified. In contrast to the cell lines, the ccRCC tumors demonstrated increased Src family kinase signaling but less RTK signaling. Among the pRCC tumors, 113 phosphosites (98 proteins) were identified, including 37 not identified in the ccRCC tumors. This data, coupled with the TKI screen, offered some interesting observations. MET phosphotyrosine peptide intensity was relatively low in ccRCC compared to pRCC and among the eight MET inhibitors tested, seven failed to significantly inhibit cell viability. These results suggest that MET signaling may be more active in pRCC than ccRCC. Other divergent patterns of phosphotyrosine signaling emerged. For example, certain tyrosine phosphatases that could impact signaling displayed higher phosphorylation patterns in ccRCC. Other kinases currently not targeted by RCC therapeutics were more highly phosphorylated in pRCC relative to ccRCC tumors. The functional impact of these findings is currently undergoing evaluation. Conclusions: Integrating global phosphoproteomics of cell lines and tumors with functional analyses can shed light on key survival and growth pathways in clear cell and papillary RCC. Further studies in human tissues are ongoing and will be presented. Citation Format: Scott M. Haake, Jiannong Li, Yun Bai, Bin Fang, Julio Pow-Sang, John Koomen, Mayer Fishman, Eric B. Haura. Phosphoproteomics analysis reveals differential signaling pathways among clear cell and papillary renal cell carcinoma tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5305. doi:10.1158/1538-7445.AM2014-5305

Abstract 137: Tumor-associated ECM induces renal cell carcinoma tumorigenic responses via α6β1-integrin regulation of ITPKA

Abstract It is estimated that over 65,150 patients were diagnosed with renal cell carcinoma (RCC) with 13,680 deaths in 2013. Surgery and targeted therapies have limited impact on survival in patients with advanced metastatic RCC. Tumor-stroma plays a pivotal role in RCC tumorigenesis including metastasis. One of the striking features of RCC is a fibro vascular stromal reaction with an altered tumor-associated extracellular matrix (TA-ECM) that directly intercalates with the tumoral epithelia playing a functional role in RCC progression. We previously suggested that stromal activation characterized by the expression of specific tumor-associated stromal proteins and the TA-ECM not only constitutes an independent worse prognostic marker, but also comprises a predictive risk indicator of recurrent RCC. Our work is based on the fact that stromal-tumor interactions are most readily studied in in vivo-mimetic 3D models. Among the most promising systems are in vitro 3D stromal models developed by our group in which tumor cells are plated within TA-ECMs derived from fibroblasts harvested from surgical tissue samples comprised of patient-matched normal and tumor-associated fibroblasts. We have demonstrated the physiological relevance of this system in vivo and found that mesenchymal RCC stromal cells and matrices are modified during epithelial tumor progression. Here we show that ECMs produced by normal fibroblasts are restrictive, while syngeneic tumor-associated ECMs induce increased RCC tumorigenic responses including tumor growth, resistance to apoptosis and promotion of invasion. An unbiased gene expression array was conducted using RNA obtained from RCC cells cultured within the assorted ECMs. Classic RCC signaling pathways were evident, and in addition proteins previously unsuspected to play important roles in stromal regulation of RCC progression were identified. Amid these, we observed significant increases in the levels of inositol 1,4,5-trisphosphate 3-kinase-A (IP3KA; also known as ITPKA). Our data suggests that ITPKA's activity is necessary for the above-stated TA-ECM induced tumorigenic responses. The study describes how, in response to tumor-associated but not normal ECM, α6β1-integrin activity regulates ITPKA via increased cytosolic Ca2+ stabilizing constitutive Raf1 and Erk1/2 activities to promote tumorigenic responses. Moreover, in vitro experiments were confirmed using the original patient samples while clinical relevance was established in a well-annotated RCC tissue microarray cohort. We propose that activated stromal RCC triggers a novel α6β1/ITPKA/Erk1/2 pro-tumorigenic signaling pathway. In consequence, patients presenting activated stroma, together with high tumoral α6β1-integrin and/or ITPKA expression, are predicted to present unfavorable outcomes. This work is expected to facilitate future clinical testing of the new targets to aid development of novel RCC therapeutics. Citation Format: Vivekanand Gupta, Janusz Franco-Barraza, Neelima Shah, Essel Dulaimi, Yan Zhou, Karthik Devarajan, Kathy Q. Cai, Katherine R. Alpaugh, Robert G. Uzzo, Edna Cukierman. Tumor-associated ECM induces renal cell carcinoma tumorigenic responses via α6β1-integrin regulation of ITPKA. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 137. doi:10.1158/1538-7445.AM2014-137

Modeling spontaneous metastatic renal cell carcinoma (mRCC) in mice following nephrectomy.

One of the key challenges to improved testing of new experimental therapeutics in renal cell carcinoma (RCC) is the development of models that faithfully recapitulate early- and late-stage metastatic disease progression. Typical tumor implantation models utilize ectopic or orthotopic primary tumor implantation, but few include systemic spontaneous metastatic disease that mimics the clinical setting. This protocol describes the key steps to develop RCC disease progression stages similar to patients. First, it uses a highly metastatic mouse tumor cell line in a syngeneic model to show orthotopic tumor cell implantation. Methods include superficial and internal implantation into the sub-capsular space with cells combined with matrigel to prevent leakage and early spread. Next it describes the procedures for excision of tumor-bearing kidney (nephrectomy), with critical pre- and post- surgical mouse care. Finally, it outlines the steps necessary to monitor and assess micro-and macro-metastatic disease progression, including bioluminescent imaging as well provides a detailed visual necropsy guide to score systemic disease distribution. The goal of this protocol description is to facilitate the widespread use of clinically relevant metastatic RCC models to improve the predictive value of future therapeutic testing.

Chromophobe renal cell carcinoma: A review of an uncommon entity

Renal cell carcinoma is the most common neoplasm of the kidney. It is a heterogeneous disease, comprised of different histological variants with a distinct clinical course, genetics and response to treatment. The various subtypes identified include clear cell, papillary and chromophobe, among others. Chromophobe renal cell carcinoma is a rare variant and accounts for 5% of all cases. These tumors are macroscopically larger when compared with other forms and are commonly diagnosed at an early stage. Despite significant advances in renal cell carcinoma therapeutics in the past decade, no standard treatment has been identified for advanced chromophobe renal cell carcinoma. Nevertheless, new molecular insights have recently become available. A familial form of renal cell carcinoma, the Birt-Hogg-Dubé syndrome, has been described and the knowledge obtained has opened research opportunities in the therapeutic arena of chromophobe renal cell carcinoma. The following manuscript will endeavor to provide an overview of this uncommon entity including pathology, epidemiology, genetics, clinical aspects, and current and future treatment options.

Breaking through a Plateau in Renal Cell Carcinoma Therapeutics: Development and Incorporation of Biomarkers

With the Food and Drug Administration approval of 6 novel targeted agents since December 2005 and limited comparative trials to discern relative efficacy, the treatment of metastatic renal cell carcinoma (RCC) has become immensely complex. The research community must look to novel ways in which to identify appropriate candidates for selected targeted therapies; one potential strategy is the use of clinical and molecular biomarkers. A growing body of knowledge-related von Hippel Lindau-driven pathways in this disease has highlighted the potential role of hypoxia-inducible factor subtypes in distinguishing RCC patients clinically. Techniques applied in other malignancies, such as gene expression and proteomic profiling, may also ultimately allow for clinical stratification. An emerging understanding of immunologic phenomena that may affect cancer progression (i.e., tumor infiltration by CD68 lymphocytes, memory T-cells, etc.) has unveiled a number of other potential biomarkers of response. Several vascular endothelial growth factor receptor-directed therapies classically thought to function as antiangiogenics may also have complex effects upon the tumor microenvironment including the associated immune cell milieu. As such, immunologic parameters could potentially predict response to current therapies. Finally, clinical biomarkers, such as hypertension, may predict the efficacy of several currently available targeted agents, although implementation of such biomarkers remains challenging. Herein, the clinical relevance of putative RCC biomarkers is examined in detail.

The intersection of sunitinib with the immunosuppressive microenvironment of renal cell carcinoma: implications for future therapeutics

Renal cell carcinoma (RCC) is known to be a model of an immune-influenced malignancy. The immunobiology of RCC has three main immune cell types known to contribute to immunosuppression: T regulatory (Treg) cells, Type 2 T helper (Th2) cells, and myeloid derived suppressor cells. Sunitinib has rapidly revolutionized RCC treatment and is now a first-line standard of care for advanced RCC. Preliminary evidence reviewed here reveals that, in addition to antiangiogenic effects, sunitinib may have a direct or secondary effect on reversing the immunosuppressive environment by decreasing Treg cells and reversing the Th2 bias. Hypotheses for these observed effects and others are postulated based upon the mechanism of action. Current research is underway to further delineate the effect sunitinib has on the immune system and its mechanisms. Future therapeutics in RCC may include combination therapies that function collaboratively with sunitinib to harness an antitumor immune effect.

Targeted Therapy for Renal Cell Carcinoma: A New Therapeutic Paradigm

Renal cell carcinoma is the most common tumor of the kidney. It has an unpredictable behavior and poor response to systemic therapy. Developing newer therapy for this disease is a priority considering the high recurrence rate and the small subset of patients who benefit from the use of cytokines such as interferon-α or interleukin-2. Identifying molecular targets and targeting various biomarkers has revolutionized the therapeutic approach to advanced and metastatic renal cell carcinoma. Although some of the antiangiogenic agents and receptor tyrosine kinase inhibitors appear promising, further understanding of their mechanism of action and the patient population who would benefit most from such agents is still being explored. As numerous targeted agents are entering the clinical investigation arena in a relatively short period of time, newer challenges in renal cell carcinoma therapeutics are emerging. Some of the future challenges in using targeted antineoplastic agents in renal cell carcinoma will include evaluating their long-term safety and benefit, using the particular drug in the appropriate patient population after appropriate stratification and studying the combination of some of these drugs for synergy or additive effects.