Generation of Kidney Cancer-Specific Antitumor Immune Responses Using Peripheral Blood Monocytes Transduced With a Recombinant Adenovirus Encoding Carbonic Anhydrase 9

A Phase I, Open-label, Dose-escalation, and Cohort Expansion Study to Evaluate the Safety and Immune Response to Autologous Dendritic Cells Transduced With AdGMCA9 (DC-AdGMCAIX) in Patients With Metastatic Renal Cell Carcinoma

Expression of carbonic-anhydrase IX (CAIX) in clear cell renal cell carcinoma (RCC) makes it an attractive vaccine target. We developed a fusion-gene construct, granulocyte-macrophage (GM) colony-stimulating factor+CAIX, delivered by an adenoviral vector (Ad) into autologous dendritic cells (DCs) in this phase 1 study. The injected immature DCs were expected to stimulate an antigen-specific immune response against CAIX expressing RCC. Three dose-escalation cohorts (5, 15, and 50×10 cells/administration) were injected intradermally q2wk×3 doses based on a 3+3 design. The primary objective was the safety of the injections. Secondary objectives were immune responses using enzyme-linked immunosorbent spot, a serum biomarker panel, and clinical response. Fifteen patients with metastatic RCC were enrolled, and 9 patients received all 3 doses. No serious adverse events were seen. There were 3 (33%) patients with grade 1 fatigue, 1 of whom subsequently experienced grade 2 fatigue. One patient (11%) experienced grade 1-2 leukopenia. Only 1 patient (11%) experienced grade 2 flu-like symptoms. Of the 9 patients who received treatment, 1 expired of progressive disease, 2 patients were lost to follow-up and 6 patients are alive. Of the 6 patients, 5 have progressive disease, and 1 has completed treatment with stable disease at 27 months follow-up. Immune response measurements appeared more robust in higher dose cohorts, which appeared to be related to patients with stable disease at 3 months. These early data show that autologous immature DC-AdGMCAIX can be safely given to metastatic RCC patients without any serious adverse events with CAIX-specific immune response elicited by the treatment. These preliminary data support further study of Ad-GMCAIX, particularly with combination therapies that may enhance clinical activity.

CA9 transcriptional expression determines prognosis and tumour grade in tongue squamous cell carcinoma patients

CA9 is a member of the carbonic anhydrases’ family, that is often expressed in cancer cells under hypoxic condition. However, the role of CA9 in the molecular mechanisms of tongue squamous cell carcinoma (TSCC) pathogenesis remains unclear. CA9 expression was analysed using the TCGA database, and its influence on survival was performed using Kaplan‐Meier, LASSO and COX regression analyses. The correlation between CA9 and immune infiltration was investigated by CIBERSORT and ESTIMATE. Moreover, the relationship between CA9 expression and downstream molecular regulation pathways was analysed by GSEA, GO and WGCNA. CA9 expression correlated with clinical prognosis and tumour grade in TSCC. Moreover, CA9 expression potentially contributes to the regulation of cancer cell differentiation and mediates tumour‐associated genes and signalling pathways, including apoptosis, hypoxia, G2M checkpoint, PI3K/AKR/mTOR signalling and TGF‐beta signalling pathways. However, the follicular helper T cells, regulatory T cells, immune and stromal scores showed no significance between high and low CA9 expression groups. These findings suggested that CA9 plays a critical role of TSCC prognosis and tumour grade. CA9 expression significantly correlated with the regulation of cell differentiation, various oncogenes and cancer‐associated pathways.

PD-1 expression on peripheral blood cells increases with stage in renal cell carcinoma patients and is rapidly reduced after surgical tumor resection

Programmed death-1 (PD-1) receptor is an inhibitory receptor on hematopoietic cells that can negatively regulate immune responses, particularly responses to tumors, which often upregulate PD-1 ligands. PD-1/PD-1 ligand blocking antibodies can reverse the inhibition and show significant therapeutic promise in treating renal cell carcinoma (RCC), lung cancer, and melanoma. While PD-1 expression on tumor-infiltrating lymphocytes has been associated with poor outcome in RCC, we sought to define immune cell biomarkers, including PD-1, on peripheral blood mononuclear cells (PBMC) that could predict disease progression of RCC patients before and after nephrectomy. We analyzed expression of numerous immune cell markers on fresh PBMCs from 90 RCC patients preoperatively and 25 age-matched healthy controls by 10-color flow cytometry. Postoperative blood samples were also analyzed from 23 members of the RCC patient cohort. The most striking phenotypic immune biomarker in RCC patients was a significant increase in PD-1 expression on certain PBMCs in a subset of patients. Increased PD-1 expression on CD14(bright) myelomonocytic cells, effector T cells, and natural killer (NK) cells correlated to disease stage, and expression was significantly reduced on all cell types soon after surgical resection of the primary tumor. The results indicate that PD-1 expression on fresh peripheral blood leukocytes may provide a useful indicator of RCC disease progression. Furthermore, measuring PD-1 levels in peripheral blood may assist in identifying patients likely to respond to PD-1 blocking antibodies, and these therapies may be most effective before and immediately after surgical resection of the primary tumor, when PD-1 expression is most prominent.

Dendritic cell-based immunotherapy in prevention and treatment of renal cell carcinoma: efficacy, safety, and activity of Ad-GM·CAIX in immunocompetent mouse models

The dendritic cell vaccine DC-Ad-GM·CAIX is an active, specific immunotherapy with the potential of providing a safe and effective therapy against renal cell carcinoma (RCC). Using immunocompetent Balb/c mouse models we tested the efficacy and mechanism of the vaccine to prevent and treat the growth of a syngeneic RCC (RENCA) engineered to overexpress the human TAA carbonic anhydrase IX (NPR-IX). In a prevention model, NPR-IX tumor development was specifically and significantly delayed by 13 days in DC-Ad-GM·CAIX-treated mice (P < 0.001), tumor volumes were 79% smaller (day 24, P < 0.007), and body weight was maintained at study termination compared with the controls. Six of these mice remained tumor-free for > 1 year. In a treatment model, NPR-IX tumors remained smaller in DC-Ad-GM·CAIX-treated mice for 8 days (P < 0.002), achieving a 60% growth inhibition at termination. No vaccine-related organ toxicity was observed in either model. The critical mechanistic parameter separating responsive from nonresponsive tumors was hCAIX protein expression, demonstrated by aggressive growth of tumors that did not express hCAIX protein and in sham-treated mice (DC-Ad-Null). No murine serum anti-hCAIX antibodies were detected. Moreover, altered mechanisms of immunoediting as a means for immune evasion were suggested by differential gene expression (Ccl1, Hmgb1, Fgl2, Cd209a, and Klra2) and therapy evasion miRNAs (miR-1186, miR-98, miR-5097, miR-1942, and miR-708) in tumors that evaded DC-Ad-GM·CAIX immunotherapy. This is the first study in immunocompetent mice that provides a proof of concept for the specificity, efficacy, safety, and activity of the DC-Ad-GM·CAIX immunotherapy, forming the basis for a first-in-human phase I trial in RCC patients.

Ultrasound-based combination therapy: potential in urologic cancer

Immune-sensitive urologic malignancies include prostate, kidney and bladder cancers. To date, most immunotherapeutic treatments have been applied to advanced metastatic disease. Limited efficacy in this setting is likely due to an excessive disease burden, which overwhelms the capacity of the immune system. Immunotherapy has not been widely utilized in a low-disease-burden state - a setting in which the immune system may be best suited to effectively mount a clinically meaningful response. The emergence of high-intensity focused ultrasound, and more recently, low-intensity focused ultrasound technologies, have demonstrated not only immune-stimulatory effects but also an interesting capacity to alter tissue architecture and cell membrane properties, which may be exploited to increase tumoral uptake of drugs and vaccines. In this article, we review the literature supporting the novel use of ultrasound combination therapy with adjunctive agents in the treatment of urologic malignancy.

Immunostimulatory activity of dendritic cells pulsed with carbonic anhydrase IX and Acinetobacter baumannii outer membrane protein A for renal cell carcinoma

Dendritic cell (DC)-based immunotherapy is a potent therapeutic modality for treating renal cell carcinoma (RCC), but development of antigens specific for tumor-targeting and anti-tumor immunity is of great interest for clinical trials. The present study investigated the ability of DCs pulsed with a combination of carbonic anhydrase IX (CA9) as an RCC-specific biomarker and Acinetobacter baumannii outer membrane protein A (AbOmpA) as an immunoadjuvant to induce anti-tumor immunity against murine renal cell carcinoma (RENCA) in a murine model. Murine bone-marrow-derived DCs pulsed with a combination of RENCA lysates and AbOmpA were tested for their capacity to induce DC maturation and T cell responses in vitro. A combination of RENCA lysates and AbOmpA up-regulated the surface expression of co-stimulatory molecules, CD80 and CD86, and the antigen presenting molecules, major histocompatibility (MHC) class I and class II, in DCs. A combination of RENCA lysates and AbOmpA also induced interleukin-12 (IL-12) production in DCs. Next, the immunostimulatory activity of DCs pulsed with a combination of CA9 and AbOmpA was determined. A combination of CA9 and AbOmpA up-regulated the surface expression of co-stimulatory molecules and antigen presenting molecules in DCs. DCs pulsed with a combination of CA9 and AbOmpA effectively secreted IL-12 but not IL-10. These cells interacted with T cells and formed clusters. DCs pulsed with CA9 and AbOmpA elicited the secretion of interferon-γ and IL-2 in T cells. In conclusion, a combination of CA9 and AbOmpA enhanced the immunostimulatory activity of DCs, which may effectively induce anti-tumor immunity against human RCC.

Immunological therapy in urological malignancy: novel combination strategies

At present, immunotherapy in urological malignancy is experiencing a renaissance, particularly with the emergence of a host of innovative cancer vaccines. Herein, we will review promising immunotherapeutic approaches and evaluate the data supporting their inclusion in novel combination strategies.

Biomarkers in renal cell carcinoma

PURPOSE OF REVIEW

To review the latest information on biomarkers in renal cell carcinoma and their use in integrated staging systems.

RECENT FINDINGS

The discovery of the Von Hippel-Lindau defect and the hypoxia inducible factor-1alpha transcripted genes has led to an explosion in the understanding of molecular pathways in renal cell carcinoma. The two most prominent biomarkers are carbonic anhydrase IX and vascular endothelial-derived growth factor. Carbonic anhydrase IX has demonstrated excellent specificity and ability to predict treatment response. Vascular-derived growth factor has good correlation with stage, grade and increased levels with adverse survival. Markers such as CXCL16, ADAM10, B7-H1, Ki-67, survivin, P53, GLUT-1, calveolin-1 and endoglin are continuously being validated. CXCL16 is one of the newest biomarkers, is significantly expressed in papillary renal cell carcinoma and is an independent prognostic marker for better patient survival. The incorporation of biomarkers into integrated staging systems such as UCLA Integrated Staging System, SSIGN and Bioscore are discussed and compared.

SUMMARY

The use of novel molecular biomarkers are being incorporated into clinical practice. The understanding of molecular pathways will lead to tailored treatment to the individual patient.

Carbonic anhydrase IX has chaperone-like functions and is an immunoadjuvant

Carbonic anhydrase IX (CA9) is a hypoxia-regulated, transmembrane protein associated with neoplastic growth in a large spectrum of human tumors. CA9 is expressed in nearly all clear-cell renal tumors; levels of CA9 expression predict prognosis and response to interleukin-2 therapy. These observations may be explained by a novel chaperone-like function of CA9, which allows it to serve as an immunoadjuvant and stimulate an adaptive immune response against tumor antigens. Classic heat shock proteins (HSP) such as HSP110 and HSP70 are up-regulated in response to cellular stress and function to protect intracellular proteins from aggregation. Similarly, CA9 formed complexes with client proteins and inhibited heat-induced aggregation and enabled refolding of denatured client protein. HSP released from injured cells activate an immune response. CA9 bound dendritic cells in a receptor-specific manner. Bound CA9 was internalized by dendritic cells and processed primarily through the proteosomal pathway. In a murine melanoma model, a complex of CA9 and gp100 generated a gp100-specific antitumor response. A soluble form of CA9 shed from tumor cells had the same chaperone-like functions, providing renal tumors and hypoxic cells with a mechanism for stimulating an immune response against extracellular antigens. Interleukin-2 treatment of patient renal tumors in short-term culture increased CA9 shedding, suggesting a strategy for augmenting the immunogenicity of renal tumors. CA9 has chaperone-like functions and CA9 shed from tumors may play a direct role in stimulating an adaptive immune response.

Molecular and cytogenetic insights into the pathogenesis, classification, differential diagnosis, and prognosis of renal epithelial neoplasms

Renal cell carcinomas comprise a heterogeneous group of epithelial neoplasms with diverse biologic potential and variable clinical outcomes. The application of molecular and cytogenetic techniques to the study of renal neoplasms has improved our understanding of the molecular mechanisms responsible for tumor initiation and progression. Molecular classification of renal cell carcinomas has also provided new avenues for diagnosis, clinical outcome, and therapy response prediction. In this article, we review the molecular markers for various renal epithelial neoplasms and discuss the mechanisms underlying the development of these neoplasms. We also evaluate the use of molecular and cytogenetic techniques in establishing an accurate diagnosis in difficult cases and their potential usefulness in accurately classifying renal neoplasms, assessing prognosis, and selecting appropriate therapy.

Transplantation of allogeneic hematopoietic stem cells: an emerging treatment modality for solid tumors

Allogeneic transplantation of hematopoietic cells from an HLA-compatible donor has been used to treat hematologic malignancies. Allogeneic transplantation not only replaces the marrow affected by the disease, but exerts an immune graft-versus-tumor (GVT) effect mediated by donor lymphocytes. The development of nonmyeloablative conditioning regimens before allogeneic transplantation has allowed this therapy to be used in elderly and disabled patients. An allogeneic GVT effect is observed in a proportion of patients with renal, breast, colorectal, ovarian, and pancreatic cancer treated with allogeneic transplantation. In general, the tumor response is associated with the development of acute and chronic graft-versus-host disease. Further improvements will depend on the identification of the antigen targets of GVT, and on reduction of the toxicity of the procedure. Targeted therapies may complement the immune effect of allogeneic transplantation. We present updated results from the literature and data recently placed on file at the European Bone Marrow Transplantation Solid Tumors Working Party.

RENCA/carbonic anhydrase-IX: a murine model of a carbonic anhydrase-IX-expressing renal cell carcinoma

OBJECTIVES

Carbonic anhydrase-IX (CA-IX) is a cell surface tumor-associated antigen expressed by most clear cell renal cell carcinomas (RCCs). The specificity and the prognostic value of CA-IX provide impetus to create a mouse model of CA-IX-expressing RCC for testing CA-IX-targeted therapies against RCC.

METHODS

A retrovirus encoding the human CA-IX gene was used to transduce the murine RCC line, RENCA. In vivo growth kinetics and CA-IX expression were compared between RENCA and RENCA/CA-IX using heterotopic, metastatic, and orthotopic models.

RESULTS

Transduction of RENCA created the RENCA/CA-IX line with nearly 100% CA-IX surface expression. In the heterotopic model, subcutaneous injection of 500,000 and 50,000 cells led to tumor formation at 2 to 2.5 weeks after injection, with similar growth kinetics between the two cell lines at either cell number. In the pulmonary metastatic model, a similar number of metastases was noted after inoculation of RENCA and RENCA/CA-IX. In the orthotopic model, autopsy revealed a CA-IX-expressing renal tumor, as well as CA-IX-expressing metastases to the lungs, liver, contralateral kidney, intestines, and lymph nodes. In all the above models, the RENCA/CA-IX tumors retained expression of CA-IX, as demonstrated by immunohistochemistry staining.

CONCLUSIONS

RENCA/CA-IX is the first tumor model that manifests in immunocompetent Balb/c mice and stably expresses a defined kidney cancer-associated antigen. It maintains antigen expression, forms metastases, and produces reliable tumor growth kinetics equivalent to that of its parental cell line.

Anti-tumoural activity of peripheral blood mononuclear cells against melanoma cells: discrepant in-vitro and in-vivo effects

As tumour cells use multiple mechanisms to escape from chemotherapeutic drugs, the anti-tumoural activity of naive mouse peripheral blood mononuclear cells was examined in this study, using a mouse melanoma cell subline resistant to doxorubicin (B16R). Multicellular spheroids are known to be the most adapted in-vitro model to mimic solid tumours in vivo and are used to investigate many aspects of tumour biology. For in-vitro studies, murine peripheral blood mononuclear cells recovered by Ficoll gradient centrifugation after caudal puncture were co-cultured with multicellular tumour spheroids of B16R cells. Morphological investigations show that peripheral blood mononuclear cells were gathered and focused around the spheroids after 14 h of co-culture and contacts were established within 32 h. Between 38 and 62 h of co-culture, the size of the spheroids decreased significantly. The peripheral blood mononuclear cells exerted cytolytic effects that correlated with the induction of cell death in spheroids of B16R melanoma cells. Immunological investigations to localize and identify peripheral blood mononuclear cells that exerted anti-tumoural effects have shown that spheroids were deeply infiltrated by monocytes/macrophages at a stage in which a significant cytolytic activity and a strong cell death rate were observed. For in-vivo studies, intratumoural injections of syngeneic naive peripheral blood mononuclear cells were administered. A weak potential in-vivo anti-tumoural effect of these cells was observed (inhibition of B16R melanoma growth by 20-25%) but the median survival time of mice treated with peripheral blood mononuclear cells did not increase compared with untreated control mice. Thus, despite anti-tumoural activities of peripheral blood mononuclear cells against the poorly immunogenic and highly metastatic chemoresistant B16 melanoma cells in vitro, a potential anti-melanoma effect in vivo, if present, did not increase the life span of B16R melanoma-bearing mice.

Nonmetastatic renal-cell carcinoma: is it really possible to define rational guidelines for post-treatment follow-up?

Defining rational follow-up guidelines in patients treated for cancer is important, from both a medical and an economical perspective. Renal-cell carcinoma is reputed to be unpredictable in its course and only a few, and often contradictory, follow-up guidelines exist for patients treated for nonmetastatic renal-cell carcinoma. Recent advances in tumor biology have contributed to a better understanding of this cancer and have indicated that personalized follow-up regimens, based on tumor and host molecular characteristics, might be possible in the near future.

Differential gene expression identifies subgroups of renal cell carcinoma

Clear cell carcinoma of the kidney, the most common subtype of renal cell cancer, displays different biological behavior in different patients. This heterogeneity cannot be recognized by light microscopy. In this study, gene expression in 16 clear cell renal cell carcinoma samples and 17 non-malignant tissue types comprising 539 samples was determined using oligonucleotide microarrays representing approximately 40,000 known genes and ESTs. Differences in gene expression were quantified as the fold change in gene expression between the various sets of samples. A set of genes was identified that was overexpressed in the renal cell carcinoma samples compared with the normal kidney samples. Principle component analysis of the set of renal cell carcinomas using this set of genes overexpressed in renal cell cancer revealed the existence of 2 major subgroups among the renal carcinomas. A series of principle component analyses of the set of renal cell carcinomas using different gene sets composed of genes involved in different metabolic pathways also revealed the same 2 major subgroups of the renal cell cancers. Eisen clustering using the same genes also revealed the same 2 major renal cell cancer subsets. Review of the pathology suggested that these 2 subgroups differed in pathologic grade. Genes differentially expressed between the 2 renal cell cancer subsets were identified. Examination of gene expression in each renal cell cancer subset and the pool of renal cell carcinoma samples compared with that in 17 different normal tissues revealed genes specifically overexpressed in renal cell cancer compared with these normal tissues. The authors conclude that gene expression patterns may be useful in helping to further classify subtypes of renal cell carcinoma that may have clinical significance. In addition, the genes identified as overexpressed in each set of clear cell renal cell carcinomas compared with normal tissues may represent useful targets for therapy.

Adjuvant treatment for renal cell carcinoma

Despite significant advances in the diagnosis, staging and treatment of patients with renal cell carcinoma, recurrence rates following surgical resection of locally aggressive tumours remain high. In an effort to delay disease progression and improve survival, the concept of adjuvant therapy has been proposed. Optimal adjuvant therapy for surgically resected renal cell carcinoma remains to be defined and the evaluation of adjuvant therapies will require properly controlled and adequately powered randomised trials. Promising preliminary results have been seen with active immunotherapies and agents that target critical signalling pathways, and there are several Phase III trials of these novel treatment options that are underway. In addition, classification of patients into high- and low-risk subgroups on the basis of a prognosis profile will serve as a useful means to guide clinicians in improving the selection of patients who are likely to derive benefit from adjuvant therapy. This will lead to a future area of investigation, which will be the identification of patients within the target population that should respond to a given treatment. This review will discuss the role and current status of adjuvant therapies for renal cell carcinoma.

Emerging drugs for renal cell carcinoma

Renal cell carcinoma (RCC) still represents a therapeutic challenge when patients have advanced or metastatic disease. Treatment using IL-2 and IFN-alpha continues to be the standard of care in patients who are able to tolerate such regimens. Targeted therapy may become the first-line treatment for patients resistant or intolerant to cytokines as new emerging drugs continue to be investigated. Understanding the genetic abnormalities related to the development of RCC (e.g., VHL gene abnormalities) and identifying molecular targets (e.g., epidermal growth factor, vascular endothelial growth factor and carbonic anhydrase IX) are playing a major role in the emergence of these novel agents for the treatment of this malignancy. Overall, these drugs are better tolerated and more acceptable to use by patients than the traditional cytokine-based regimens. The use of oral drugs to treat various malignancies including RCC seems to be the new paradigm of the future. Further understanding of their mechanisms of action and confirmation of their benefits on the clinical outcome is needed.

Carbonic anhydrase IX and the future of molecular markers in renal cell carcinoma

The use of carbonic anhydrase IX as a promising molecular marker in RCC is described by authors from Los Angeles, who discuss the promise that molecular markers hold to improve diagnosis, staging, treatment, surveillance and survival of patients with RCC. There is a whole range of new treatments being introduced in the management of metastatic renal cancer. The use of VEGF-targeted therapy has particular importance, especially as it has a strong genetically linked rationale for its potential success in this area. Authors from the USA show that substantial clinical activity has been reported in initial clinical trials. In prostate cancer, drugs targeting microtubules, such as taxanes, have already been introduced clinically, and their success has received widespread attention. A new group of drugs, the epothilones, have similar but not identical binding properties to microtubules, and authors from the USA describe how they have shown activity in hormone-refractory prostate cancer, and are moving to phase III testing.

Novel approaches in the therapy of metastatic renal cell carcinoma

Renal cell carcinoma (RCC) is the most lethal of the common urologic malignancies, with approximately 40% of patients eventually dying of cancer progression. Approximately one third of patients present with metastatic disease, and up to 40% treated for localized disease have a recurrence. Recent advances in the understanding of the pathogenesis, behavior, and molecular biology of RCC have paved the way for developments that may enhance early diagnosis, better predict tumor prognosis, and improve survival for RCC patients. The recent discovery of molecular tumor markers is expected to revolutionize the staging of RCC in the future and lead to the development of new therapies based on molecular targeting. Cytokine-based immunotherapy can be considered standard therapy in the treatment of metastatic RCC today. However, new therapies such as tumor vaccines, anti-angiogenesis agents, and small molecule inhibitors are being developed to improve efficacy and treat those patients who are unable to tolerate or are resistant to systemic immunotherapy. The aim of this review is to provide an update on current therapeutic approaches and targeted molecular therapy for metastatic RCC.

Ontogeny and Oncogenesis Balance the Transcriptional Profile of Renal Cell Cancer

Global transcript analysis is increasingly used to describe cancer taxonomies beyond the microscopic reach of the eye. Diagnostic and prognostic portraits are formulated by ranking cancers according to transcriptional proximity. However, the role that distinct biological factors play in defining these portraits remains undefined. It is likely that the transcriptional repertoire of cancers depends, on one hand, on the anamnestic retention of their ontogenesis and, on the other, on the emergence of novel expression patterns related to oncogenesis. We compared the transcriptional profile of primary renal cell cancers (RCCs) with that of normal kidney tissue and several epithelial cancers of nonrenal origin to weigh the contribution that ontogeny and oncogenesis make in molding their genetic profile. Unsupervised global transcript analysis demonstrated that RCCs retain transcriptional signatures related to their ontogeny and cluster close to normal renal epithelium. When renal lineage-associated genes are removed from the analysis and cancer-specific genes are analyzed, RCCs segregate with other cancers with limited lineage specificity underlying a predominance of the oncogenic process over lineage specificity. However, a RCC-specific set of oncogenesis-related genes was identified and surprisingly shared by sarcomas. In summary, the transcriptional portrait of primary RCCs is largely dominated by ontogeny. Genes responsible for lineage specificity may represent poor molecular targets for immune or drug therapy. Most genes associated with oncogenesis are shared with other cancers and may represent better therapeutic targets. Finally, a small subset of genes is associated with lineage-specific oncogenesis, and these may provide information regarding the biological behavior of RCCs and facilitate diagnostic classification of RCCs.