Renal cell carcinoma: Current status and emerging therapies

Pharmacotherapy options in advanced renal cell carcinoma: what role for pazopanib?

Over the last 6 years, the treatment of metastatic renal cell carcinoma (mRCC) has undergone dramatic changes. A better understanding of the pathogenesis and tumor biology of sporadic renal cell carcinoma has led to the approval of 6 drug regimens: 3 oral multi-targeted tyrosine-kinase inhibitors (sorafenib, sunitinib, and pazopanib), 2 inhibitors of the mammalian target of rapamycin (temsirolimus and everolimus), and 1 monoclonal antibody against the vascular endothelial growth factor (bevacizumab). Pazopanib, a multi-targeted tyrosine kinase inhibitor that targets VEGFR-1, -2, and-3; PDGFR-α and PDGFR-β, and c-Kit, was approved for the treatment of mRCC in October 2009, several years after the other drugs in its class. The efficacy and safety of pazopanib in Phase I, II, and III trials will be examined and its role in mRCC treatment will be described. Future studies that may clarify pazopanib’s role in mRCC will be discussed. Based on pazopanib’s demonstrated efficacy in treatment-naïve and cytokine-refractory patients, along with a seemingly favorable toxicity profile compared with other multi-targeted tyrosine-kinase inhibitors, pazopanib may have a unique niche in the armamentarium of treatment options for mRCC. Results from ongoing studies are awaited to confirm pazopanib’s favorable efficacy-toxicity ratio, especially in comparison with the previous first-line standard-of-care, sunitinib.

Familial renal cancer: molecular genetics and surgical management

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

Isolation and characterization of progenitor-like cells from human renal proximal tubules

The tubules of the kidney display a remarkable capacity for self-renewal on damage. Whether this regeneration is mediated by dedifferentiating surviving cells or, as recently suggested, by stem cells has not been unequivocally settled. Herein, we demonstrate that aldehyde dehydrogenase (ALDH) activity may be used for isolation of cells with progenitor characteristics from adult human renal cortical tissue. Gene expression profiling of the isolated ALDH(high) and ALDH(low) cell fractions followed by immunohistochemical interrogation of renal tissues enabled us to delineate a tentative progenitor cell population scattered through the proximal tubules (PTs). These cells expressed CD24 and CD133, previously described markers for renal progenitors of Bowman's capsule. Furthermore, we show that the PT cells, and the glomerular progenitors, are positive for KRT7, KRT19, BCL2, and vimentin. In addition, tubular epithelium regenerating on acute tubular necrosis displayed long stretches of CD133(+)/VIM(+) cells, further substantiating that these cells may represent a progenitor cell population. Furthermore, a potential association of these progenitor cells with papillary renal cell carcinoma was discovered. Taken together, our data demonstrate the presence of a previously unappreciated subset of the PT cells that may be endowed with a more robust phenotype, allowing increased resistance to acute renal injury, enabling rapid repopulation of the tubules.

VHL genetic alteration in CCRCC does not determine de-regulation of HIF, CAIX, hnRNP A2/B1 and osteopontin

BACKGROUND

Von Hippel-Lindau (VHL) tumour suppressor gene inactivation is associated with clear cell renal cell carcinoma (CCRCC) development. The VHL protein (pVHL) has been proposed to regulate the expression of several proteins including Hypoxia Inducible Factor-α (HIF-α), carbonic anhydrase (CA)IX, heterogeneous nuclear ribonucleoprotein (hnRNP)A2/B1 and osteopontin. pVHL has been characterized in vitro, however, clinical studies are limited. We evaluated the impact of VHL genetic alterations on the expression of several pVHL protein targets in paired normal and tumor tissue.

METHODS

The VHL gene was sequenced in 23 CCRCC patients and VHL transcript levels were evaluated by Real-Time RT-PCR. Expression of pVHL's protein targets were determined by Western blotting in 17 paired patient samples.

RESULTS

VHL genetic alterations were identified in 43.5% (10/23) of CCRCCs. HIF-1α, HIF-2α and CAIX were up-regulated in 88.2% (15/17), 100% (17/17) and 88.2% (15/17) of tumors respectively and their expression is independent of VHL status. hnRNP A2/B1 and osteopontin expression was variable in CCRCCs and had no association with VHL genetic status.

CONCLUSION

As expression of these proposed pVHL targets can be achieved independently of VHL mutation (and possibly by hypoxia alone), this data suggests that other pVHL targets may be more crucial in renal carcinogenesis.

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.

Fatigue in renal cell carcinoma: the hidden burden of current targeted therapies

Fatigue is one of the most common symptoms associated with cancer. Persistent fatigue can impair multiple aspects of daily functioning and quality of life, and patients report that treatment-related fatigue has a greater impact than other symptoms, including pain, nausea, and depression. Thus, management of fatigue is recognized as an important component of care for patients with cancer. Treatment of advanced and metastatic renal cell carcinoma (RCC) was, until recently, limited to cytokine-based therapies, which are associated with modest response rates and significant toxicity, including high rates of treatment-related fatigue. The paradigm for RCC treatment has shifted dramatically in the last 5 years with the advent of efficacious targeted therapies. These agents provide the promise of better tolerability because of their more selective mechanisms of action. However, there is considerable variation in the selectivity of targeted agents for RCC, and a review of randomized clinical trials in patients with advanced and/or metastatic disease reveals that there is considerable variation in the tolerability of these agents. Fatigue remains a prominent toxicity with current targeted therapies. Future agents that show better selectivity and potency than current targeted therapies should help to provide better efficacy and tolerability.

How do cost-effectiveness analyses inform reimbursement decisions for oncology medicines in Canada? The example of sunitinib for first-line treatment of metastatic renal cell carcinoma

BACKGROUND

Canadian oncology decision-makers have reimbursed cancer drugs at incremental cost-effectiveness ratios (ICER) higher than those considered acceptable in other therapeutic areas. Sunitinib is a multitargeted receptor tyrosine kinase inhibitor, indicated for metastatic renal-cell carcinoma (MRCC) of clear cell histology. Canadian decision-makers evaluated sunitinib funding in the presence of important data limitations (including interim analysis of a surrogate outcome) and in the context of a high ICER.

METHODS

First, a description was presented of the cost-effectiveness analysis submitted for sunitinib reimbursement decision-making in Canada before conclusive survival evidence had been available. Second, sunitinib access decisions and the oncology drug reimbursement literature were reviewed to explore the interpretation of sunitinib perceived value in the context of the decision-making framework in Canada.

RESULTS

The economic evaluation yielded an ICER of $144K/quality-adjusted life-year gained for sunitinib compared with interferon-alfa. This high ratio was not an insurmountable barrier to access in Canada because all provinces now reimburse sunitinib for first-line treatment of MRCC. In this particular instance, payers were receptive to immature survival data but substantial progression-free gains, for patients with a relatively rare cancer and few treatment options.

CONCLUSION

  This demonstrates that the cost-effectiveness ratio is only one of many factors that affect an access decision in oncology.

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.

Renal cell carcinoma: screening, diagnosis, and prognosis

Kidney cancer is most often diagnosed incidentally at the time of radiographic imaging for other complaints. Although numerous improvements and greater use of screening measures have occurred in the setting of renal cell carcinoma (RCC), screening for this disease is usually only carried out for patients who have been identified as having one of the known genetic lineages linked with specific RCC subtypes. This article reviews key concepts in the screening, diagnosis, and prognosis of patients with RCC.

4-Pyridylanilinothiazoles that selectively target von Hippel-Lindau deficient renal cell carcinoma cells by inducing autophagic cell death

Renal cell carcinomas (RCC) are refractory to standard therapy with advanced RCC having a poor prognosis; consequently treatment of advanced RCC represents an unmet clinical need. The von Hippel-Lindau (VHL) tumor suppressor gene is mutated or inactivated in a majority of RCCs. We recently identified a 4-pyridyl-2-anilinothiazole (PAT) with selective cytotoxicity against VHL-deficient renal cells mediated by induction of autophagy and increased acidification of autolysosomes. We report exploration of structure-activity relationships (SAR) around this PAT lead. Analogues with substituents on each of the three rings, and various linkers between rings, were synthesized and tested in vitro using paired RCC4 cell lines. A contour map describing the relative spatial contributions of different chemical features to potency illustrates a region, adjacent to the pyridyl ring, with potential for further development. Examples probing this domain validated this approach and may provide the opportunity to develop this novel chemotype as a targeted approach to the treatment of RCC.

Pazopanib in locally advanced or metastatic renal cell carcinoma: results of a randomized phase III trial

PURPOSE Pazopanib is an oral angiogenesis inhibitor targeting vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit. This randomized, double-blind, placebo-controlled phase III study evaluated efficacy and safety of pazopanib monotherapy in treatment-naive and cytokine-pretreated patients with advanced renal cell carcinoma (RCC). PATIENTS AND METHODS Adult patients with measurable, locally advanced, and/or metastatic RCC were randomly assigned 2:1 to receive oral pazopanib or placebo. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, tumor response rate (Response Evaluation Criteria in Solid Tumors), and safety. Radiographic assessments of tumors were independently reviewed. Results Of 435 patients enrolled, 233 were treatment naive (54%) and 202 were cytokine pretreated (46%). PFS was significantly prolonged with pazopanib compared with placebo in the overall study population (median, PFS 9.2 v 4.2 months; hazard ratio [HR], 0.46; 95% CI, 0.34 to 0.62; P < .0001), the treatment-naive subpopulation (median PFS 11.1 v 2.8 months; HR, 0.40; 95% CI, 0.27 to 0.60; P < .0001), and the cytokine-pretreated subpopulation (median PFS, 7.4 v 4.2 months; HR, 0.54; 95% CI, 0.35 to 0.84; P < .001). The objective response rate was 30% with pazopanib compared with 3% with placebo (P < .001). The median duration of response was longer than 1 year. The most common adverse events were diarrhea, hypertension, hair color changes, nausea, anorexia, and vomiting. There was no evidence of clinically important differences in quality of life for pazopanib versus placebo. CONCLUSION Pazopanib demonstrated significant improvement in PFS and tumor response compared with placebo in treatment-naive and cytokine-pretreated patients with advanced and/or metastatic RCC.

Efficacy and safety of pazopanib in patients with metastatic renal cell carcinoma

PURPOSE

Inactivation of the von Hippel-Lindau gene in clear-cell renal cell carcinomas (RCC) leads to overexpression of hypoxia inducible factor, a transcription factor regulating vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) gene expression. Pazopanib, an angiogenesis inhibitor targeting VEGF receptor, PDGF receptor, and c-KIT, was evaluated in patients with RCC.

PATIENTS AND METHODS

This phase II study was designed as a randomized discontinuation study but was revised to an open-label study on the recommendation of the data monitoring committee (based on week 12 response rate [RR] of 38% in the first 60 patients). The primary end point was changed from progressive disease rate at 16 weeks postrandomization to RR. Pazopanib 800 mg was administered orally once daily. Pazopanib 800 mg was administered orally once daily.

RESULTS

The study enrolled 225 patients with metastatic RCC; 155 patients (69%) were treatment naïve, and 70 patients (31%) had received one prior cytokine- or bevacizumab-containing regimen. Overall RR was 35%; median duration of response was 68 weeks. Median progression-free survival (PFS) was 52 weeks. Eastern Cooperative Oncology Group performance status of 0 and time from diagnosis to treatment of more than 1 year were correlated with prolonged PFS. Pazopanib was generally well tolerated. The most common adverse events were diarrhea, fatigue, and hair depigmentation. The most common laboratory abnormalities were elevated AST and ALT.

CONCLUSION

Pazopanib demonstrated durable activity in patients with advanced RCC and was generally well tolerated in this population. These findings support the further development of pazopanib in advanced RCC.

Incidences of kidney, pelvis, ureter, and bladder cancer in a nationwide, population-based cancer registry, Denmark, 1944-2003

OBJECTIVES

To determine changes in the population-based incidence rates, degree of histologic verification, and morphologic distribution of tumors of the kidney, pelvis, and ureter and bladder in both sexes for the duration of 60 years in Denmark.

METHODS

Age-standardized incidence rates in 5-year age and calendar intervals, histologic verification and morphologic distribution were derived from reports to the Danish Cancer Registry.

RESULTS

The incidence of kidney tumors increased by 78% among men and 32% among women during the study period; the incidence of pelvis and ureter tumors increased by 1070% and 2785%, respectively, and those of bladder tumors increased by 325% and 195%, respectively. The incidence of Wilms tumor was stable; the incidence of other kidney tumors leveled out during the last 30 years of the period and those of other 2 groups during the last 20 years. The frequency of histologic verification was stable for pelvis and ureter cancers and Wilms tumor and increased for kidney and bladder tumors. Most of the kidney tumors were of epithelial origin and most others were of urothelial origin.

CONCLUSIONS

The overall incidences of all tumors increased in both sexes during the 60-year period. Some of the increase could be due to improved diagnosis. The recent decline in rates might be due to reduced exposure to risk factors.

Expression of apoptotic tumour necrosis factor receptor-associated factor, caspase recruitment domain and cell death-inducing DFF-45 effector genes in therapy-treated renal cell carcinoma

AIM

Dysfunction in apoptosis plays a role in development of renal cell carcinoma (RCC). This investigation aimed to identify expression of apoptosis-related genes not previously characterized in human RCC.

METHODS

The RCC ACHN cell line was treated with radiation plus interferon-alpha to induce significant apoptosis. Apoptosis RNA microarrays were used to compare control and treated RCC for apoptosis-regulatory genes with significantly altered expression (>or= twofold). Translational correlates were analysed using western blot. Immunohistochemistry of human RCC and non-cancerous kidney in tissue microarrays was also completed.

RESULTS

Several gene families, not well characterized in RCC, were significantly upregulated in RNA microarray. These were the tumour necrosis factor receptor-associated factors (TRAF1, 3 and 4), caspase recruitment domain (NOL3 and PYCARD), and cell death-inducing DFF-45 effector domain (ICAD/CAD) genes. The protein expression patterns did not always increase similarly, perhaps indicating some post-transcriptional controls needing further investigation. TRAF1 had significantly increased expression for RNA and protein (P<0.01). NOL3 had significantly decreased whole-cell protein expression (P<0.05), but had strongly localized nuclear positivity in RCC in the immunohistochemistry.

CONCLUSION

These newly identified RCC apoptosis genes have shown potential for improving outcome in other cancers and may prove to have the same potential in RCC with further study.

MUC1, a new hypoxia inducible factor target gene, is an actor in clear renal cell carcinoma tumor progression

The hypoxia inducible factor (HIF) signaling pathway is known as the main renal carcinogenetic pathway. MUC1, an O-glycoprotein membrane-bound mucin, is overexpressed in clear renal cell carcinomas (cRCC) with correlation to two major prognostic factors: tumor-node-metastasis stage and nuclear Fürhman grade. We questioned whether there is a direct link between the HIF pathway and MUC1 overexpression in renal tumors. Interestingly, we observed concomitant increase of HIF-1alpha and MUC1 in metastatic cRCC group versus nonmetastatic cRCC group. Using different renal cell models and small interfering RNA assays targeting either HIF-1alpha or YC-1, a HIF-1 pharmacologic inhibitor, we showed induction of MUC1 expression under hypoxia by a HIF-dependent mechanism. Chromatin immunoprecipitation assay showed a direct binding of HIF-1alpha at the MUC1 promoter. In addition, combined site-directed mutagenesis and gel shift assay allowed the identification of two functional putative hypoxia responsive elements at -1488/-1485 and at -1510/-1507 in the promoter. Using a rat kidney model of ischemia/reperfusion, we confirmed in vivo that clamping renal pedicle for 1 hour followed by 2 hours of reperfusion induced increased MUC1 expression. Furthermore, MUC1 knockdown induced significant reduction of invasive and migration properties of renal cancer cells under hypoxia. Altogether, these results show that MUC1 is directly regulated by HIF-1alpha and affects the invasive and migration properties of renal cancer cells. Thus, MUC1 could serve as a potential therapeutic target in cRCC.

Cytoreductive nephrectomy for metastatic RCC in the era of targeted therapy

Metastatic renal cell carcinoma (RCC) has traditionally been associated with a poor prognosis with few effective treatments. In the multimodal treatment of metastatic RCC, cytoreductive nephrectomy (CN) became the standard of care after two randomized trials demonstrated a benefit in overall survival in patients who received CN prior to treatment with interferon. More recently, several agents (sunitinib, sorafenib, temsirolimus, everolimus and bevacizumab) have been developed that target angiogenesis and the cellular growth pathways involved in metastatic RCC. These targeted agents have demonstrated improved outcomes compared to cytokine therapy, and have transformed metastatic RCC treatment. Targeted agents are being used as a first-line systemic treatment in patients with metastatic RCC with unprecedented success, and many studies are now focusing on the role of CN in combination with these agents for patients with metastatic RCC.

How patients make treatment choices

The medical field has undergone a quiet revolution during the past three decades. Patients have been brought into the treatment decision process as never before. Gone are the days when the patient was delivered the diagnosis and simply told how their disorder was to be treated. Rather, widespread use of shared decision making has changed the way that patients and their physicians interact. The development of best clinical practices from concepts of evidence-based medicine has shown that, for many disorders, the various treatment options result in near-equivalent outcomes. More recently, the democratization of medical information by the internet has made the patient a much better informed consumer, and thus a more active participant in his or her own care.

Dedifferentiated chromophobe renal cell carcinoma with massive osteosarcoma-like divergent differentiation: a singular entity in the spectrum of retroperitoneal calcifying tumors

Sarcomatoid change in renal cell carcinoma is the result of the dedifferentiation of the "parent" tumor into a high-grade malignancy characterized by sarcoma-like features and associated with an accelerated clinical course and poorer prognosis. Any of the renal cell carcinoma subtypes can undergo sarcomatoid dedifferentiation, with the chromophobe variant being the most prone. The present report describes the case of a woman affected by a classic chromophobe renal cell carcinoma that developed dedifferentiation accompanied by a very rare osteosarcoma-like divergent differentiation, which constituted about 90% of the entire retroperitoneal mass. In addition to presenting the relevant imaging, histopathological, and immunohistochemical findings, this article briefly discusses the main differential diagnosis of retroperitoneal ossifying/ calcifying masses, which could give rise to diagnostic problems either in small biopsies or at imaging.

Predictors of survival of advanced renal cell carcinoma: long-term results from Southwest Oncology Group Trial S8949

PURPOSE

S8949 demonstrated improved overall survival for debulking nephrectomy in interferon treated patients with advanced renal cell carcinoma. We present an updated analysis of S8949, now with a median followup of 9 years. We explored clinical predictors of overall survival.

MATERIALS AND METHODS

Univariate and multivariate Cox regression analysis was performed to evaluate the impact of clinical variables potentially influencing survival.

RESULTS

Of 246 patients 241 were eligible and randomized to interferon with or without nephrectomy. Patients randomized to nephrectomy continued to have improved overall survival (HR 0.74, 95% CI 0.57-0.96, p = 0.022). Multivariate analysis showed that performance status 1 vs 0 (HR 1.95, p <0.0001), high alkaline phosphatase (HR 1.5, p = 0.002) and lung metastasis only (HR 0.73, p = 0.028) were overall survival predictors. There was no evidence of an interaction of performance status, measurable disease or lung metastases with nephrectomy (each p >0.30). In a patient subset that survived at least 90 days after randomization early progressive disease within 90 days was prognostic of overall survival in a multivariate model (HR 2.1, p <0.0001), as was performance status (HR 1.7, p = 0.0006).

CONCLUSIONS

Nephrectomy prolonged long-term overall survival in this updated analysis, supporting its role as standard therapy in patients with advanced renal cell carcinoma. A nephrectomy benefit was seen across all prespecified patient subsets. Early progressive disease and performance status were strong predictors of overall survival. These results support efforts to identify biomarkers of renal cell carcinoma resistance to treatment and early progressive disease to facilitate rational patient selection for systemic therapy.

Identification of molecular targets in urologic oncology

OBJECTIVES

Molecular targets in cancer diagnosis and therapy have come to the fore of the oncology field in the last decade. Their identification is rooted in basic science investigation and enhanced knowledge in the fields of genetics, biochemistry, molecular and tumor biology, and pathology among others.

METHODS

A medical literature search in English using MEDLINE/PUBMed was performed on the topics of molecular targets, targeted therapy, and biomarkers in the areas of bladder, prostate, and renal cancers. This information was analyzed and combined with the author's personal knowledge in the identification and development of molecular targets. Data is included from the author's laboratory regarding examples of target development and clinical translation.

RESULTS

Molecular targets are often biomarkers; either prognostic ones that reflect the natural history of the cancer or predictive ones that reflect the impact of a therapy. Molecular targets in urologic cancer may arise from four sources: the host, the tumor, as a result of a treatment, or associated with a specific disease stage. Understanding the continuum of targets through the progression of a urologic cancer is central to the translational applications of diagnostics, individualized medicine and targeted therapeutics. Urologists are most familiar with targeted therapy in renal cancer with the introduction of tyrosine kinase inhibitors. Yet, herein are examples of biomarkers and targets across the spectrum of urologic tumors, stages and treatments.

CONCLUSIONS

Identification of events, signals, and pathways in urologic cancer are opportunities to develop biomarkers and targets for diagnosis and treatment.

Survival Analysis of Clear Cell Renal Carcinoma According to the Charlson Comorbidity Index

PURPOSE

We assessed the convenience of elective surgery for clear cell renal carcinoma with regard to overall survival in accordance with established comorbidity criteria.

MATERIAL AND METHODS

This retrospective study included all patients with a histological diagnosis of clear cell renal carcinoma diagnosed between July 1, 1983 and June 1, 2006 in a population of 200,000 inhabitants. All tumors were classified in stages according to the classification of the American Joint Committee on Cancer based on the 2002 UICC TNM classification. Comorbidity in each patient was assessed by the Charlson comorbidity index. Study variables were gender, age, smoking, Charlson index, Charlson index 2 or less and greater than 2, tumor stage, localized stage and locally advanced or metastatic stage. The chi-square or Fisher exact test, or ANOVA was used to analyze the groups, as applicable. Survival associated with each tumor stage and comorbidity group was evaluated by the Kaplan-Meier test. Similarly a binary logistical regression model was used to assess survival after 1, 5 and 10 years. No minimum followup was established for including a patient in the analysis. SPSS, version 12.0 for Windows software was used for statistical analysis with a probability of the null hypothesis of lower than 0.05 considered significant.

RESULTS

A total of 232 renal masses were diagnosed during the study period, of which 192 (82.7%) were useful for the study. There were no significant differences between the genders in age (p = 0.486), stage (p = 0.659) and Charlson index (p = 0.463). Median followup was 1,416 days. Of the 192 patients 33 (17.2%), 28 (14.6%), 32 (16.7%), 29 (15.1%), 32 (16.7%) and 38 (19.8%) showed a Charlson index of 1 to 5 or greater, respectively. Stage was I to IV in 29 (15.1%), 69 (35.9%), 40 (20.8%) and 47 cases (24.5%), respectively. It proved impossible to determine tumor stage in 4 cases (2.1%). There were 72 deaths (37.5%), including 25 (34.7%) from intercurrent disease and 45 (62.5%) from clear cell renal carcinoma. The cause of death could not be determined in 2 cases (2.8%). Survival analysis revealed significant differences in overall survival according to stage (p <0.001) and Charlson index (p = 0.02), between localized stages and locally advanced or metastatic stages (p <0.001) and between patients with a Charlson index of 2 or less vs greater than 2 (p <0.001), particularly in those with local stage (p <0.001) but not in those with locally advanced or metastatic stage (p >0.05). In the logistical regression model tumor stage and the comorbidity index were prognostic factors after 1 year (B exponential 2.4 and 1.3, respectively, p <0.05), after 5 years (B exponential 1.6 and 1.3, p <0.05) and after 10 years (B exponential 1.5 and 1.4, respectively, p <0.05). The first was of greatest importance for short-term survival.

CONCLUSIONS

Patients with localized clear cell renal carcinoma and a comorbidity index of greater than 2 may choose observation as treatment for the condition.

Combined expression of caveolin-1 and an activated AKT/mTOR pathway predicts reduced disease-free survival in clinically confined renal cell carcinoma

We previously reported that tumour-associated caveolin-1 is a potential biomarker in renal cell carcinoma (RCC), whose overexpression predicts metastasis following surgical resection for clinically confined disease. Much attention has recently focused on the AKT/mTOR pathway in a number of malignancies, including RCC. Since caveolin-1 and the AKT/mTOR signalling cascade are independently shown to be important regulators of tumour angiogenesis, we hypothesised that caveolin-1 interacts with the AKT/mTOR pathway to drive disease progression and metastasis in RCC. The aims of this study were to determine (i) the expression status of the activated AKT/mTOR pathway components (phosphorylated forms) in RCC and (ii) their prognostic value when combined with caveolin-1. Immunohistochemistry for caveolin-1, pAKT, pmTOR, pS6 and p4E-BP1 was performed on tissue microarrays from 174 clinically confined RCCs. Significantly decreased mean disease-free survival was observed when caveolin-1 was coexpressed with either pAKT (2.95 vs 6.14 years), pmTOR (3.17 vs 6.28 years), pS6 (1.45 vs 6.62 years) or p4E-BP1 (2.07 vs 6.09 years) than when neither or any one single biomarker was expressed alone. On multivariate analysis, the covariate of ‘caveolin-1/AKT’ (neither alone were influential covariates) was a significant influential indicator of poor disease-free survival with a hazard ratio of 2.13 (95% CI: 1.15–3.92), higher than that for vascular invasion. Tumours that coexpressed caveolin-1 and activated mTOR components were more likely to be larger, higher grade and to show vascular invasion. Our results provide the first clinical evidence that caveolin-1 cooperates with an activated AKT/mTOR pathway in cancer and may play an important role in disease progression. We conclude that evaluation of the ‘caveolin-1/AKT/mTOR axis’ in primary kidney tumours will identify subsets of RCC patients who require greater postoperative surveillance and more intensive treatment.

Nuclear E-cadherin and VHL immunoreactivity are prognostic indicators of clear-cell renal cell carcinoma

The loss of functional von Hippel-Lindau (VHL) tumor suppressor gene is associated with the development of clear-cell renal cell carcinoma (CC-RCC). Recently, VHL was shown to promote the transcription of E-cadherin, an adhesion molecule whose expression is inversely correlated with the aggressive phenotype of numerous epithelial cancers. Here, we performed immunohistochemistry on CC-RCC tissue microarrays to determine the prognostic value of E-cadherin and VHL with respect to Fuhrman grade and clinical prognosis. Low Fuhrman grade and good prognosis associated with positive VHL and E-cadherin immunoreactivity, whereas poor prognosis and high-grade tumors associated with a lack of E-cadherin and lower frequency of VHL staining. A significant portion of CC-RCC with positive VHL immunostaining correlated with nuclear localization of C-terminally cleaved E-cadherin. DNA sequencing revealed in a majority of nuclear E-cadherin-positive CC-RCC, subtle point mutations, deletions and insertions in VHL. Furthermore, nuclear E-cadherin was not observed in chromophobe or papillary RCC, as well as matched normal kidney tissue. In addition, nuclear E-cadherin localization was recapitulated in CC-RCC xenografts devoid of functional VHL or reconstituted with synthetic mutant VHL grown in SCID mice. These findings provide the first evidence of aberrant nuclear localization of E-cadherin in CC-RCC harboring VHL mutations, and suggest potential prognostic value of VHL and E-cadherin in CC-RCC.