Understanding pathologic variants of renal cell carcinoma: distilling therapeutic opportunities from biologic complexity

Clinically localized type 1 and 2 papillary renal cell carcinomas have similar survival outcomes following surgery

PURPOSE

We aimed to determine incidence, pathologic findings, prognostic factors and clinical outcomes for patients with clinically localized papillary RCC.

METHODS

Demographic, clinical and pathologic findings were collected on all patients with PRCC undergoing surgery at four academic medical centers. The primary endpoint was cancer-specific survival (CSS). Relapse-free survival (RFS) and overall survival (OS) were secondary endpoints. Kaplan-Meier estimates were obtained, and Cox proportional hazard regression models were used to assess predictors of mortality and relapse.

RESULTS

We identified 626 PRCC, of which 373 (60 %) were type 1 and 253 (40 %) were type 2, with three-quarters of all tumors being pT1. Compared to patients with type 1, those with type 2 were older (mean age: 63 vs 61; p = 0.02), presented more commonly with symptoms (13 vs 7 %; p = 0.02) and had larger mean tumor size (5.2 vs 4.3 cm; p = 0.001). With a median follow-up of 41 months (IQR: 16-68), 92 patients had died of PRCC (15 %), 48 (8 %) experienced relapse, and 101 died from all causes (16 %). The estimated 5-year CSS, RFS and OS were 83, 91 and 82 %, respectively. In multivariable analysis, older age, T stage and nodal status were predictors of CSS and OS. However, PRCC subtype was not a predictor of CSS, RFS or OS.

CONCLUSION

While patients with type 2 PRCC appear to present with more advanced disease than patients with type 1, PRCC subtype does not appear to be an independent predictor of CSS, RFS or OS for treated localized disease.

Expression pattern of autophagy-related markers in non-metastatic clear cell renal cell carcinoma: association with disease recurrence following radical nephrectomy

PURPOSE

To evaluate the expression of multiple molecular markers associated with autophagy, a cellular degradation pathway for the clearance of damaged or superfluous proteins and organelles, in clear cell renal cell carcinoma (CCRCC) in order to identify the prognostic significance of these markers in patients undergoing radical nephrectomy.

METHODS

Expression levels of five markers, including autophagy-related gene 5 (Atg5), Atg9, Beclin 1, microtubule-associated protein light chain 3 (LC3), and UNC-51-like kinase 1 (ULK1), in radical nephrectomy specimens from a total of 100 patients with non-metastatic CCRCC were measured by immunohistochemical staining.

RESULTS

All the five markers were significantly correlated with some pathological factors reflecting an aggressive phenotype, including the pathological T stage, tumor grade, and microvascular invasion. During the follow-up period of this series (median 58.0 months), disease recurrence developed in 41 of the 100 patients, with a 5-year recurrence-free survival (RFS) rate of 61.3%. On univariate analysis, expression levels of Atg5 and Beclin 1, in addition to the pathological T stage, microvascular invasion, and preoperative CRP level, were identified as significant predictors of disease recurrence. Of these factors, the expression of Beclin 1 and preoperative CRP level were independently correlated with RFS on multivariate analysis.

CONCLUSION

These findings suggest that the combined assessment of expression levels of autophagy-associated markers, particularly Beclin 1, in radical nephrectomy specimens with conventional prognostic parameters, would contribute to the precise prediction of postoperative disease recurrence in patients with non-metastatic CCRCC.

The hallmarks of cancer: relevance to the pathogenesis of polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive inherited disorder in which renal tissue is gradually replaced with fluid-filled cysts, giving rise to chronic kidney disease (CKD) and progressive loss of renal function. ADPKD is also associated with liver ductal cysts, hypertension, chronic pain and extra-renal problems such as cerebral aneurysms. Intriguingly, improved understanding of the signalling and pathological derangements characteristic of ADPKD has revealed marked similarities to those of solid tumours, even though the gross presentation of tumours and the greater morbidity and mortality associated with tumour invasion and metastasis would initially suggest entirely different disease processes. The commonalities between ADPKD and cancer are provocative, particularly in the context of recent preclinical and clinical studies of ADPKD that have shown promise with drugs that were originally developed for cancer. The potential therapeutic benefit of such repurposing has led us to review in detail the pathological features of ADPKD through the lens of the defined, classic hallmarks of cancer. In addition, we have evaluated features typical of ADPKD, and determined whether evidence supports the presence of such features in cancer cells. This analysis, which places pathological processes in the context of defined signalling pathways and approved signalling inhibitors, highlights potential avenues for further research and therapeutic exploitation in both diseases.

National nephrectomy registries: Reviewing the need for population-based data

Nephrectomy is the cornerstone therapy for renal cell carcinoma (RCC) and continued refinement of the procedure through research may enhance patient outcomes. A national nephrectomy registry may provide the key information needed to assess the procedure at a national level. The aim of this study was to review nephrectomy data available at a population-based level in Australia and to benchmark these data against data from the rest of the world as an examination of the national nephrectomy registry model. A PubMed search identified records pertaining to RCC nephrectomy in Australia. A similar search identified records relating to established nephrectomy registries internationally and other surgical registries of clinical importance. These records were reviewed to address the stated aims of this article. Population-based data within Australia for nephrectomy were lacking. Key issues identified were the difficulty in benchmarking outcomes and no ongoing monitoring of trends. The care centralization debate, which questions whether small-volume centers provide comparable outcomes to high-volume centers, is ongoing. Patterns of adherence and the effectiveness of existing protocols are uncertain. A review of established international registries demonstrated that the registry model can effectively address issues comparable to those identified in the Australian literature. A national nephrectomy registry could address deficiencies identified in a given nation's nephrectomy field. The model is supported by evidence from international examples and will provide the population-based data needed for studies. Scope exists for possible integration with other registries to develop a more encompassing urological or surgical registry. Need remains for further exploration of the feasibility and practicalities of initiating such a registry including a minimum data set, outcome indicators, and auditing of data.

Three Dimensional Culture of Human Renal Cell Carcinoma Organoids

Renal cell carcinomas arise from the nephron but are heterogeneous in disease biology, clinical behavior, prognosis, and response to systemic therapy. Development of patient-specific in vitro models that efficiently and faithfully reproduce the in vivo phenotype may provide a means to develop personalized therapies for this diverse carcinoma. Studies to maintain and model tumor phenotypes in vitro were conducted with emerging three-dimensional culture techniques and natural scaffolding materials. Human renal cell carcinomas were individually characterized by histology, immunohistochemistry, and quantitative PCR to establish the characteristics of each tumor. Isolated cells were cultured on renal extracellular matrix and compared to a novel polysaccharide scaffold to assess cell-scaffold interactions, development of organoids, and maintenance of gene expression signatures over time in culture. Renal cell carcinomas cultured on renal extracellular matrix repopulated tubules or vessel lumens in renal pyramids and medullary rays, but cells were not observed in glomeruli or outer cortical regions of the scaffold. In the polysaccharide scaffold, renal cell carcinomas formed aggregates that were loosely attached to the scaffold or free-floating within the matrix. Molecular analysis of cell-scaffold constructs including immunohistochemistry and quantitative PCR demonstrated that individual tumor phenotypes could be sustained for up to 21 days in culture on both scaffolds, and in comparison to outcomes in two-dimensional monolayer cultures. The use of three-dimensional scaffolds to engineer a personalized in vitro renal cell carcinoma model provides opportunities to advance understanding of this disease.

Oncocytic Renal Cell Carcinoma with Tubulopapillary Growth Having a Fat Component

We report a rare case of oncocytic renal cell carcinoma (RCC) with tubulopapillary growth in the background of tuberculous end-stage kidney disease. Histology of the renal mass consisted of oncocytic cells forming solid, thin tubules and rare papillae. The tumor had abundant eosinophilic oncocytic cells containing occasional cytoplasmic Mallory body–like hyaline globules and a tiny focus of clear cells with intervening mature fat. Both the oncocytic cells and clear cells were immunoreactive for a-methylacyl-CoA racemase, vimentin, pancytokeratin, and CD10, and negative for transcription factor E3, CD15, human melanoma black 45, and c-kit. Mallory body–like hyaline globules were positive for CAM 5.2 and periodic acid–Schiff with or without diastase. Ultrastructurally, the tumor cells had abundant cytoplasmic mitochondria. The present case is a rare case of oncocytic RCC with tubulopapillary growth pattern. The case is unique in that the tumor was mixed with fat component, which is not common in RCC and thus can lead to misdiagnosis.

Survival Prediction of Clear Cell Renal Cell Carcinoma Based on Gene Expression Similarity to the Proximal Tubule of the Nephron

There is evidence that molecular features support subclassification of tumours, thereby improving prediction of patient outcome. Currently, two gene expression signatures (ccA/ccB and ClearCode34) have been established to classify clear cell renal cell carcinoma (ccRCC). Because RCC arises from nephron cell types, we aimed to explore its heterogeneity on a molecular level by comparing gene expression between tumour tissue and nephron regions. Based on genes that differ in expression between nephron regions, expression data of 479 ccRCCs and 212 papillary and 66 chromophobe RCCs from The Cancer Genome Atlas were correlated to those of nephron cell types. Cancer-specific survival (CSS) of ccRCC patients was significantly associated with gene expression similarity to the proximal tubules. Subsequently, a ccRCC risk score (S3-score) was established. Survival analyses indicated that the S3-score was significantly associated with CSS considering all cases of ccRCC, as well as metastatic and nonmetastatic ccRCC. Results could be validated in an independent cohort. The S3-score significantly improved the predictive ability of the ccA/ccB and ClearCode34 signatures, and the clinicopathologic-based stage, size, grade, and necrosis score (p [chi-square] = 1.56E-04). Intratumour heterogeneity of the S3-score was observed in 6 of 10 ccRCCs. In summary, the nephron-based S3-score enables prognostic risk stratification for ccRCC. Further studies are needed to evaluate its clinical utility.

PATIENT SUMMARY

We developed a novel risk score for clear cell renal cell carcinoma to identify patients at risk of worse outcome that may improve patient care in the future.

Comparison of the prognostic value of pretreatment measurements of systemic inflammatory response in patients undergoing curative resection of clear cell renal cell carcinoma

PURPOSE

Pretreatment measurements of systemic inflammatory response, including the Glasgow prognostic score (GPS), the neutrophil-to-lymphocyte ratio (NLR), the monocyte-to-lymphocyte ratio (MLR), the platelet-to-lymphocyte ratio (PLR) and the prognostic nutritional index (PNI) have been recognized as prognostic factors in clear cell renal cell carcinoma (CCRCC), but there is at present no study that compared these markers.

METHODS

We evaluated the pretreatment GPS, NLR, MLR, PLR and PNI in 430 patients, who underwent surgery for clinically localized CCRCC (pT1-3N0M0). Associations with disease-free survival were assessed with Cox models. Discrimination was measured with the C-index, and a decision curve analysis was used to evaluate the clinical net benefit.

RESULTS

On multivariable analyses, all measures of systemic inflammatory response were significant prognostic factors. The increase in discrimination compared with the stage, size, grade and necrosis (SSIGN) score alone was 5.8 % for the GPS, 1.1-1.4 % for the NLR, 2.9-3.4 % for the MLR, 2.0-3.3 % for the PLR and 1.4-3.0 % for the PNI. On the simultaneous multivariable analysis of all candidate measures, the final multivariable model contained the SSIGN score (HR 1.40, P < 0.001), the GPS (HR 2.32, P < 0.001) and the MLR (HR 5.78, P = 0.003) as significant variables. Adding both the GPS and the MLR increased the discrimination of the SSIGN score by 6.2 % and improved the clinical net benefit.

CONCLUSIONS

In patients with clinically localized CCRCC, the GPS and the MLR appear to be the most relevant prognostic measures of systemic inflammatory response. They may be used as an adjunct for patient counseling, tailoring management and clinical trial design.

Expression Profiles and Clinical Significance of MicroRNAs in Papillary Renal Cell Carcinoma: A STROBE-Compliant Observational Study

Papillary renal cell carcinoma (pRCC) is the second most prevalent subtype of kidney cancers. In the current study, we analyzed the global microRNA (miRNA) expression profiles in pRCC, with the aim to evaluate the relationship of miRNA expression with the progression and prognosis of pRCC.A total of 163 treatment-naïve primary pRCC patients were identified from the Cancer Genome Atlas dataset and included in this retrospective observational study. The miRNA expression profiles were graded by tumor-node-metastasis information, and compared between histologic subtypes. Furthermore, the training-validation approach was applied to identify miRNAs of prognostic values, with the aid of Kaplan-Meier survival, and univariate and multivariate Cox regression analyses. Finally, the online DAVID (Database for Annotation, Visualization, and Integrated Discover) program was applied for the pathway enrichment analysis with the target genes of prognosis-associated miRNAs, which were predicted by 3 computational algorithms (PicTar, TargetScan, and Miranda).In the progression-related miRNA profiles, 26 miRNAs were selected for pathologic stage, 28 for pathologic T, 16 for lymph node status, 3 for metastasis status, and 32 for histologic types, respectively. In the training stage, the expression levels of 12 miRNAs (mir-134, mir-379, mir-127, mir-452, mir-199a, mir-200c, mir-141, mir-3074, mir-1468, mir-181c, mir-1180, and mir-34a) were significantly associated with patient survival, whereas mir-200c, mir-127, mir-34a, and mir-181c were identified by multivariate Cox regression analyses as potential independent prognostic factors in pRCC. Subsequently, mir-200c, mir-127, and mir-34a were confirmed to be significantly correlated with patient survival in the validation stage. Finally, target gene prediction analysis identified a total of 113 target genes for mir-200c, 37 for mir-127, and 180 for mir-34a, which further generated 15 molecular pathways.Our results identified the specific miRNAs associated with the progression and aggressiveness of pRCC, and 3 miRNAs (mir-200c, mir-127, and mir-34a) as promising prognostic factors of pRCC.

A tumor-specific microRNA signature predicts survival in clear cell renal cell carcinoma

PURPOSE

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancers in adults, and microRNAs (miRNAs) differentially expressed in ccRCC tumors have been identified and proposed to predict prognosis. In the present study, we comprehensively analyzed the genome-wide miRNA expression profiles in ccRCC, with the aim to generate a tumor-specific miRNA signature of prognostic values.

METHODS

The miRNA profiles in tumor and the adjacent normal tissue were analyzed, and the association of the differentially expressed miRNAs with patient survival was examined with univariate Cox regression analysis. Finally, a tumor-specific miRNA signature was generated and examined with Kaplan-Meier survival, univariate, and multivariate Cox regression analyses.

RESULTS

A total of 147 miRNAs were found differentially expressed between tumor and matched non-tumor tissues from 58 ccRCC patients. The prognostic values of these differentially expressed miRNAs were subsequently analyzed in the 411 ccRCC patients, and 22 miRNAs were found significantly correlated with patient survival. Finally, a tumor-specific miRNA signature of 22 miRNAs was generated and validated as an independent prognostic parameter.

CONCLUSIONS

A tumor-specific miRNA signature consisting of 22 miRNAs was identified and validated as an independent prognostic factor, which could serve as a novel biomarker for ccRCC prognostication and help in predicting treatment outcome.

Profilin-1 expression is associated with high grade and stage and decreased disease-free survival in renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is associated with high mortality, although individual outcomes are highly variable. Identification of patients with increased risk of disease progression can guide customizing management plan according to disease severity. Profilin-1 (Pfn1) has been recently identified as overexpressed in metastatic ccRCC compared with primary tumors. We examined Pfn1 expression in a tissue microarray of 384 cases of histologically confirmed primary ccRCC with detailed clinical follow-up. Profilin-1 expression showed both cytoplasmic and nuclear staining patterns. The immunoexpression of Pfn1 was scored in a semiquantitative fashion. There was no significant difference in Pfn1 expression between normal kidney and kidney ccRCC. Our results show that strong cytoplasmic Pfn1 expression is associated with high-grade (P < .001) and high-stage (III-IV) (P = .018) disease. Univariate analysis of the data set showed that higher Pfn1 expression is associated with significantly shorter disease-free survival (hazard ratio 7.36, P = .047) and also lower overall survival. Kaplan-Meier analysis showed that high cytoplasmic expression of Pfn1 was also associated with a statistically significant lower disease-free survival (P = .018). It was also associated with lower overall survival, although this was not statistically significant. Profilin-1 lost its prognostic significance in the multivariate analysis when controlling for grade and stage. Profilin-1 expression was not associated with significant prognostic deference in the subgroup of patients with stage 1 disease. Our results suggest that the evaluation of Pfn1 by immunohistochemistry may help to identify patients with an increased risk of disease progression. We validated our results at the messenger RNA level on an independent patient cohort. Higher messenger RNA expression of Pfn1 is associated with significantly lower survival.

Genomic Analysis as the First Step toward Personalized Treatment in Renal Cell Carcinoma

Drug resistance mechanisms in renal cell carcinoma (RCC) still remain elusive. Although most patients initially respond to targeted therapy, acquired resistance can still develop eventually. Most of the patients suffer from intrinsic (genetic) resistance as well, suggesting that there is substantial need to broaden our knowledge in the field of RCC genetics. As molecular abnormalities occur for various reasons, ranging from single nucleotide polymorphisms to large chromosomal defects, conducting whole-genome association studies using high-throughput techniques seems inevitable. In principle, data obtained via genome-wide research should be continued and performed on a large scale for the purposes of drug development and identification of biological pathways underlying cancerogenesis. Genetic alterations are mostly unique for each histological RCC subtype. According to recently published data, RCC is a highly heterogeneous tumor. In this paper, the authors discuss the following: (1) current state-of-the-art knowledge on the potential biomarkers of RCC subtypes; (2) significant obstacles encountered in the translational research on RCC; and (3) recent molecular findings that may have a crucial impact on future therapeutic approaches.