Towards a new WHO classification of renal cell tumor: what the clinician needs to know-a narrative review

Loss of SETD2 in wild-type VHL clear cell renal cell carcinoma sensitizes cells to STF-62247 and leads to DNA damage, cell cycle arrest, and cell death characteristic of pyroptosis

Loss of chromosome 3p and loss of heterogeneity of the von Hippel-Lindau (VHL) gene are common characteristics of clear cell renal cell carcinoma (ccRCC). Despite frequent mutations on VHL, a fraction of tumors still grows with the expression of wild-type (WT) VHL and evolve into an aggressive subtype. Additionally, mutations on chromatin-modifying genes, such as the gene coding for the histone methyltransferase SET containing domain 2 (SETD2), are essential to ccRCC evolution. We previously identified STF-62247, a small molecule first discovered as a synthetically lethal molecule for VHL-deficient cells by blocking late stages of autophagy. This study investigated how other commonly mutated genes in ccRCC could impact the response to STF-62247. We showed that SETD2 inactivation in ccRCC cells expressing WT-VHL became vulnerable to STF-62247, as indicated by decreases in cell proliferation and survival. Furthermore, activation of the DNA damage response pathway leads to the loss of M-phase inducer phosphatase 1 (CDC25A) and cell cycle arrest in S phase. Cleavage of both caspase-3 and gasdermin E suggests that STF-62247 eliminates WT-VHL ccRCC cells through pyroptosis specifically when SETD2 is inactivated.

Varieties of altered TFE3 can occur in MiT-family-related renal cell carcinomas

BACKGROUND

In TFE3 translocation renal cell carcinoma (RCC), rearrangements involving the TFE3 gene can lead to overexpression of the TFE3 transcription factor. This upregulation increases lysosomal activity and autophagy, which in turn contributes to tumor cell proliferation. Although TFE3 translocation RCC is one of the more extensively studied RCC subtypes, other genetic abnormalities, such as gene copy number alterations, may also play a role in disease development. Accordingly, this study aimed to more precisely categorize TFE3-altered RCC variants using fluorescence in situ hybridization (FISH), while also evaluating their histopathological characteristics and clinical behavior.

METHODS

In this retrospective study spanning the past 9 years, 16 cases of renal cell carcinoma (RCC) were examined for TFE3 gene alterations using FISH. The cohort was divided into two groups: TFE3-altered RCC cases as the positive group (n = 6) and TFE3-negative RCC cases as the negative group (n = 10). TFE3 alterations, tumor pathology, and clinical outcomes were systematically evaluated.

RESULTS

The age of patients with TFE3-altered RCC ranged from 6 to 70 years old. There were five female patients and one male patient, which is consistent with the known female predominance of this RCC subtype. The TFE3 alterations observed in this cohort included: TFE3 gene rearrangement (n = 1), TFE3 gene rearrangement with copy number gain (n = 1), copy number gain of intact TFE3 gene (n = 3), and copy number loss of TFE3 gene (n = 1). Clinical outcomes varied, with some patients experiencing poor prognoses, including the development of distant metastases.

CONCLUSIONS

Our data show that TFE3 alterations in RCC span a range of genetic events, from gene rearrangements to copy number variations, as determined by FISH. These TFE3-altered RCCs in adults may be associated with unfavorable outcomes, underscoring the value of FISH in both diagnosing and refining our understanding of TFE3-altered RCC.

Hallmark discoveries in the biology of non-Wilms tumour childhood kidney cancers

Approximately 20% of paediatric and adolescent/young adult patients with renal tumours are diagnosed with non-Wilms tumour, a broad heterogeneous group of tumours that includes clear-cell sarcoma of the kidney, congenital mesoblastic nephroma, malignant rhabdoid tumour of the kidney, renal-cell carcinoma, renal medullary carcinoma and other rare histologies. The differential diagnosis of these tumours dates back many decades, when these pathologies were identified initially through clinicopathological observation of entities with outcomes that diverged from Wilms tumour, corroborated with immunohistochemistry and molecular cytogenetics and, subsequently, through next-generation sequencing. These advances enabled near-definitive recognition of different tumours and risk stratification of patients. In parallel, the generation of new renal-tumour models of some of these pathologies including cell lines, organoids, xenografts and genetically engineered mouse models improved our understanding of the development of these tumours and have facilitated the identification of new therapeutic targets. Despite these many achievements, paediatric and adolescent/young adult patients continue to die from such rare cancers at higher rates than patients with Wilms tumour. Thus, international coordinated efforts are needed to answer unresolved questions and improve outcomes.

Clinical and molecular prognostic nomograms for patients with papillary renal cell carcinoma

OBJECTIVE

To summarize the clinicopathological characteristics and prognostic factors of papillary renal cell carcinoma (pRCC) and to construct clinical and molecular prognostic nomograms using existing databases.

METHODS

Clinical prognostic models were developed using the Surveillance, Epidemiology, and End Results (SEER) database, while molecular prognostic models were constructed using The Cancer Genome Atlas (TCGA) database. Cox regression and LASSO regression were employed to identify clinicopathological features and molecular markers related to prognosis. The accuracy of the prognostic models was assessed using ROC curves, C-index, decision curve analysis (DCA) curves, and calibration plots.

RESULTS

In the 2004-2015 SEER cohort, Cox regression analysis revealed that age, grade, AJCC stage, N stage, M stage, and surgery were independent predictors of overall survival (OS) and cancer-specific survival (CSS) in pRCC patients. ROC curves, C-index, and DCA curves indicated that the prognostic nomogram based on clinical independent predictors had better predictive ability than TNM staging and SEER staging. Additionally, in the TCGA cohort, M stage, clinical stage, and the molecular markers IDO1 and PLK1 were identified as independent risk factors. The prognostic nomogram based on molecular independent risk factors effectively predicted the 3-year and 5-year OS and CSS for pRCC patients.

CONCLUSIONS

The clinical and molecular nomograms constructed in this study provide robust predictive tools for individualized prognosis in pRCC patients, offering better accuracy than traditional staging systems.

Pediatric thyroid-like follicular renal cell carcinoma-a post-neuroblastoma case with comprehensive genomic profiling data

Thyroid-like follicular renal cell carcinoma (TLFRCC), an emerging subtype of renal cell carcinoma, presents diagnostic challenges due to its resemblance to normal thyroid tissue. Here, we report a rare case of TLFRCC in a pediatric patient, a demographic rarely affected by this subtype. Histologically resembling a typical TLFRCC, our case exhibited unique features including post-neuroblastoma development, occurrence in a male teenager, and diffuse MelanA expression, which has not been previously reported in TLFRCC. Comprehensive genomic profiling revealed the EWSR1::PATZ1 fusion, confirming its genetic basis. Due to the advanced tumor stage, the patient received combined immunotherapy, and after a 9-month follow-up, remains tumor-free. Our case broadens the diagnostic spectrum of pediatric renal cell carcinomas, highlighting the importance of comprehensive molecular profiling in rare subtypes such as TLFRCC. Further research is needed to better understand TLFRCC's genetic landscape and optimize therapeutic strategies, especially in pediatric populations with evolving treatment protocols.

Acquired cystic disease associated renal cell carcinoma: A clinicopathologic and molecular study of 31 tumors

Acquired cystic disease associated renal cell carcinomas (ACD-RCC) are rare and their molecular and histopathological characteristics are still being explored. We therefore investigated the clinicopathologic and molecular characteristics of 31 tumors. The patients were predominantly male (n = 30), with tumors mainly left-sided (n = 17), unifocal (n = 19), and unilateral (n = 29) and a mean tumor size of 25 mm (range, 3-65 mm). Microscopically, several histologic patterns were present, including pure classic sieve-like (n = 4), and varied proportions of mixed classic sieve-like with papillary (n = 23), tubulocystic (n = 9), compact tubular (n = 4) and solid (n = 1) patterns. Calcium-oxalate crystals were seen in all tumors. Molecular analysis of 9 tumors using next generation sequencing showed alterations in SMARCB1 in 3 tumors (1 with frameshift deletion and 2 with copy number loss in chromosome 22 involving SMARCB1 region), however, INI1 stain was retained in all. Nonrecurrent genetic alterations in SETD2, NF1, NOTCH4, BRCA2 and CANT1 genes were also seen. Additionally, MTOR p.Pro351Ser was identified in one tumor. Copy number analysis showed gains in chromosome 16 (n = 5), 17 (n = 2) and 8 (n = 2) as well as loss in chromosome 22 (n = 2). In summary, ACD-RCC is a recognized subtype of kidney tumors, with several histological architectural patterns. Our molecular data identifies genetic alterations in chromatin modifying genes (SMARCB1 and SETD2), which may suggest a role of such genes in ACD-RCC development.

Incidental Detection of TFEB-Amplified Renal Cell Carcinoma by Colocated Gene Amplification of CCND3 (6p21): A Case Report and Review of the Literature

TFEB-amplified renal cell carcinoma (RCC), which belongs to the MITF family of RCC, is characterized by genomic amplification at the 6p21.1 locus where the TFEB gene is located. The vascular endothelial growth factor A and cyclin D3 genes are also located at this same locus. When tumors lack classic morphologic features, they may be classified as "RCC not otherwise specified (NOS)." However, it is increasingly important to accurately diagnose the RCC subtype to define the patient's individual prognosis and select the subsequent therapeutic modalities, which now include targeted agents. Therefore, knowledge of the diagnostic features of TFEB-altered RCCs, such as t(6;11) RCCs and TFEB-amplified RCCs, is critical for identifying these tumors. Herein, we present an interesting case of TFEB-amplified RCC that was initially diagnosed as RCC NOS on biopsy of a renal tumor in a community practice setting with available molecular findings demonstrating CCND3 amplification. The genetic abnormality was "accidentally" detected due to the amplification of the colocated CCND3 gene at the 6p21 locus of the TFEB gene on a limited genetic sequencing panel. This case highlights the importance of molecular tests in accurately diagnosing RCC and carefully interpreting molecular findings in the context of histomorphologic features.

Navigating the ICI Combination Treatment Journey: Patterns of Response and Progression to First-Line ICI-Based Combination Treatment in Metastatic Renal Cell Carcinoma

The use of immune checkpoint inhibitors (ICIs) in combination with tyrosine kinase inhibitors or other ICIs has significantly improved the prognosis for patients with mccRCC. This marks a major milestone in the treatment of mccRCC. Nonetheless, most patients will discontinue first-line therapy. In this narrative review, we analyze the different patterns of treatment discontinuation in the four pivotal phase III trials that have shown an improvement in overall survival in mccRCC first-line therapy, starting from 1 January 2017 to 1 June 2023. We highlight the different discontinuation scenarios and their influences on subsequent treatment options, aiming to provide more data to clinicians to navigate a complex decision-making process through a narrative review approach. We have identified several causes for discontinuations for patients treated with ICI-based combinations, such as interruption for drug-related adverse events, ICI treatment completion, treatment discontinuation due to complete response or maximum clinical benefit, or due to progression (pseudoprogression, systemic progression, and oligoprogression); for each case, an extensive analysis of the trials and current medical review has been conducted.

Effect of smoking, hypertension and lifestyle factors on kidney cancer - perspectives for prevention and screening programmes

Renal cell carcinoma (RCC) incidence has doubled over the past few decades. However, death rates have remained stable as the number of incidental renal mass diagnoses peaked. RCC has been recognized as a European health care issue, but to date, no screening programmes have been introduced. Well-known modifiable risk factors for RCC are smoking, obesity and hypertension. A direct association between cigarette consumption and increased RCC incidence and RCC-related death has been reported, but the underlying mechanistic pathways for this association are still unclear. Obesity is associated with an increased risk of RCC, but interestingly, improved survival outcomes have been reported in obese patients, a phenomenon known as the obesity paradox. Data on the association between other modifiable risk factors such as diet, dyslipidaemia and physical activity with RCC incidence are conflicting, and potential mechanisms underlying these associations remain to be elucidated.

Artificial Intelligence in Renal Cell Carcinoma Histopathology: Current Applications and Future Perspectives

Renal cell carcinoma (RCC) is characterized by its diverse histopathological features, which pose possible challenges to accurate diagnosis and prognosis. A comprehensive literature review was conducted to explore recent advancements in the field of artificial intelligence (AI) in RCC pathology. The aim of this paper is to assess whether these advancements hold promise in improving the precision, efficiency, and objectivity of histopathological analysis for RCC, while also reducing costs and interobserver variability and potentially alleviating the labor and time burden experienced by pathologists. The reviewed AI-powered approaches demonstrate effective identification and classification abilities regarding several histopathological features associated with RCC, facilitating accurate diagnosis, grading, and prognosis prediction and enabling precise and reliable assessments. Nevertheless, implementing AI in renal cell carcinoma generates challenges concerning standardization, generalizability, benchmarking performance, and integration of data into clinical workflows. Developing methodologies that enable pathologists to interpret AI decisions accurately is imperative. Moreover, establishing more robust and standardized validation workflows is crucial to instill confidence in AI-powered systems' outcomes. These efforts are vital for advancing current state-of-the-art practices and enhancing patient care in the future.

Succinate Dehydrogenase Defects Giant Renal Cell Carcinoma

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a new subtype of RCC included in the 2016 edition of the WHO classification in RCC. SDH-defective RCC accounts for 0.05-0.2%, and preoperative diagnosis is difficult. We report a severe adherent RCC of inferior vena cava that underwent open radical nephrectomy after preoperative renal artery embolization. Postoperative histopathological examination diagnosed SDH-defective RCC; the clinicopathological stage was pT2b. After 10 months of follow-up, the patient had no evidence of disease recurrence. For patients with large RCC, interventional embolization can be selected to reduce intraoperative bleeding and blood transfusion, and it is recommended to complete interventional surgery within 3-4 h before surgery. SDH-deficient RCC is difficult to distinguish from other renal tumors in imaging, so immunohistochemical examination of SDHB is recommended for young and middle-aged patients, especially those under 45.

Selective HIF2A Inhibitors in the Management of Clear Cell Renal Cancer and Von Hippel-Lindau-Disease-Associated Tumors

Von Hippel-Lindau (VHL) loss is the hallmark event characterizing the clear cell renal cancer subtype (ccRCC). Carriers of germinal VHL mutations have an increased prevalence of kidney cysts and ccRCC as well as hemangioblastoma, pheochromocytoma and pancreatic neuroendocrine tumors. In both sporadic and inherited ccRCC, the primary mechanism of VHL-mediated carcinogenesis is the abnormal stabilization of hypoxia-inducible factors (HIF1A and HIF2A). While HIF1A acts as a tumor suppressor and is frequently lost through inactivating mutations/14q chromosome deletions, HIF2A acts as an oncogene promoting the expression of its target genes (VEGF, PDGF, CAIX Oct4, among others). Selective HIF2a inhibitors block the heterodimerization between HIF2A and ARNT, stopping HIF2A-induced transcription. Several HIF2A inhibitors have entered clinical trials, where they have shown a favorable toxicity profile, characterized by anemia, fatigue and edema and promising activity in heavily pretreated ccRCC patients. Belzutifan, a second-generation HIF2a inhibitor, was the first to receive FDA approval for the treatment of unresectable ccRCC in VHL syndrome. In this review, we recapitulate the rationale for HIF2a blockade in ccRCC, summarize the development of HIF2a inhibitors from preclinical models up to its introduction to the clinic with emphasis on Belzutifan, and discuss their role in VHL disease management.

Evolving Treatment Options for Metastatic Renal Cell Carcinoma (mRCC)

Approximately a third of patients diagnosed with kidney cancer in the United States present with advanced disease and those who present with distant metastases historically had dismal 5-year relative survival. However, over the last several years, advancements have led to improved life expectancy and patient outcomes in those who develop advanced renal cell carcinoma. Metastatic clear cell renal cell carcinoma (mccRCC) treatment has rapidly evolved with multiple drug approvals since 2006. Moreover, multiple combination regimens including a vascular endothelial growth factor tyrosine kinase inhibitor (VEGF-TKI) plus immune checkpoint inhibitor (ICI) and the combination of ipilimumab plus nivolumab have supplanted first-line VEGF-TKI monotherapy. Thus, the insights we gained from prospective randomized controlled trials focusing on systemic therapy beyond first-line therapy in mRCC patients treated in the TKI monotherapy era quickly became less relevant with the adoption of contemporary first-line combination regimens. Herein, we will review contemporary first- and second-line therapies for mccRCC, as well as highly anticipated clinical trials looking into novel regimens beyond first-line therapy in patients who have received combination therapy.

Identification and validation of NFIA as a novel prognostic marker in renal cell carcinoma

Prognostic tools are an essential component of the clinical management of patients with renal cell carcinoma (RCC). Although tumour stage and grade can provide important information, they fail to consider patient- and tumour-specific biology. In this study, we set out to find a novel molecular marker of RCC by using hepatocyte nuclear factor 4A (HNF4A), a transcription factor implicated in RCC progression and malignancy, as a blueprint. Through transcriptomic analyses, we show that the nuclear factor I A (NFIA)-driven transcription network is active in primary RCC and that higher levels of NFIA confer a survival benefit. We validate our findings using immunohistochemical staining and analysis of a 363-patient tissue microarray (TMA), showing for the first time that NFIA can independently predict poor cancer-specific survival in clear cell RCC (ccRCC) patients (hazard ratio = 0.46, 95% CI = 0.24-0.85, p value = 0.014). Furthermore, we confirm the association of HNF4A with higher grades and stages in ccRCC in our TMA cohort. We present novel data that show HNF4A protein expression does not confer favourable prognosis in papillary RCC, confirming our survival analysis with publicly available HNF4A RNA expression data. Further work is required to elucidate the functional role of NFIA in RCC as well as the testing of these markers on patient material from diverse multi-centre cohorts, to establish their value for the prognostication of RCC.

Clinical features and Surgical Outcome of Clear Cell Papillary Renal Cell Tumor: result from a prospective cohort

BACKGROUND

Clear cell papillary renal cell tumor (CCPRCT) was first reported in 2006 a patient with end stage renal disease. After that it was discovered in the kidney without end stage renal disease in the 2010s and started to be mentioned in pathology and urology. The incidence of CCPRCT is low and most of it is discovered incidentally, so there is a lack of reports on clinical characteristics and surgical outcome.

METHODS

This study used clinical data from the Seoul National University Prospectively Enrolled Registry for Renal Cell Carcinoma-Nephrectomy (SUPER-RCC-Nx). Between August 2016 and July 2022, patients who underwent radical or partial nephrectomy with clear cell papillary RCC with pathological finding were included in this study. All patients' pathologic reports were reviewed by 1 pathologist. Clinical characteristics and surgical outcomes were presented through descriptive statistics, and Kaplan-Meier curve used for survival analysis.

RESULTS

Of the 2057 patients, CCPRCT was reported in 36 patients (1.8%). The median follow up period was 26.8 months. The median age was 67 years, and there were 10 females and 26 males. The median tumor size was 1.2 cm. Twenty-nine patients underwent partial nephrectomy. Seven patients with end-stage renal disease underwent radical nephrectomy. The median operative time for patients who underwent partial nephrectomy was 97.5 min and the estimated blood loss was 100 cc. The median hospital days was 4 and 30-day complications were 2 cases with clavien-dindo classification III or higher. During the follow-up period, there was no recurrence and cancer specific mortality.

CONCLUSIONS

The size of CCPRCT was small and there was no advanced stage at that time of diagnosis. There was no recurrence or cancer specific mortality during the follow-up period. A multi-center study with a large scale is needed in the future.

TRIAL REGISTRATION

Seoul National University Hospital (SNUH) Institutional Review Board (IRB) (approval number: 2210-126-1371).

Durable Response to Pazopanib in a Patient with Fumarate Hydratase-Mutant Tubulocystic Renal Cell Carcinoma

Tubulocystic carcinoma of the kidney (TC-RCC) is a rare renal tumor and has been recently included as a distinct entity in WHO classification of renal neoplasms. We report the case of a patient with metastatic tubulocystic RCC whose disease progressed through standard of care treatment for nonclear RCC. However, genetic analysis revealed a germline pathogenic variant of fumarate hydratase (FH) gene, and the patient had a sustained and durable response to pazopanib.

Are Renal Cell Carcinoma with Fibromyomatous Stroma (RCC-FMS) and Thyroid-like Follicular Carcinoma of the Kidney (TLFCK) Really Independent Variants?

BACKGROUND

Renal cell carcinoma with fibromyomatous stroma (RCC-FMS) is a recent provisional entity already recognised in the 2016 WHO Classification of Cancer of the Urinary Tract and Male Genital Organs 4th Edition as renal cell carcinoma with (angio)leiomyomatous stroma, histologically defined as a tumour characterised by clear cells intertwined in a conspicuous vascular stroma. In the casuistry taken into consideration, another proposed variant, thyroid-like follicular carcinoma of the kidney (TLFCK), endowed with a morphology mimicking thyroid parenchyma, was examined. The aim of this work was to parse the theoretical system, experimental data and diagnostic impact of these new entities proposed in the field of renal neoplasms.

MATERIALS AND METHODS

An analysis of 120 cases of kidney tumours from the Department of Surgical, Medical, Molecular and Critical Area at the University of Pisa was run. Subsequently, all samples were reassessed by two pathologists with expertise in uropathology, whose revaluation provided a histomorphological study combined with subsequent and coherent immunohistochemical analyses of CK7, CD10, CAIX, CK34betaE12, CD117, vimentin, TTF-1 and thyroglobulin. These analyses were performed using the Ventana Benchmark Automated Staining System (Ventana Medical Systems, Tucson, AZ, USA) and Ventana reagents.

RESULTS

On the one hand, the data, thus brought to light, did not show an immunohistochemical profile consistent with that proposed for RCC-FMS. However, it should be emphasised that the morphological background also unearthed a poor specificity for RCC-FMS. This was specifically due to a stromal component which was, in any case, evident, although characterised by a wide range of presentation, in clear cell renal cell carcinoma (ccRCC). This latter is, indeed, the reference background for this theorised variant. On the other hand, a thyroid-like pattern was highlighted in 11 cases, more specifically in 10 ccRCCs and in one oncocytoma, presenting itself as a type of neoplastic appearance rather than as the peculiar morphological pattern of a standalone cancer.

CONCLUSIONS

In the light of these results, RCC-FMS and TLFCK appear to be more appropriately variants of already categorised neoplastic entities rather than new independent neoplasias.

Low grade oncocytic tumors of the kidney: a clinically relevant approach for the workup and accurate diagnosis

Renal oncocytoma and chromophobe renal cell carcinoma were accepted as unique renal tumors in the late 1990s. Since their formal description, criteria for diagnosis have evolved and additional distinct tumor subtypes originally considered as one these two entities are now recognized. The last two decades have witnessed unprecedented interest in the spectrum of low grade oncocytic renal neoplasms in three specific areas: (1) histologic characterization of tumors with overlapping morphologic features between oncocytoma and chromophobe renal cell carcinoma; (2) description of potentially unique entities within this spectrum, such as eosinophilic vacuolated tumor and low-grade oncocytic tumor; and (3) better appreciation of the association between a subset of low grade oncocytic tumors and hereditary renal neoplasia. While this important work has been academically rewarding, the proposal of several histologic entities with overlapping morphologic and immunophenotypic features (which may require esoteric adjunctive immunohistochemical and/or molecular techniques for confirmation) has created frustration in the diagnostic pathology and urology community as information evolves regarding classification within this spectrum of renal neoplasia. Pathologists, including genitourinary subspecialists, are often uncertain as to the "best practice" diagnostic approach to such tumors. In this review, we present a practical clinically relevant algorithmic approach to classifying tumors within the low grade oncocytic family of renal neoplasia, including a proposal for compressing terminology for evolving categories where appropriate without sacrificing prognostic relevance.

WHO 2022 landscape of papillary and chromophobe renal cell carcinoma

The 5th edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems contains relevant revisions and introduces a group of molecularly defined renal tumour subtypes. Herein we present the World Health Organization (WHO) 2022 perspectives on papillary and chromophobe renal cell carcinoma with emphasis on their evolving classification, differential diagnosis, and emerging entities. The WHO 2022 classification eliminated the type 1/2 papillary renal cell carcinoma (pRCC) subcategorization, given the recognition of frequent mixed tumour phenotypes and the existence of entities with a different molecular background within the type 2 pRCC category. Additionally, emerging entities such as biphasic squamoid alveolar RCC, biphasic hyalinising psammomatous RCC, papillary renal neoplasm with reverse polarity, and Warthin-like pRCC are included as part of the pRCC spectrum, while additional morphological and molecular data are being gathered. In addition to oncocytomas and chromophobe renal cell carcinoma (chRCC), a category of 'other oncocytic tumours' with oncocytoma/chRCC-like features has been introduced, including emerging entities, most with TSC/mTOR pathway alterations (eosinophilic vacuolated tumour and so-called 'low-grade' oncocytic tumour), deserving additional research. Eosinophilic solid and cystic RCC was accepted as a new and independent tumour entity. Finally, a highly reproducible and clinically relevant universal grading system for chRCC is still missing and is another niche of ongoing investigation. This review discusses these developments and highlights emerging morphological and molecular data relevant for the classification of renal cell carcinoma.

The 2022 revision of World Health Organization classification of tumors of the urinary system and male genital organs: advances and challenges

The fifth edition of the World Health Organization (WHO) classification of urinary and male genital organ tumors has been recently published in 2022. The application of molecular profiling has made a substantial impact on classification of urologic tumors. The new WHO classification introduces a group of molecularly well-defined renal tumor subtypes. The significant changes include addition of a category of "other oncocytic tumors" with oncocytoma/chromophobe renal cell carcinoma (chRCC)-like features, elimination of the subcategorization of type1/2 papillary RCC and inclusion of eosinophilic solid and cystic RCC as an independent tumor entity. The WHO/ISUP grading now has been recommended for all RCCs. Major nomenclature changes include replacement of histologic 'variants' by 'subtypes', 'clear cell papillary renal cell carcinoma' to 'clear cell renal cell tumor','TCEB1-mutated RCC' to 'ELOC-mutated RCC', 'hereditary leiomyomatosis and renal cell carcinoma' to 'fumarate hydratase-deficient RCC', 'RCC-Unclassified' to 'RCC-NOS', 'primitive neuroectodermal tumor' to 'embryonic neuroectodermal tumor', 'testicular carcinoid' to 'testicular neuroendocrine tumor', and 'basal cell carcinoma of the prostate' to 'adenoid-cystic (basal-cell) carcinoma of the prostate'. Metastatic, hematolymphoid, mesenchymal, melanocytic, soft tissue and neuroendocrine tumors are collectively discussed in separate chapters. It has been suggested that the morphological classification of urothelial cancer be replaced with a new molecular taxonomic classification system.

Epidemiology and Prevention of Renal Cell Carcinoma

With 400,000 diagnosed and 180,000 deaths in 2020, renal cell carcinoma (RCC) accounts for 2.4% of all cancer diagnoses worldwide. The highest disease burden developed countries, primarily in Europe and North America. Incidence is projected to increase in the future as more countries shift to Western lifestyles. Risk factors for RCC include fixed factors such as gender, age, and hereditary diseases, as well as intervening factors such as smoking, obesity, hypertension, diabetes, diet and alcohol, and occupational exposure. Intervening factors in primary prevention, understanding of congenital risk factors and the establishment of early diagnostic tools are important for RCC. This review will discuss RCC epidemiology, risk factors, and biomarkers involved in reducing incidence and improving survival.

Papillary renal cell carcinoma: current and controversial issues

PURPOSE OF THE REVIEW

Papillary renal cell carcinoma (pRCC) is the second most frequent renal cancer subtype and represents 15-20% of all RCC. Classification of pRCC is changing because novel tumour entities have been discovered in the last years. In this review, we summarise recent studies relevant for the understanding of the molecular complexity and the broader differential diagnosis of pRCC.

RECENT FINDINGS

It has been 25 years ago, that pRCC was morphologically subdivided into type 1 and type 2. Recently described tumour entities in the 2022 WHO classification challenged this concept and allow a new view on the molecular background in pRCC. Biphasic hyalinizing psammomatous RCC and papillary renal neoplasm with reversed polarity are emerging tumour entities derived from the new concept of molecularly defined RCC subtypes. Immune checkpoint inhibition and tyrosine kinase inhibitors have been introduced as the new backbone in the first-line treatment of advanced pRCCs. To identify novel targeted treatments for patients with pRCC it is crucial to investigate the specific molecular background of pRCC considering emerging pRCC subtypes.

SUMMARY

In the future, a deeper understanding of the correlation between molecular aberrations and new pRCC subtypes may improve the classification of pRCC patients and could reveal potential predictive biomarkers for each subgroup.

Construction and validation of an autophagy-related long non-coding RNA signature to predict the prognosis of kidney renal papillary cell carcinoma

To identify the autophagy-related long non-coding RNAs (ARlncRNAs) associated with the prognosis of kidney renal papillary cell carcinoma (KIRP), thereby establishing a clinical prognostic model. The gene expression matrix and clinical survival information of patients with KIRP were downloaded from The Cancer Genome Atlas database, and were divided into the training and testing groups. ARlncRNAs associated with the KIRP prognosis were analyzed by univariate, Least Absolute Shrinkage and Selection Operator (LASSO(, and multivariate Cox regression to construct a signature. We combined clinical factors associated with the prognosis with ARlncRNAs to establish a prognostic model of patients with KIRP. A nomogram was established to predict 1-year, 3-year, and 5-year survival of patients with KIRP. Besides, we built the lncRNA-messenger RNA co-expression network and used Kyoto Encyclopedia of Genes and Genomes and Gene Set Enrichment Analysis to detect the biological functions of ARlncRNAs. LEF1-AS1, CU634019.6, C2orf48, AC027228.2, and AC107464.3 were identified. A prognosis-related ARlncRNAs signature was constructed in the training group and validated in the testing group. Patients with KIRP with a low risk score had significantly longer survival time than those with a high risk score. The risk score significantly affected the prognosis of patients, thereby being used for modeling. The area under the receiver operating characteristic curve values of 1-year, 3-year, and 5-year overall survival were 0.80, 0.78, and 0.84 in the training group, respectively. The signature had high concordance index and good accuracy in predicting the prognosis, which were confirmed by the nomogram. The prognosis-related ARlncRNAs signature we identified had a more accurate prediction for the prognosis of patients with KIRP.

Kidney Cancer Models for Pre-Clinical Drug Discovery: Challenges and Opportunities

Renal cell carcinoma (RCC) is among the most lethal urological malignancies once metastatic. The introduction of immune checkpoint inhibitors has revolutionized the therapeutic landscape of metastatic RCC, nevertheless, a significant proportion of patients will experience disease progression. Novel treatment options are therefore still needed and in vitro and in vivo model systems are crucial to ultimately improve disease control. At the same time, RCC is characterized by a number of molecular and functional peculiarities that have the potential to limit the utility of pre-clinical model systems. This includes not only the well-known genomic intratumoral heterogeneity (ITH) of RCC but also a remarkable functional ITH that can be shaped by influences of the tumor microenvironment. Importantly, RCC is among the tumor entities, in which a high number of intratumoral cytotoxic T cells is associated with a poor prognosis. In fact, many of these T cells are exhausted, which represents a major challenge for modeling tumor-immune cell interactions. Lastly, pre-clinical drug development commonly relies on using phenotypic screening of 2D or 3D RCC cell culture models, however, the problem of “reverse engineering” can prevent the identification of the precise mode of action of drug candidates thus impeding their translation to the clinic. In conclusion, a holistic approach to model the complex “ecosystem RCC” will likely require not only a combination of model systems but also an integration of concepts and methods using artificial intelligence to further improve pre-clinical drug discovery.

Models of Renal Cell Carcinoma Used to Investigate Molecular Mechanisms and Develop New Therapeutics

Modeling renal cell carcinoma is critical to investigating tumor biology and therapeutic mechanisms. Multiple systems have been developed to represent critical components of the tumor and its surrounding microenvironment. Prominent in vitro models include traditional cell cultures, 3D organoid models, and microphysiological devices. In vivo models consist of murine patient derived xenografts or genetically engineered mice. Each system has unique advantages as well as limitations and researchers must thoroughly understand each model to properly investigate research questions. This review addresses common model systems for renal cell carcinoma and critically evaluates their performance and ability to measure tumor characteristics.

Eosinophilic solid and cystic renal cell carcinoma and renal cell carcinomas with TFEB alterations: a comparative study

AIMS

Eosinophilic solid and cystic renal cell carcinoma (ESC RCC) is a recently described renal tumour entity with frequent CK20 positivity, commonly harbouring TSC mutations. In contrast, frequency of CK20 expression and presence of TSC mutations are unclear in TFEB-amplified RCC and TFEB-translocated RCC, which frequently express Melan A. Herein, we provide a comparative analysis of 6 ESC RCC with 4 TFEB-amplified/translocated RCC.

METHODS AND RESULTS

We assessed the frequency of CK20 and Melan A expression by immunohistochemistry, and of TSC mutations by next generation sequencing. TFEB alterations were confirmed by fluorescence in situ hybridization (FISH). All tumours showed voluminous eosinophilic cells with granular cytoplasm, prominent nucleoli, and most showed admixture of solid and cystic areas. CK20 expression was found in all 6 ESC RCC and in all RCCs with TFEB alterations. Melan A positivity was identified in 5/6 ESC RCC and 4/4 RCC with TFEB alterations. We found TSC mutations in 2 ESC RCCs, including in one case also harbouring a CIC fusion, and identified a TSC mutation in one TFEB-amplified RCC.

CONCLUSIONS

ESC RCC represents an emerging renal tumour entity with some histological, immunohistochemical and molecular overlap to TFEB-amplified/translocated RCC. FISH for TFEB aids in this differential diagnosis in challenging cases.

Activity of ALK Inhibitors in Renal Cancer with ALK Alterations: A Systematic Review

Renal cell carcinoma (RCC) associated with anaplastic lymphoma kinase (ALK) gene rearrangements (ALK-RCC) is currently considered an “emerging or provisional” tumor entity by the last World Health Organization classification published in 2016. Although several studies assessing ALK-RCC’s clinical and histological characteristics have been published in recent years, only a few publications have evaluated the activity of ALK inhibitors (ALK-i) in this subgroup of patients. Considering the well-recognized efficacy of this evolving class of targeted therapies in other ALK-positive tumors, we conducted a systematic review to evaluate the reported activity of ALK-i in the ALK-RCC subtype. MEDLINE was searched from its inception to 7 January 2022 for case reports and case series on adult metastatic ALK-RCC patients treated with ALK-i whose therapeutic outcomes were available. A virtual cohort of ALK-RCC patients was created. Our results showed a favorable activity of first- and second-generation ALK-i in pretreated ALK-RCC patients in terms of either radiological response or performance status improvement. We hope that the present work will prompt the creation of large, multi-institutional clinical trials to confirm these promising early data.

A review of neoplasms with MITF/MiT family translocations

Microphthalmia-associated transcription factor (MITF/MiT) family is a group of basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factors including TFE3 (TFEA), TFEB, TFEC and MITF. The first renal neoplasms involving MITF family translocation were renal cell carcinomas with chromosome translocations involving ASPL-TFE3/t(X;17)(p11.23;q25) or MALAT1-TFEB/t(6;11)(p21.1;q12), and now it is known as MiT family translocation RCC in 2016 WHO classification. Translocations involving MITF family genes also are found in other tumor types, such as perivascular epithelioid cell neoplasm (PEComa), Alveolar soft part sarcoma (ASPS), epithelioid hemangioendothelioma, ossifying fibromyxoid tumor (OFMT), and clear cell tumor with melanocytic differentiation and ACTIN-MITF translocation. In this review, we summarize the features of different types of neoplasms with MITF family translocations.

The Morphological Spectrum of Papillary Renal Cell Carcinoma and Prevalence of Provisional/Emerging Renal Tumor Entities with Papillary Growth

Renal cell carcinoma (RCC) represents a heterogeneous disease, encompassing an increasing number of tumor subtypes. Post-2016, the World Health Organization (WHO) classification recognized that the spectrum of papillary renal cell carcinoma is evolving and has long surpassed the dichotomic simplistic "type 1 versus type 2" classification. The differential diagnosis of pRCC includes several new provisional/emerging entities with papillary growth. Type 2 tumors have been cleared out of several confounding entities, now regarded as independent tumors with specific clinical and molecular backgrounds. In this work we describe the prevalence and characteristics of emerging papillary tumor entities in two renal tumor cohorts (one consisting of consecutive papillary tumors from a single institute, the other consisting of consultation cases from several centers). After a review of 154 consecutive pRCC cases, 58% remained type 1 pRCC, and 34% type 2 pRCC. Papillary renal neoplasm with reversed polarity (1.3%), biphasic hyalinizing psammomatous RCC (1.3%), and biphasic squamoid/alveolar RCC (4.5%) were rare. Among 281 consultation cases, 121 (43%) tumors had a dominant papillary growth (most frequently MiT family translocation RCCs, mucinous tubular and spindle cell carcinoma and clear cell papillary RCC). Our data confirm that the spectrum of RCCs with papillary growth represents a major diagnostical challenge, frequently requiring a second expert opinion. Papillary renal neoplasm with reversed polarity, biphasic hyalinizing psammomatous RCC, and biphasic squamoid/alveolar RCC are rarely sent out for a second opinion, but correct classification and knowledge of these variants will improve our understanding of the clinical behavior of renal tumors with papillary growth.

Sex and Gender Differences in Kidney Cancer: Clinical and Experimental Evidence

Simple Summary

Kidney cancer is a frequent malignant tumor that accounts for approximately 5% of all cancer incidences. It affects both males and females, but males are twice as likely to develop kidney cancer than females. Evidence shows that this discrepancy takes root in individual differences, such as genetics or pathologies that affect the patient. It is then reflected in the clinical characteristics of the tumors, as males have larger and more aggressive tumors. Understanding the sex- and gender-based differences in kidney cancer is essential to be able to offer patients individualized medicine that would better cover their needs in terms of prevention, diagnosis and treatment.

Abstract

Sex and gender disparities have been reported for different types of non-reproductive cancers. Males are two times more likely to develop kidney cancer than females and have a higher death rate. These differences can be explained by looking at genetics and genomics, as well as other risk factors such as hypertension and obesity, lifestyle, and female sex hormones. Examination of the hormonal signaling pathways bring further insights into sex-related differences. Sex and gender-based disparities can be observed at the diagnostic, histological and treatment levels, leading to significant outcome difference. This review summarizes the current knowledge about sex and gender-related differences in the clinical presentation of patients with kidney cancer and the possible biological mechanisms that could explain these observations. Underlying sex-based differences may contribute to the development of sex-specific prognostic and diagnostic tools and the improvement of personalized therapies.