Timing the Landmark Events in the Evolution of Clear Cell Renal Cell Cancer: TRACERx Renal.

Clear cell renal cell carcinoma (ccRCC) is characterized by near-universal loss of the short arm of chromosome 3, deleting several tumor suppressor genes. We analyzed whole genomes from 95 biopsies across 33 patients with clear cell renal cell carcinoma. We find hotspots of point mutations in the 5' UTR of TERT, targeting a MYC-MAX-MAD1 repressor associated with telomere lengthening. The most common structural abnormality generates simultaneous 3p loss and 5q gain (36% patients), typically through chromothripsis. This event occurs in childhood or adolescence, generally as the initiating event that precedes emergence of the tumor's most recent common ancestor by years to decades. Similar genomic changes drive inherited ccRCC. Modeling differences in age incidence between inherited and sporadic cancers suggests that the number of cells with 3p loss capable of initiating sporadic tumors is no more than a few hundred. Early development of ccRCC follows well-defined evolutionary trajectories, offering opportunity for early intervention.

Deterministic Evolutionary Trajectories Influence Primary Tumor Growth: TRACERx Renal.

The evolutionary features of clear-cell renal cell carcinoma (ccRCC) have not been systematically studied to date. We analyzed 1,206 primary tumor regions from 101 patients recruited into the multi-center prospective study, TRACERx Renal. We observe up to 30 driver events per tumor and show that subclonal diversification is associated with known prognostic parameters. By resolving the patterns of driver event ordering, co-occurrence, and mutual exclusivity at clone level, we show the deterministic nature of clonal evolution. ccRCC can be grouped into seven evolutionary subtypes, ranging from tumors characterized by early fixation of multiple mutational and copy number drivers and rapid metastases to highly branched tumors with >10 subclonal drivers and extensive parallel evolution associated with attenuated progression. We identify genetic diversity and chromosomal complexity as determinants of patient outcome. Our insights reconcile the variable clinical behavior of ccRCC and suggest evolutionary potential as a biomarker for both intervention and surveillance.

Tracking Cancer Evolution Reveals Constrained Routes to Metastases: TRACERx Renal.

Clear-cell renal cell carcinoma (ccRCC) exhibits a broad range of metastatic phenotypes that have not been systematically studied to date. Here, we analyzed 575 primary and 335 metastatic biopsies across 100 patients with metastatic ccRCC, including two cases sampledat post-mortem. Metastatic competence was afforded by chromosome complexity, and we identify 9p loss as a highly selected event driving metastasis and ccRCC-related mortality (p = 0.0014). Distinct patterns of metastatic dissemination were observed, including rapid progression to multiple tissue sites seeded by primary tumors of monoclonal structure. By contrast, we observed attenuated progression in cases characterized by high primary tumor heterogeneity, with metastatic competence acquired gradually and initial progression to solitary metastasis. Finally, we observed early divergence of primitive ancestral clones and protracted latency of up to two decades as a feature of pancreatic metastases.

The Expression of Alamandine Receptor MrgD in Clear Cell Renal Cell Carcinoma Is Associated with a Worse Prognosis and Unfavorable Response to Antiangiogenic Therapy.

Renal cell carcinoma (RCC) ranks among the most prevalent malignancies in Western countries, marked by its notable heterogeneity, which contributes to an unpredictable clinical trajectory. The insufficiency of dependable biomarkers adds complexity to assessing this tumor progression. Imbalances of several components of the intrarenal renin-angiotensin system (iRAS) significantly impact patient prognoses and responses to first-line immunotherapies. In this study, we analyzed the immunohistochemical expression of the Mas-related G-protein-coupled receptor D (MrgD), which recognizes the novel RAS peptide alamandine (ALA), in a series of 87 clear cell renal cell (CCRCCs), 19 papillary (PRCC), 7 chromophobe (ChRCC) renal cell carcinomas, and 11 renal oncocytomas (RO). MrgD was expressed in all the renal tumor subtypes, with a higher mean staining intensity in the PRCCs, ChRCCs, and ROs. A high expression of MrgD at the tumor center and at the infiltrative front of CCRCC tissues was significantly associated with a high histological grade, large tumor diameter, local invasion, and locoregional node and distant metastasis. Patients with worse 5-year cancer-specific survival and a poorer response to antiangiogenic tyrosine-kinase inhibitors (TKIs) showed higher MrgD expression at the center of their primary tumors. These findings suggest a possible role of MrgD in renal carcinogenetic processes. Further studies are necessary to unveil its potential as a novel biomarker for CCRCC prognosis and response to frontline therapies.

Effects of Heterogeneity on Cancer: A Game Theory Perspective.

In this study, we explore interactions between cancer cells by using the hawk-dove game. We analyze the heterogeneity of tumors by considering games with populations composed of 2 or 3 types of cell. We determine what strategies are evolutionarily stable in the 2-type and 3-type population games and what the corresponding expected payoffs are. Our results show that the payoff of the best-off cell in the 2-type population game is higher than that of the best-off cell in the 3-type population game. When these mathematical findings are transferred to the field of oncology they suggest that a tumor with low intratumor heterogeneity pursues a more aggressive course than one with high intratumor heterogeneity. Some histological and genomic data on clear cell renal cell carcinomas is consistent with these results. We underline the importance of identifying intratumor heterogeneity in routine practice and suggest that therapeutic strategies that preserve heterogeneity may be promising as they may slow down cancer growth.

Eosinophilic vacuolated tumor (EVT) of kidney demonstrates sporadic TSC/MTOR mutations: next-generation sequencing multi-institutional study of 19 cases.

A distinct renal tumor has recently been described as "high-grade oncocytic renal tumor" and "sporadic renal cell carcinoma with eosinophilic and vacuolated cytoplasm". The Genitourinary Pathology Society (GUPS) consensus proposed a unifying name "eosinophilic vacuolated tumor" (EVT) for this emerging entity. In this multi-institutional study, we evaluated 19 EVTs, particularly their molecular features and mutation profile, using next-generation sequencing. All cases were sporadic and none of the patients had a tuberous sclerosis complex. There were 8 men and 11 women, with a mean age of 47 years (median 50; range 15-72 years). Average tumor size was 4.3 cm (median 3.8 cm; range 1.5-11.5 cm). All patients with available follow-up data (18/19) were alive and without evidence of disease recurrence or progression during the follow-up, ranging from 12 to 198 months (mean 56.3, median 41.5 months). The tumors were well circumscribed, but lacked a well-formed capsule, had nested to solid growth, focal tubular architecture, and showed ubiquitous, large intracytoplasmic vacuoles, round to oval nuclei, and prominent nucleoli. Immunohistochemically, cathepsin K, CD117, CD10, and antimitochondrial antigen were expressed in all cases. Other positive stains included: PAX8, AE1/AE3 and CK18. CK7 was typically restricted only to rare scattered cells. Vimentin, HMB45, melan-A, and TFE3 were negative in all cases. All tumors showed retained SDHB. All cases (19/19) showed non-overlapping mutations of the mTOR pathway genes: TSC1 (4), TSC2 (7), and MTOR (8); one case with MTOR mutation showed a coexistent RICTOR missense mutation. Low mutational rates were found in all samples (ranged from 0 to 6 mutations/Mbp). Microsatellite instability and copy number variations were not found in any of the 17 analyzable cases. EVT represents an emerging renal entity that shows a characteristic and readily identifiable morphology, consistent immunohistochemical profile, indolent behavior, and mutations in either TSC1, TSC2, or MTOR genes.

Algorithm-Based Approach to the Histological Routine Diagnosis of Renal Oncocytic Tumors in Core Biopsy Specimens.

PURPOSE OF REVIEW: A growing number of tumor entities with badly defined limits are enlarging in the last years the family of oncocytic tumors in the kidney. RECENT FINDINGS: Chromophobe renal cell carcinoma (ChRCC) and renal oncocytoma (RO) are classically well-known tumors, but the borderland between them, and their precise connection, remains a matter of debate. Aside from that, other emerging and provisional entities, like eosinophilic solid and cystic renal cell carcinoma (ESC RCC), eosinophilic vacuolated tumor (EVT), low-grade oncocytic tumor (LOT), and papillary renal neoplasm with reverse polarity (PRRP), have been recently described. This spectrum of tumors remains a diagnostic challenge in renal pathology, especially if the specimen obtained is scarce. This review focuses on practical diagnostic problems when managing core biopsies and proposes a diagnostic algorithm maximizing the information provided by both morphology and immunohistochemistry. So, a combination of morphologic features on hematoxylin-eosin and six antibodies (CK7, CD117, CK20, CD10, GATA-3, and cathepsin K) is advised to be used in a stepwise fashion.

Clear Cell Renal Cell Carcinomas with Aggressive Behavior Display Low Intratumor Heterogeneity at the Histological Level.

PURPOSE OF REVIEW: Intratumor heterogeneity (ITH) is an inherent characteristic of most tumors and its detection remains a key task for pathologists. However, the clinical significance of the degree of development of this feature is still poorly understood. RECENT FINDINGS: A series of 28 clear cell renal cell carcinomas (CCRCC) have been exhaustively analyzed with two different sampling protocols [multisite tumor sampling (MSTS) and total sampling] to evaluate to what point the level (low vs. high) of histological ITH detected in routine practice influences tumor behavior and patients' survival. All CCRCC (n = 14) pursuing an aggressive clinical course presented low levels of ITH. A significant worse survival was detected in CCRCC with low ITH (p < 0.001). The simple quantification of the level of ITH using extensive sampling protocol may be of help in predicting tumor evolution, since all CCRCC with aggressive behavior demonstrated low levels of histological ITH.

A global analysis of the reconstitution of PTEN function by translational readthrough of PTEN pathogenic premature termination codons.

The PTEN tumor suppressor gene is mutated with high incidence in tumors and in the germline of patients with cancer predisposition or with macrocephaly associated with autism. PTEN nonsense mutations generating premature termination codons (PTC) and producing nonfunctional truncated PTEN proteins are frequent in association with human disease. However, there are no studies addressing the restoration of full-length PTEN proteins from the PTC-mutated PTEN gene by translational readthrough. Here, we have performed a global translational and functional readthrough analysis of the complete collection of PTEN PTC somatic or hereditary mutations found in tumors or in the germline of patients (disease-associated PTEN PTCome), and we set standards for the analysis of the potential of readthrough functional reconstitution in disease-relevant genes. Our analysis indicates that prevalent pathogenic PTEN PTC mutations are susceptible to PTEN functional restoration in response to readthrough-inducing compounds. Comprehensive readthrough analyses of disease-associated PTComes will be valuable tools for the implementation of readthrough-based precision interventions in specific groups of patients.

Immune checkpoint B7-H3 protein expression is associated with poor outcome and androgen receptor status in prostate cancer.

BACKGROUND: Novel immune checkpoint-based immunotherapies may benefit specific groups of prostate cancer patients who are resistant to other treatments. METHODS: We analyzed by immunohistochemistry the expression of B7-H3, PD-L1/B7-H1, and androgen receptor (AR) in tissue samples from 120 prostate adenocarcinoma patients treated with radical prostatectomy in Spain, and from 206 prostate adenocarcinoma patients treated with radical prostatectomy in Norway. RESULTS: B7-H3 expression correlated positively with AR expression and was associated with biochemical recurrence in the Spanish cohort, but PD-L1 expression correlated with neither of them. Findings for B7-H3 were validated in the Norwegian cohort, where B7-H3 expression correlated positively with Gleason grade, surgical margins, seminal vesicle invasion, and CAPRA-S risk group, and was associated with clinical recurrence. High B7-H3 expression in the Norwegian cohort was also consistent with positive AR expression. CONCLUSION: These results suggest distinct clinical relevance of the two immune checkpoint proteins PD-L1 and B7-H3 in prostate cancer. Our findings highlight B7-H3 as an actionable novel immune checkpoint protein in prostate cancer.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia.

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

Novel, emerging and provisional renal entities: The Genitourinary Pathology Society (GUPS) update on renal neoplasia.

The Genitourinary Pathology Society (GUPS) undertook a critical review of the recent advances in renal neoplasia, particularly focusing on the newly accumulated evidence post-2016 World Health Organization (WHO) classification. In the era of evolving histo-molecular classification of renal neoplasia, morphology is still key. However, entities (or groups of entities) are increasingly characterized by specific molecular features, often associated either with recognizable, specific morphologies or constellations of morphologies and corresponding immunohistochemical profiles. The correct diagnosis has clinical implications leading to better prognosis, potential clinical management with targeted therapies, may identify hereditary or syndromic associations, which may necessitate appropriate genetic testing. We hope that this undertaking will further facilitate the identification of these entities in practice. We also hope that this update will bring more clarity regarding the evolving classification of renal neoplasia and will further reduce the category of "unclassifiable renal carcinomas/tumors". We propose three categories of novel entities: (1) "Novel entity", validated by multiple independent studies; (2) "Emerging entity", good compelling data available from at least two or more independent studies, but additional validation is needed; and (3) "Provisional entity", limited data available from one or two studies, with more work required to validate them. For some entities initially described using different names, we propose new terminologies, to facilitate their recognition and to avoid further diagnostic dilemmas. Following these criteria, we propose as novel entities: eosinophilic solid and cystic renal cell carcinoma (ESC RCC), renal cell carcinoma with fibromyomatous stroma (RCC FMS) (formerly RCC with leiomyomatous or smooth muscle stroma), and anaplastic lymphoma kinase rearrangement-associated renal cell carcinoma (ALK-RCC). Emerging entities include: eosinophilic vacuolated tumor (EVT) and thyroid-like follicular renal cell carcinoma (TLFRCC). Finally, as provisional entities, we propose low-grade oncocytic tumor (LOT), atrophic kidney-like lesion (AKLL), and biphasic hyalinizing psammomatous renal cell carcinoma (BHP RCC).

Core-needle biopsy in thyroid nodules: performance, accuracy, and complications.

OBJECTIVE: To evaluate the performance of core-needle biopsy (CNB) in thyroid using a cohort of patients in which it was used as first choice. METHODS: Our institutional review board approved this retrospective study. We reviewed all CNB performed in our center over a period of 11 years. Ultrasound-guided CNBs were performed using a spring-loaded 18-gauge biopsy needle. We used a classification with four diagnostic categories for CNB results: insufficient, benign, follicular lesion (indeterminate), and malignant. Final diagnosis was based on surgical diagnosis or follow-up of at least 2 years in non-operated patients. RESULTS: The study included 4412 CNB in 4112 nodules of 3768 patients, 300 of them repeated biopsies. Results were 148 insufficient (3.4%), 3706 benign (84%), 278 follicular lesions (6.3%), and 280 malignant (6.3%). Considering follicular lesion and malignancy CNB results as positive (both lead to the recommendation of surgery) sensitivity was 96% (CI 93.2-97.8) and specificity 93.7% (CI 92.9-94.5). Predictive positive value for a follicular lesion diagnosis was 12.2% and for a malignancy diagnosis, 98.6%. CNB likelihood ratio for malignancy of a malignant diagnosis was 841.9 (CI 315.8-2313.3), of a malignant/follicular lesion diagnosis was 23.4 (CI 20.1-27.3), and of a benign diagnosis was 0.04 (CI 0.02-0.07). Repeated CNB in 53 insufficient biopsies obtained 50 diagnostic results. Minor complications occurred in 2.2% of CNB, and major in four procedures (0.09%). CONCLUSIONS: CNB in thyroid nodules is accurate and has few complications and a low rate of non-diagnostic and indeterminate diagnoses. It can be an alternative method when FNAC has poor performance. Repeating biopsy is useful after non-diagnostic biopsies. KEY POINTS: • Core-needle biopsy of thyroid has a low ratio non-diagnostic and indeterminate results. • Core-needle biopsy results are highly reliable, especially benign results. • Complication rate of core-needle biopsy of thyroid is low.

A Critical Insight into the Clinical Translation of PD-1/PD-L1 Blockade Therapy in Clear Cell Renal Cell Carcinoma.

PURPOSE OF REVIEW: Targeting PD-1/PD-L1 immune checkpoints is a new therapeutic tool in patients with locally advanced and metastatic clear cell renal cell carcinoma (CCRCC). The purpose of this review is to offer clinicians an updated translational insight into the current status of a therapeutic alternative that may impact significantly patient's life. RECENT FINDINGS: Immune checkpoint inhibition has recently demonstrated promising results in selected CCRCC patients with respect to tumor progression and survival. The decision to treat these patients with immune checkpoint inhibitors (ICI) relies on the immunohistochemical detection of PD-1/PD-L1 positivity in inflammatory cells in the tumor, which makes the role of the pathologist crucial, but clinical concern upon the reliability to use immunohistochemistry (IHC) to predict therapeutic response is increasing. We review the state of the art of the immune checkpoint inhibition in CCRCC, from the basic science and its fundamentals to the daily application in clinical routine.

Dual-Specificity Phosphatases in Neuroblastoma Cell Growth and Differentiation.

Dual-specificity phosphatases (DUSPs) are important regulators of neuronal cell growth and differentiation by targeting proteins essential to neuronal survival in signaling pathways, among which the MAP kinases (MAPKs) stand out. DUSPs include the MAPK phosphatases (MKPs), a family of enzymes that directly dephosphorylate MAPKs, as well as the small-size atypical DUSPs, a group of low molecular-weight enzymes which display more heterogeneous substrate specificity. Neuroblastoma (NB) is a malignancy intimately associated with the course of neuronal and neuroendocrine cell differentiation, and constitutes the source of more common extracranial solid pediatric tumors. Here, we review the current knowledge on the involvement of MKPs and small-size atypical DUSPs in NB cell growth and differentiation, and discuss the potential of DUSPs as predictive biomarkers and therapeutic targets in human NB.

Biphasic papillary renal cell carcinoma is a rare morphological variant with frequent multifocality: a study of 28 cases.

AIMS: To further characterise biphasic squamoid renal cell carcinoma (RCC), a recently proposed variant of papillary RCC. METHODS AND RESULTS: We identified 28 tumours from multiple institutions. They typically showed two cell populations-larger cells with eosinophilic cytoplasm and higher-grade nuclei, surrounded by smaller, amphophilic cells with scanty cytoplasm. The dual morphology was variable (median 72.5% of tumour, range 5-100%); emperipolesis was found in all cases. The male/female ratio was 2:1, and the median age was 55 years (range 39-86 years). The median tumour size was 20 mm (range 9-65 mm). Pathological stage pT1a was found in 21 cases, pT1b in three, and pT3a and pT3b in one each (two not available). Multifocality was found in 32%: multifocal biphasic RCC in one case, biphasic + papillary RCC in two cases, biphasic + clear cell RCC in three cases, biphasic + low-grade urothelial carcinoma of the renal pelvis in one case, and biphasic + Birt-Hogg-Dubé syndrome in one case. Positive immunostains included: PAX8, cytokeratin (CK) 7, α-methylacyl-CoA racemase, epithelial membrane antigen, and vimentin. Cyclin D1 was expressed only in the larger cells. The Ki67 index was higher in the larger cells (median 5% versus ≤1%). Negative stains included: carbonic anhydrase 9, CD117, GATA-3, WT1, CK5/6, and CK20; CD10 and 34ßE12 were variably expressed. Gains of chromosomes 7 and 17 were found in two evaluated cases. Follow-up was available for 23 patients (median 24 months, range 1-244 months): 19 were alive without disease, one was alive with recurrence, and one had died of disease (two had died of other causes). CONCLUSIONS: Biphasic papillary RCC is a rare variant of papillary RCC, and is often multifocal.

DUSP5 expression associates with poor prognosis in human neuroblastoma.

Regulation of growth and differentiation of neuroblastoma (NB) cells is the rational of some maintenance therapies for high-risk NB. MAP kinase phosphatases (MKPs) are potential physiologic regulators of neuronal differentiation and survival, but their expression patterns in NB are scarcely known. Here, an expression analysis of the MKP family has been performed using human NB tumor samples and human NB cell lines (SH-SY5Y, SMS-KCNR, and IMR-32) undergoing retinoic acid (RA)-induced differentiation or subjected to stimuli that activate the MAPK ERK1/2 pathway. We have identified candidate MKPs that could modulate differentiation and growth of NB cells. pERK1/2 high expression correlated with high expression of the MKP DUSP5 in NB tumors, and was associated with poor prognosis. ERK1/2 activation on SH-SY5Y cells was accompanied by increased cell proliferation, and correlated with the expression levels of DUSP5. Accordingly, siRNA knock-down of DUSP5 augmented proliferation of SH-SY5Y cells. Our findings provide insights into the dynamic expression of MKPs in NB cells, disclose DUSP5 as a potential marker of NB poor prognosis, and suggest a role for DUSP5 in limiting ERK1/2-mediated NB proliferation.

Pathological Bases and Clinical Impact of Intratumor Heterogeneity in Clear Cell Renal Cell Carcinoma.

PURPOSE OF REVIEW: Intratumor heterogeneity is an inherent event in tumor development that is receiving much attention in the last years since it is responsible for most failures of current targeted therapies. The purpose of this review is to offer clinicians an updated insight of the multiple manifestations of a complex event that impacts significantly patient's life. RECENT FINDINGS: Clear cell renal cell carcinoma is the most common renal tumor and a paradigmatic example of a heterogeneous neoplasm. Next-generation sequencing has demonstrated that intratumor heterogeneity encompasses genetic, epigenetic, and microenvironmental variability. Currently accepted protocols of tumor sampling seem insufficient in unveiling intratumor heterogeneity with reliability and need to be updated. This variability challenges the precise morphological diagnosis, its molecular characterization, and the selection of optimal personalized therapies in clear cell renal cell carcinoma, a neoplasm traditionally considered chemo- and radio-resistant. We review the state of the art of the different approaches to intratumor heterogeneity in clear cell renal cell carcinomas, from the simple morphology to the most sophisticated massive sequencing tools.

Loss of PD-L1 (SP-142) expression characterizes renal vein tumor thrombus microenvironment in clear cell renal cell carcinoma.

Immunotherapy is a promising tool in the treatment of patients with advancer renal cancer, in particular the blockage of immune checkpoint inhibitors. Clear cell renal cell carcinoma is an example of heterogeneous neoplasm and this particular characteristic is responsible of many therapeutic failures so far. Since variations in the local microenvironment across a tumor may conditionate the effect of this new therapy, a deeper knowledge of this issue seems advisable for any treatment success. We have analyzed the PD-L1 (SP142) expression in three different areas in the tumor and in two areas in the renal vein/caval thrombi in 39 advanced clear cell renal cell carcinomas to determine the extent and potential clinical significance of this regional variability. A statistically significant decrease in PD-L1 expression has been detected between the main tumor and its thrombus faction (p < 0.0001). Also, we have observed a high variability in the PD-L1 positivity across the three different areas of the main tumor tested, with only three cases being uniformly positive in all tested areas. In conclusion, PD-L1 expression display a highly variable distribution in clear cell renal cell carcinomas and this particularity should be kept in mind when selecting the tumor samples to be tested for immunotherapy.

High levels of intratumor heterogeneity characterize the expression of epithelial-mesenchymal transition markers in high-grade clear cell renal cell carcinoma.

Immunohistochemistry is a basic routine in establishing the diagnosis of many tumors. However, immunomarkers are often irregularly distributed across different regions of the same tumor, alternating positive and negative areas without any apparent cause. Full identification of this type of intratumor heterogeneity is crucial for patients since the expression of many markers is linked to the prognosis and/or treatment of some tumors. We have quantified this variability testing 406 tumor samples from eight clear cell renal cell carcinomas using four epithelial-mesenchymal transition markers (vimentin, ZEB-1, ß-catenin, and E-cadherin) and two different sampling protocols. Routine sampling included an amount of 59 samples (average, 7.3 samples/case) and multisite tumor sampling did a total of 347 samples (average, 43.3 samples/case). High variability of immunostaining was detected with E-cadherin and ZEB-1 in all high-grade cases. Irregular patterns of expression were detected in all tumors including all histologically homogeneous low-grade tumors. Multisite tumor sampling protocol detected a significant decreased number of E-cadherin, ß-catenin and ZEB-1 positive samples in high-grade tumors. We conclude that high levels of intratumor heterogeneity characterize the immunohistochemical expression of epithelial-mesenchymal transition markers in high-grade clear cell renal cell carcinomas. Multisite tumor sampling protocol outperforms routine sampling in detecting immunohistochemical intratumor heterogeneity.