Special populations in metastatic renal cell carcinoma.

PURPOSE OF REVIEW: This review focuses on special populations poorly represented in current evidence-based practice for metastatic renal cell carcinoma (mRCC). This includes the elderly and frail, patients on immunosuppression or with autoimmune diseases, patients with brain, liver, and/or bone metastases, and RCC with sarcomatoid features. RECENT FINDINGS: Certain populations are poorly represented in current trials for mRCC. Patients with central nervous system (CNS) metastases are often excluded from first-line therapy trials. Modern doublet systemic therapy appears to benefit patients with bone or liver metastases, but data supporting this conclusion is not robust. Post-hoc analyses on patients with sarcomatoid differentiation have shown improved response to modern doublet therapy over historical treatments. The elderly are underrepresented in current clinical trials, and most trials exclude all but high-performing (nonfrail) patients, though true frailty is likely poorly captured using the current widely adopted indices. It is difficult to make conclusions about the efficacy of modern therapy in these populations from subgroup analyses. Data from trials on other malignancies in patients with autoimmune diseases or solid organ transplant recipients on immunosuppression suggest that immune checkpoint inhibitors (ICIs) may still have benefit, though at the risk of disease flare or organ rejection. The efficacy of ICIs has not been demonstrated specifically for RCC in this group of patients. SUMMARY: The elderly, frail, and immunosuppressed, those with tumors having aggressive histologic features, and patients with brain, bone, and/or liver metastases represent the populations least understood in the modern era of RCC treatment.

Belzutifan for von Hippel-Lindau Disease: Pancreatic Lesion Population of the Phase 2 LITESPARK-004 Study.

PURPOSE: Primary analysis of the ongoing, single-arm, phase 2 LITESPARK-004 study (NCT03401788) showed clinically meaningful antitumor activity in von Hippel-Lindau (VHL) disease-associated renal cell carcinoma (RCC) and other neoplasms with belzutifan treatment. We describe results of belzutifan treatment for VHL disease-associated pancreatic lesions [pancreatic neuroendocrine tumors (pNET) and serous cystadenomas]. PATIENTS AND METHODS: Adults with VHL diagnosis based on germline VHL alteration, ≥1 measurable RCC tumor, no renal tumor >3 cm or other VHL neoplasm requiring immediate surgery, Eastern Cooperative Oncology Group performance status of 0 or 1, and no prior systemic anticancer treatment received belzutifan 120 mg once daily. End points included objective response rate (ORR), duration of response (DOR), progression-free survival (PFS), and linear growth rate (LGR) in all pancreatic lesions and pNETs per RECIST version 1.1 by independent review committee, and safety. RESULTS: All 61 enrolled patients (100%) had ≥1 pancreatic lesion and 22 (36%) had ≥1 pNET measurable at baseline. Median follow-up was 37.8 months (range, 36.1-46.1). ORR was 84% [51/61; 17 complete responses (CR)] in pancreatic lesions and 91% (20/22; 7 CRs) in pNETs. Median DOR and median PFS were not reached in pancreatic lesions or pNETs. After starting treatment, median LGR for pNETs was -4.2 mm per year (range, -7.9 to -0.8). Eleven patients (18%) had ≥1 grade 3 treatment-related adverse event (AE). No grade 4 or 5 treatment-related AEs occurred. CONCLUSIONS: Belzutifan continued to show robust activity and manageable safety in VHL disease-associated pNETs.

PRDM10 RCC: A Birt-Hogg-Dubé-like Syndrome Associated With Lipoma and Highly Penetrant, Aggressive Renal Tumors Morphologically Resembling Type 2 Papillary Renal Cell Carcinoma.

OBJECTIVE: To characterize the clinical manifestations and genetic basis of a familial cancer syndrome in patients with lipomas and Birt-Hogg-Dubé-like clinical manifestations including fibrofolliculomas and trichodiscomas and kidney cancer. METHODS: Genomic analysis of blood and renal tumor DNA was performed. Inheritance pattern, phenotypic manifestations, and clinical and surgical management were documented. Cutaneous, subcutaneous, and renal tumor pathologic features were characterized. RESULTS: Affected individuals were found to be at risk for a highly penetrant and lethal form of bilateral, multifocal papillary renal cell carcinoma. Whole genome sequencing identified a germline pathogenic variant in PRDM10 (c.2029 T>C, p.Cys677Arg), which cosegregated with disease. PRDM10 loss of heterozygosity was identified in kidney tumors. PRDM10 was predicted to abrogate expression of FLCN, a transcriptional target of PRDM10, which was confirmed by tumor expression of GPNMB, a TFE3/TFEB target and downstream biomarker of FLCN loss. In addition, a sporadic papillary RCC from the TCGA cohort was identified with a somatic PRDM10 mutation. CONCLUSION: We identified a germline PRDM10 pathogenic variant in association with a highly penetrant, aggressive form of familial papillary RCC, lipomas, and fibrofolliculomas/trichodiscomas. PRDM10 loss of heterozygosity and elevated GPNMB expression in renal tumors indicate that PRDM10 alteration leads to reduced FLCN expression, driving TFE3-induced tumor formation. These findings suggest that individuals with Birt-Hogg-Dubé-like manifestations and subcutaneous lipomas, but without a germline pathogenic FLCN variant, should be screened for germline PRDM10 variants. Importantly, kidney tumors identified in patients with a pathogenic PRDM10 variant should be managed with surgical resection instead of active surveillance.

Two is company, is three a crowd? Triplet therapy, novel molecular targets, and updates on the management of advanced renal cell carcinoma.

PURPOSE OF REVIEW: The purpose of this review is to highlight the most recent changes in the management of advanced renal cell carcinoma, a complicated and ever-changing field of research. RECENT FINDINGS: A recent meta-analysis examining combination therapy favors nivolumab plus cabozantinib as the overall survival leader in doublet therapy. Initial results on the first ever trial of triplet therapy have demonstrated improved progression-free survival over current standard of care. The hypoxia-inducible factor-2α (HIF-2α) inhibitor belzutifan is FDA approved for patients with von Hippel-Lindau disease and is currently being investigated in patients with nonhereditary renal cell carcinoma. The new glutamate synthesis inhibitor, telaglenastat, perhaps confers synergistic benefit when combined with everolimus, but combination with cabozantinib was not so effective. Dual mammalian target of rapamycin (mTOR) inhibition with sapanisertib does not appear to be an effective therapeutic option. New biomarkers and targets are actively being investigated. Four recent trials examining alternative agents to pembrolizumab in the adjuvant setting did not demonstrate an improvement in recurrence-free survival. Cytoreductive nephrectomy in the combination therapy era is supported by retrospective data; clinical trials are recruiting patients. SUMMARY: The last year ushered in novel approaches of varying success for managing advanced renal cell carcinoma, including triplet therapy, HIF-2α inhibitors, metabolic pathway inhibitors, and dual mTOR inhibitors. Pembrolizumab remains the only modern therapy available in the adjuvant setting, and the waters surrounding cytoreductive nephrectomy are still murky.

High-throughput and targeted drug screens identify pharmacological candidates against MiT-translocation renal cell carcinoma.

BACKGROUND: MiT-Renal Cell Carcinoma (RCC) is characterized by genomic translocations involving microphthalmia-associated transcription factor (MiT) family members TFE3, TFEB, or MITF. MiT-RCC represents a specific subtype of sporadic RCC that is predominantly seen in young patients and can present with heterogeneous histological features making diagnosis challenging. Moreover, the disease biology of this aggressive cancer is poorly understood and there is no accepted standard of care therapy for patients with advanced disease. Tumor-derived cell lines have been established from human TFE3-RCC providing useful models for preclinical studies. METHODS: TFE3-RCC tumor derived cell lines and their tissues of origin were characterized by IHC and gene expression analyses. An unbiased high-throughput drug screen was performed to identify novel therapeutic agents for treatment of MiT-RCC. Potential therapeutic candidates were validated in in vitro and in vivo preclinical studies. Mechanistic assays were conducted to confirm the on-target effects of drugs. RESULTS: The results of a high-throughput small molecule drug screen utilizing three TFE3-RCC tumor-derived cell lines identified five classes of agents with potential pharmacological efficacy, including inhibitors of phosphoinositide-3-kinase (PI3K) and mechanistic target of rapamycin (mTOR), and several additional agents, including the transcription inhibitor Mithramycin A. Upregulation of the cell surface marker GPNMB, a specific MiT transcriptional target, was confirmed in TFE3-RCC and evaluated as a therapeutic target using the GPNMB-targeted antibody-drug conjugate CDX-011. In vitro and in vivo preclinical studies demonstrated efficacy of the PI3K/mTOR inhibitor NVP-BGT226, Mithramycin A, and CDX-011 as potential therapeutic options for treating advanced MiT-RCC as single agents or in combination. CONCLUSIONS: The results of the high-throughput drug screen and validation studies in TFE3-RCC tumor-derived cell lines have provided in vitro and in vivo preclinical data supporting the efficacy of the PI3K/mTOR inhibitor NVP-BGT226, the transcription inhibitor Mithramycin A, and GPNMB-targeted antibody-drug conjugate CDX-011 as potential therapeutic options for treating advanced MiT-RCC. The findings presented here should provide the basis for designing future clinical trials for patients with MiT-driven RCC.

TFEB and TFE3 drive kidney cystogenesis and tumorigenesis.

Birt-Hogg-Dubé (BHD) syndrome is an inherited familial cancer syndrome characterized by the development of cutaneous lesions, pulmonary cysts, renal tumors and cysts and caused by loss-of-function pathogenic variants in the gene encoding the tumor-suppressor protein folliculin (FLCN). FLCN acts as a negative regulator of TFEB and TFE3 transcription factors, master controllers of lysosomal biogenesis and autophagy, by enabling their phosphorylation by the mechanistic Target Of Rapamycin Complex 1 (mTORC1). We have previously shown that deletion of Tfeb rescued the renal cystic phenotype of kidney-specific Flcn KO mice. Using Flcn/Tfeb/Tfe3 double and triple KO mice, we now show that both Tfeb and Tfe3 contribute, in a differential and cooperative manner, to kidney cystogenesis. Remarkably, the analysis of BHD patient-derived tumor samples revealed increased activation of TFEB/TFE3-mediated transcriptional program and silencing either of the two genes rescued tumorigenesis in human BHD renal tumor cell line-derived xenografts (CDXs). Our findings demonstrate in disease-relevant models that both TFEB and TFE3 are key drivers of renal tumorigenesis and suggest novel therapeutic strategies based on the inhibition of these transcription factors.

A Phase II Trial of Guadecitabine in Children and Adults with SDH-Deficient GIST, Pheochromocytoma, Paraganglioma, and HLRCC-Associated Renal Cell Carcinoma.

PURPOSE: Succinate dehydrogenase (dSDH)-deficient tumors, including pheochromocytoma/paraganglioma, hereditary leiomyomatosis and renal cell cancer-associated renal cell carcinoma (HLRCC-RCC), and gastrointestinal stromal tumors (GIST) without KIT or platelet-derived growth factor receptor alpha mutations are often resistant to cytotoxic chemotherapy, radiotherapy, and many targeted therapies. We evaluated guadecitabine, a dinucleotide containing the DNA methyltransferase inhibitor decitabine, in these patient populations. PATIENTS AND METHODS: Phase II study of guadecitabine (subcutaneously, 45 mg/m2/day for 5 consecutive days, planned 28-day cycle) to assess clinical activity (according to RECISTv.1.1) across three strata of patients with dSDH GIST, pheochromocytoma/paraganglioma, or HLRCC-RCC. A Simon optimal two-stage design (target response rate 30% rule out 5%) was used. Biologic correlates (methylation and metabolites) from peripheral blood mononuclear cells (PBMC), serum, and urine were analyzed. RESULTS: Nine patients (7 with dSDH GIST, 1 each with paraganglioma and HLRCC-RCC, 6 females and 3 males, age range 18-57 years) were enrolled. Two patients developed treatment-limiting neutropenia. No partial or complete responses were observed (range 1-17 cycles of therapy). Biologic activity assessed as global demethylation in PBMCs was observed. No clear changes in metabolite concentrations were observed. CONCLUSIONS: Guadecitabine was tolerated in patients with dSDH tumors with manageable toxicity. Although 4 of 9 patients had prolonged stable disease, there were no objective responses. Thus, guadecitabine did not meet the target of 30% response rate across dSDH tumors at this dose, although signs of biologic activity were noted.

Understanding the Impact of Belzutifan on Treatment Strategies for Patients with VHL.

Belzutifan was recently approved for the management of Von Hippel-Lindau disease (VHL). Given the morbidity of recurrent treatment, systemic therapy to reduce or eliminate the need for surgery has been long-awaited. Herein, we sought to gain insight about future utilization by surveying VHL kidney cancer experts in the United States. A survey developed by members of the VHL Alliance (VHLA) Clinical Advisory Council was distributed to kidney cancer providers at VHLA and National Comprehensive Cancer Network (NCCN) centers. Surveys were administered on a secure web-based platform. A total of 60 respondents from 29 institutions participated. Urologists (50%) and medical oncologists (43%) represented the majority of participants. The majority (98%) of respondents anticipated that belzutifan's approval would significantly change the current treatment landscape. Most reported that therapy should be continuous (76%). There was a difference in willingness to prescribe belzutifan by specialty (38% of urologists vs 91% of medical oncologists (P = 0.02)). In individuals with renal tumors <3 cm, 36% would still recommend surveillance, while 36% would initiate belzutifan to prevent growth. In those with multifocal renal lesions and growth of a solitary tumor on belzutifan, 50% would proceed with only treatment of that site. In conclusion, VHL kidney cancer specialists anticipate a paradigm shift with the approval of belzutifan. Provider roles may change with movement away from surgical management. Opinions on treatment indications, such as when to initiate therapy and how to best salvage, vary widely and therefore collaborative efforts among experts may assist in the development of new clinical guidelines.

Inhibition of HSP 90 is associated with potent anti-tumor activity in Papillary Renal Cell Carcinoma.

BACKGROUND: There is no universally accepted treatment for patients with advanced papillary renal cell carcinoma (PRCC). The presence of activating mutations in MET, as well as gain of chromosome 7, where the MET gene is located, are the most common genetic alterations associated with PRCC, leading to the clinical evaluation of MET tyrosine kinase inhibitors (TKIs) in this cancer. However, TKIs targeting MET selectively, as well as multitargeted TKIs with activity against MET demonstrate modest efficacy in PRCC and primary and secondary treatment failure is common; other approaches are urgently needed to improve outcomes in these patients. METHODS: High throughput screening with small molecule libraries identified HSP90 inhibitors as agents of interest based on antitumor activity against patient derived PRCC cell lines. We investigated the activity of the orally available HSP90 inhibitor, SNX2112 in vitro, using 2D/3D PRCC cell culture models and in vivo, in mice tumor xenograft models. The molecular pathways mediating antitumor activity of SNX2112 were assessed by Western blot analysis, Flow cytometry, RNA-seq analysis, Real Time qPCR and imaging approaches. RESULTS: SNX2112 significantly inhibited cellular proliferation, induced G2/M cell cycle arrest and apoptosis in PRCC lines overexpressing MET. In contrast to TKIs targeting MET, SNX2112 inhibited both MET and known downstream mediators of MET activity (AKT, pAKT1/2 and pERK1/2) in PRCC cell lines. RNAi silencing of AKT1/2 or ERK1/2 expression significantly inhibited growth in PRCC cells. Furthermore, SNX2112 inhibited a unique set of E2F and MYC targets and G2M-associated genes. Interestingly, interrogation of the TCGA papillary RCC cohort revealed that these genes were overexpressed in PRCC and portend a poor prognosis. Finally, SNX-2112 demonstrated strong antitumor activity in vivo and prolonged survival of mice bearing human PRCC xenograft. CONCLUSIONS: These results demonstrate that HSP90 inhibition is associated with potent activity in PRCC, and implicate the PI3K/AKT and MEK/ERK1/2 pathways as important mediators of tumorigenesis. These data also provide the impetus for further clinical evaluation of HSP90, AKT, MEK or E2F pathway inhibitors in PRCC.

The roaring 2020s: a new decade of systemic therapy for renal cell carcinoma.

PURPOSE OF REVIEW: The genomic and immunologic profiling of renal cell carcinoma (RCC) has provided the impetus for advancements in systemic treatments using combination therapy - either with immune check point inhibitor (ICI) + ICI or with ICI + targeted therapy. This approach has been examined in several landmark trials, treating both clear cell (ccRCC) and nonclear cell (nccRCC) histologies. In this review, we highlight systemic therapy advancements made in this new decade, the 2020s. RECENT FINDINGS: Targeting the programmed death receptor 1/PD-L1 pathway has created more tolerable and effective immunotherapy regimens, expanding the applications of ICIs. These new applications, paired with trial data, include ICI monotherapy in nccRCC and adjuvant pembrolizumab in resected, high-risk RCC. In addition, ICI + ICI and ICI + TKI combination therapy have demonstrated oncologic efficacy in advanced ccRCC and sarcomatoid RCC. Similar progress has been noted regarding new targeted therapies. Along the hypoxia inducible factor pathway, belzutifan has received FDA approval in von Hippel-Lindau-associated RCC. In addition, in papillary RCC, agents such as cabozantinib target the MET proto-oncogene pathway and have demonstrated impressive oncologic outcomes. SUMMARY: The 2020s utilize the molecular profiling of advanced RCC as a scaffold for recent trials in immunotherapy and targeted therapies. Going forward, emphasizing patient-reported outcomes and careful clinical trial construction remain critical to improve systemic therapy in RCC.

Telaglenastat Plus Cabozantinib or Everolimus for Advanced or Metastatic Renal Cell Carcinoma: An Open-Label Phase I Trial.

PURPOSE: Dual inhibition of glucose and glutamine metabolism results in synergistic anticancer effects in solid tumor models. Telaglenastat, an investigational, small-molecule, glutaminase inhibitor, exhibits modest single-agent activity in renal cell carcinoma (RCC) patients. This phase Ib trial evaluated telaglenastat plus cabozantinib or everolimus, agents known to impair glucose metabolism in patients with metastatic RCC (mRCC). PATIENTS AND METHODS: mRCC patients received escalating doses of telaglenastat [400-800 mg per os (p.o.) twice daily] in a 3 + 3 design, plus either everolimus (10 mg daily p.o.; TelaE) or cabozantinib (60 mg daily p.o.; TelaC). Tumor response (RECISTv1.1) was assessed every 8 weeks. Endpoints included safety (primary) and antitumor activity. RESULTS: Twenty-seven patients received TelaE, 13 received TelaC, with median 2 and 3 prior therapies, respectively. Treatment-related adverse events were mostly grades 1 to 2, most common including decreased appetite, anemia, elevated transaminases, and diarrhea with TelaE, and diarrhea, decreased appetite, elevated transaminases, and fatigue with TelaC. One dose-limiting toxicity occurred per cohort: grade 3 pruritic rash with TelaE and thrombocytopenia with TelaC. No maximum tolerated dose (MTD) was reached for either combination, leading to a recommended phase II dose of 800-mg telaglenastat twice daily with standard doses of E or C. TelaE disease control rate (DCR; response rate + stable disease) was 95.2% [20/21, including 1 partial response (PR)] among 21 patients with clear cell histology and 66.7% (2/3) for papillary. TelaC DCR was 100% (12/12) for both histologies [5/10 PRs as best response (3 confirmed) in clear cell]. CONCLUSIONS: TelaE and TelaC showed encouraging clinical activity and tolerability in heavily pretreated mRCC patients.

Belzutifan for Renal Cell Carcinoma in von Hippel-Lindau Disease.

BACKGROUND: Patients with von Hippel-Lindau (VHL) disease have a high incidence of renal cell carcinoma owing to VHL gene inactivation and constitutive activation of the transcription factor hypoxia-inducible factor 2α (HIF-2α). METHODS: In this phase 2, open-label, single-group trial, we investigated the efficacy and safety of the HIF-2α inhibitor belzutifan (MK-6482, previously called PT2977), administered orally at a dose of 120 mg daily, in patients with renal cell carcinoma associated with VHL disease. The primary end point was objective response (complete or partial response) as measured according to the Response Evaluation Criteria in Solid Tumors, version 1.1, by an independent central radiology review committee. We also assessed responses to belzutifan in patients with non-renal cell carcinoma neoplasms and the safety of belzutifan. RESULTS: After a median follow-up of 21.8 months (range, 20.2 to 30.1), the percentage of patients with renal cell carcinoma who had an objective response was 49% (95% confidence interval, 36 to 62). Responses were also observed in patients with pancreatic lesions (47 of 61 patients [77%]) and central nervous system hemangioblastomas (15 of 50 patients [30%]). Among the 16 eyes that could be evaluated in 12 patients with retinal hemangioblastomas at baseline, all (100%) were graded as showing improvement. The most common adverse events were anemia (in 90% of the patients) and fatigue (in 66%). Seven patients discontinued treatment: four patients voluntarily discontinued, one discontinued owing to a treatment-related adverse event (grade 1 dizziness), one discontinued because of disease progression as assessed by the investigator, and one patient died (of acute toxic effects of fentanyl). CONCLUSIONS: Belzutifan was associated with predominantly grade 1 and 2 adverse events and showed activity in patients with renal cell carcinomas and non-renal cell carcinoma neoplasms associated with VHL disease. (Funded by Merck Sharp and Dohme and others; MK-6482-004 ClinicalTrials.gov number, NCT03401788.).

Genetic risk assessment for hereditary renal cell carcinoma: Clinical consensus statement.

BACKGROUND: Although renal cell carcinoma (RCC) is believed to have a strong hereditary component, there is a paucity of published guidelines for genetic risk assessment. A panel of experts was convened to gauge current opinions. METHODS: A North American multidisciplinary panel with expertise in hereditary RCC, including urologists, medical oncologists, clinical geneticists, genetic counselors, and patient advocates, was convened. Before the summit, a modified Delphi methodology was used to generate, review, and curate a set of consensus questions regarding RCC genetic risk assessment. Uniform consensus was defined as ≥85% agreement on particular questions. RESULTS: Thirty-three panelists, including urologists (n = 13), medical oncologists (n = 12), genetic counselors and clinical geneticists (n = 6), and patient advocates (n = 2), reviewed 53 curated consensus questions. Uniform consensus was achieved on 30 statements in specific areas that addressed for whom, what, when, and how genetic testing should be performed. Topics of consensus included the family history criteria, which should trigger further assessment, the need for risk assessment in those with bilateral or multifocal disease and/or specific histology, the utility of multigene panel testing, and acceptance of clinician-based counseling and testing by those who have experience with hereditary RCC. CONCLUSIONS: In the first ever consensus panel on RCC genetic risk assessment, 30 consensus statements were reached. Areas that require further research and discussion were also identified, with a second future meeting planned. This consensus statement may provide further guidance for clinicians when considering RCC genetic risk assessment. LAY SUMMARY: The contribution of germline genetics to the development of renal cell carcinoma (RCC) has long been recognized. However, there is a paucity of guidelines to define how and when genetic risk assessment should be performed for patients with known or suspected hereditary RCC. Without guidelines, clinicians struggle to define who requires further evaluation, when risk assessment or testing should be done, which genes should be considered, and how counseling and/or testing should be performed. To this end, a multidisciplinary panel of national experts was convened to gauge current opinion on genetic risk assessment in RCC and to enumerate a set of recommendations to guide clinicians when evaluating individuals with suspected hereditary kidney cancer.

Kidney cancer: from genes to therapy.

Renal cell carcinoma incidence is rising worldwide with increasing subtype stratification by the World Health Organization. Each subtype has unique genetic alterations, cell biology changes and clinical findings. Such genetic alterations offer the potential for individualized therapeutic approaches that are rapidly progressing. This review highlights the most common subtypes of renal cell carcinoma, including both hereditary and sporadic forms, with a focus on genetic changes, clinical findings and ongoing clinical trials.

A challenging frontier - the genomics and therapeutics of nonclear cell renal cell carcinoma.

PURPOSE OF REVIEW: As molecular profiling of renal cell carcinoma (RCC) continues to elucidate novel targets for nonclear cell histologies, understanding the landscape of these targets is of utmost importance. In this review, we highlight the genomic landscape of nonclear cell RCC and its implications for current and future systemic therapies. RECENT FINDINGS: Several genomic studies have described the mutational burden among nonclear cell histologies. These studies have highlighted the importance of MET in papillary RCC and led to several clinical trials evaluating the efficacy of MET inhibitors for papillary RCC. The success of immune checkpoint inhibitors, such as ipilimumab and nivolumab, in clear cell RCC has led to ongoing trials evaluating these novel therapeutics in nonclear cell RCC. SUMMARY: Genomic profiling has allowed for the evaluation of novel targets for nonclear cell RCC. This evolving therapeutic landscape is being explored in promising, ongoing trials that have the potential for changing how nonclear cell RCC is managed.

18Fluorodeoxyglucose-positron emission tomography/computed tomography for differentiation of renal tumors in hereditary kidney cancer syndromes.

PURPOSE: To assess differences in FDG-PET/CT uptake among four subtypes of renal tumors: clear cell RCC (ccRCC), papillary type I and II RCC (pRCC), and oncocytoma. METHODS: This retrospective study investigated 33 patients with 98 hereditary renal tumors. Lesions greater than 1 cm and patients with a timeframe of less than 18 months between preoperative imaging and surgery were considered. FDG-PET/CT images were independently reviewed by two nuclear medicine physicians, blinded to clinical information. Volumetric lesion SUVmean was measured and used to calculate a target-to-background ratio respective to liver (TBR). The Shrout-Fleiss intra-class correlation coefficient was used to assess reliability between readers. A linear mixed effects model, accounting for within-patient correlations, was used to compare TBR values of primary renal lesions with and without distant metastasis. RESULTS: The time interval between imaging and surgery for all tumors had a median of 77 (Mean: 139; Range: 1-512) days. Intra-class reliability of mean TBR resulted in a mean κ score of 0.93, indicating strong agreement between the readers. The mixed model showed a significant difference in mean TBR among the subtypes (p < 0.0001). Pairwise comparison showed significant differences between pRCC type II and ccRCC (p < 0.0001), pRCC type II and pRCC type I (p = 0.0001), and pRCC type II and oncocytoma (p = 0.0016). Furthermore, a significant difference in FDG uptake was present between primary pRCC type II renal lesions with and without distant metastasis (p = 0.023). CONCLUSION: pRCC type II lesions demonstrated significantly higher FDG activity than ccRCC, pRCC type I, or oncocytoma. These findings indicate that FDG may prove useful in studying the metabolic activity of renal neoplasms, identifying lesions of highest clinical concern, and ultimately optimizing active surveillance, and personalizing management plans.

Characterization of genetically defined sporadic and hereditary type 1 papillary renal cell carcinoma cell lines.

Renal cell carcinoma (RCC) is not a single disease but is made up of several different histologically defined subtypes that are associated with distinct genetic alterations which require subtype specific management and treatment. Papillary renal cell carcinoma (pRCC) is the second most common subtype after conventional/clear cell RCC (ccRCC), representing ~20% of cases, and is subcategorized into type 1 and type 2 pRCC. It is important for preclinical studies to have cell lines that accurately represent each specific RCC subtype. This study characterizes seven cell lines derived from both primary and metastatic sites of type 1 pRCC, including the first cell line derived from a hereditary papillary renal carcinoma (HPRC)-associated tumor. Complete or partial gain of chromosome 7 was observed in all cell lines and other common gains of chromosomes 16, 17, or 20 were seen in several cell lines. Activating mutations of MET were present in three cell lines that all demonstrated increased MET phosphorylation in response to HGF and abrogation of MET phosphorylation in response to MET inhibitors. CDKN2A loss due to mutation or gene deletion, associated with poor outcomes in type 1 pRCC patients, was observed in all cell line models. Six cell lines formed tumor xenografts in athymic nude mice and thus provide in vivo models of type 1 pRCC. These type 1 pRCC cell lines provide a comprehensive representation of the genetic alterations associated with pRCC that will give insight into the biology of this disease and be ideal preclinical models for therapeutic studies.

Mitochondrial DNA alterations underlie an irreversible shift to aerobic glycolysis in fumarate hydratase-deficient renal cancer.

Understanding the mechanisms of the Warburg shift to aerobic glycolysis is critical to defining the metabolic basis of cancer. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an aggressive cancer characterized by biallelic inactivation of the gene encoding the Krebs cycle enzyme fumarate hydratase, an early shift to aerobic glycolysis, and rapid metastasis. We observed impairment of the mitochondrial respiratory chain in tumors from patients with HLRCC. Biochemical and transcriptomic analyses revealed that respiratory chain dysfunction in the tumors was due to loss of expression of mitochondrial DNA (mtDNA)-encoded subunits of respiratory chain complexes, caused by a marked decrease in mtDNA content and increased mtDNA mutations. We demonstrated that accumulation of fumarate in HLRCC tumors inactivated the core factors responsible for replication and proofreading of mtDNA, leading to loss of respiratory chain components, thereby promoting the shift to aerobic glycolysis and disease progression in this prototypic model of glucose-dependent human cancer.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome: Spectrum of imaging findings.

PURPOSE: To retrospectively investigate the radiological presentations of HLRCC-associated renal tumors to facilitate accurate lesion characterization and compare these presentations with simple cysts and characteristics of other subtypes of renal cell carcinoma (RCC) as reported in the literature. METHODS: The MRI and CT imaging characteristics of 39 pathologically confirmed lesions from 30 patients (20 male, 10 female) with HLRCC syndrome were evaluated by two radiologists. Patients had an average age at diagnosis of 43.8 ± 13.1 years. Lesion characteristics including laterality, homogeneity, diameter (cm), nodularity, septations, T1 and T2 signal intensity, enhancement, and restricted diffusion were recorded. Imaging characteristics of the lesions were further compared to characteristics of benign simple cysts surgically removed at the same time point. RESULTS: The examined lesions had a mean diameter of 5.06 ± 3.80 cm, an average growth rate of 2.91 × 10-3 cm/day and an estimated annual growth rate of 1.06 cm/year. 50% of lesions demonstrated nodularity, 65% were mostly T2-hyperintense, 83% demonstrated restricted diffusion in solid portions of the lesions, and 65% had well-defined margins. 76% of patients demonstrated extra-renal manifestations, 53% lymphadenopathy, and 43% distant metastasis. CONCLUSIONS: Our analysis confirmed that while HLRCC-associated renal lesions demonstrate diversity in imaging presentations, the majority are unilateral and solitary, T2-hyperintense, heterogeneous with well-defined margins, and frequently demonstrate restricted diffusion and nodularity.