Growth Rates of Genetically Defined Renal Tumors: Implications for Active Surveillance and Intervention

PURPOSE

Published series of growth rates of renal tumors on active surveillance largely consist of tumors without pathologic or genetic data. Growth kinetics of genetically defined renal tumors are not well known. Here, we evaluate the growth of genetically defined renal tumors and their association with patient clinical and genetic characteristics.

PATIENTS AND METHODS

We evaluated patients with an inherited kidney cancer susceptibility syndrome as a result of a pathologic germline alteration of VHL, MET, FLCN, or BAP1 with at least 1 solid renal mass managed with active surveillance at our institution. Tumor growth rates (GR) were calculated and patients were stratified by genetic alteration and other clinical and genetic factors to analyze differences in growth rates using linear regression and comparative statistics.

RESULTS

A total of 292 patients with 435 genetically defined tumors were identified, including 286 VHL-deficient, 91 FLCN-deficient, 52 MET-activated, and 6 BAP1-deficient tumors. There were significant differences in GRs when stratified by genetic alteration. BAP1-deficient tumors had the fastest median GR (0.6 cm/y; interquartile range [IQR], 0.57-0.68 cm/y), followed by VHL-deficient tumors (GR, 0.37 cm/y; IQR, 0.25-0.57 cm/y), FLCN-deficient tumors (GR, 0.10 cm/y; IQR, 0.04-0.24 cm/y), and tumors with MET activation (GR, 0.15 cm/y; IQR, 0.053-0.32 cm/y; P < .001). Tumors from the same patient had similar GRs. Younger age was independently associated with higher GR (P = .005).

CONCLUSION

In a cohort of genetically defined tumors, tumor growth rates varied in a clinically and statistically different manner according to genetic subtype. Rapid growth of BAP1-deficient tumors indicates that these patients should be managed with caution. The faster growth of tumors in younger patients may support more frequent imaging, whereas the slower growth of other tumors may support extended surveillance beyond annual imaging in some instances.

Clear Cell Renal Cell Carcinoma Growth Correlates with Baseline Diffusion-weighted MRI in Von Hippel-Lindau Disease

Background Identification of markers to aid in understanding the growth kinetics of Von Hippel-Lindau (VHL)-associated clear cell renal cell carcinoma (ccRCC) has the potential to allow individualization of patient care, thereby helping prevent unnecessary screening and optimizing intervention. Purpose To determine whether the degree of restricted diffusion at baseline MRI holds predictive potential for the growth rate of VHL-associated ccRCC. Materials and Methods Patients with VHL disease who underwent surgical resection of tumors between November 2014 and October 2017 were analyzed retrospectively in this HIPAA-compliant study. The change in ccRCC volume between two time points and apparent diffusion coefficient (ADC) at baseline was calculated by using segmentations by two readers at nephrographic-phase CT and diffusion-weighted MRI, respectively. Intraclass correlation coefficient was used to assess agreement between readers. Repeated-measures correlation was used to investigate relationships between ADC (histogram parameters) and tumor size at baseline with growth rate and volume doubling time (VDT). Predictive performance of the ADC parameter with highest correlation and tumor size at baseline was reviewed to differentiate tumors based on their VDT (≤1 year or >1 year). Results Forty-six patients (mean age, 46 years ± 7 [standard deviation]; 25 women) with 100 ccRCCs were evaluated. Interreader agreement resulted in mean κ scores of 0.89, 0.82, and 0.93 for mean ADC, baseline tumor volume, and follow-up tumor volume, respectively. ADC percentiles correlated negatively with tumor growth rate but correlated positively with VDT. Lower ADC values demonstrated stronger correlations. The 25th percentile ADC had the strongest correlation with growth rate (ρ = -0.52, P < .001) and VDT (ρ = 0.60, P < .001) and enabled prediction of VDT (≤1 year or >1 year) with an area under the receiver operating characteristic curve of 0.86 (sensitivity, 67%; specificity, 89%) (P < .001). Conclusion Apparent diffusion coefficient at baseline was negatively correlated with tumor growth rate. Diffusion-weighted MRI may be useful to identify clear cell renal cell carcinomas with higher growth rates. © RSNA, 2020See also the editorial by Goh and Prezzi in this issue.

Determination of the Expression of PD-L1 in the Morphologic Spectrum of Renal Cell Carcinoma

Immunotherapy is reportedly an effective form of therapy for some advanced cancers such as lung adenocarcinoma, malignant melanoma and colorectal adenocarcinoma. In renal cell carcinoma (RCC), the role of immunotherapy is under investigation. Programmed Death-Ligand 1 (PD-L1) is a molecule expressed on the surface of certain tumor cells and binds to the Programmed cell death protein 1 (PD-1) on cytotoxic T-cells, an interaction that inhibits the antitumor immune response. The aim of this study is to evaluate PD-L1 expression in the morphologic spectrum of RCC. A total of 172 cases of RCC comprising all types were studied and the PD-L1 was correlated with immune response for CD4 and CD8. Positive membranous staining for PD-L1 was seen in 59 (34%) of the 172 samples. The positive cases were HLRCC (31/53), Type 1 Papillary RCC (10/31), Chromophobe (7/20), Hybrid (3/9), TFE-3 related cancer (3/8), Undifferentiated (3/5), and TFEB tumors (2/2). Clear cell carcinomas, Oncocytomas and SDHB deficient-RCC didn't show any expression of PD-L1; (0/34;0/7;0/3). Our results demonstrated that aggressive forms of RCC such as HLRCC have high expression of PD-L1, in contrast to clear cell renal carcinomas. Our findings support a possible role of anti-PD-L1/PD-1 immunotherapies in the treatment of PD-L1-positive RCC.

Salvage robotic transmesenteric off-clamp partial nephrectomy after multiple prior open kidney surgeries

Repeat renal surgery is technically demanding with a high morbidity rate. We describe a novel surgical approach, a salvage robotic transmesenteric off-clamp partial nephrectomy for the management of a renal cell carcinoma in a patient with a history of VHL and multiple prior renal surgeries on the affected kidney. Upon pathological review, the specimen was diagnosed as clear cell RCC, Fuhrman Grade 3, with negative surgical margins. The patient suffered no post-operative complications and had a rapid convalescence. This approach is a feasible and safe alternative in select patients with a significant history of renal surgeries and favorable anatomy.

MRI-Targeted, Systematic, and Combined Biopsy for Prostate Cancer Diagnosis

BACKGROUND

The use of 12-core systematic prostate biopsy is associated with diagnostic inaccuracy that contributes to both overdiagnosis and underdiagnosis of prostate cancer. Biopsies performed with magnetic resonance imaging (MRI) targeting may reduce the misclassification of prostate cancer in men with MRI-visible lesions.

METHODS

Men with MRI-visible prostate lesions underwent both MRI-targeted and systematic biopsy. The primary outcome was cancer detection according to grade group (i.e., a clustering of Gleason grades). Grade group 1 refers to clinically insignificant disease; grade group 2 or higher, cancer with favorable intermediate risk or worse; and grade group 3 or higher, cancer with unfavorable intermediate risk or worse. Among the men who underwent subsequent radical prostatectomy, upgrading and downgrading of grade group from biopsy to whole-mount histopathological analysis of surgical specimens were recorded. Secondary outcomes were the detection of cancers of grade group 2 or higher and grade group 3 or higher, cancer detection stratified by previous biopsy status, and grade reclassification between biopsy and radical prostatectomy.

RESULTS

A total of 2103 men underwent both biopsy methods; cancer was diagnosed in 1312 (62.4%) by a combination of the two methods (combined biopsy), and 404 (19.2%) underwent radical prostatectomy. Cancer detection rates on MRI-targeted biopsy were significantly lower than on systematic biopsy for grade group 1 cancers and significantly higher for grade groups 3 through 5 (P<0.01 for all comparisons). Combined biopsy led to cancer diagnoses in 208 more men (9.9%) than with either method alone and to upgrading to a higher grade group in 458 men (21.8%). However, if only MRI-target biopsies had been performed, 8.8% of clinically significant cancers (grade group ≥3) would have been misclassified. Among the 404 men who underwent subsequent radical prostatectomy, combined biopsy was associated with the fewest upgrades to grade group 3 or higher on histopathological analysis of surgical specimens (3.5%), as compared with MRI-targeted biopsy (8.7%) and systematic biopsy (16.8%).

CONCLUSIONS

Among patients with MRI-visible lesions, combined biopsy led to more detection of all prostate cancers. However, MRI-targeted biopsy alone underestimated the histologic grade of some tumors. After radical prostatectomy, upgrades to grade group 3 or higher on histopathological analysis were substantially lower after combined biopsy. (Funded by the National Institutes of Health and others; Trio Study ClinicalTrials.gov number, NCT00102544.).

Surgical learning curve for robotic multiplex partial nephrectomy: The National Cancer Institute Experience

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Background: Multiplex partial nephrectomy (MPN) remains the standard of care for hereditary and bilateral kidney tumors. Our institution is an international referral center for the management of hereditary renal cell carcinoma, and therefore has considerable experience with MPN. The objective of this study was to evaluate surgical learning curve for MPN among multiple surgeons at a single institution over an 11-year period. Methods: Retrospective review of a prospectively maintained registry of patients who underwent MPN from 2007-present. The first 100 consecutive surgeries of 3 NIH fellowship trained Urologic Oncologists were identified and evaluated in quartiles. Surgical outcome measures including operative duration (OD), estimated blood loss (EBL), number of tumors resected, and complication rate were chosen as surrogate markers of learning curve. Differences in individual surgeon outcomes were evaluated and variables including re-do surgery and surgical approach were considered. Significant differences found among quartiles or among surgeon were evaluated with multivariate logistic regression analysis. Results: A total of 300 MPN's were identified. In the quartile analysis, there were no significant differences in OD, EBL, numbers of tumors resected or rates of complication. Among surgeon factors, there were differences in surgical approach and EBL (table). In a multivariate analysis of factors associated with EBL, open approach (95%CI 245-831), p < 0.0001) and number of tumors (95%CI 43-82), p < 0.0001) were independently associated. No factors were associated increased rate of complication. Conclusions: As surgeons progressed through their first 100 operations, no true learning curve was appreciated, with similar outcomes in each quartile. Among surgeon factors, open surgical approach appears to drive difference in EBL.[Table: see text]

Selecting the surgical approach in complex reoperative partial nephrectomies: Does robotics have a role?

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Background: Minimally invasive surgery (MIS) has shown equal oncologic efficacy as the open approach for treating small renal masses but results in improved perioperative parameters. Surgical principles also dictate that the open technique should be considered when facing difficult surgeries though this is experience and not evidenced based. The goal of our study is to explore differences in outcomes amongst open or robotic approaches in complex reoperative partial nephrectomies. Methods: 194 patients who had prior renal surgery from 2008 to 2019 were identified, the majority of which presented with multiple tumors due to known or suspected hereditary kidney cancer syndrome. Patients were stratified into the following cohorts based on surgical history: open after open surgery, open after MIS, robotic after open surgery, and robotic after MIS. Perioperative outcomes were compared amongst cohorts. Results: Significant differences were noted in estimated blood loss (EBL), number of tumors resected, and postoperative complications as assessed by Clavien score. Univariate regression analysis of EBL showed that the number of tumors resected (p <.0001, coefficient: 111 ml), number of prior renal procedures (p=.012, coefficient: 419 ml), hilar clamping (p = .015, coefficient: 840 ml), and intended surgical approach (p = .001; coefficient: 905 ml) were significant. On multivariate analysis, number of tumors resected (p<.0001, coefficient: 97 ml) was the only significant factor. Univariate analysis on post-operative complications showed that number of prior surgeries (p = 0.03, OR: 1.5) and final intended approach (p < .0001, OR: 4.6) were significant. On multivariate analysis, the final intended surgical approach (p = .001, OR: 4.3) was shown to be significant. Conclusions: These data show that the surgical approach of prior procedures is not a significant factor that affects perioperative outcomes, but the use of robotic surgery was associated with decreased post-operative complications in reoperative renal surgery . While open surgery will likely continue to be the standard of care for complex reoperative procedures, these data suggest that robotic surgery is safe and well tolerated in select cases.

A novel multiplex score to predict outcomes of partial nephrectomy for multiple tumors

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Background: The RENAL nephrometry score (RNS) is widely used to describe renal mass complexity and inform patient counseling for partial nephrectomy (PN). However, in cases with multiple lesions (commonly seen in hereditary cancer syndromes) it is unknown which features drive postoperative complications. Here, we employed a novel scoring equation (Multiplex Score, MS) derived from RNS and assessed outcomes of multiplex PN at our institution. Methods: The MS was defined a priori as a weighted score (# low risk (LR) lesions) + 2*(# intermediate risk (IR)) + 4*(# high risk (HR)) based on published Clavien-Dindo III-V complication rates of 6.4%, 11.1%, and 21.9% for LR, IR, and HR RNS respectively. MS was dichotomized into favorable/unfavorable based on median score. Patient outcomes were maintained prospectively. Binary outcomes were evaluated with logistic regression and continuous outcomes were evaluated with linear regression. Results: From 10/2017-8/2019, 62 consecutive multiplex PN (median (range) # tumors = 4 (2-11), 65% robotic) were performed by a single surgeon. Median (range) MS was 6 (2-20). Of 13 complications, urine leak (N = 5, 8%) and bleed requiring embolization (N = 4, 6%) were the most common. Only 1 complication occurred in the favorable score group and MS was significantly associated with perioperative complication (OR 1.21, p = 0.018) and blood loss (242.42 mL, p < 0.001). Hilar clamping was omitted in 32 (52%) cases with median 18.5 min when used. Every 1 additional HR or IR tumor was associated with a 2 minute increase in clamp time (2.01, p = 0.048). Median clamp time for favorable/unfavorable cases was 0 vs. 10 minutes. Change in renal function was negligible in our cohort (median ΔCr 0 mg/dL, IQR -0.61–0.1). There were no conversions from partial to radical nephrectomy and open conversion was only done in 3 (7.5%) cases, all assigned unfavorable MS. Conclusions: The novel Multiplex Score associated well with complications, blood loss, and open conversion. This tool may facilitate standardized reporting of complexity for multiplex series, with special relevance for hereditary cancer syndromes.

Genetic risk assessment for hereditary RCC: Report from the consensus panel meeting

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Background: While many genes are now known to be associated with hereditary kidney cancer syndromes, there is a paucity of guidelines or uniform consensus on genetic testing for these patients. An expert panel was organized to assess who, what, when and how patients should be evaluated and what testing should be initiated. Methods: A national, multidisciplinary, panel of experts in urology, medical oncology, clinical geneticists, genetic counselors and patient advocates with background and knowledge in hereditary syndromic kidney cancer convened in person in September 2019. A renal cell carcinoma (RCC) genetic risk assessment questionnaire consisting of 52 questions was compiled prior to the meeting using modified Delphi methodology. The questions were then discussed and reviewed with uniform consensus defined as a minimum of 85% agreement in accordance with the National Comprehensive Cancer Network criteria. Results: The panel consisted of twenty-six attendees represented by urologists (43%), medical oncologist (23%), genetic counselors (13%), clinical geneticists (7%), and patient advocates (3%). The questionnaire consisted of fifty-five statements focusing on who, what, when and how genetic testing should be performed in a patient suspected of hereditary RCC syndrome. A >85% agreement was reached on 30/52 statements with 18/25 (72%) achieving consensus addressing “who”, 2/6 (33%) achieving consensus in “what’ category, 2/7 (29%) in ‘when’ and 4/6 (67%) on how. The questions with least consensus were found in the “what/when?” category with only 4/13 questions with minimum 85% agreement. Specific areas of debate included an age cutoff for prompting a genetic risk assessment as well as need for familial testing in patients with variants of unknown significance. Conclusions: Despite experience of the panel in management of hereditary RCC, the consensus was reached only on 66% of genetic testing. While many issues will need to be discussed further, those statements with consensus may be used to guide physicians and patients on who, what, when and how genetic RCC risk assessment should be performed.

FLCN alteration drives metabolic reprogramming towards nucleotide synthesis and cyst formation in salivary gland

FLCN is a tumor suppressor gene which controls energy homeostasis through regulation of a variety of metabolic pathways including mitochondrial oxidative metabolism and autophagy. Birt-Hogg-Dubé (BHD) syndrome which is driven by germline alteration of the FLCN gene, predisposes patients to develop kidney cancer, cutaneous fibrofolliculomas, pulmonary cysts and less frequently, salivary gland tumors. Here, we report metabolic roles for FLCN in the salivary gland as well as their clinical relevance. Screening of salivary glands of BHD patients using ultrasonography demonstrated increased cyst formation in the salivary gland. Salivary gland tumors that developed in BHD patients exhibited an upregulated mTOR-S6R pathway as well as increased GPNMB expression, which are characteristics of FLCN-deficient cells. Salivary gland-targeted Flcn knockout mice developed cytoplasmic clear cell formation in ductal cells with increased mitochondrial biogenesis, upregulated mTOR-S6K pathway, upregulated TFE3-GPNMB axis and upregulated lipid metabolism. Proteomic and metabolite analysis using LC/MS and GC/MS revealed that Flcn inactivation in salivary gland triggers metabolic reprogramming towards the pentose phosphate pathway which consequently upregulates nucleotide synthesis and redox regulation, further supporting that Flcn controls metabolic homeostasis in salivary gland. These data uncover important roles for FLCN in salivary gland; metabolic reprogramming under FLCN deficiency might increase nucleotide production which may feed FLCN-deficient salivary gland cells to trigger tumor initiation and progression, providing mechanistic insight into salivary gland tumorigenesis as well as a foundation for development of novel therapeutics for salivary gland tumors.

A FLCN-TFE3 Feedback Loop Prevents Excessive Glycogenesis and Phagocyte Activation by Regulating Lysosome Activity

The tumor suppressor folliculin (FLCN) suppresses nuclear translocation of TFE3, a master transcription factor for lysosomal biogenesis, via regulation of amino-acid-sensing Rag GTPases. However, the importance of this lysosomal regulation in mammalian physiology remains unclear. Following hematopoietic-lineage-specific Flcn deletion in mice, we found expansion of vacuolated phagocytes that accumulate glycogen in their cytoplasm, phenotypes reminiscent of lysosomal storage disorder (LSD). We report that TFE3 acts in a feedback loop to transcriptionally activate FLCN expression, and FLCN loss disrupts this loop, augmenting TFE3 activity. Tfe3 deletion in Flcn knockout mice reduces the number of phagocytes and ameliorates LSD-like phenotypes. We further reveal that TFE3 stimulates glycogenesis by promoting the expression of glycogenesis genes, including Gys1 and Gyg, upon loss of Flcn. Taken together, we propose that the FLCN-TFE3 feedback loop acts as a rheostat to control lysosome activity and prevents excessive glycogenesis and LSD-like phagocyte activation.

Proteasome inhibition disrupts the metabolism of fumarate hydratase- deficient tumors by downregulating p62 and c-Myc

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is characterized by germline mutations of the FH gene that encodes for the TCA cycle enzyme, fumarate hydratase. HLRCC patients are at risk for the development of an aggressive form of type 2 papillary renal cell carcinoma. By studying the mechanism of action of marizomib, a proteasome inhibitor able to cross the blood-brain barrier, we found that it modulates the metabolism of HLRCC cells. Marizomib decreased glycolysis in vitro and in vivo by downregulating p62 and c-Myc. C-Myc downregulation decreased the expression of lactate dehydrogenase A, the enzyme catalyzing the conversion of pyruvate to lactate. In addition, proteasomal inhibition lowered the expression of the glutaminases GLS and GLS2, which support glutamine metabolism and the maintenance of the redox balance. Thus, in HLRCC cells, proteasome inhibition disrupts glucose and glutamine metabolism, restricting nutrients and lowering the cells’ anti-oxidant response capacity. Although the cytotoxicity induced by proteasome inhibitors is complex, the understanding of their metabolic effects in HLRCC may lead to the development of effective therapeutic strategies or to the development of markers of efficacy.

Familial Kidney Cancer: Implications of New Syndromes and Molecular Insights

CONTEXT

Hereditary cases account for about 5% of all cases of renal cell carcinoma (RCC). With advances in next-generation sequencing, several new hereditary syndromes have been described in the last few years.

OBJECTIVE

To review and summarise the recent preclinical and clinical literature in hereditary renal cancer.

EVIDENCE ACQUISITION

A systematic review of the literature was performed in November 2018 using PubMed and OMIM databases, with an emphasis on kidney cancer, genetics and genomics, clinical criteria, and management.

EVIDENCE SYNTHESIS

Several autosomal dominant hereditary RCC syndromes have been described, including those related to germline pathogenic variants in VHL, MET, FH, TSC1/TSC2, FLCN, SDHA/B/C/D, BAP1, CDC73, and MITF. Clinical spectrum of SDH, BAP1, and MITF is still being defined, although these appear to be associated with a lower incidence of RCC. FH and likely BAP1 RCC are associated with more aggressive disease. Preclinical and clinical studies show that using systemic therapy that exploits specific genetic pathways is a promising strategy.

CONCLUSIONS

There are several well-described hereditary RCC syndromes, as well as recently identified ones, for which the full clinical spectrum is yet to be defined. In the new era of precision medicine, identification of these syndromes may play an important role in management and systemic treatment selection.

PATIENT SUMMARY

This review covers updates in the diagnosis and management of familial kidney cancer syndromes. We describe updates in testing and management of the most common syndromes such as von Hippel-Lindau, and hereditary leiomyomatosis and renal cell carcinoma. We also provide insights into recently described familial kidney cancer syndromes.

Dual functions of angiopoietin-like protein 2 signaling in tumor progression and anti-tumor immunity

Angiopoietin-like protein 2 (ANGPTL2) is a secreted glycoprotein homologous to angiopoietins. Previous studies suggest that tumor cell-derived ANGPTL2 has tumor-promoting function. Here, we conducted mechanistic analysis comparing ANGPTL2 function in cancer progression in a murine syngeneic model of melanoma and a mouse model of translocation renal cell carcinoma (tRCC). ANGPTL2 deficiency in tumor cells slowed tRCC progression, supporting a tumor-promoting role. However, systemic ablation of ANGPTL2 accelerated tRCC progression, supporting a tumor-suppressing role. The syngeneic model also demonstrated a tumor-suppressing role of ANGPTL2 in host tumor microenvironmental cells. Furthermore, the syngeneic model showed that PDGFRα⁺ fibroblasts in the tumor microenvironment express abundant ANGPTL2 and contribute to tumor suppression. Moreover, host ANGPTL2 facilitates CD8⁺ T-cell cross-priming and enhances anti-tumor immune responses. Importantly, ANGPTL2 activates dendritic cells through PIR-B-NOTCH signaling and enhances tumor vaccine efficacy. Our study provides strong evidence that ANGPTL2 can function in either tumor promotion or suppression, depending on what cell type it is expressed in.

Obstructive azoospermia secondary to bilateral epididymal cystadenomas in a patient with von Hippel-Lindau

von Hippel-Lindau (VHL) is a heritable cancer syndrome associated with findings in multiple organ systems. Male patients can be affected by epididymal cystadenomas which are benign tumors localized to the epididymis. While benign, these tumors can cause pain and in very rare circumstances can have an effect on fertility especially when present bilaterally. We present a case of a young man with obstructive azoospermia secondary to bilateral cystadenomas, with a focus on his work-up and management.

A Phase II Trial of Vandetanib in Children and Adults with Succinate Dehydrogenase-Deficient Gastrointestinal Stromal Tumor

PURPOSE

Gastrointestinal stromal tumors (GIST) are resistant to cytotoxic chemotherapy and radiotherapy. Most GIST in children are wild-type for KIT and PDGFRA (WT GIST) and deficient in expression of succinate dehydrogenase (dSDH GIST). We tested the activity of vandetanib, an oral small-molecule inhibitor of VEGFR2, EGFR, and RET, in patients with dSDH GIST.

PATIENTS AND METHODS

Phase II study of vandetanib (300 mg orally once daily to patients ≥18 years, and 100 mg/m2/dose to patients < 18 years) on a continuous dosing schedule (1 cycle = 28 days) to assess the clinical activity (partial and complete response rate RECIST v1.1) in patients with dSDH GIST. A Simon optimal two-stage design (target response rate 25%, rule out 5%) was used: If ≥1 of 9 patients in stage 1 responded, enrollment would be expanded to 24 patients, and if ≥3 of 24 responded, vandetanib would be considered active.

RESULTS

Nine patients (7 female and 2 male; median age, 24 years; range, 11-52) with metastatic disease were enrolled. Three of the initial 5 adult patients developed treatment-modifying toxicities. After a protocol amendment, two adults received vandetanib at 200 mg/dose with improved tolerability. The two children (<18 years old) enrolled did not experience treatment-modifying toxicities. No partial or complete responses were observed (median number of cycles, 4; range, 2-18).

CONCLUSIONS

Vandetanib at a dose of 300 mg daily was not well tolerated by adults with dSDH GIST. Two of 9 patients had prolonged stable disease, but no partial or complete responses were observed, and vandetanib is thus not considered active in dSDH GIST.

Integrated Proteogenomic Characterization of Clear Cell Renal Cell Carcinoma

To elucidate the deregulated functional modules that drive clear cell renal cell carcinoma (ccRCC), we performed comprehensive genomic, epigenomic, transcriptomic, proteomic, and phosphoproteomic characterization of treatment-naive ccRCC and paired normal adjacent tissue samples. Genomic analyses identified a distinct molecular subgroup associated with genomic instability. Integration of proteogenomic measurements uniquely identified protein dysregulation of cellular mechanisms impacted by genomic alterations, including oxidative phosphorylation-related metabolism, protein translation processes, and phospho-signaling modules. To assess the degree of immune infiltration in individual tumors, we identified microenvironment cell signatures that delineated four immune-based ccRCC subtypes characterized by distinct cellular pathways. This study reports a large-scale proteogenomic analysis of ccRCC to discern the functional impact of genomic alterations and provides evidence for rational treatment selection stemming from ccRCC pathobiology.

Imaging of glucose metabolism by 13C-MRI distinguishes pancreatic cancer subtypes in mice

Metabolic differences among and within tumors can be an important determinant in cancer treatment outcome. However, methods for determining these differences non-invasively in vivo is lacking. Using pancreatic ductal adenocarcinoma as a model, we demonstrate that tumor xenografts with a similar genetic background can be distinguished by their differing rates of the metabolism of 13C labeled glucose tracers, which can be imaged without hyperpolarization by using newly developed techniques for noise suppression. Using this method, cancer subtypes that appeared to have similar metabolic profiles based on steady state metabolic measurement can be distinguished from each other. The metabolic maps from 13C-glucose imaging localized lactate production and overall glucose metabolism to different regions of some tumors. Such tumor heterogeneity would not be not detectable in FDG-PET.

TFE3 Xp11.2 Translocation Renal Cell Carcinoma Mouse Model Reveals Novel Therapeutic Targets and Identifies GPNMB as a Diagnostic Marker for Human Disease

Renal cell carcinoma (RCC) associated with Xp11.2 translocation (TFE3-RCC) has been recently defined as a distinct subset of RCC classified by characteristic morphology and clinical presentation. The Xp11 translocations involve the TFE3 transcription factor and produce chimeric TFE3 proteins retaining the basic helix-loop-helix leucine zipper structure for dimerization and DNA binding suggesting that chimeric TFE3 proteins function as oncogenic transcription factors. Diagnostic biomarkers and effective forms of therapy for advanced cases of TFE3-RCC are as yet unavailable. To facilitate the development of molecular based diagnostic tools and targeted therapies for this aggressive kidney cancer, we generated a translocation RCC mouse model, in which the PRCC-TFE3 transgene is expressed specifically in kidneys leading to the development of RCC with characteristic histology. Expression of the receptor tyrosine kinase Ret was elevated in the kidneys of the TFE3-RCC mice, and treatment with RET inhibitor, vandetanib, significantly suppressed RCC growth. Moreover, we found that Gpnmb (Glycoprotein nonmetastatic B) expression was notably elevated in the TFE3-RCC mouse kidneys as seen in human TFE3-RCC tumors, and confirmed that GPNMB is the direct transcriptional target of TFE3 fusions. While GPNMB IHC staining was positive in 9/9 cases of TFE3-RCC, Cathepsin K, a conventional marker for TFE3-RCC, was positive in only 67% of cases. These data support RET as a potential target and GPNMB as a diagnostic marker for TFE3-RCC. The TFE3-RCC mouse provides a preclinical in vivo model for the development of new biomarkers and targeted therapeutics for patients affected with this aggressive form of RCC. IMPLICATIONS: Key findings from studies with this preclinical mouse model of TFE3-RCC underscore the potential for RET as a therapeutic target for treatment of patients with TFE3-RCC, and suggest that GPNMB may serve as diagnostic biomarker for TFE3 fusion RCC.

Abstract 2759: Chemoproteomic profiling of the oncometabolite fumarate

Dysregulated metabolism is a feature of many diseases, including cancer. In addition to providing energy and building blocks to growing cells, altered metabolism can assist in tumor growth by producing “oncometabolites”. For example, in hereditary leiomyomatosis and renal cell carcinoma (HLRCC) inactivating mutations in fumarate hydratase (FH) leads to accumulation of millimolar levels of an oncometabolite, fumarate. At such high concentrations, fumarate can spontaneously react with protein cysteine residues leading to a post-translational modification (PTM) called cysteine succination. This PTM can directly stimulate tumorigenic signaling, however, current methods to study this PTM are limited. Our lab has developed chemical proteomic methods to investigate proteome-wide targets of cysteine succination. Using these methods, we have identified hundreds of targets of fumarate in normal kidney cells as well as HLRCC cells. One interesting target identified that has implications in cancer progression is SMARCC1, a core subunit of a nucleosome remodeling complex known as the SWI/SNF complex. The SWI/SNF complex is a well-known tumor suppressor and mutation of this complex leads to cancer development. We have demonstrated that excess fumarate levels result in hyper-modification of SMARCC1 and decrease in SWI/SNF complex stability. This instability also results in an increase in EZH2 expression as well as activity, and an increase in H3K27Me3. Our current efforts are aimed at understanding how fumarate affects the function of this complex in vivo and exploring the potential of using EZH2 inhibitors in the treatment of HLRCC.

Citation Format: Sarah E. Bergholtz, Chloe A. Briney, Rhushikesh A. Kulkarni, David Wei, Daniel W. Bak, Jonathan H. Shrimp, Eranthie Weerapana, W. Marston Linehan, Jordan L. Meier. Chemoproteomic profiling of the oncometabolite fumarate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2759.

Abstract 2760: Photoinducible detection of the oncometabolite fumarate

Dysregulated metabolism is an important marker of many disease states, including cancer. For example, in hereditary leiomyomatosis and renal cell cancer (HLRCC), inactivating mutations in fumarate hydratase (FH) lead to accumulation of high levels of fumarate, a so-called “oncometabolite.” Substantial evidence indicates that fumarate stimulates various oncogenic signaling pathways, necessitating sensitive methods to detect the oncometabolite in order to more rapidly diagnose HLRCC as well as to identify new disease settings in which fumarate may play a signaling role. Here, we report development of novel photoactivatable, fluorogenic chemical probes for detection and profiling of fumarate in biological systems. These chemical probes, diaryl tetrazoles, are by themselves inert towards fumarate. However, upon irradiation with UV light, they release nitrileimines that can form fluorescent cycloadducts with fumarate. We have demonstrated that diaryl tetrazoles can sensitively detect FH activity as well as low micromolar levels of fumarate in complex biological samples. We have also shown that diaryl tetrazoles can be used to monitor changes in intracellular fumarate levels in biological samples by live-cell imaging and flow cytometry. Moreover, these compounds are capable of visualizing differences between patient-derived primary HLRCC tumors lacking FH activity and the adjacent normal kidney, highlighting their potential utility in clinical diagnostics. By offering new insights into fumarate reactivity, our studies provide the chemical basis for novel approaches to therapy and diagnosis in cancers driven by oncometabolite accumulation.

Citation Format: Chloe Briney, Sarah Bergholtz, Rhushikesh Kulkarni, Daniel Crooks, Chandrasekhar Mushti, Stephen Lockett, Rolf Swenson, W. Marston Linehan, Jordan Meier. Photoinducible detection of the oncometabolite fumarate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2760.