Germline FH Research Articles

Clinical and molecular risk factors for repeat interventions due to symptomatic uterine leiomyomas

BackgroundRepeat leiomyoma occurrence or even reintervention is common after myomectomy. Little is known about the factors related to repeat interventions. ObjectivesThis study aimed to determine the frequency of leiomyoma-related reintervention after an initial laparoscopic or abdominal myomectomy and to analyze both clinical and molecular risk factors for reinterventions. Another objective was to define the frequency of clonally related tumors from repeat operations. Study DesignThis retrospective cohort study included 234 women who had undergone laparoscopic or abdominal myomectomy in 2009-2014. Information on repeat leiomyoma-related interventions as well as on other clinical factors was collected from medical records after a median follow-up time of 11,4 years (range 7,9-13,8 years) after the index procedure. The effect of clinical risk factors on the risk of reintervention was analyzed by the Kaplan-Meier estimator and the Cox proportional hazards model. For molecular analyses, we examined the mutation profiles of 133 formalin-fixed paraffin-embedded leiomyoma samples from 33 patients with repeat operations. We screened the tumors for the three primary leiomyoma driver alterations—MED12 mutations, HMGA2 overexpression, and FH-deficiency—utilizing Sanger sequencing and immunohistochemistry. To further assess the clonal relationship of the tumors, we executed whole-exome sequencing for 52 leiomyomas from 21 patients who exhibited the same driver alteration in tumors obtained from multiple procedures. ResultsReintervention rate at 11,4 years after myomectomy was 20% (46/234). Number of leiomyomas removed at the index myomectomy was a risk factor (hazard ratio 1.21; 95% confidence interval 1.09-1.34). Age at index myomectomy (hazard ratio 0.94; 95% confidence interval 0.89-0.99) and postoperative parity (hazard ratio 0.23; 95% confidence interval 0.09-0.60) were protective factors. Molecular characterization of tumors from index and non-index operations confirmed a clonal relationship of the tumors in 3/33 (9%) patients. None of the leiomyomas harboring a MED12 mutation —the most common leiomyoma driver— were confirmed clonally related. FH-deficiency was detected in repeat leiomyomas from 3/33 (9%) patients. All these patients harbored a germline FH mutation, which is distinctive for the hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome. Finally, we identified three (3/33; 9%) patients with two tumors each displaying somatic mutations in a recently identified novel leiomyoma driver gene, YEATS4. All YEATS4 mutations were different and thus the tumors were not clonally related. ConclusionOur study shows that reintervention is common after surgical myomectomy. Uterine leiomyomas typically develop independently, but some share a clonal origin. Repeat leiomyoma occurrence may be due to genetic predisposition, such as a germline FH mutation. Distinct somatic YEATS4 mutations identified in multiple leiomyomas from the same patient indicate a possible role for YEATS4 in repeat leiomyomas.

Benign metastasizing fumarate hydratase (FH)-deficient uterine leiomyomas: clinicopathological and molecular study with first documentation of multi-organ metastases

Leiomyoma is the most prevalent benign tumor of the female reproductive system. Benign metastasizing leiomyoma (BML) is a rare phenomenon that presents at distant sites, typically the lungs, exhibiting histopathological features similar to the primary uterine tumor in the absence of malignancy features in both. Fumarate hydratase-deficient uterine leiomyoma (FH-d UL) is an uncommon subtype among uterine smooth muscle tumors (0.5–2%), showing distinctive histomorphology and FH inactivation. The majority of FH-d ULs are sporadic, caused by somatic FH inactivation, while a minority of cases occur in the context of the hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome caused by germline FH inactivation. Metastasizing FH-d UL has not been well documented and might be under-reported. Here, we present two cases (21- and 34-year-old females) who presented with metastasizing FH-d UL after myomectomy/hysterectomy with histologically proven multiple lung metastases in both, in addition to multi-organ involvement in one case (cervical-thoracic lymph nodes, left kidney, perihepatic region, left zygomatic bone, and soft tissues). Pathological examination confirmed FH-d leiomyomas in the primary/recurrent uterine tumors, multiple lung lesions, and a renal mass. The minimal criteria for diagnosis of leiomyosarcoma were not fulfilled. Genetic testing revealed germline pathogenic FH variants in both cases (c.1256C > T; p.Ser419Leu in Case 1 and c.425A > G; p.Gln142Arg in Case 2). These novel cases highlight a rare but possibly under-recognized presentation of FH-d BML. Our study suggests that FH-d BML cases might be enriched for the HLRCC syndrome.

Abstract 5055: Genetic background of recurrent uterine leiomyomas

Abstract Uterine leiomyomas, also known as fibroids, are common benign smooth muscle tumors in women of reproductive age. Leiomyomas can cause symptoms that can significantly reduce the quality of life. Treatment mainly involves hysterectomy or myomectomy, the latter for women who wish to preserve their uterus. Most leiomyomas harbor one of the three driver mutations affecting either MED12, HMGA2, or FH. Recently identified rare subtypes include tumors with mutations in genes linked to the neddylation of the Cullin 3-RING E3 ligase or SRCAP complex. Recurrence of leiomyomas is poorly understood in relation to their clonal origins and molecular factors. The aim of this study was to characterize the mutational profiles of leiomyomas from recurrent operations and to identify the frequency of clonally related tumors. We utilized a retrospective cohort of 234 women who underwent laparoscopic or open abdominal myomectomy, with 46 (20%) of them experiencing multiple procedures related to leiomyomas. We examined the mutation profiles of 133 leiomyomas (62 index and 71 recurrent tumors) from 33 patients who required multiple tumor removal surgeries. We screened the tumors for the three primary leiomyoma drivers—MED12 mutations, HMGA2 overexpression, and FH-deficiency—to identify potentially clonal tumors. We found that 21 out of 33 (64%) patients had tumors from multiple operations with identical leiomyoma driver alterations. To further assess the clonal relationship, we executed whole exome sequencing on these 52 tumors. We identified three patients with two clonally related tumors each through shared somatic copy number alterations and point mutations. The clonally related tumors included HMGA2, FH, and wild-type tumors. Notably, leiomyomas with MED12 mutations—the most common molecular leiomyoma subtype—were not found among the clonally related tumors. Three patients harbored numerous FH-deficient tumors from recurrent operations. In all those patients, we found FH germline mutations, characteristic of Hereditary Leiomyomatosis and Renal Cell Cancer syndrome (HLRCC). Moreover, we identified somatic mutations in YEATS4, a member of the SRCAP complex, in four recurrent tumors from three patients. Interestingly, all YEATS4 mutations were different, and the tumors were not clonally related. Further research is required to elucidate the role of YEATS4 in leiomyoma recurrence. In conclusion, our systematic study confirms that reinterventions are common after myomectomy, and while uterine leiomyomas typically develop independently, some share a clonal origin. Additionally, we show that recurrence may be due to genetic predispositions, such as germline FH mutations. Citation Format: Sara Khamaiseh, Anna Äyräväinen, Maare Arffman, Siiri Reinikka, Annukka Pasanen, Ralf Bützow, Päivi Härkki, Pia Vahteristo. Genetic background of recurrent uterine leiomyomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5055.

Metabolic Signatures and Pathway Rewiring in TET2-Mutated Myeloid Neoplasia

Background. TET2 mutations ( TET2 MT) are the most frequently observed somatic lesions in myeloid neoplasms (MN). TET2 belongs to an Fe2+ and α-ketoglutarate (αKG) dependent DNA-dioxygenase family that progressively oxidizes 5-methyldeoxycytidine (5mC), leading to promoter and enhancer mCpG demethylation essential for efficient transcription. TET2 accounts for the majority of DNA dioxygenase activity in hematopoietic stem and progenitor cells (HSPCs), and following its loss, the resulting accumulation of 5mC leads to a loss of lineage plasticity and transcriptional repression of tumor suppressor genes, thereby establishing a volatile pre-neoplastic state. TET2 is one of the major consumers of αKG, a major cofactor produced by the tricarboxylic acid (TCA) cycle. Therefore, loss of TET2 creates a metabolic perturbation in HSPCs. However, the impact of TET2 loss on the metabolism of leukemic cells and its subsequent effects on malignant evolution remains unclear. Methods. We generated isogenic TET2 -/- ( TET2 ko) leukemic cell models in THP1 and K562 using CRISPR-Cas9 knockout. We then utilized targeted and untargeted metabolic analyses by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry in these models. We aimed to investigate the intricate metabolic changes associated with TET2 and TET2 MT. To validate our findings, we extended our studies to primary cells derived from MN patients with and without TET2 lesions. We performed extensive cellular metabolism studies using 13C isotope labelled glucose and glutamine. Additionally, levels of 5mC and its oxidation products, namely 5-hydroxymethyldeoxycytidine, 5-formyldeoxycytidine, and 5-carboxydeoxycytidine were documented for correlating epigenetic modifications with TET2 activities. Results. Targeted metabolic analysis uncovered profound impacts of TET2 MT on key metabolic pathways including the TCA cycle, glycolysis, glutamine metabolism, and nucleoside biosynthesis (Figure A). Distinct changes were observed in cells from different lineage backgrounds, suggesting diverse metabolic pathway rewiring specific to cell origin. Despite the divergence among lineages, loss of TET2 created common and unique metabolic signatures, highlighting their crucial role in sustaining the survival and clonal advantages specific to TET2 MT. Representative signature compounds and their relative quantities in TET2 wildtype (WT) and TET2 MT are depicted in Figure A. The targeted metabolic analysis revealed a significantly lower level of glutamine in TET2 MTcells, suggesting a potential preference for exhausting glutamine as a source of energy production. For validation, we conducted 13C metabolic flux analysis (13C-MFA) using glucose (U-13C, 99%) and L-glutamine (U-13C, 99%). 13C-MFA revealed distinct enrichment patterns (Figure B). In the TCA cycle, the dominant isotopologues receiving [U-13C]-glucose were M+2 for citrate and isocitrate. However, for aKG, succinate (SA) and fumarate (FA), the M+2s were significantly lower in TET2 -/- compared to WT, suggesting that the major source for these metabolites were rewired from glycolysis to glutamine metabolism in TET2 -/-. This was confirmed by [U-13C]-glutamine labeling where dominant isotopologues, M+5 for aKG and M+4 for SA, FA and malate, were significantly higher at 24-hour time point in in TET2 -/- compared to WT. Untargeted metabolic analyses from isogenic cells were used to identify metabolic features associated with TET2 loss. These metabolic features were also assayed in primary AML cells with TET2 MT (n=12) and without: RUNX1 (n=20), SF3B1 (n=11), IDH1 (n=10), IDH2 (n=13), FH (n=3), as well as healthy donors as controls (n=6). Based on the molecular features identified in the TET2 ko isogenic cells, MN patients with TET2, IDH1/2, and germline FH mutations clustered more closely, suggesting shared metabolic signatures among these groups. In contrast, patients with RUNX1 and SF3B1 mutations formed separate clusters, demonstrating distinct metabolic profiles associated with these genetic alterations. Conclusion. Our findings provide comprehensive and novel insights into the metabolic consequences of TET2 inactivation in MN. The identified metabolic signatures and rewiring of key pathways may hold promise as potential therapeutic targets and offer opportunities for tailored treatment approaches in TET2MT MN.

The use of Clinicopathological, immunohistochemistry and molecular detection in the diagnosis of fumarate hydratase-deficient uterine leiomyomas

BackgroundFumarate hydratase-deficient uterine leiomyomas (FH-dUL) are rare, accounting for only 0.4–1.6% of uterine leiomyomas. FH germline mutation gene is associated with hereditary leiomyomatosis and renal cell carcinoma syndrome (HLRCC). MethodsIn this study, we aim to investigate Clinicopathological features and FH mutation in FH-dUL. We performed a retrospective analysis of 300 cases of uterine leiomyoma, diagnosed from January 2017 to December 2021, within the archives of the Department of Pathology at Peking University People's Hospital. In our review of the immunohistochemical(IHC) staining was performed on 300 uSMTs to detect FH deficiency. ResultsWe identified 21cases (21/300,7%) of FH-dUL. Nineteen cases (6.33%) displayed negative FH. Twenty-one cases (7%) displayed 2SC diffuse plasma and nuclear staining. The most common FH-d morphological features included staghorn vasculature ( 100%,21/21), alveolar-pattern oedema (71.43%, 15/21), scattered bizarre nuclei (23.81%, 5/21), eosinophilic cytoplasmic (rhabdoid) inclusions (47.62%, 10/21), significant eosinophilic nucleolus with peri-nucleolus hollowing (23.81%, 5/21), ovoid nuclei sometimes arranged in chains (9.52%, 2/21). DNA sequencing for the 21 cases was performed using Next Generation Sequencing (NGS). 6 cases were detected significant variations for the FH gene, 11 cases were detected FH gene mutation forvariants of uncertain significance (VUS), and 2 cases were detected a TP53 gene mutation. No related mutations were detected in the other two cases. ConclusionsFH-dUL is rare. The combination of predictive Clinicopathological evaluation,FH and 2SC IHC test, and molecular test were helpful for the screening of FH-dUL from uSMTs,or even the screening of HLRCC.

EDITORIAL COMMENT

Paragangliomas and pheochromocytomas (PGL/PCC) are rare tumors that are derived from neural crest chromaffin cells either from neuroendocrine tissues distributed along the spine or from within the adrenal gland respectively. Approximately 40% of cases are associated with pathogenic germline variants in genes associated to cancer susceptibility syndromes, such as MAX, NF1, RET, SDHA, and SDHAF2, including several gene that associated with inherited kidney cancer, such as VHL, SDHB, SDHC, SDHD, and TMEM127. 1 Shuch B Ricketts CJ Metwalli AR Pacak K Linehan WM. The genetic basis of pheochromocytoma and paraganglioma: implications for management. Urology. 2014; 83: 1225-1232 Google Scholar ,2 Dahia PL. Pheochromocytoma and paraganglioma pathogenesis: learning from genetic heterogeneity. Nat Rev Cancer. 2014; 14: 108-119 Google Scholar A recent addition to this list is germline alteration of the FH gene, known to cause hereditary leiomyomatosis and renal cell cancer (HLRCC). 3 Richter S Gieldon L Pang Y et al. Metabolome-guided genomics to identify pathogenic variants in isocitrate dehydrogenase, fumarate hydratase, and succinate dehydrogenase genes in pheochromocytoma and paraganglioma. Genet Med. 2019; 21: 705-717 Google Scholar , 4 Clark GR Sciacovelli M Gaude E et al. Germline FH mutations presenting with pheochromocytoma. J Clin Endocrinol Metab. 2014; 99: E2046-E2050 Google Scholar , 5 Muller M Ferlicot S Guillaud-Bataille M et al. Reassessing the clinical spectrum associated with hereditary leiomyomatosis and renal cell carcinoma syndrome in French FH mutation carriers. Clin Genet. 2017; 92: 606-615 Google Scholar

Consensus on clinical diagnosis and treatment of fumarate hydratase-deficient renal cell carcinoma

Fumarate hydratase-deficient renal cell carcinoma (FH-RCC) is an independent pathological subtype of renal cell carcinoma with a clear driver gene and a high degree of malignancy. Recent studies have found that patients with somatic FH mutations have similar clinico-biological behavior and poor prognosis to patients with germline FH mutations. FH-RCC has the characteristics of early age of onset, atypical imaging manifestations, variable pathological patterns, difficult clinical diagnosis and poor effect on traditional drug treatment, thus greatly endangering the life and health of patients. Under the organization of the Rare Kidney Cancer Collaborative Group, Genitourinary Cancer Committee, China Anti-Cancer Association, this guideline was developed based on basic research, clinical cohort and evidence-based medicine evidence, including imaging manifestations, pathological diagnosis, genetic testing, surgical and systemic treatment options, and provided recommendations and references for the diagnosis and treatment norms.

Genomic Profiling and Response to Immune Checkpoint Inhibition plus Tyrosine Kinase Inhibition in FH-Deficient Renal Cell Carcinoma

BackgroundFH-deficient renal cell carcinoma (RCC) is a rare and exceptionally aggressive RCC subtype. There is currently limited understanding of the molecular alterations, pathogenesis, survival outcomes, and systemic therapy efficacy for this cancer. ObjectiveTo perform a retrospective multicenter analysis of molecular profiling and clinical outcomes for patients with FH-deficient RCC, with an emphasis on treatment response to first-line immune checkpoint inhibitor plus tyrosine kinase inhibitor (ICI/TKI) versus bevacizumab plus erlotinib (Bev/Erlo) combination therapy in patients with advanced disease. Design, setting, and participantsThe study included 77 cases of FH-deficient RCC from 15 centers across China. Outcome measurements and statistical analysisClinical characteristics, molecular correlates, 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging, and treatment outcomes were analyzed. Results and limitationsA total of 77 patients were identified, including 70 cases with a germline FH alteration (hereditary leiomyomatosis RCC syndrome [HLRCC]-associated RCC) and seven patients with somatic FH loss. Recurrent pathogenic alterations were found in NF2 (six/57, 11%), CDH1 (six/57, 11%), PIK3CA (six/57, 11%), and TP53 (five/57, 8.8%). Sixty-seven patients were evaluable for response to first-line systemic therapy with Bev/Erlo (n = 12), TKI monotherapy (n = 29), or ICI/TKI (n = 26). ICI/TKI combination therapy was associated with more favorable overall survival on systemic treatment (hazard ratio [HR] 0.19, 95% confidence interval [CI] 0.04–0.90) and progression-free survival on first-line therapy (HR 0.22, 95% CI 0.07–0.71) compared to Bev/Erlo combination therapy. The main limitation is the retrospective study design. ConclusionsWe described the genomic characteristics of FH-deficient RCC in an Asian population and observed a favorable response to ICI/TKI combinational therapy among patients with advanced disease. Patient summaryThis real-world study provides evidence supporting the antitumour activity of combining molecular targeted therapy plus immunotherapy for kidney cancer deficient in fumarate hydratase. Further studies are needed to investigate the efficacy of this combination strategy in this rare cancer.

Genomic and Metabolic Hallmarks of SDH- and FH-deficient Renal Cell Carcinomas

BackgroundSuccinate dehydrogenase-deficient and fumarate hydratase-deficient renal cell carcinomas (SDHRCC and FHRCC) are rare kidney cancers driven by loss of TCA cycle enzymes. ObjectiveTo define and compare the genomic and metabolomic hallmarks of SDHRCC and FHRCC. Design, setting, and participantsWe analyzed SDHRCC and FHRCC tumors with either immunohistochemical evidence of loss of protein expression or genomically confirmed biallelic inactivation of SDHA/B/C/D/AF2 or FH. Outcome measurements and statistical analysisSomatic alterations were identified using clinical pipelines, with allele-specific copy number alterations (CNAs) identified using FACETS. Mass spectrometry–based metabolomic profiling was performed on available SDHRCC and FHRCC tumors. Results and limitationsTumors were analyzed for 42 patients (25 FHRCC, 17 SDHRCC). In the germline analysis, 16/17 SDHRCCs harbored a germline alteration in SDHB, whereas only 17/22 FHRCCs had pathogenic germline FH variants. SDHRCCs had a lower mutation burden (p = 0.02) and CNA burden (p = 0.0002) than FHRCCs. All SDHRCCs presented with deletion of chromosome 1p (overlapping SDHB), whereas FHRCCs demonstrated high but not ubiquitous loss of 1q (FH locus). Both SDHRCCs and FHRCCs exhibited significant idiopathic accumulation of the metabolite guanine. FHRCC tumors had elevated levels of urea cycle metabolites (argininosuccinate, citrulline, and fumarate), whereas SDHRCC tumors had elevation of numerous acylcarnitines. These characteristic metabolic changes allowed identification of a previously unrecognized SDH-deficient RCC. ConclusionsDespite sharing similar genetic etiology, SDHRCC and FHRCC represent distinct molecular entities with unique genetic and metabolic abnormalities. Patient summaryKidney cancers driven by loss of the gene encoding either the succinate dehydrogenase or fumarate hydratase enzyme are rare. We sought to define and compare the genetic and metabolic features of these cancer entities.

Fumarate Hydratase Deficiency Should be Considered in the Differential Diagnosis of Uterine and Extrauterine Smooth Muscle Tumors of Uncertain Malignant Potential (STUMP).

Fumarate hydratase-deficient leiomyomas (dFH leiomyomas) often display atypical pathologic features yet exhibit a benign clinical course. Recent data suggest that dFH leiomyomas may be misclassified as smooth muscle tumors of uncertain malignant potential, a category that encompasses a heterogenous subgroup of uterine neoplasms with smooth muscle differentiation and atypical features that impart ambiguity regarding their expected clinical behavior. dFH leiomyomas can be seen in the context of hereditary leiomyomatosis and renal cell carcinoma syndrome or in the sporadic setting. In this retrospective study, we sought to examine the prevalence and clinicopathologic characteristics of dFH leiomyomas in 48 tumors previously diagnosed as smooth muscle tumors of uncertain malignant potential from 38 patients. Of these 48 tumors, 3 (6.3%) occurring in 2 patients were found to be deficient for FH by immunohistochemistry, including 1 uterine and 2 extrauterine (abdominopelvic) tumors. The 3 tumors showed histologic features typical of dFH leiomyomas, including hemangiopericytoma-like vessels, edema, macronucleoli, and atypia. Neither patient developed recurrent leiomyomas or renal cell carcinoma, and both were alive without disease at last follow-up. Our data suggest that dFH leiomyomas should be considered in the differential diagnosis of smooth muscle tumors of uncertain malignant potential, even in the context of extrauterine disease. Identification of FH deficiency in these tumors supports their classification as dFH leiomyomas despite their atypical morphologic features and/or clinical presentation. Importantly, detection of dFH in these cases may identify women at increased risk for hereditary leiomyomatosis and renal cell carcinoma who would benefit from genetic counseling and consideration for FH germline testing.

Prevalence of pathogenic germline variants in patients with metastatic renal cell carcinoma

Germline pathogenic variants are estimated to affect 3-5% of renal cell carcinoma (RCC) patients. However, higher mutational prevalence in non-clear cell RCC (non-ccRCC) and advanced disease has been suggested. To clarify the prevalence of pathogenic germline variants in metastatic RCC, we sequenced 29 cancer susceptibility genes in 294 unselected metastatic RCC cases plus 21 patients with clinical hereditary features. In 145 tumors, genes frequently mutated in RCC were sequenced and methylation was assessed in selected cases. Germline variants in RCC predisposition genes (FH, VHL) were detected in 1.4% of the unselected metastatic patients, with higher frequency in non-ccRCC versus ccRCC (6.4% and 0.4%; P = 0.0025) and in younger patients (P = 0.036). Among the 315 studied patients, 14% of non-type 1 papillary cases (4 of 28), all metastatic <1 year after diagnosis, carried a FH germline variant with loss of heterozygosity and tumor genome hypermethylation. Variants in other cancer-associated genes (e.g., MUTYH, BRCA2, CHEK2) occurred in 5.1% of the unselected series, with unclear significance for RCC. Our findings confirm a high prevalence of pathogenic germline variants in RCC predisposition genes in metastatic non-ccRCC, and highlight that metastatic patients with papillary type 2 or unconventional histologies compatible with FH would benefit from genetic screening.

Comprehensive Molecular Characterization and Response to Therapy in Fumarate Hydratase-Deficient Renal Cell Carcinoma.

Fumarate hydratase-deficient renal cell carcinoma (FH-RCC) is a rare, aggressive form of RCC associated with hereditary leiomyomatosis and RCC syndrome. Evidence for systemic therapy efficacy is lacking. We studied clinical and genomic characteristics of FH-RCC, including response [objective response rate (ORR)] to systemic therapies and next-generation sequencing (NGS). Patients with metastatic FH-RCC, defined by presence of pathogenic germline or somatic FH mutation plus IHC evidence of FH loss, were included. A total of 28 of 32 included patients (median age 46; range, 20-74; M:F, 20:12) underwent germline testing; 23 (82%) harbored a pathogenic FH germline variant. Five (16%) were negative for germline FH mutations; all had biallelic somatic FH loss. Somatic NGS (31/32 patients) revealed co-occurring NF2 mutation most frequently (n = 5). Compared with clear-cell RCC, FH-RCC had a lower mutation count (median 2 vs. 4; P < 0.001) but higher fraction of genome altered (18.7% vs. 10.3%; P = 0.001). A total of 26 patients were evaluable for response to systemic therapy: mTOR/VEGF combination (n = 18, ORR 44%), VEGF monotherapy (n = 15, ORR 20%), checkpoint inhibitor therapy (n = 8, ORR 0%), and mTOR monotherapy (n = 4, ORR 0%). No complete responses were seen. Median overall and progression-free survival were 21.9 months [95% confidence interval (CI): 14.3-33.8] and 8.7 months (95% CI: 4.8-12.3), respectively. Although most FH-RCC tumors are due to germline FH alterations, a significant portion result from biallelic somatic FH loss. Both somatic and germline FH-RCC have similar molecular characteristics, with NF2 mutations, low tumor mutational burden, and high fraction of genome altered. Although immunotherapy alone produced no objective responses, combination mTOR/VEGF therapy showed encouraging results.

Imaging features of fumarate hydratase-deficient renal cell carcinomas: a retrospective study

BackgoundFumarate hydratase-deficient renal cell carcinoma (FH-RCC) is a subtype of RCC that is increasingly recognized pathologically. The aim of this study was to evaluate the imaging features of FH-RCC on computed tomography (CT), magnetic resonance imaging (MRI), and fluorodeoxyglucose positron emission tomography (FDG PET), and to determine the pre-operative diagnostic potential of imaging.MethodsThis single-site retrospective study included patients with histologically confirmed FH-RCC or with a renal cancer and known germline FH mutation; imaging of the renal mass before treatment with contrast-enhanced CT, contrast-enhanced MRI, or FDG PET/CT between October 2007 and May 2019. Clinical information, pathological data, and imaging features were analyzed and reported descriptively.ResultsSixteen patients with sixteen tumors were included (median age 46 years, interquartile range 38–53 years; 31 % female). Almost all tumors were unifocal (15/16, 94 %). Most tumors had infiltrative margins (14/16, 88 %); few were circumscribed (2/16, 12 %). A large cystic tumor component (> 75 % of tumor volume) was seen in 8/16 (50 %) of tumors. Involvement of renal sinus fat was seen in 13/16 (81 %) of tumors, involvement of the hilar collecting system in 8/16 (50 %), and renal vein tumor thrombus in 6/16 (38 %). All 12 tumors (100 %) imaged with MRI had heterogenous tumor enhancement and heterogenous T2 signal. Of those patients that had diffusion-weighted imaging, 11/11 (100 %) of tumors had diffusion restriction in the solid portions of the tumor. Of the patients who had PET, 3/3 (100 %) tumors showed high metabolic activity with mean maximum standardized uptake value (SUVmax) of 16.4 (range 9.6–21.9). Patients presented with retroperitoneal nodal metastases in 69 % of cases and distant metastases in 75 %. Of those four patients without metastatic disease at presentation, three (75 %) developed metastases within 4 years of diagnosis.ConclusionsIn our study, the majority of tumors (≥ 75 %) were unifocal, had an infiltrative margin, invaded the renal sinus fat, and presented with distant metastases. On MRI, most tumors had heterogenous T2 signal and diffusion restriction in their solid components. The small number of cases that had PET imaging showed high metabolic activity.

Multidetector CT Characteristics of Fumarate Hydratase-Deficient Renal Cell Carcinoma and Papillary Type II Renal Cell Carcinoma.

ObjectiveTo investigate the multidetector computed tomography (MDCT) features of fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) with germline or somatic mutations, and compare them with those of papillary type II RCC (pRCC type II).Materials and MethodsA total of 24 patients (mean ± standard deviation, 40.4 ± 14.7 years) with pathologically confirmed FH-deficient RCC (15 with germline and 9 with somatic mutations) and 54 patients (58.6 ± 12.6 years) with pRCC type II were enrolled. The MDCT features were retrospectively reviewed and compared between the two entities and mutation subgroups, and were correlated with the clinicopathological findings.ResultsAll the lesions were unilateral and single. Compared with pRCC type II, FH-deficient RCC was more prevalent among younger patients (40.4 ± 14.7 vs. 58.6 ± 12.6, p < 0.001) and tended to be larger (8.1 ± 4.1 vs. 5.4 ± 3.2, p = 0.002). Cystic solid patterns were more common in FH-deficient RCC (20/24 vs. 16/54, p < 0.001), with 16 of the 20 (80.0%) cystic solid tumors having showed typical polycystic and thin smooth walls and/or septa, with an eccentric solid component. Lymph node (16/24 vs. 16/54, p = 0.003) and distant (11/24 vs. 3/54, p < 0.001) metastases were more frequent in FH-deficient RCC. FH-deficient RCC and pRCC type II showed similar attenuation in the unenhanced phase. The attenuation in the corticomedullary phase (CMP) (76.3% ± 25.0% vs. 60.2 ± 23.6, p = 0.008) and nephrographic phase (NP) (87.7 ± 20.5, vs. 71.2 ± 23.9, p = 0.004), absolute enhancement in CMP (39.0 ± 24.8 vs. 27.1 ± 22.7, p = 0.001) and NP (50.5 ± 20.5 vs. 38.2 ± 21.9, p = 0.001), and relative enhancement ratio to the renal cortex in CMP (0.35 ± 0.26 vs. 0.24 ± 0.19, p = 0.001) and NP (0.43 ± 0.24 vs. 0.29 ± 0.19, p < 0.001) were significantly higher in FH-deficient RCC. No significant difference was found between the FH germline and somatic mutation subgroups in any of the parameters.ConclusionThe MDCT features of FH-deficient RCC were different from those of pRCC type II, whereas there was no statistical difference between the germline and somatic mutation subgroups. A kidney mass with a cystic solid pattern and metastatic tendency, especially in young patients, should be considered for FH-deficient RCC.

Fumaratehydratase-deficient renal cell carcinoma: a clinicopathological and molecular study of 13 cases

AimsHereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a newly recognised entity in the WHO 2016 classification defined as the germline mutation of FH gene. Fumaratehydratase-deficient renal cell carcinoma (FH-deficient...

Abstract 730: Genomic characterization of hereditary leiomyomatosis and renal cell carcinoma (HLRCC), a rare and aggressive kidney cancer

Abstract Background Hereditary Leiomyomatosis and Renal Cell Carcinoma (HLRCC) is a rare autosomal-dominant syndromic disorder associated with germline FH mutations. Affected individuals have a predisposition to cutaneous and uterine leiomyoma’s, and are at increased risk of developing a renal cell carcinoma (HLRCC- associated RCC) with aggressive clinical outcome. However, aside from FH bi-allelic loss, additional genomic features of HLRCC are currently poorly understood. Method Five cases of HLRCC-associated RCC were characterized using integrated next generation sequencing (NGS) technology. This included an index case where multiple tumor sites (kidney, lung, liver, lymph node, skin, and uterine) from a single patient were characterized. For integrative analysis, in-house data were combined with five RCC cases with FH bi-allelic loss from The Cancer Genome Atlas Study. Single cell sequencing was carried out on normal human kidney to study the cell of origin for HLRCC- associated RCC. Results: Integrative NGS profiling and analysis of HLRCC-associated RCC tumors (n=10) revealed several important observations such as 1) a high frequency loss of whole chromosomes, which is reminiscent of tumors arising from the distal nephron, 2) low mutational burden similar to that observed in other kidney tumors and, 3) a HLRCC specific gene expression signature and discovery of a novel therapeutic candidate (HLRCC-TC1). Importantly, among renal tumors, HLRCC-TC1 was specifically expressed in HLRCC and other RCCs with poor clinical outcome. Application of siRNAs and neutralizing antibodies to HLRCC-TC1 reduced cell proliferation of the HLRCC cell line UOK262, but did not for that of control cell lines. Conclusion: The observed FH bi-allelic mutation along with recurrent chromosome-wide losses and integrative analysis with human kidney single cell sequencing data support a distal nephron origin for HLRCC- associated RCC. In addition, our study provides evidence for nominating HLRCC-TC1 as a novel cancer-specific therapeutic target. Further studies are needed to conduct an in-depth characterization of HLRCC-TC1. Citation Format: Pankaj Vats, Yuping Zhang, Sarvana Mohan Dhanashekaran, Narayanan Sathiya Pandi, Xuhong Cao, Fengyun Su, Sudhanshu Shukla, Rui Wang, Marcin Cieslik, Jincheng Pan, Christopher J. Ricketts, Prem Kumar Kumpati, Ajjai Alva, Marston W. Linehan, Rohit Mehra, Arul M. Chinnaiyan. Genomic characterization of hereditary leiomyomatosis and renal cell carcinoma (HLRCC), a rare and aggressive kidney cancer [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 730.

Prospective Detection of Germline Mutation of Fumarate Hydratase in Women With Uterine Smooth Muscle Tumors Using Pathology-based Screening to Trigger Genetic Counseling for Hereditary Leiomyomatosis Renal Cell Carcinoma Syndrome

Pathology-based screening of uterine smooth muscle tumors (uSMT) for morphology suggestive of fumarate hydratase deficiency (FH-d morphology) has been proposed as a method to identify women at increased risk for hereditary leiomyomatosis renal cell carcinoma (HLRCC) syndrome. For 5 years our clinical diagnostic practice has evaluated all women with any type of uSMT for FH-d morphology (defined, at low magnification, as staghorn shaped blood vessels and alveolar pattern edema and, at high magnification, as tumor macronucleoli surrounded by a halo and cytoplasmic eosinophilic globules) and, when present, used the pathology report to advise genetic counseling to further evaluate for HLRCC syndrome. We now report the results of this prospective screening strategy, with emphasis on the incidence and clinicopathologic features of FH-d morphology in uSMT, the rate of patient uptake of referral to genetic counseling, and the results of genetic testing for FH germline mutation. Among 2060 women with a uSMT, FH-d morphology was reported in 1.4% (30 women). Ten women elected to undergo FH genetic testing and 6 of 10 (60%) had a FH germline mutation: 5 were pathogenic mutations and 1 was a mutation variant of unknown significance. Therefore, the screening program led to a confirmed genetic diagnosis of HLRCC syndrome in 0.24% of all women with any type of uSMT. The women with a pathogenic mutation were ages 24 to 40 years. Although the majority of leiomyoma with bizarre nuclei exhibited FH-d morphology, the uSMT were conventional leiomyomas with FH-d morphology in 2 of 5 women found to have a pathogenic FH germline mutation. Relying on an abnormal FH immunostain result to trigger genetic counseling referral would have resulted in 2 of 5 (40%) cases with pathogenic FH germline mutation but normal FH immunoexpression going undetected, both of which were missense type mutations. There was no difference in the incidence of pathogenic FH germline mutation between FH-d morphology uSMT with an abnormal versus a normal FH immunostain result. Overall, this study demonstrates that prospective morphology-based screening, integrated with referral for genetic counseling, can result in the diagnosis of HLRCC syndrome in otherwise unselected women with uSMT. We conclude that this strategy should be incorporated in the routine pathologic examination of all uterine smooth muscle tumors.

OR29-6 Brown Adipose Tissue Activation in SDHx-Related Pheochromocytoma and Paraganglioma: An Ominous Sign?

Brown adipose tissue (BAT) activation after cold exposure and its subsequent detection via18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is mediated through norepinephrine (NE) induced β3-adrenoceptor activation. Pheochromocytoma/paragangliomas (PPGLs), especially SDH, VHL, and FH germline variants (cluster 1 tumors), predominantly secrete NE and often has higher maximal standardized uptake values of tumors on18F-FDG PET/CT1. Therefore, 18F-FDG PET/CT scans of these NE-secreting PPGLs should also reveal higher BAT activity. Because BAT activation is also associated with cancer-induced cachexia and thus poor outcomes 2, BAT activation in PPGLs could also indicate aggressive tumor behavior. To study the relationship between BAT activation detected on 18F-FDG PET/CT and the clinical behavior of PPGLs, we performed a retrospective study of 343 patients with genetically characterized and histopathologically confirmed PPGLs who underwent 18F-FDG PET/CT imaging for disease surveillance between 2013 and 2017. After excluding patients with only post-operative PET scans and those with normal serum catecholamines and/or metanephrines, 205 patients were included in the final analysis. BAT activation was observed in 16 patients (7.8%; 28±17y; 10F/6M, 23.4±4.2 kg/m2). Hereditary PPGLs were present in 12/16 patients of which, 10 had cluster 1 variants (SDHx, n=7; HIF2A, n=2; VHL, n=1), 2 had cluster 2 variants (NF1, n=2), and 4 had sporadic PPGL. Elevated plasma biomarkers were as follows: epinephrine (n=0/16); metanephrine (n=2/16); NE (n=11/16); normetanephrine (n=16/16); and dopamine (n=8/16). A matched control group of 36 PPGL patients without detectable BAT activation (34±13y, 21F/15M,23.9±2.5 kg/m2, 12/36 SDHx, p=0.47) revealed a significantly lower mortality rate (n=2/36 vs n=4/16; p=0.043). All deaths in the BAT activation group were found in patients with SDHx variants compared to sporadic PPGL patients in the control group. The development of metastasis was similar in both groups (n=10/16, 62.5% vs. n=27/36, 75%; p=0.36). In conclusion, cluster 1 PPGLs are more likely to be associated with BAT activation. We show for the first time that particularly the combination of an SDHx mutation and BAT activation is associated with a higher mortality. Further investigation is necessary to establish the mechanistic connection between PPGLs, especially those with SDHx mutations, BAT activation, and poorer prognosis.

SWI/SNF protein expression status in fumarate hydratase–deficient renal cell carcinoma: immunohistochemical analysis of 32 tumors from 28 patients

Fumarate hydratase-deficient renal cell carcinoma (FH-RCC) is a rare, aggressive RCC type, originally described in the setting of hereditary leiomyomatosis and RCC syndrome, which is defined by germline FH gene inactivation. Inactivation of components of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex is involved in renal medullary carcinoma (SMARCB1/INI1 loss), clear cell RCC (PBRM1 loss), and subsets of dedifferentiated RCC of clear cell, chromophobe, and papillary types (loss of different SWI/SNF components). FH-RCC and SWI/SNF-deficient RCC share anaplastic nuclear features and highly aggressive course. We analyzed 32 FH-RCCs from 28 patients using 7 commercially available SWI/SNF antibodies (SMARCB1/INI1, SMARCA2, SMARCA4, SMARCC1, SMARCC2, PBRM1, and ARID1A). Variable loss of SMARCB1, ARID1A, and SMARCC1 was observed in 1 of 31, 2 of 31, and 1 of 29 evaluable cases, respectively; 3 of these 4 SWI/SNF-deficient tumors had confirmed FH mutations. No correlation of SWI/SNF loss with solid or sarcomatoid features was observed. Two tumors with SMARCB1 and ARID1A deficiency had available SWI/SNF molecular data; both lacked SMARCB1 and ARID1A mutations. The remaining 5 SWI/SNF components were intact in all cases. Especially PBRM1 seems not to be involved in the pathogenesis or progression of FH-RCC. Our data showed that a subset of FH-RCC (12%) have a variable loss of SWI/SNF complex subunits, likely as secondary genetic events. This should not be confused with SWI/SNF-deficient RCC of other types. Evaluation of FH and SWI/SNF together with comprehensive molecular genetic profiling is needed to explore possible prognostic implications of FH/SWI-SNF double deficiency and to better understand the somatic mutation landscape in high-grade RCC.

Germline Mutations in the Mitochondrial 2-Oxoglutarate/Malate Carrier SLC25A11 Gene Confer a Predisposition to Metastatic Paragangliomas.

Comprehensive genetic analyses have identified germline SDHB and FH gene mutations as predominant causes of metastatic paraganglioma and pheochromocytoma. However, some suspicious cases remain unexplained. In this study, we performed whole-exome sequencing of a paraganglioma exhibiting an SDHx-like molecular profile in the absence of SDHx or FH mutations and identified a germline mutation in the SLC25A11 gene, which encodes the mitochondrial 2-oxoglutarate/malate carrier. Germline SLC25A11 mutations were identified in six other patients, five of whom had metastatic disease. These mutations were associated with loss of heterozygosity, suggesting that SLC25A11 acts as a tumor-suppressor gene. Pseudohypoxic and hypermethylator phenotypes comparable with those described in SDHx- and FH-related tumors were observed both in tumors with mutated SLC25A11 and in Slc25a11Δ/Δ immortalized mouse chromaffin knockout cells generated by CRISPR-Cas9 technology. These data show that SLC25A11 is a novel paraganglioma susceptibility gene for which loss of function correlates with metastatic presentation.Significance: A gene encoding a mitochondrial carrier is implicated in a hereditary cancer predisposition syndrome, expanding the role of mitochondrial dysfunction in paraganglioma. Cancer Res; 78(8); 1914-22. ©2018 AACR.