Targeted next-generation sequencing detects rare genetic events in pheochromocytoma and paraganglioma

Patient Sex and Origin Influence Distribution of Driver Genes and Clinical Presentation of Paraganglioma

Context

Sexual and ancestral differences in driver gene prevalence have been described in many cancers but have not yet been investigated in pheochromocytoma and paraganglioma (PPGL).

Objective

This study aims to assess whether sex and ancestry influence prevalence of PPGL driver genes and clinical presentation.

Methods

We conducted a retrospective analysis of patients with PPGL considering studies from 2010 onwards that included minimal data of type of disease, sex, mutated gene, and country of origin. Additional features were recorded when available (age, tumor location, bilateral or multifocal, somatic or germline, and metastatic disease).

Results

We included 2162 patients: 877 in Europe and 757 in Asia. Males presented more often with germline pathogenic variants (PVs) in genes activating hypoxia pathways (P = .0006) and had more often sympathetic paragangliomas (P = .0005) and metastasis (P = .0039). On the other hand, females with PPGLs due to MAX PVs were diagnosed later than males (P = .0378) and more often developed metastasis (P = .0497). European but not Asian females presented more often with PPGLs due to PVs in genes related to kinase signaling (P = .0052), particularly RET and TMEM127. Contrary to experiences from Europe, Asian patients with PPGL due to PVs in kinase signaling genes NF1, HRAS, and FGFR1 showed a high proportion of sympathetic tumors, while European patients almost exclusively had adrenal tumors (P < .005).

Conclusion

Personalized management of patients with PPGL might benefit from considering sexual and ancestral differences. Further studies with better clinically aligned cohorts from various origins are required to better dissect ancestral influences on PPGL development.

Phaeochromocytoma and paraganglioma

Phaeochromocytomas and paragangliomas are rare catecholamine-producing neuroendocrine tumours which can potentially cause catastrophic crises with high morbidity and mortality. This best practice article considers the causes and presentation of such tumours, screening and diagnostic tests, management of these patients and consideration of family members at risk.

EPAS1-mutated paragangliomas associated with haemoglobin disorders

We report a large series of 40 patients presenting EPAS1-mutated paraganglioma (PGL) in whom we investigated a cause underlying chronic hypoxia. Four patients suffered from hypoxaemic heart disease. In patients with available haemoglobin electrophoresis results, 59% presented with a haemoglobin disorder, including six with sickle cell disease, five with sickle cell trait and two with heterozygous haemoglobin C disease. Histological and transcriptomic characterization of EPAS1 tumours revealed increased angiogenesis and high similarities with pseudohypoxic PGLs caused by VHL gene mutations. Sickle haemoglobinopathy carriers could thus be at increased risk for developing EPAS1-PGLs, which should be taken into account in their management and surveillance.

Somatic EPAS1 Variants in Pheochromocytoma and Paraganglioma in Patients With Sickle Cell Disease

CONTEXT

Somatic EPAS1 variants account for 5% to 8% of all pheochromocytoma and paragangliomas (PPGL) but are detected in over 90% of PPGL in patients with congenital cyanotic heart disease, where hypoxemia may select for EPAS1 gain-of-function variants. Sickle cell disease (SCD) is an inherited hemoglobinopathy associated with chronic hypoxia and there are isolated reports of PPGL in patients with SCD, but a genetic link between the conditions has yet to be established.

OBJECTIVE

To determine the phenotype and EPAS1 variant status of patients with PPGL and SCD.

METHODS

Records of 128 patients with PPGL under follow-up at our center from January 2017 to December 2022 were screened for SCD diagnosis. For identified patients, clinical data and biological specimens were obtained, including tumor, adjacent non-tumor tissue and peripheral blood. Sanger sequencing of exons 9 and 12 of EPAS1, followed by amplicon next-generation sequencing of identified variants was performed on all samples.

RESULTS

Four patients with both PPGL and SCD were identified. Median age at PPGL diagnosis was 28 years. Three tumors were abdominal paragangliomas and 1 was a pheochromocytoma. No germline pathogenic variants in PPGL-susceptibility genes were identified in the cohort. Genetic testing of tumor tissue detected unique EPAS1 variants in all 4 patients. Variants were not detected in the germline, and 1 variant was detected in lymph node tissue of a patient with metastatic disease.

CONCLUSION

We propose that somatic EPAS1 variants may be acquired through exposure to chronic hypoxia in SCD and drive PPGL development. Future work is needed to further characterize this association.

Research in the genetics of pheochromocytoma and paraganglioma: a bibliometric analysis from 2002 to 2022

Over the past two decades, there has been a significant growth in articles focusing on the genetics of pheochromocytoma and paraganglioma (PPGL). We used bibliometric methods to investigate the historical changes and trend in PPGL research. There was a total of 1263 articles published in English from 2002 to 2022 included in our study. The number of annual publications and citations in this field has been increasing in the past 20 years. Furthermore, most of the publications originated from the European countries and the United States. The co-occurrence analysis showed close cooperation between different countries, institutions, or authors. The dual-map discipline analysis revealed that majority articles focused on four disciplines: #2 (Medicine, Medical, Clinical), #4 (Molecular, Biology, Immunology), #5 (Health, Nursing, Medicine), and #8 (Molecular, Biology, Genetics). The hotspot analysis revealed the keywords that have been landmark for PPGL genetics research in different time periods, and there was continued interest in gene mutations, especially on SDHX family genes. In conclusion, this study displays the current status of research and future trends in the genetics of PPGL. In future, more in-depth research should concentrate on crucial mutation genes and their specific mechanisms to assist in molecular target therapy. It is hoped that this study may help to provide directions for future research on genes and PPGL.

Pheochromocytoma: a changing perspective and current concepts

This article aims to review current concepts in diagnosing and managing pheochromocytoma and paraganglioma (PPGL). Personalized genetic testing is vital, as 40-60% of tumors are linked to a known mutation. Tumor DNA should be sampled first. Next-generation sequencing is the best and most cost-effective choice and also helps with the expansion of current knowledge. Recent advancements have also led to the increased incorporation of regulatory RNA, metabolome markers, and the NETest in PPGL workup. PPGL presentation is highly volatile and nonspecific due to its multifactorial etiology. Symptoms mainly derive from catecholamine (CMN) excess or mass effect, primarily affecting the cardiovascular system. However, paroxysmal nature, hypertension, and the classic triad are no longer perceived as telltale signs. Identifying high-risk subjects and diagnosing patients at the correct time by using appropriate personalized methods are essential. Free plasma/urine catecholamine metabolites must be first-line examinations using liquid chromatography with tandem mass spectrometry as the gold standard analytical method. Reference intervals should be personalized according to demographics and comorbidity. The same applies to result interpretation. Threefold increase from the upper limit is highly suggestive of PPGL. Computed tomography (CT) is preferred for pheochromocytoma due to better cost-effectiveness and spatial resolution. Unenhanced attenuation of >10HU in non-contrast CT is indicative. The choice of extra-adrenal tumor imaging is based on location. Functional imaging with positron emission tomography/computed tomography and radionuclide administration improves diagnostic accuracy, especially in extra-adrenal/malignant or familial cases. Surgery is the mainstay treatment when feasible. Preoperative α-adrenergic blockade reduces surgical morbidity. Aggressive metastatic PPGL benefits from systemic chemotherapy, while milder cases can be managed with radionuclides. Short-term postoperative follow-up evaluates the adequacy of resection. Long-term follow-up assesses the risk of recurrence or metastasis. Asymptomatic carriers and their families can benefit from surveillance, with intervals depending on the specific gene mutation. Trials primarily focusing on targeted therapy and radionuclides are currently active. A multidisciplinary approach, correct timing, and personalization are key for successful PPGL management.

Management of pheochromocytomas and paragangliomas: Review of current diagnosis and treatment options

Pheochromocytomas (PCCs) are rare neuroendocrine tumors derived from the chromaffin cells of the adrenal medulla. When these tumors have an extra-adrenal location, they are called paragangliomas (PGLs) and arise from sympathetic and parasympathetic ganglia, particularly of the para-aortic location. Up to 25% of PCCs/PGLs are associated with inherited genetic disorders. The majority of PCCs/PGLs exhibit indolent behavior. However, according to their affiliation to molecular clusters based on underlying genetic aberrations, their tumorigenesis, location, clinical symptomatology, and potential to metastasize are heterogenous. Thus, PCCs/PGLs are often associated with diagnostic difficulties. In recent years, extensive research revealed a broad genetic background and multiple signaling pathways leading to tumor development. Along with this, the diagnostic and therapeutic options were also expanded. In this review, we focus on the current knowledge and recent advancements in the diagnosis and treatment of PCCs/PGLs with respect to the underlying gene alterations while also discussing future perspectives in this field.

Hypoxia-Inducible Factor 2 Alpha (HIF2α) Inhibitors: Targeting Genetically Driven Tumor Hypoxia

Tumors driven by deficiency of the VHL gene product, which is involved in degradation of the hypoxia-inducible factor subunit 2 alpha (HIF2α), are natural candidates for targeted inhibition of this pathway. Belzutifan, a highly specific and well-tolerated HIF2α inhibitor, recently received FDA approval for the treatment of nonmetastatic renal cell carcinomas, pancreatic neuroendocrine tumors, and central nervous system hemangioblastomas from patients with von Hippel-Lindau disease, who carry VHL germline mutations. Such approval is a milestone in oncology; however, the full potential, and limitations, of HIF2α inhibition in the clinic are just starting to be explored. Here we briefly recapitulate the molecular rationale for HIF2α blockade in tumors and review available preclinical and clinical data, elaborating on mutations that might be particularly sensitive to this approach. We also outline some emerging mechanisms of intrinsic and acquired resistance to HIF2α inhibitors, including acquired mutations of the gatekeeper pocket of HIF2α and its interacting partner ARNT. Lastly, we propose that the high efficacy of belzutifan observed in tumors with genetically driven hypoxia caused by VHL mutations suggests that a focus on other mutations that similarly lead to HIF2α stabilization, such as those occurring in neuroendocrine tumors with disruptions in the tricarboxylic acid cycle (SDHA/B/C/D, FH, MDH2, IDH2), HIF hydroxylases (EGLN/PHDs), and the HIF2α-encoding gene, EPAS1, are warranted.

Genomic and immune landscape Of metastatic pheochromocytoma and paraganglioma

The mechanisms triggering metastasis in pheochromocytoma/paraganglioma are unknown, hindering therapeutic options for patients with metastatic tumors (mPPGL). Herein we show by genomic profiling of a large cohort of mPPGLs that high mutational load, microsatellite instability and somatic copy-number alteration burden are associated with ATRX/TERT alterations and are suitable prognostic markers. Transcriptomic analysis defines the signaling networks involved in the acquisition of metastatic competence and establishes a gene signature related to mPPGLs, highlighting CDK1 as an additional mPPGL marker. Immunogenomics accompanied by immunohistochemistry identifies a heterogeneous ecosystem at the tumor microenvironment level, linked to the genomic subtype and tumor behavior. Specifically, we define a general immunosuppressive microenvironment in mPPGLs, the exception being PD-L1 expressing MAML3-related tumors. Our study reveals canonical markers for risk of metastasis, and suggests the usefulness of including immune parameters in clinical management for PPGL prognostication and identification of patients who might benefit from immunotherapy.

Co-occurrence of mutations in NF1 and other susceptibility genes in pheochromocytoma and paraganglioma

Introduction

The percentage of patients diagnosed with pheochromocytoma and paraganglioma (altogether PPGL) carrying known germline mutations in one of the over fifteen susceptibility genes identified to date has dramatically increased during the last two decades, accounting for up to 35-40% of PPGL patients. Moreover, the application of NGS to the diagnosis of PPGL detects unexpected co-occurrences of pathogenic allelic variants in different susceptibility genes.

Methods

Herein we uncover several cases with dual mutations in NF1 and other PPGL genes by targeted sequencing. We studied the molecular characteristics of the tumours with co-occurrent mutations, using omic tools to gain insight into the role of these events in tumour development.

Results

Amongst 23 patients carrying germline NF1 mutations, targeted sequencing revealed additional pathogenic germline variants in DLST (n=1) and MDH2 (n=2), and two somatic mutations in H3-3A and PRKAR1A. Three additional patients, with somatic mutations in NF1 were found carrying germline pathogenic mutations in SDHB or DLST, and a somatic truncating mutation in ATRX. Two of the cases with dual germline mutations showed multiple pheochromocytomas or extra-adrenal paragangliomas - an extremely rare clinical finding in NF1 patients. Transcriptional and methylation profiling and metabolite assessment showed an "intermediate signature" to suggest that both variants had a pathological role in tumour development.

Discussion

In conclusion, mutations affecting genes involved in different pathways (pseudohypoxic and receptor tyrosine kinase signalling) co-occurring in the same patient could provide a selective advantage for the development of PPGL, and explain the variable expressivity and incomplete penetrance observed in some patients.

Immune signature of pheochromocytoma and paraganglioma in context of neuroendocrine neoplasms associated with prognosis

PURPOSE

To understand prognostic immune cell infiltration signatures in neuroendocrine neoplasms (NENs), particularly pheochromocytoma and paraganglioma (PCPG), we analyzed tumor transcriptomic data from The Cancer Genome Atlas (TCGA) and other published tumor transcriptomic data of NENs.

METHODS

We used CIBERSORT to infer immune cell infiltrations from bulk tumor transcriptomic data from PCPGs, in comparison to gastroenteropancreatic neuroendocrine tumors (GEPNETs) and small cell lung carcinomas (SCLCs). PCPG immune signature was validated with NanoString immune panel in an independent cohort. Unsupervised clustering of the immune infiltration scores from CIBERSORT was used to find immune clusters. A prognostic immune score model for PCPGs and the other NENs were calculated as a linear combination of the estimated infiltration of activated CD8+/CD4+ T cells, activated NK cells, and M0 and M2 macrophages.

RESULTS

In PCPGs, we found five dominant immune clusters, associated with M2 macrophages, monocytes, activated NK cells, M0 macrophages and regulatory T cells, and CD8+/CD4+ T cells respectively. Non-metastatic tumors were associated with activated NK cells and metastatic tumors were associated with M0 macrophages and regulatory T cells. In GEPNETs and SCLCs, M0 macrophages and regulatory T cells were associated with unfavorable outcomes and features, such as metastasis and high-grade tumors. The prognostic immune score model for PCPGs and the NENs could predict non-aggressive and non-metastatic diseases. In PCPGs, the immune score was also an independent predictor of metastasis-free survival in a multivariate Cox regression analysis.

CONCLUSION

The transcriptomic immune signature in PCPG correlates with clinical features like metastasis and prognosis.

New Biology of Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas continue to be defined by significant morbidity and mortality despite their several recent advances in diagnosis, localization, and management. These adverse outcomes are largely related to mass effect as well as catecholamine-induced hypertension, tachyarrhythmias and consequent target organ damage, acute coronary syndromes, and strokes (ischemic and hemorrhagic stroke). Thus, a proper understanding of the physiology and pathophysiology of these tumors and recent advances are essential to affording optimal care. These major developments largely include a redefinition of metastatic behavior, a novel clinical categorization of these tumors into 3 genetic clusters, and an enhanced understanding of catecholamine metabolism and consequent specific biochemical phenotypes. Current advances in imaging of these tumors are shifting the paradigm from poorly specific anatomical modalities to more precise characterization of these tumors using the advent and development of functional imaging modalities. Furthermore, recent advances have revealed new molecular events in these tumors that are linked to their genetic landscape and, therefore, provide new therapeutic platforms. A few of these prospective therapies translated into new clinical trials, especially for patients with metastatic or inoperable tumors. Finally, outcomes are ever-improving as patients are cared for at centers with cumulative experience and well-established multidisciplinary tumor boards. In parallel, these centers have supported national and international collaborative efforts and worldwide clinical trials. These concerted efforts have led to improved guidelines collaboratively developed by healthcare professionals with a growing expertise in these tumors and consequently improving detection, prevention, and identification of genetic susceptibility genes in these patients.

Lim E, Challis BG, Park S, Izatt L, Carroll PV, Velusamy A, Hulse T, Whitelaw BC, Martin E, Rodger F, Maranian M, Clark GR, A. Akker S, Maher ER, Casey RT. Investigating the role of somatic sequencing platforms for phaeochromocytoma and paraganglioma in a large UK cohort

OBJECTIVES

Phaeochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumours with malignant potential and a hereditary basis in almost 40% of patients. Germline genetic testing has transformed the management of PPGL enabling stratification of surveillance approaches, earlier diagnosis and predictive testing of at-risk family members. Recent studies have identified somatic mutations in a further subset of patients, indicating that molecular drivers at either a germline or tumour level can be identified in up to 80% of PPGL cases. The aim of this study was to investigate the clinical utility of somatic sequencing in a large cohort of patients with PPGL in the United Kingdom.

DESIGN AND PATIENTS

Prospectively collected matched germline and tumour samples (development cohort) and retrospectively collected tumour samples (validation cohort) of patients with PPGL were investigated.

MEASUREMENTS

Clinical characteristics of patients were assessed and tumour and germline DNA was analysed using a next-generation sequencing strategy. A screen for variants within 'mutation hotspots' in 68 human cancer genes was performed.

RESULTS

Of 141 included patients, 45 (32%) had a germline mutation. In 37 (26%) patients one or more driver somatic variants were identified including 26 likely pathogenic or pathogenic variants and 19 variants of uncertain significance. Pathogenic somatic variants, observed in 25 (18%) patients, were most commonly identified in the VHL, NF1, HRAS and RET genes. Pathogenic somatic variants were almost exclusively identified in patients without a germline mutation (all but one), suggesting that somatic sequencing is likely to be most informative for those patients with negative germline genetic test results.

CONCLUSIONS

Somatic sequencing may further stratify surveillance approaches for patients without a germline genetic driver and may also inform targeted therapeutic strategies for patients with metastatic disease.

Succinate: A Serum Biomarker of SDHB-Mutated Paragangliomas and Pheochromocytomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors that are frequently associated with succinate dehydrogenase (SDH) germline mutations. When mutated, SDH losses its function, thus leading to succinate accumulation.

OBJECTIVE

In this study, we evaluated serum succinate levels as a new metabolic biomarker in SDHx-related carriers.

METHODS

Retrospective monocentric study of 88 PPGL patients (43 sporadic, 35 SDHB, 10 SDHA/C/D), 17 tumor-free familial asymptomatic carriers (13 SDHB, 4 SDHC/D), and 60 healthy controls. Clinical, biological, and imaging data were reviewed. Serum succinate levels (n = 280) were quantified by an ultra-performance liquid chromatography coupled to a tandem mass spectrometry method and correlated to SDHx mutational status, disease extension, and other biological biomarkers.

RESULTS

Serum succinate levels > 7 μM allowed identification of tumor-free asymptomatic SDHB-mutated cases compared to a healthy control group (100% specificity; 85% sensitivity). At PPGL diagnosis, SDHB-mutated patients had a significantly increased median succinate level (14 μM) compared to sporadic patients (8 μM) (P < 0.01). Metastatic disease extension was correlated to serum succinate levels (r = 0.81). In the SDHB group, patients displaying highest tumor burdens showed significant increased succinate levels compared to the sporadic group (P < 0.0001).

CONCLUSIONS

In this pilot study, we showed that serum succinate level is an oncometabolic biomarker that should be useful to identify SDHB-related carriers. Succinate levels are also a marker of metabolic tumor burden in patients with a metastatic PPGL and a potential marker of treatment response and follow-up.

Genetic Analysis of Pheochromocytoma and Paraganglioma Complicating Cyanotic Congenital Heart Disease

CONTEXT

Pheochromocytoma and paraganglioma (PPGL) may appear as a complication of cyanotic congenital heart disease (CCHD-PPGL) with frequent EPAS1 mutations, suggesting a close link between EPAS1 mutations and tissue hypoxia in CCHD-PPGL pathogenesis.

OBJECTIVE

Our aim is to further investigate the role of EPAS1 mutations in the hypoxia-driven mechanism of CCHD-PPGL pathogenesis, particularly focusing on metachronous and/or multifocal CCHD-PPGL tumors.

METHODS

We performed whole-exome sequencing (WES) for somatic and germline mutations in 15 PPGL samples from 7 CCHD patients, including 3 patients with metachronous and/or multifocal tumors, together with an adrenal medullary hyperplasia (AMH) sample.

RESULTS

We detected EPAS1 mutations in 15 out of 16 PPGL/AMH samples from 7 cases. Conspicuously, all EPAS1 mutations in each of 3 cases with multifocal or metachronous tumors were mutually independent and typical examples of parallel evolution, which is suggestive of strong positive selection of EPAS1-mutated clones. Compared to 165 The Cancer Genome Atlas non-CCHD-PPGL samples, CCHD-PPGL/AMH samples were enriched for 11p deletions (13/16) and 2p amplifications (4/16). Of particular note, the multiple metachronous PPGL tumors with additional copy number abnormalities developed 18 to 23 years after the resolution of hypoxemia, suggesting that CCHD-induced hypoxic environments are critical for positive selection of EPAS1 mutants in early life, but may no longer be required for development of PPGL in later life.

CONCLUSION

Our results highlight a key role of activated hypoxia-inducible factor 2α due to mutated EPAS1 in positive selection under hypoxic environments, although hypoxemia itself may not necessarily be required for the EPAS1-mutated clones to progress to PPGL.

Systematic review: Incidence of Pheochromocytoma and Paraganglioma over 70 years

Context

Pheochromocytomas and paragangliomas (PPGLs) are known to be rare. However, there is scant literature reporting their epidemiology, particularly whether the diagnosis of PPGL has increased with advances in medical imaging and biochemical and genetic testing.

Objective

The primary objective of this systematic review was to determine the annual incidence of PPGLs and change over time.

Design

A systematic review was performed. Medline, Embase, PubMed, and Web of Science Core Collection databases were searched to identify studies reporting PPGL incidence. Studies were eligible for inclusion from the database’s inception until August 30, 2021.

Results

A total of 6109 manuscripts were identified; 2282 duplicates were excluded, and a further 3815 papers were excluded after abstract and/or full text review. Twelve studies were included in the final review. The incidence of PPGL ranged from 0.04 to 0.95 cases per 100 000 per year. Incidence increased over time, from approximately 0.2/100,000 individuals in studies performed before 2000, to approximately 0.6/100,000 in studies undertaken after 2010. The mode of diagnosis changed over the same time period, with more patients diagnosed from incidental imaging findings, and fewer at autopsy or from symptoms.

Conclusion

The annual incidence of PPGL has increased over time. Much of this increase is likely from incidental identification of tumors on imaging. However, the epidemiology of PPGL remains understudied, in particular, in associations with altitude, ethnicity, and genetics. To improve early detection and management guidelines, these gaps should be addressed.

Genetic spectrum in a Canadian cohort of apparently sporadic pheochromocytomas and paragangliomas: New data on multigene panel retesting over time

OBJECTIVE

Pheochromocytomas (PHEOs) and paragangliomas (PGLs), collectively known as PPGLs, are tumours with high heritability. The prevalence of germline mutations in apparently sporadic PPGLs varies depending on the study population. The objective of this study was to determine the spectrum of germline mutations in a cohort of patients with apparently sporadic PPGLs over time.

DESIGN

We performed a retrospective review of patients with apparently sporadic PPGLs who underwent genetic testing at our referral centre from 2005 to 2020.

PATIENTS

We included patients with apparently sporadic PPGLs who underwent genetic testing at our referral center.

MEASUREMENTS

Genetic analysis included sequential gene sequencing by Sanger method or next generation sequencing (NGS) with a multigene panel.

RESULTS

The prevalence of germline mutations was 26.2% (43/164); 40.0% (30/75) in PGLs and 14.6% (13/89) in PHEOs. We identified four novel pathogenic variants (two SDHB and two SDHD). Patients carrying germline mutations were younger (38.7 vs. 49.7 years old) than patients with no identified germline mutations. From 2015 to 2020, we performed NGS with a multigene panel on 12 patients for whom the initial genetic analysis was negative. Germline mutations in previously untested genes were found in four (33.3%) of these patients (two MAX and two SDHA), representing 9.3% (4/43) of the mutation carriers.

CONCLUSION

The prevalence of germline mutations in our cohort of patients with apparently sporadic PPGLs was 26.2%. Genetic re-evaluation over time using multigene sequencing by NGS assay in a subgroup of patients leads to an increase in the detection of mutations.

Cancer Predisposition Genes in Adolescents and Young Adults (AYAs): a Review Paper from the Italian AYA Working Group

PURPOSE OF REVIEW

The present narrative systematic review summarizes current knowledge on germline gene mutations predisposing to solid tumors in adolescents and young adults (AYAs).

RECENT FINDINGS

AYAs with cancer represent a particular group of patients with specific challenging characteristics and yet unmet needs. A significant percentage of AYA patients carry pathogenic or likely pathogenic variants (PV/LPVs) in cancer predisposition genes. Nevertheless, knowledge on spectrum, frequency, and clinical implications of germline variants in AYAs with solid tumors is limited. The identification of PV/LPV in AYA is especially critical given the need for appropriate communicative strategies, risk of second primary cancers, need for personalized long-term surveillance, potential reproductive implications, and cascade testing of at-risk family members. Moreover, these gene alterations may potentially provide novel biomarkers and therapeutic targets that are lacking in AYA patients. Among young adults with early-onset phenotypes of malignancies typically presenting at later ages, the increased prevalence of germline PV/LPVs supports a role for genetic counseling and testing irrespective of tumor type.

Expression of LHCGR (Luteinizing Hormone/Chorionic Gonadotrophin Receptor) in Pheochromocytomas Unveils an Endocrine Mechanism Connecting Pregnancy and Epinephrine Overproduction

BACKGROUND

The mechanisms by which pregnancy may unmask pheochromocytomas and paragangliomas are not totally understood. We hypothesized that gestational hormones may participate in the pathophysiology of catecholamine excess during pregnancy. We report a case of silent pheochromocytoma revealed in a pregnant woman by life-threatening adrenergic myocarditis.

METHODS

In vitro studies were conducted to investigate the effect of estradiol and the pregnancy hormone hCG (human chorionic gonadotropin) on epinephrine secretion by cultured cells derived from the patient's tumor. Expression of LHCG (luteinizing hormone/chorionic gonadotropin) receptor was searched for in the patient's tumor, and a series of 12 additional pheochromocytoma by RT-Q-PCR and immunohistochemistry. LHCGR expression was also analyzed in silico in the pheochromocytomas and paragangliomas cohorts of the Cortico et Médullosurrénale: les Tumeurs Endocrines and The Cancer Genome Atlas databases.

RESULTS

hCG stimulated epinephrine secretion by cultured cells derived from the patient's pheochromocytoma. The patient's tumor expressed the LHCG receptor, which was colocalized with catecholamine-producing enzymes. A similar expression pattern of the LHCG receptor was also observed in 5 out of our series of pheochromocytoma. Moreover, in silico studies revealed that pheochromocytomas and paragangliomas display the highest expression levels of LHCG receptor mRNA among the 32 solid tumor types of The Cancer Genome Atlas cohort.

CONCLUSIONS

Pregnancy may thus favor surges in plasma catecholamine and hypertensive crises through hCG-induced stimulation of epinephrine production by pheochromocytomas.

Genetics of Pheochromocytomas and Paragangliomas Determine the Therapeutical Approach

Pheochromocytomas and paragangliomas are the most heritable endocrine tumors. In addition to the inherited mutation other driver mutations have also been identified in tumor tissues. All these genetic alterations are clustered in distinct groups which determine the pathomechanisms. Most of these tumors are benign and their surgical removal will resolve patient management. However, 5–15% of them are malignant and therapeutical possibilities for them are limited. This review provides a brief insight about the tumorigenesis associated with pheochromocytomas/paragangliomas in order to present them as potential therapeutical targets.

New Insights on the Genetics of Pheochromocytoma and Paraganglioma and Its Clinical Implications

Simple Summary

Pheochromocytoma and paraganglioma (together PPGL) are rare neuroendocrine tumors that arise from chromaffin tissue and produce catecholamines. Approximately 40% of cases of PPGL carry a germline mutation, suggesting that they have a high degree of heritability. The underlying mutation influences the PPGL clinical presentation such as cell differentiation, specific catecholamine production, tumor location, malignant potential and genetic anticipation, which helps to better understand the clinical course and tailor treatment accordingly. Genetic testing for pheochromocytoma and paraganglioma allows an early detection of hereditary syndromes and facilitates a close follow-up of high-risk patients. In this review article, we present the most recent advances in the field of genetics and we discuss the latest guidelines on the surveillance of asymptomatic SDHx mutation carriers.

Abstract

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are rare neuroendocrine tumors that arise from chromaffin cells. PHEOs arise from the adrenal medulla, whereas PGLs arise from the neural crest localized outside the adrenal gland. Approximately 40% of all cases of PPGLs (pheochromocytomas/paragangliomas) are associated with germline mutations and 30–40% display somatic driver mutations. The mutations associated with PPGLs can be classified into three groups. The pseudohypoxic group or cluster I includes the following genes: SDHA, SDHB, SDHC, SDHD, SDHAF2, FH, VHL, IDH1/2, MHD2, EGLN1/2 and HIF2/EPAS; the kinase group or cluster II includes RET, NF1, TMEM127, MAX and HRAS; and the Wnt signaling group or cluster III includes CSDE1 and MAML3. Underlying mutations can help understand the clinical presentation, overall prognosis and surveillance follow-up. Here we are discussing the new genetic insights of PPGLs.

A long noncoding RNA-microRNA expression signature predicts metastatic signature in pheochromocytomas and paragangliomas

PURPOSE

In hopes of discovering new markers for metastatic or aggressive phenotypes of pheochromocytomas and paragangliomas (PCPG), we analyzed the noncoding transcriptome from patient gene expression data in The Cancer Genome Atlas.

METHODS

Differential expression of miRNAs was observed between PCPG molecular subtypes. We specifically characterized candidate miRNAs that are upregulated in pseudohypoxic PCPGs with mutations in succinate dehydrogenase complex subunits, B and/or D (SDHB and/or SDHD, respectively), which are mutations associated with unfavorable clinical outcomes.

RESULTS

Our computational analysis identified four candidate miRNAs that showed elevated expression in metastatic compared to non-metastatic PCPGs: miR-182, miR-183, miR-96, and miR-383. We also found six candidate lncRNAs harboring opposite expression patterns from the miRNAs when we analyzed the expression profiles of their predicted target lncRNAs. Three of these lncRNA candidates, USP3-AS1, LINC00877, and AC009312.1, were validated to have reduced expression in metastatic compared to non-metastatic PCPGs. Finally, using univariate and multivariate analysis, we found miRNA miR-182 to be an independent predictor of metastasis-free survival in PCPGs.

CONCLUSIONS

We identified candidate miRNA and lncRNAs associated with metastasis-free survival in PCPGs.

Precision Medicine in Phaeochromocytoma and Paraganglioma

Precision medicine is a term used to describe medical care, which is specifically tailored to an individual patient or disease with the aim of ensuring the best clinical outcome whilst reducing the risk of adverse effects. Phaeochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumours with uncertain malignant potential. Over recent years, the molecular profiling of PPGLs has increased our understanding of the mechanisms that drive tumorigenesis. A high proportion of PPGLs are hereditary, with non-hereditary tumours commonly harbouring somatic mutations in known susceptibility genes. Through detailed interrogation of genotype-phenotype, correlations PPGLs can be classified into three different subgroups or clusters. Thus, PPGLs serve as an ideal paradigm for developing, testing and implementing precision medicine concepts in the clinic. In this review, we provide an overview of PPGLs and highlight how detailed molecular characterisation of these tumours provides current and future opportunities for precision oncology.

Insights into Mechanisms of Pheochromocytomas and Paragangliomas Driven by Known or New Genetic Drivers

Simple Summary

Pheochromocytomas and paragangliomas are rare neuroendocrine tumors that are often hereditary. Although research has advanced considerably, significant gaps still persist in understanding risk factors, predicting metastatic potential and treating aggressive tumors. The study of rare mutations can provide new insights into how pheochromocytomas and paragangliomas develop. In this review, we provide examples of such rare events and how they can inform our understanding of the spectrum of mutations that can lead to these tumors and improve our ability to provide a genetic diagnosis.

Abstract

Pheochromocytomas and paragangliomas are rare tumors of neural crest origin. Their remarkable genetic diversity and high heritability have enabled discoveries of bona fide cancer driver genes with an impact on diagnosis and clinical management and have consistently shed light on new paradigms in cancer. In this review, we explore unique mechanisms of pheochromocytoma and paraganglioma initiation and management by drawing from recent examples involving rare mutations of hypoxia-related genes VHL, EPAS1 and SDHB, and of a poorly known susceptibility gene, TMEM127. These models expand our ability to predict variant pathogenicity, inform new functional domains, recognize environmental-gene connections, and highlight persistent therapeutic challenges for tumors with aggressive behavior.

International initiative for a curated SDHB variant database improving the diagnosis of hereditary paraganglioma and pheochromocytoma

BACKGROUND

SDHB is one of the major genes predisposing to paraganglioma/pheochromocytoma (PPGL). Identifying pathogenic SDHB variants in patients with PPGL is essential to the management of patients and relatives due to the increased risk of recurrences, metastases and the emergence of non-PPGL tumours. In this context, the 'NGS and PPGL (NGSnPPGL) Study Group' initiated an international effort to collect, annotate and classify SDHB variants and to provide an accurate, expert-curated and freely available SDHB variant database.

METHODS

A total of 223 distinct SDHB variants from 737 patients were collected worldwide. Using multiple criteria, each variant was first classified according to a 5-tier grouping based on American College of Medical Genetics and NGSnPPGL standardised recommendations and was then manually reviewed by a panel of experts in the field.

RESULTS

This multistep process resulted in 23 benign/likely benign, 149 pathogenic/likely pathogenic variants and 51 variants of unknown significance (VUS). Expert curation reduced by half the number of variants initially classified as VUS. Variant classifications are publicly accessible via the Leiden Open Variation Database system (https://databases.lovd.nl/shared/genes/SDHB).

CONCLUSION

This international initiative by a panel of experts allowed us to establish a consensus classification for 223 SDHB variants that should be used as a routine tool by geneticists in charge of PPGL laboratory diagnosis. This accurate classification of SDHB genetic variants will help to clarify the diagnosis of hereditary PPGL and to improve the clinical care of patients and relatives with PPGL.

Analytical Performance of NGS-Based Molecular Genetic Tests Used in the Diagnostic Workflow of Pheochromocytoma/Paraganglioma

Next Generation Sequencing (NGS)-based methods are high-throughput and cost-effective molecular genetic diagnostic tools. Targeted gene panel and whole exome sequencing (WES) are applied in clinical practice for assessing mutations of pheochromocytoma/paraganglioma (PPGL) associated genes, but the best strategy is debated. Germline mutations of at the least 18 PPGL genes are present in approximately 20-40% of patients, thus molecular genetic testing is recommended in all cases. We aimed to evaluate the analytical and clinical performances of NGS methods for mutation detection of PPGL-associated genes. WES (three different library preparation and bioinformatics workflows) and an in-house, hybridization based gene panel (endocrine-onco-gene-panel- ENDOGENE) was evaluated on 37 (20 WES and 17 ENDOGENE) samples with known variants. After optimization of the bioinformatic workflow, 61 additional samples were tested prospectively. All clinically relevant variants were validated with Sanger sequencing. Target capture of PPGL genes differed markedly between WES platforms and genes tested. All known variants were correctly identified by all methods, but methods of library preparations, sequencing platforms and bioinformatical settings significantly affected the diagnostic accuracy. The ENDOGENE panel identified several pathogenic mutations and unusual genotype-phenotype associations suggesting that the whole panel should be used for identification of genetic susceptibility of PPGL.

Recurrence-Free Survival Analysis in Locally Advanced Pheochromocytoma: First Appraisal

CONTEXT

The behavior of locally advanced pheochromocytoma (LAP) remains unknown.

OBJECTIVE

We characterized the population with LAP and recurrence-free survival (RFS).

METHODS

This retrospective multicentric study was run within the ENDOCAN-COMETE network and French Group of Endocrine Tumors (GTE) from 2003 to 2018, including patients from 11 French referral centers with LAP as defined by capsular invasion, vascular invasion, adipose tissue invasion, and/or positive locoregional lymph nodes at diagnosis without evidence of distant metastasis. The main outcome measure was recurrence, defined as tumor reappearance, including local site and/or distant metastasis. The primary endpoint was RFS analysis; secondary endpoints were characterization, overall survival (OS), and prognostic factors of recurrence.

RESULTS

Among 950 patients, 90 (9%) exhibited LAP criteria and 55 met inclusion criteria (median age, 53 years; 61% males; 14% with germline mutation; 84% with catecholamine excess). LAP was defined by 31 (56%) capsular invasions, 27 (49%) fat invasions, 6 (11%) positive lymph nodes, and 22 (40%) vascular invasions. After median follow-up of 54 months (range, 6-180), 12 patients (22%) had recurrences and 3 (5%) died of metastatic disease. Median RFS was 115 months (range, 6-168). Recurrences were local in 2 patients, distant in 2, and both local and distant in 8 patients. Median OS of patients was not reached. Size above 6.5 cm (P = 0.019) and Ki-67 > 2% (P = 0.028) were identified as independent significant prognostic factors in multivariate analysis.

CONCLUSION

LAP represents 9% of pheochromocytoma's population and has a metastatic behavior. This study paves the way for future pathological TNM classification.

Composite pheochromocytoma/paraganglioma-ganglioneuroma: analysis of SDH and ATRX status, and identification of frequent HRAS and BRAF mutations

INTRODUCTION

Composite pheochromocytoma/paraganglioma (CP) is a rare neoplasm with most cases presented as single reports. Little is known about its pathogenesis and relationship with ordinary pheochromocytoma (PCC) or paraganglioma (PGL). Our study is aimed at analyzing the status of SDH and ATRX and identifying novel genetic changes in CP.

METHODS

Eighteen CP cases were collected. SDH and ATRX status was screened by immunohistochemistry. Targeted region sequencing (TRS) was successfully performed on formalin-fixed paraffin-embedded tissues in two cases within 3 years. Based on the TRS result, Sanger sequencing of BRAF and HRAS was performed in fifteen cases (including the two cases with TRS performed), with three cases excluded due to the limited amount of tissue.

RESULTS

Histopathologically, all the cases were composite PCC/PGL-ganglioneuroma (GN). The GN components were either closely admixed or juxtaposed with the PCC/PGL components, with a highly variable percentage (10-80%). All cases stained positive for SDHB and ATRX. HRAS and BRAF mutations were identified during TRS. In the subsequent Sanger sequencing, 20.0% (3/15) harbored BRAF mutations (K601E and K601N) and 46.7% (7/15) harbored HRAS mutations (Q61R, Q61L, G13R). The mutation rates were both significantly higher than reported in ordinary PCC/PGL.

CONCLUSIONS

We demonstrated that composite PCC/PGL-GN might be a unique entity with frequent HRAS and BRAF mutations rather than genetic changes of SDH and ATRX. Our findings revealed the possible pathogenesis of composite PCC/PGL-GN and provided clues for potential treatment targets.

International consensus on initial screening and follow-up of asymptomatic SDHx mutation carriers

Approximately 20% of patients diagnosed with a phaeochromocytoma or paraganglioma carry a germline mutation in one of the succinate dehydrogenase (SDHx) genes (SDHA, SDHB, SDHC and SDHD), which encode the four subunits of the SDH enzyme. When a pathogenic SDHx mutation is identified in an affected patient, genetic counselling is proposed for first-degree relatives. Optimal initial evaluation and follow-up of people who are asymptomatic but might carry SDHx mutations have not yet been agreed. Thus, we established an international consensus algorithm of clinical, biochemical and imaging screening at diagnosis and during surveillance for both adults and children. An international panel of 29 experts from 12 countries was assembled, and the Delphi method was used to reach a consensus on 41 statements. This Consensus Statement covers a range of topics, including age of first genetic testing, appropriate biochemical and imaging tests for initial tumour screening and follow-up, screening for rare SDHx-related tumours and management of elderly people who have an SDHx mutation. This Consensus Statement focuses on the management of asymptomatic SDHx mutation carriers and provides clinicians with much-needed guidance. The standardization of practice will enable prospective studies in the near future.

Genetics of pheochromocytoma and paraganglioma

PURPOSE OF REVIEW

This review summarizes our current understanding of germline and somatic genetics and genomics of pheochromocytomas and paragangliomas (PCC/PGL), describes existing knowledge gaps, and discusses future research directions.

RECENT FINDINGS

Germline pathogenic variants (PVs) are found in up to 40% of those with PCC/PGL. Tumors with germline PVs are broadly categorized as Cluster 1 (pseudohypoxia), including those with SDH, VHL, FH, and EPAS1 PVs, or Cluster 2 (kinase signaling) including those with NF1, RET, TMEM127, and MAX PVs. Somatic driver mutations exist in some of the same genes (RET, VHL, NF1, EPAS1) as well as in additional genes including HRAS, CSDE1 and genes involved in cell immortalization (ATRX and TERT). Other somatic driver events include recurrent fusion genes involving MAML3.

SUMMARY

PCC/PGL have the highest association with germline PVs of all human solid tumors. Expanding our understanding of the molecular pathogenesis of PCC/PGL is essential to advancements in diagnosis and surveillance and the development of novel therapies for these unique tumors.

Mutation Profile of Aggressive Pheochromocytoma and Paraganglioma with Comparison of TCGA Data

Simple Summary

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors arising from chromaffin cells of the adrenal medulla, or extra-adrenal paraganglia, respectively. In PPGLs, germline or somatic mutations in one of the known susceptibility genes are identified in up to 60% patients. Recent WHO classification defines that all PPGLs can have metastatic potential. The term, ‘malignant’ is replaced with ‘metastatic’ in this group of tumors. However, the peculiar genetic events that drive the aggressive behavior, including metastasis in PPGLs are yet poorly understood. We performed targeted next-generation sequencing analysis to characterize the mutation profile in fifteen aggressive PPGL patients and compared accessible data of aggressive PPGLs from The Cancer Genome Atlas (TCGA) with findings of our cohort. This targeted mutational analysis might expand the mutation profile of aggressive PPGLs, and may also be useful in detecting the possible experimental therapeutic options or predicting poor prognosis.

Abstract

In pheochromocytoma and paraganglioma (PPGL), germline or somatic mutations in one of the known susceptibility genes are identified in up to 60% patients. However, the peculiar genetic events that drive the aggressive behavior including metastasis in PPGL are poorly understood. We performed targeted next-generation sequencing analysis to characterize the mutation profile in fifteen aggressive PPGL patients and compared accessible data of aggressive PPGLs from The Cancer Genome Atlas (TCGA) with findings of our cohort. A total of 115 germline and 34 somatic variants were identified with a median 0.58 per megabase tumor mutation burden in our cohort. The most frequent mutation was SDHB germline mutation (27%) and the second frequent mutations were somatic mutations for SETD2, NF1, and HRAS (13%, respectively). Patients were subtyped into three categories based on the kind of mutated genes: pseudohypoxia (n = 5), kinase (n = 5), and unknown (n = 5) group. In copy number variation analysis, deletion of chromosome arm 1p harboring SDHB gene was the most frequently observed. In our cohort, SDHB mutation and pseudohypoxia subtype were significantly associated with poor overall survival. In conclusion, subtyping of mutation profile can be helpful in aggressive PPGL patients with heterogeneous prognosis to make relevant follow-up plan and achieve proper treatment.

Incomplete penetrance of a novel SDHD variation causing familial head and neck paraganglioma

Objective

Identification of variations in tumour suppressor genes encoding the tetrameric succinate dehydrogenase (SDHx) mitochondrial enzyme complex may lead to personalised therapeutic concepts for the orphan disease, familial paraganglioma (PGL) type 1‐5. We undertook to determine the causative variation in a family suffering from idiopathic early‐onset (22 ± 2 years) head and neck PGL by PCR and Sanger sequencing.

Design

Prospective genetic study.

Setting

Tertiary Referral Otolaryngology Centre.

Participants

Twelve family members.

Main outcome measures

Main outcomes were clinical analysis and SDH genotyping

Results and Conclusions

A novel heterozygous c.298delA frameshift variation in exon 3 of SDH subunit D (SDHD) was associated with a paternal transmission pattern of PGL in affected family members available to the study. Family history over five generations in adulthood indicated a variable penetrance for PGL inheritance in older generations. The c.298delA variant would cause translation of a 34‐residue C‐terminus distal to lysine residue 99 in the predicted transmembrane domain II of the full‐length sequence p.(Thr100LeufsTer35) and would affect the translation products of all protein‐coding SDHD isoforms containing transmembrane topologies required for positional integration in the inner mitochondrial membrane and complex formation. These results underly the importance of genetic screening for PGL also in cases of unclear inheritance, and variation carriers should benefit from screening and lifelong follow‐up.

Diagnosis for Pheochromocytoma and Paraganglioma: A Joint Position Statement of the Korean Pheochromocytoma and Paraganglioma Task Force

Pheochromocytoma and paraganglioma (PPGLs) are rare catecholamine-secreting neuroendocrine tumors but can be life-threatening. Although most PPGLs are benign, approximately 10% have metastatic potential. Approximately 40% cases are reported as harboring germline mutations. Therefore, timely and accurate diagnosis of PPGLs is crucial. For more than 130 years, clinical, molecular, biochemical, radiological, and pathological investigations have been rapidly advanced in the field of PPGLs. However, performing diagnostic studies to localize lesions and detect metastatic potential can be still challenging and complicated. Furthermore, great progress on genetics has shifted the paradigm of genetic testing of PPGLs. The Korean PPGL task force team consisting of the Korean Endocrine Society, the Korean Surgical Society, the Korean Society of Nuclear Medicine, the Korean Society of Pathologists, and the Korean Society of Laboratory Medicine has developed this position statement focusing on the comprehensive and updated diagnosis for PPGLs.

The North American Neuroendocrine Tumor Society Consensus Guidelines for Surveillance and Management of Metastatic and/or Unresectable Pheochromocytoma and Paraganglioma

ABSTRACT

This manuscript is the result of the North American Neuroendocrine Tumor Society consensus conference on the medical management and surveillance of metastatic and unresectable pheochromocytoma and paraganglioma held on October 2 and 3, 2019. The panelists consisted of endocrinologists, medical oncologists, surgeons, radiologists/nuclear medicine physicians, nephrologists, pathologists, and radiation oncologists. The panelists performed a literature review on a series of questions regarding the medical management of metastatic and unresectable pheochromocytoma and paraganglioma as well as questions regarding surveillance after resection. The panelists voted on controversial topics, and final recommendations were sent to all panel members for final approval.

Screening of a Large Cohort of Asymptomatic SDHx Mutation Carriers in Routine Practice

CONTEXT

When an SDHx mutation is identified in a patient with a pheochromocytoma (PCC) or a paraganglioma (PGL), predictive genetic testing can detect mutation carriers that would benefit from screening protocols.

OBJECTIVE

To define the tumor detection rate in a large cohort of asymptomatic SDHX mutation carriers.

DESIGN AND SETTING

Retrospective multicentric study in 6 referral centers.

PATIENTS

Between 2005 and 2019, 249 asymptomatic SDHx (171 SDHB, 31 SDHC, 47 SDHD) mutation carriers, with at least 1 imaging work-up were enrolled.

RESULTS

Initial work-up, including anatomical (98% of subjects [97-100% according to center]) and/or functional imaging (67% [14-90%]) detected 48 tumors in 40 patients. After a negative initial work-up, 124 patients benefited from 1 to 9 subsequent follow-up assessments (mean: 1.9 per patient), with a median follow-up time of 5 (1-13) years. Anatomical (86% [49-100 %]) and/or functional imaging (36% [7-60 %]) identified 10 new tumors (mean size: 16 mm [4-50]) in 10 patients. Altogether, 58 tumors (55 paraganglioma [PGL], including 45 head and neck PGL, 2 pheochromocytoma [PCC], 1 gastrointestinal stromal tumor [GIST]), were detected in 50 patients (22 [13%] SDHB, 1 [3.2%] SDHC, and 27 [57%] SDHD), with a median age of 41 years old [11-86], 76% without catecholamine secretion and 80% during initial imaging work-up.

CONCLUSIONS

Imaging screening enabled detection of tumors in 20% of asymptomatic SDHx mutation carriers, with a higher detection rate in SDHD (57%) than in SDHB (13%) and SDHC (3%) mutation carriers, arguing for a gene-by-gene approach. Prospective studies using well-defined protocols are needed to obtain strong and useful data.

Hereditary leiomyomatosis and renal cell carcinoma: a case series and literature review

Background

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a rare genodermatosis characterized by cutaneous leiomyoma (CLM), uterine leiomyoma (ULM) and renal cell carcinoma (RCC). Five HLRCC patients are presented with a compiled database of published HLRCC cases to increase understanding of HLRCC. Furthermore, a surveillance program is suggested. Our review is based on a PubMed search which retrieved case reports and cohort studies published before November 2019. The search yielded 97 original papers with a total of 672 HLRCC patients.

Results

CLMs were present in 474 patients (71.5%), developed at the mean age of 28 years. Five patients had cutaneous leiomyosarcomas. ULMs were present in 356 women (83%), while two had uterine leiomyosarcoma. ULMs were diagnosed at a mean age of 32 years, with the youngest diagnosed at age 17 years. The most common surgical treatment for ULMs was hysterectomy, performed at a mean age of 35 years, with the youngest patient being 19 years old. RCCs were present in 189 patients (34.9%), of which half had metastatic disease. The mean age of diagnosis was 36 years with the youngest patient diagnosed with RCC at the age of 11 years.

Conclusion

We suggest a surveillance program for HLRCC including a dermatological examination once every 2 years, annual magnetic resonance imaging starting at the age of 10 years to monitor for early RCCs, annual gynecological examinations from the age of 15 years and counseling regarding risk of hysterectomy and family planning at the age of 18 years. CLMs are often the earliest manifestation of HLRCC, which is why recognizing these lesions, performing a biopsy, and making a prompt referral to genetic counseling is important in order to diagnose HLRCC early.

Genotype-Phenotype Features of Germline Variants of the TMEM127 Pheochromocytoma Susceptibility Gene: A 10-Year Update

PURPOSE

This work aimed to evaluate genotype-phenotype associations in individuals carrying germline variants of transmembrane protein 127 gene (TMEM127), a poorly known gene that confers susceptibility to pheochromocytoma (PHEO) and paraganglioma (PGL).

DESIGN

Data were collected from a registry of probands with TMEM127 variants, published reports, and public databases.

MAIN OUTCOME ANALYSIS

Clinical, genetic, and functional associations were determined.

RESULTS

The cohort comprised 110 index patients (111 variants) with a mean age of 45 years (range, 21-84 years). Females were predominant (76 vs 34, P < .001). Most patients had PHEO (n = 94; 85.5%), although PGL (n = 10; 9%) and renal cell carcinoma (RCC, n = 6; 5.4%) were also detected, either alone or in combination with PHEO. One-third of the cases had multiple tumors, and known family history was reported in 15.4%. Metastatic PHEO/PGL was rare (2.8%). Epinephrine alone, or combined with norepinephrine, accounted for 82% of the catecholamine profiles of PHEO/PGLs. Most variants (n = 63) occurred only once and 13 were recurrent (2-12 times). Although nontruncating variants were less frequent than truncating changes overall, they were predominant in non-PHEO clinical presentations (36% PHEO-only vs 69% other, P < .001) and clustered disproportionately within transmembrane regions (P < .01), underscoring the relevance of these domains for TMEM127 function. Integration of clinical and previous experimental data supported classification of variants into 4 groups based on mutation type, localization, and predicted disruption.

CONCLUSIONS

Patients with TMEM127 variants often resemble sporadic nonmetastatic PHEOs. PGL and RCC may also co-occur, although their causal link requires further evaluation. We propose a new classification to predict variant pathogenicity and assist with carrier surveillance.

An update on adult forms of hereditary pheochromocytomas and paragangliomas

PURPOSE OF REVIEW

Pheochromocytomas and paragangliomas (PPGL) display a strong genetic determinism with 40% of inherited forms. The purpose of this review is to provide an update on current knowledge on adult forms of hereditary PPGL and their management.

RECENT FINDINGS

PPGL are genetically-driven in 70% of cases, with germline and/or somatic mutations identified in more than 20 genes. Although eight new susceptibility genes have recently emerged, mutations on SDHx genes remain the most frequent. In addition to SDHB, mutations in SLC25A11, FH and MDH2 may predispose to a metastatic disease and somatic alterations including TERT and ATRX mutations, and the differential expression on noncoding RNAs are also associated with the occurrence of metastases.The biochemical diagnosis remains the mainstay of functional PPGL and does not differ between hereditary PPGL while the choice of the best nuclear imaging approach is dictated by the tumor type and can be influenced by the presence of a germline mutation (18F-DOPA PET/CT for cluster 2 mutation and Ga-DOTATATE PET/CT for cluster 1 mutation).

SUMMARY

A systematic genetic testing and counselling is recommended for all PPGL patients and should lead to conservative surgery and an adapted follow up, in case of hereditary form.

Whole Exome Sequencing Identifies Novel Genetic Alterations in Patients with Pheochromocytoma/Paraganglioma

BACKGROUND

Pheochromocytoma and paragangliomas (PPGL) are known as tumors with the highest level of heritability, approximately 30% of all cases. Clinical practice guidelines of PPGL recommend genetic testing for germline variants in all patients. In this study, we used whole exome sequencing to identify novel causative variants associated with PPGL to improve the detection of rare genetic variants in our cohort.

METHODS

Thirty-six tested negative for pathogenic variants in previous Sanger sequencing or targeted gene panel testing for PPGL underwent whole exome sequencing. Whole exome sequencing was performed using DNA samples enriched using TruSeq Custom Enrichment Kit and sequenced with MiSeq (Illumina Inc.). Sequencing alignment and variant calling were performed using SAMtools.

RESULTS

Among previously mutation undetected 36 patients, two likely pathogenic variants and 13 variants of uncertain significance (VUS) were detected in 32 pheochromocytoma-related genes. SDHA c.778G>A (p.Gly260Arg) was detected in a patient with head and neck paraganglioma, and KIF1B c.2787-2A>C in a patient with a bladder paraganglioma. Additionally, a likely pathogenic variant in BRCA2, VUS in TP53, and VUS in NFU1 were detected.

CONCLUSION

Exome sequencing further identified genetic alterations by 5.6% in previously mutation undetected patients in PPGL. Implementation of targeted gene sequencing consisted of extended genes of PPGL in routine clinical screening can support the level of comprehensive patient assessment.

Mutation profiling in eight cases of vagal paragangliomas

Background

Vagal paragangliomas (VPGLs) belong to a group of rare head and neck neuroendocrine tumors. VPGLs arise from the vagus nerve and are less common than carotid paragangliomas. Both diagnostics and therapy of the tumors raise significant challenges. Besides, the genetic and molecular mechanisms behind VPGL pathogenesis are poorly understood.

Methods

The collection of VPGLs obtained from 8 patients of Russian population was used in the study. Exome library preparation and high-throughput sequencing of VPGLs were performed using an Illumina technology.

Results

Based on exome analysis, we identified pathogenic/likely pathogenic variants of the SDHx genes, frequently mutated in paragangliomas/pheochromocytomas. SDHB variants were found in three patients, whereas SDHD was mutated in two cases. Moreover, likely pathogenic missense variants were also detected in SDHAF3 and SDHAF4 genes encoding for assembly factors for the succinate dehydrogenase (SDH) complex. In a patient, we found a novel variant of the IDH2 gene that was predicted as pathogenic by a series of algorithms used (such as SIFT, PolyPhen2, FATHMM, MutationTaster, and LRT). Additionally, pathogenic/likely pathogenic variants were determined for several genes, including novel genes and some genes previously reported as associated with different types of tumors.

Conclusions

Results indicate a high heterogeneity among VPGLs, however, it seems that driver events in most cases are associated with mutations in the SDHx genes and SDH assembly factor-coding genes that lead to disruptions in the SDH complex.

Usefulness of FDG-PET/CT-Based Radiomics for the Characterization and Genetic Orientation of Pheochromocytomas Before Surgery

Simple Summary

Around 40% of patients with pheochromocytomas (PHEO) carry a germline mutation. Early germline mutation identification is important for accurate treatment and follow-up in affected patients. The aim of our retrospective study was to assess the potential added value of FDG-PET/CT radiomics for the characterization of PHEO and their genetic orientation prior to surgery and genetic testing. We confirmed in an homogeneous population of 52 PHEO (49 patients) the usual avidity of these tumors for FDG (92%) and the impact of germline mutation on their phenotypic presentations with higher SUVmax observed in Cluster-1-related genes. Radiomics biomarkers provided valuable additional and independent information for discriminating genetically determined PHEO (Cluster-1 or Cluster-2-related genes) as well as sporadic forms. FDG-PET/CT is then useful for preoperative detection of PHEO, and when combined with texture features, provides evidences for a genetic predisposition.

Abstract

Purpose: To assess the potential added value of FDG-PET/CT radiomics for the characterization of pheochromocytomas (PHEO) and their genetic orientation prior to surgery and genetic testing. Methods: This retrospective monocentric study, included 49 patients (52 tumors) that underwent both FDG-PET/CT and MIBG scan before surgery. A germline mutation was secondarily identified in 13 patients in one of the genes related to Cluster 1 (n = 4) or Cluster 2 (n = 9). No mutation was identified in 32 patients and 4 did not have genetic testing. Correlation between several PET-based biomarkers, including SUVmax, metabolic tumor volume (MTV), total lesion glycolysis (TLG) and textural features, and biochemical and genetic features were analyzed. Results: Sensitivity of FDG-PET/CT alone was 92%, and 98% when combined to MIBG. The SUVmax was significantly higher for mutated tumors classified in Cluster 1 than in Cluster 2 (p = 0.002) or for tumors with no identified mutations (p = 0.04). MTV and TLG of the tumors with the most intense uptake discriminated mutated Cluster 2 from sporadic tumors, but not from Cluster 1 tumors. Textural features combined with MTV led to better differentiation between sporadic and mutated tumors (p < 0.05). Conclusion: FDG-PET/CT is useful for preoperative characterization of PHEO, and when combined with radiomics biomarkers, provides evidences for a genetic predisposition.

Genetics, diagnosis, management and future directions of research of phaeochromocytoma and paraganglioma: a position statement and consensus of the Working Group on Endocrine Hypertension of the European Society of Hypertension

: Phaeochromocytoma and paraganglioma (PPGL) are chromaffin cell tumours that require timely diagnosis because of their potentially serious cardiovascular and sometimes life- threatening sequelae. Tremendous progress in biochemical testing, imaging, genetics and pathophysiological understanding of the tumours has far-reaching implications for physicians dealing with hypertension and more importantly affected patients. Because hypertension is a classical clinical clue for PPGL, physicians involved in hypertension care are those who are often the first to consider this diagnosis. However, there have been profound changes in how PPGLs are discovered; this is often now based on incidental findings of adrenal or other masses during imaging and increasingly during surveillance based on rapidly emerging new hereditary causes of PPGL. We therefore address the relevant genetic causes of PPGLs and outline how genetic testing can be incorporated within clinical care. In addition to conventional imaging (computed tomography, MRI), new functional imaging approaches are evaluated. The novel knowledge of genotype-phenotype relationships, linking distinct genetic causes of disease to clinical behaviour and biochemical phenotype, provides the rationale for patient-tailored strategies for diagnosis, follow-up and surveillance. Most appropriate preoperative evaluation and preparation of patients are reviewed, as is minimally invasive surgery. Finally, we discuss risk factors for developing metastatic disease and how they may facilitate personalised follow-up. Experts from the European Society of Hypertension have prepared this position document that summarizes the current knowledge in epidemiology, genetics, diagnosis, treatment and surveillance of PPGL.

[Pathologist contribution in the diagnosis of hereditary predisposition to paranganglioma and pheochromocytoma]

Hereditary predispositions are responsible for more than 30% of or paraganglioma. Their identification is essential to optimize medical care and to offer an appropriate screening to relatives. To date, there are more than 15 known paraganglioma/pheochromocytoma predisposing genes. The most frequently involved are those encoding the succinate dehydrogenase (SDHx), accounting for half of cases and the VHL gene, causing the Von Hippel Lindau syndrome and representing approximately 20% of genetically determined cases. Patients with SDHB genes mutations have a higher risk of metastatic disease. An oncogenetic counseling is recommended to all patients developing one or several paragangliomas, isolated or associated with other tumors. Apart from the clinical presentation and in particular the syndromic forms characterized by specific tumor spectra, there is no validated morphological criterion allowing to suspect a hereditary form. On the other hand, pathologists have now access to several immunohistochemical tools allowing the identification of some hereditary forms, in particular those linked to the SDHx, VHL and FH genes. Thus, the loss of expression in immunohistochemistry of the SDHB or FH proteins orientates respectively, towards SDHx and FH genes, while the membrane expression of carbonic anhydrase IX (CA-IX) is a sensitive and specific tool pointing towards a VHL anomaly. Other immunohistochemical markers are under evaluation. A systematic SDHB immunohistochemical staining is recommended on all paragangliomas/pheochromocytomas in order to allow an early detection of the most common hereditary forms and to contribute to the interpretation of the genetic results in these patients seen in oncogenetics consultation.

An overview of 20 years of genetic studies in pheochromocytoma and paraganglioma

Paragangliomas and pheochromocytomas (PPGL) are rare neuroendocrine tumours characterized by a strong genetic determinism. Over the past 20 years, evolution of PPGL genetics has revealed that around 40% of PPGL are genetically determined, secondary to a germline mutation in one of more than twenty susceptibility genes reported so far. More than half of the mutations occur in one of the SDHx genes (SDHA, SDHB, SDHC, SDHD, SDHAF2), which encode the different subunits and assembly protein of a mitochondrial enzyme, succinate dehydrogenase. These susceptibility genes predispose to early forms (VHL, RET, SDHD, EPAS1, DLST), syndromic (RET, VHL, EPAS1, NF1, FH), multiple (SDHD, TMEM127, MAX, DLST, MDH2, GOT2) or malignant (SDHB, FH, SLC25A11) PPGL. The discovery of a germline mutation in one of these genes changes the patient's follow-up and allows genetic screening of affected families and the presymptomatic follow-up of relatives carrying a mutation.

Transcriptome Analysis of lncRNAs in Pheochromocytomas and Paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors explained by germline or somatic mutations in about 70% of cases. Patients with SDHB mutations are at high risk of developing metastatic disease, yet no reliable tumor biomarkers are available to predict tumor aggressiveness.

OBJECTIVE

We aimed at identifying long noncoding RNAs (lncRNAs) specific for PPGL molecular groups and metastatic progression.

DESIGN AND METHODS

To analyze the expression of lncRNAs, we used a mining approach of transcriptome data from a well-characterized series of 187 tumor tissues. Clustering consensus analysis was performed to determine a lncRNA-based classification, and informative transcripts were validated in an independent series of 51 PPGLs. The expression of metastasis-related lncRNAs was confirmed by RT-qPCR. Receiver operating characteristic (ROC) curve analysis was used to estimate the predictive accuracy of potential markers.

MAIN OUTCOME MEASURE

Univariate/multivariate and metastasis-free survival (MFS) analyses were carried out for the assessment of risk factors and clinical outcomes.

RESULTS

Four lncRNA-based subtypes strongly correlated with mRNA expression clusters (chi-square P-values from 1.38 × 10-32 to 1.07 × 10-67). We identified one putative lncRNA (GenBank: BC063866) that accurately discriminates metastatic from benign tumors in patients with SDHx mutations (area under the curve 0.95; P = 4.59 × 10-05). Moreover, this transcript appeared as an independent risk factor associated with poor clinical outcome of SDHx carriers (log-rank test P = 2.29 × 10-05).

CONCLUSION

Our findings extend the spectrum of transcriptional dysregulations in PPGL to lncRNAs and provide a novel biomarker that could be useful to identify potentially metastatic tumors in patients carrying SDHx mutations.

Germline mutations in the new E1' cryptic exon of the VHL gene in patients with tumours of von Hippel-Lindau disease spectrum or with paraganglioma

BACKGROUNDS

The incidence of germline mutations in the newly discovered cryptic exon (E1') of VHL gene in patients with von Hippel-Lindau (VHL) disease and in patients with paraganglioma or pheochromocytoma (PPGL) is not currently known.

METHODS

We studied a large international multicentre cohort of 1167 patients with a previous negative genetic testing. Germline DNA from 75 patients with a single tumour of the VHL spectrum ('Single VHL tumour' cohort), 70 patients with multiple tumours of the VHL spectrum ('Multiple VHL tumours' cohort), 76 patients with a VHL disease as described in the literature ('VHL-like' cohort) and 946 patients with a PPGL were screened for E1' genetic variants.

RESULTS

Six different genetic variants in E1' were detected in 12 patients. Two were classified as pathogenic, 3 as variants of unknown significance and 1 as benign. The rs139622356 was found in seven unrelated patients but described in only 16 patients out of the 31 390 of the Genome Aggregation Database (p<0.0001) suggesting that this variant might be either a recurrent mutation or a modifier mutation conferring a risk for the development of tumours and cancers of the VHL spectrum.

CONCLUSIONS

VHL E1' cryptic exon mutations contribute to 1.32% (1/76) of 'VHL-like' cohort and to 0.11% (1/946) of PPGL cohort and should be screened in patients with clinical suspicion of VHL, and added to panels for Next Generation Sequencing (NGS) diagnostic testing of hereditary PPGL. Our data highlight the importance of studying variants identified in deep intronic sequences, which would have been missed by examining only coding sequences of genes/exomes. These variants will likely be more frequently detected and studied with the upcoming implementation of whole-genome sequencing into clinical practice.

Succinate dehydrogenase deficiency in a chromaffin cell model retains metabolic fitness through the maintenance of mitochondrial NADH oxidoreductase function

Mutations in succinate dehydrogenase (SDH) lead to the development of tumors in a restricted subset of cell types, including chromaffin cells and paraganglia. The molecular basis for this specificity is currently unknown. We show that loss of SDH activity in a chromaffin cell model does not perturb complex I function, retaining the ability to oxidize NADH within the electron transport chain. This activity supports continued oxidation of substrates within the tricarboxylic acid (TCA) cycle. However, due to the block in the TCA cycle at SDH, the high glutamine oxidation activity is only maintained through an efflux of succinate. We also show that although the mitochondria of SDH-deficient cells are less active per se, their higher mass per cell results in an overall respiratory rate that is comparable with wild-type cells. Finally, we observed that when their mitochondria are uncoupled, SDH-deficient cells are unable to preserve their viability, suggesting that the mitochondrial metabolic network is unable to compensate when exposed to additional stress. We therefore show that in contrast to models of SDH deficiency based on epithelial cells, a chromaffin cell model retains aspects of metabolic "health," which could form the basis of cell specificity of this rare tumor type.

Carbonic anhydrase 9 immunohistochemistry as a tool to predict or validate germline and somatic VHL mutations in pheochromocytoma and paraganglioma-a retrospective and prospective study

The development of pheochromocytomas and paragangliomas is strongly linked to the presence of germline mutations in more than 15 predisposing genes. Among them, germline and somatic VHL mutations account for ~10% of all cases. In contrast with SDHA and SDHB immunohistochemistries that are routinely used to validate SDHx gene mutations, there is no such tool available for VHL mutations. The aim of this study was to evaluate whether CA9 immunostaining could be used as a tool to predict the presence or validate the pathogenicity of VHL gene mutations in paraganglioma. Immunohistochemistry for CA9 was performed on 207 tumors. A retrospective series of 100 paragangliomas with known mutation status for paraganglioma susceptibility genes was first investigated. Then, a prospective series of 107 paragangliomas was investigated for CA9 immunostaining followed by germline and/or somatic genetic testing of all paraganglioma susceptibility genes by next-generation sequencing. Cytosolic CA9 protein expression was heterogeneous in the different samples. However, we observed that a membranous CA9 staining was almost exclusively observed in VHL-related cases. Forty two of 48 (88%) VHL-mutated samples showed a CA9 membranous immunostaining. Positive cells were either isolated, varying from 1 or 2 cells (5% of cases) to 10-20 cells per tumor block (35% of cases), grouped in areas of focal positivity representing between 1 and 20% of the tissue section (35% of cases), or widely distributed on 80-100% of the tumor sections (25% of samples). In contrast, 142/159 (91%) of non-VHL-mutated tumors presented no membrane CA9 localization. Our results demonstrate that VHL gene mutations can be predicted or validated reliably by an easy-to-perform and low-cost immunohistochemical procedure. CA9 immunohistochemistry on paragangliomas will improve the diagnosis of VHL-related disease, which is important for the surveillance and therapeutic management of paraganglioma patients, and in case of germline mutation, their family members.

Genetic and Clinical Profiles of Pheochromocytoma and Paraganglioma: A Single Center Study

Pheochromocytoma/paraganglioma (PPGL) has a high genetic heterogeneity with 40% germline variants in known pathogenic genes. Data in Chinese on this aspect are scanty. To detect the genetic and clinical profile of Chinese PPGL patients, we examined the variants of 12 known germline pathogenic genes (SDHA, SDHB, SDHC, SDHD, SDHAF2, FH, VHL, RET, NF1, MAX, TMEM127, and KIF1B) by next-generation sequencing and Sanger sequencing in 314 Chinese PPGL subjects. Twenty nine percent of Chinese PPGL patients had germline variants and SDHB was the most frequently mutated (14.6%). The most frequent SDHB variants were in exon 2, exon 7, and IVS 7. Pathogenic variants were more likely to occur in metastatic PPGL patients, paragangliomas, and patients under 30, with the ratio being 50.7% (35/69), 35.9% (56/156), and 49.5% (52/105), respectively. Our cohort included 314 patients from a single setting. The genetic and clinical features of Chinese PPGL patients were unique in some aspects compared to their non-Chinese counterparts. Identification of genotype-phenotype relation can serve as an effective tool for genetic prioritization and clinical decision-making.

Succinate detection using in vivo 1H-MR spectroscopy identifies germline and somatic SDHx mutations in paragangliomas

PURPOSE

Germline mutations in genes encoding succinate dehydrogenase (SDH) are frequent in patients with pheochromocytoma and paraganglioma (PPGL). They lead to SDH inactivation, mediating a massive accumulation of succinate, which constitutes a highly specific biomarker of SDHx-mutated tumors when measured in vitro. In a recent pilot study, we showed that magnetic resonance spectroscopy (¹H-MRS) optimized for succinate detection (SUCCES) could detect succinate in vivo in both allografted mouse models and PPGL patients. The objective of this study was to prospectively assess the diagnostic performances of ¹H-MRS SUCCES sequence for the identification of SDH deficiency in PPGL patients.

METHODS

Forty-nine patients presenting with 50 PPGLs were prospectively enrolled in our referral center for ¹H-MRS SUCCES. Two observers blinded to the clinical characteristics and genetic status analyzed the presence of a succinate peak and confronted the results to a composite gold standard combining PPGL genetic testing and/or in vitro protein analyses in the tumor.

RESULTS

A succinate peak was observed in 20 tumors, all of which had proven SDH deficiency using the gold standard (17 patients with germline SDHx mutations, 2 with a somatic SDHD mutation, and 1 with negative SDHB IHC and SDH loss of function). A false negative result was observed in 3 tumors. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ¹H-MRS SUCCES were respectively 87%, 100%, 100%, 90%, and 94%.

CONCLUSIONS

Detection of succinate using ¹H-MRS is a highly specific and sensitive hallmark of SDH-deficiency in PPGLs.