Metastatic Pheochromocytomas and Paragangliomas: Proceedings of the MEN2019 Workshop

27 8

Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T41–T52 Cancer paragangliomas THEMATIC REVIEW

HEREDITARY ENDOCRINE TUMOURS: CURRENT STATE-OF-THE-ART AND RESEARCH OPPORTUNITIES Metastatic pheochromocytomas and paragangliomas: proceedings of the MEN2019 workshop

Patricia L M Dahia1, Roderick Clifton-Bligh2, Anne-Paule Gimenez-Roqueplo3,4, Mercedes Robledo5,6 and Camilo Jimenez7

1Division of Hematology and Medical Oncology, Department of Medicine, Mays Cancer Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA 2Department of Endocrinology, Royal North Shore Hospital, Northern Clinical School, Kolling Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia 3Université de Paris, INSERM, PARCC, Paris, France 4AP-HP, Hôpital Européen Georges Pompidou, Genetics Department, Paris, France 5Human Cancer Genetics Program, Spanish National Cancer Research Center, Madrid, Spain 6Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain 7Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA

Correspondence should be addressed to P L M Dahia: [email protected]

This paper is part of a thematic section on current knowledge and future research opportunities in hereditary endocrine tumours, as discussed at MEN2019: 16th International Workshop on Multiple Endocrine Neoplasia, 27–29 March 2019, Houston, TX, USA. This meeting was sponsored by Endocrine-Related Cancer

Abstract Key Words Pheochromocytomas and paragangliomas (PPGLs) are adrenal or extra-adrenal ff pheochromocytomas autonomous nervous system-derived tumors. Most PPGLs are benign, but approximately ff paragangliomas 15% progress with metastases (mPPGLs). mPPGLs are more likely to occur in patients ff metastatic with large pheochromocytomas, sympathetic paragangliomas, and norepinephrine- ff mutation secreting tumors. Older subjects, those with larger tumors and synchronous metastases, ff SDHB advance more rapidly. Germline mutations of SDHB, FH, and possibly SLC25A11, or somatic ff therapy MAML3 disruptions relate to a higher risk for metastatic disease. However, it is unclear whether these mutations predict outcome. Once diagnosed, there are no well-established predictors of outcome in mPPGLs, and aggressive tumors have few therapeutic options and limited response. High-specific activity (HSA) metaiodine-benzyl-guanidine (MIBG) is the first FDA approved treatment and shows clinical effectiveness for MIBG-avid mPPGLs. Ongoing and future investigations should involve validation of emerging candidate outcome biomarkers, including somatic ATRX, TERT, and microRNA disruptions and identification of novel prognostic indicators. Long-term effect of HSA-MIBG and the role of other radiopharmaceuticals should be investigated. Novel trials targeting molecular events prevalent in SDHB/FH mutant tumors, such as activated hypoxia inducible factor 2 (HIF2), angiogenesis, or other mitochondrial defects that might confer unique

-19-0435 Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T42 Cancer paragangliomas vulnerability to these tumors should be developed and initiated. As therapeutic options are anticipated to expand, multi-institutional collaborations and well-defined clinical and molecular endpoints will be critical to achieve higher success rates in improving care for patients with mPPGLs. Endocrine-Related Cancer (2020) 27, T41–T52

Introduction

The 16th International Workshop on Multiple Endocrine (Ayala-Ramirez et al. 2011). Head and neck paragangliomas Neoplasia (MEN2019) focused on new concepts and are more rarely metastatic (McCrary et al. 2019). Even treatment of malignant manifestations of cancers that though family history may be negative, a hereditary comprise hereditary endocrine cancer syndromes. This basis is present in 40–50% of mPPGLs. Synchronous meeting took place 27–29 March 2019 in Houston, Texas. metastases are present in 35–50% cases; metachronous The meeting addressed the state of the field and metastases can develop within months or after more discussed important outstanding research questions and than a decade (Baudin et al. 2014, Roman-Gonzalez & challenges, in the form of symposium presentations and Jimenez 2017). Median survival of mPPGL is ~6 years, two-day workshops. Workshop attendees weighed in although the rate of progression is highly variable. on key priority areas for future research and consensus Death is usually from metastatic progression, although points were collated. The next sections summarize hypersecretion of catecholamines is often morbid and presentations and workshop discussions on metastatic sometimes fatal. pheochromocytomas and paragangliomas (mPPGLs) and Five large clinical series (Amar et al. 2007, Ayala- conclude with proposed plans for the coming years and Ramirez et al. 2011, Turkova et al. 2016, Fishbein et al. future research projects for bridging these gaps. 2017a, Hamidi et al. 2017, Hescot et al. 2019) of mPPGL are shown in Table 1. Despite the heterogeneous nature of mPPGL, group statistics for these series are strikingly similar. Diagnosis of ‘malignant’ pheochromocytoma Risk factors for mPPGL include clinical, pathological, and paraganglioma: state of the science and genetic factors. The strongest clinical risk factors Under the revised WHO classification (2018), are tumor size and thoraco-abdominal (sympathetic) pheochromocytomas and paragangliomas (PPGLs) PGL. Tumor size is incorporated in the newly published are now referred to as ‘metastatic’ or ‘non-metastatic’ AJCC Cancer Staging system for PPGL (Amin et al. 2017): rather than ‘malignant’ or ‘benign’; metastases are still T1 tumors are <5 cm in greatest dimension, T2 tumors defined by deposits at sites where normal chromaffin are ≥5 cm or sympathetic PGLs of any size, and T3 tissue is not present (Lam 2017). Approximately 10% tumors are of any size with invasion into surrounding of pheochromocytomas and ~40% of sympathetic tissues. Metastasis is rare for pheochromocytomas below paragangliomas will be associated with metastases 4 cm; conversely, metastatic paraganglioma can occur

Table 1 Clinical series of metastatic pheochromocytomas and paragangliomas.

Ayala-Ramirez Amar et al. (2007) et al. (2011) Turkova et al. (2016) Hamidi et al. (2017) Hescot et al. (2019) Fishbein et al. (2017a,b) n 54 131 132 272 169 71 Timeframe n/r 1960–2009 2000–2014 1960–2016 1998–2010 2000–2016 PC/sPGL/HNPGL (%) 54/46/0 52/48/0 29/71/0 40/47/11 53/37/10 28/45/21a Synchronous metastasis 24 (44%) 67 (51%) 26 (20%) 96 (35%) 79 (47%)b 18 (25%)c Age (Dx primary), years 37.9 n/r 39 n/r 41 Age (Dx metastases), years 42 n/r 44 48 6.2 (0–44.77)d SDHB mutations 23/54 (43%) 9/21e (43%) 73/132 (55%) 42/272 (15%)e 63/151e (42%) 37/60e (62%) Died of disease 26/54 (48%) 87/131 (66%) 39/132 (30%) 73/272 (27%) 72/169 (43%) 19/71 (27%) Age at death (range), years 45 n/r 54 (7–91) n/r n/r aAn additional 5.6% had more than one tumor location; bmetastases within 1 year; cmetastases within 3 months; dyears (range) after primary diagnosis; enot all cases had genetic testing. Dx metastases: at the time of metastases identification; Dx primary: at first diagnosis; n/r: not reported.

https://erc.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/ERC-19-0435 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/25/2021 06:36:54PM via free access Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T43 Cancer paragangliomas from smaller primaries (Ayala-Ramirez et al. 2011). likely due to the presence of SDHB mutations in the A retrospective study by Hamidi et al. (2017) examined former (Richter et al. 2014). factors associated with rapid progression (death within Genetic risk factors for mPPGL include germline 5 years of initial presentation) and found the strongest pathogenic variants in SDHB, SDHA, SDHD, FH, MAX, predictors to be older age at primary diagnosis (OR 1.054 and SLC25A11 (Castro-Vega et al. 2014, Buffet et al. 2018) (95% CI 1.01–1.08)/year), primary tumor size (OR 1.12 and somatic MAML3 fusions (Fishbein et al. 2017b). The (1.009–1.25)/cm), and the presence of synchronous strongest genetic risk factor for mPPGL is a pathogenic metastases (OR 10.24 (3.76–31.18)). Another clinical risk SDHB variant, present in 40–50% cases (Amar et al. 2007, factor for the rate of progression is the site of metastatic Ayala-Ramirez et al. 2011, Turkova et al. 2016, Hamidi et al. disease: skeletal only metastases tend to be more 2017, Hescot et al. 2019); nevertheless, accumulating indolent (median survival 12 years), compared with non- evidence suggests that SDHB mutations are not associated osseous metastases (median survival 7.5 years) (Ayala- per se with rapid progression of disease (Hamidi et al. 2017, Ramirez et al. 2013). Biochemically, mPPGL is less likely Crona et al. 2019, Hescot et al. 2019). Recently, aberrant in epinephrine-secreting tumors (Ayala-Ramirez et al. telomere maintenance mechanisms (TMMs) have 2013); conversely, elevated plasma methoxytyramine, been associated with mPPGL: somatic ATRX mutations a byproduct of dopamine, is associated with mPPGLs associated with alternate lengthening of telomeres were (Eisenhofer et al. 2012). The ASES (age, size, extra- first reported in mPPGL byFishbein et al. (2015); high adrenal, secretory) score attempts to bring these clinical TERT expression was then reported by Liu et al. in many risk factors together, by giving one point each for age mPPGLs (Liu et al. 2014); Dwight et al. reported structural ≤35 years, tumor size ≥6 cm, extra-adrenal location, and variants in TERT associated with telomerase re-expression norepinephrine secretion (Cho et al. 2018). As the ASES (Dwight et al. 2018); and most recently Job et al. (2019) score does not include genetic data, the younger age likely have shown that aberrant TMM is associated with worse acts as a surrogate for genetic risk. An ASES score of ≥2 prognosis and that a somatic hot-spot TERT promoter had a sensitivity of 61%, specificity of 80%, and negative mutation (C228T) is specifically associated with poor predictive value of 96.5%, but a positive predictive value outcomes in SDHB-associated disease, as discussed later in of only 18.4% for mPPGL. Ten-year survival rate was 30% this article. for ASES ≥2 compared with 86% for ASES <2 (Cho et al. All patients with mPPGL should be referred for 2018). genetic testing after appropriate counseling; multi-gene PET imaging has revolutionized the detection of panels facilitate comprehensive evaluation of 12 well- mPPGL: 68Ga-DOTATATE has the highest sensitivity in defined hereditary loci for PPGL NGS( in PPGL Study most cases, in particular for SDHB-associated disease Group et al. 2017), as well as additional genes recently (98.6% overall detection rate) (Janssen et al. 2015, 2016a,b, reported as related to the disease (Remacha et al. 2017, 2017, Taieb et al. 2018). Unfortunately, PET imaging has 2018, 2019, Buffet et al. 2018). Discovery of a germline not been shown to predict the tempo of mPPGL, thus variant has implications for the patient and their first- prognostic and disease modeling are not achievable with degree relatives. A recent retrospective study found that this imaging modality alone. Diagnosis of PPGL is usually delayed diagnosis of an underlying germline variant in considered an indication for surgery. An important albeit PPGL was associated with increased recurrence risk and retrospective study by Roman-Gonzalez et al. showed that reduced survival (Buffet et al. 2019). surgical resection of the primary lesion was associated In summary, mPPGL is more common in with improved survival in synchronous mPPGL (Roman- pheochromocytomas >5 cm or in sympathetic PGLs, Gonzalez et al. 2018). associated with norepinephrine and/or dopamine There is no consensus on the utility of tumor grading secretion, and pathogenic germline SDHB, FH, or possibly systems for predicting mPPGL; both the PASS and also SLC25A11 variants. Rapid progression of metastatic GAPP systems are limited by inter-observer variability disease is more likely in older subjects, with larger tumors (Baudin et al. 2014). Absent immunostaining for SDHB and synchronous metastases. The presence of somatic is strongly associated with germline SDHB pathogenic mutations in ATRX or TERT is also associated with worse variants (Papathomas et al. 2015). Tumoral succinate, prognosis. Conversely, pheochromocytomas <4 cm secreting measured by LC/MS-MS, is higher in PPGLs associated epinephrine, or head and neck PGLs, are associated with a with metastases compared with non-metastatic cases, low likelihood of metastatic disease (Table 2).

Table 2 Factors associated with metastatic risk in PPGLs. MEG3 miRNA cluster (Castro-Vega et al. 2014). More recently, an additional molecular group (MAML3 gene High risk Low risk fusions, CSDE1 somatic mutations) was described by The Tumor >5 cm Tumor <5 cm Norepinephrine secretion Epinephrine secretion Cancer Genome Atlas program that exhibits activation of Paragangliomaa Pheochromocytoma the Wnt signaling pathway (Fishbein et al. 2017b). Older age (sporadic) Younger age (sporadic and More than 10 years after the introduction of the PPGL certain genetic groups) genetic testing in routine practice, it was demonstrated SDHB, FH, SLC25A11 germline VHL, RET mutation mutation that knowledge of the genetic status in the first year after ATRX, TERT, MAML3 somatic – PPGL diagnosis has improved the patients’ outcome, even disruptions for patients with an SDHB mutation (Buffet et al. 2019). aExcluding head and neck paragangliomas, which have intrinsically low This finding provides strong support for widespread risk of metastasis. genetic testing in all patients with PPGL and not just patients with high-risk tumors. Advances in molecular aspects of PPGLs Mechanistically, there has been important progress in understanding aberrant pathways in PPGL. Letouzé Enabling replicative immortality in PPGLs et al. demonstrated that the inactivation of succinate At the beginning of the third millennium, pioneer dehydrogenase in SDHx-mutated PPGL led to marked retrospective studies carried out on the large PPGL accumulation of succinate and shed light on its role collection of the French COMETE network revealed as an oncometabolite (Letouze et al. 2013). Excess that SDHB mutation is a high risk factor of malignancy succinate is able to inhibit multiple 2-oxoglutarate- and of poor prognosis (Gimenez-Roqueplo et al. 2003, dependent dioxygenases, as prolyl-hydoxylases or DNA/ Amar et al. 2007). Independent studies, utilizing different histones demethylases (Xu et al. 2011), and to promote genomics technologies, including multi-omics integrative angiogenesis and global DNA hypermethylation that studies, classified PPGL into two main different clusters contribute to tumorigenesis (Letouze et al. 2013). driven mainly by germline or somatic mutation in a PPGL Nevertheless, only 50% of SDHx-related PPGLs go on susceptibility gene (Eisenhofer et al. 2004, Dahia et al. to develop a metastatic phenotype suggesting that 2005, Lopez-Jimenez et al. 2010, Castro-Vega et al. 2015), additional molecular(s) mechanism(s) promote malignant one containing genes enriched for hypoxia-related properties. Furthermore, patients without SDHB mutations response (named ‘Cluster 1) and another expressing can also develop metastatic disease. Job et al. recently predominantly tyrosine kinase signaling genes (Cluster addressed the question of the relative contribution of 2). Further analysis revealed that within the hypoxia- immortalization mechanisms to metastatic progression in related cluster, the subcluster C1A contains PPGL with PPGL and, for that purpose, carried out a comprehensive higher metastatic potential, that is, tumors related to analysis of two immortalization mechanisms (telomerase germline mutations in a gene encoding for a tricarboxylic reactivation and alternative lengthening of telomeres) acid cycle (also known as the Krebs cycle) protein such in the large well-annotated series of PPGL collected by as SDHx (SDHA,-B,-C,-D,-F2), FH, MDH2, SLC25A11, the French COMETE network, which had previously GOT2, and so on. (Castro-Vega et al. 2014, Cascon et al. undergone integrative genomic analyses (Job et al. 2019). 2015, Remacha et al. 2017, Buffet et al. 2018). The They found that 70% of mPPGLs become immortalized, subcluster C1A presents global DNA hypermethylation, including every metastatic case classified into cluster C1A. transcriptional signatures of reactivation of epithelial Molecularly, these tumors presented either transcriptional to mesenchymal transition and of activation of activation of TERT (via a TERT promoter mutation, angiogenesis/hypoxia signaling and overexpression of promoter hypermethylation, or copy number variation at miRNA cluster 182/96/183, miR-210, miR-483. A second the TERT locus) or somatic ATRX mutation. Importantly, group, subcluster 1B (germline or somatic VHL mutations) telomerase activation and ATRX mutation are independent tumors have intermediate methylation levels, also share risk factors for malignancy strongly associated with both a hypoxic-like transcriptional profile, and display an metastasis and overall survival. These two indicators overexpression of miR-210. Cluster 2 tumours (NF1-, RET-, appear to more accurately discriminate metastatic from TMEM127-, MAX-, HRAS-, MET-, or FGFR1-related tumors) non-mPPGL compared to an SDHB mutation and are able are characterized by global hypomethylation, activation to predict metastatic behavior irrespective of the SDHB of RAS/MAPK signaling, and down-regulation of DLK- status (Job et al. 2019). These new PPGL biomarkers are

https://erc.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/ERC-19-0435 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/25/2021 06:36:54PM via free access Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T45 Cancer paragangliomas promising candidates for prognostication of SDHB-related Krebs cycle enzymes lead to the accumulation of their PPGL, for improving risk stratification, and for tailoring corresponding substrate (for instance, succinate or fumarate patients’ monitoring. in mutant SDH or FH, respectively), which in turn inhibits the activity of enzymes dependent on 2-oxoglutarate (also known as alpha-ketoglutarate). Succinate and fumarate are Epigenetic characteristics of SDHB- structurally similar to 2-oxoglutarate, and thus abundance related paragangliomas of either substrate outcompetes the latter, leading to If we consider cancers in general, 5–10% of cases are reduced activity of 2-oxoglutarate dependent enzymes. classified as ‘hereditary’ due to inherited genetic pathogenic This broad group of enzymes includes the TET family of variants (mutations), which can be transmitted to the DNA modifying enzymes and the JmjC domain-containing next generation (Rahman 2014). There is an additional 10 histone lysine demethylases (KDMs), leading to DNA and to 15% of patients that show familial cancer aggregation, histone hypermethylation seen in these tumors. The which may be due to the combined effect of genes and resulting epigenetic alterations lead to cell differentiation other shared factors, such as environment and lifestyle. arrest and promote malignant transformation (Frezza et al. However, the vast majority of cancers are sporadic and 2011, Xu et al. 2011). associated with non-inherited gene mutations. However, As SDHB is part of mitochondrial complex II, along when we consider PPGLs, this scenario markedly changes. with SDHA, SDHC, and SDHD, it is difficult to explain Up to 40% of cases are hereditary and related to at least 12 why the former is uniquely associated with a higher risk well-recognized susceptibility PPGL genes. An additional of metastasis. In this regard, it has been suggested that the 30% of PPGLs have somatic mutations and the remainder mean methylation levels across all CpG sites are higher in are included in a heterogeneous group without a clear SDHB-mutated PPGLs than in other SDH mutant PPGLs identifiable driver event Favier( et al. 2015, Dahia 2017). (Yang & Pollard 2013). It is possible that loss of SDHB Due to the large number of genes responsible for function results in complete inactivation of the SDH PPGL, patients are required to undergo comprehensive complex, whereas enzyme activity through mutations in genetic screening not only to assist with adequate genetic other subunits may not lead to full loss of SDH function. counseling but also as an attempt to estimate the risk of This might explain higher succinate accumulation and metastatic disease. In this regard, the association between stronger inhibition of demethylation in SDHB mutant higher metastatic risk and the presence of mutations tumors, relative to mutations in the other SDH subunits affecting the SDHB gene has been well-established (Yang et al. 2013). Additional studies are required to fully (Hescot et al. 2019), as described in the preceding demonstrate this concept and its attendant impact on sections. Over the past few years, more genes associated clinical behavior of PPGLs. with increased risk of metastatic disease have also been Having demonstrated the usefulness of high- reported (Cascon et al. 2019). These additional genes throughput platforms to define genomic characteristics have received little attention because their mutations are in PPGLs (Dahia et al. 2005, Castro-Vega et al. 2014, rare and individually account for only a small percentage de Cubas et al. 2015, Fishbein et al. 2017b), a potential of patients. However, if one considers this set of genes in application of these findings is to define therapeutic aggregate, a common theme can be recognized: they belong targets or identify drug resistance mechanisms. In this to the energy metabolism, in particular the tricarboxylic regard, it has been recently reported that tumors with acid cycle. The use of high-throughput platforms in PPGLs SDHB mutations have increased activity of mitochondrial has made it possible to identify genomic characteristics complex I of the electron transport chain (Pang et al. associated with clinical variables, grade of differentiation, 2018). This augmented complex I activity could lead or with specific mutations, allowing classification of to higher NAD+ availability, and therefore, to a more these tumors beyond the driver mutation (Dahia 2017, efficient DNA repair process (Tateishi et al. 2015). It has Fishbein et al. 2017a). One of the genomic features shared been proposed that targeting poly(ADP-ribose) polymerase by PPGLs with mutations in Krebs cycle genes is a global (PARP), a highly conserved enzyme involved in DNA hypermethylation phenotype, also known as CIMP (CpG break repair and stabilization of DNA replication, could island methylator phenotype) (Letouze et al. 2013). The potentiate the therapeutic effect of genotoxic agents, such mechanism underlying this epigenetic phenotype relates as temozolomide (Pang et al. 2018). These preliminary to an effect of the actual driver genetic mutation. Defective findings need further validation.

Translational progress and (Yan et al. 2007), in general, and for chromaffin cell treatment opportunities and sympathetic nervous system development and transformation in particular (Tian et al. 1998, Comino- Pseudohypoxia as a therapeutic target: lessons from Mendez et al. 2013, Toledo et al. 2013). PPGL clusters Transcription factors have historically been As discussed in the previous sections, there are currently considered ‘undruggable’ targets (Kaelin 2018). However, no biomarkers that can reliably and prospectively the identification of a large protein cavity in the HIF2α distinguish metastatic from non-metastatic PPGLs. As PAS-B domain opened the path to development of explained, the establishment of ‘malignancy’ in PPGL inhibitors of this subunit (Scheuermann et al. 2009, 2013). requires the documentation of metastasis in non- Exploiting this structural feature, clinical-grade, potent paraganglial tissue, which by definition constitutes small molecules (PT2385 and PT2977) that efficiently either an advanced (late) or a retrospective diagnosis, and specifically prevent HIF2α/ARNT dimerization, two undesirable attributes in contemporary oncology thus blocking HIF2 transactivation, were identified and (Baudin et al. 2014). The realization that the natural developed. These HIF2a- antagonists showed tumor evolution of PPGLs with metastatic potential is poorly inhibition capacity in clear cell renal cell carcinomas in known has practical implications beyond academic vitro and in vivo (Busch et al. 2016, Cho et al. 2016). Like knowledge, as it impedes therapeutic progress for these mPPGLs, clear cell renal carcinomas are pseudohypoxic tumors. Current standard therapies for mPPGL result at (Cancer Genome Atlas Research Network 2013). HIF2α best in partial responses, do not stratify patients based inhibitors have since been tested in advanced renal on their molecular or risk group, and trials adopting carcinomas. A phase 1 clinical trial with PT2385 in emerging therapies are still in early investigational stages heavily pre-treated patients with renal carcinoma showed (Baudin et al. 2014, Roman-Gonzalez & Jimenez 2017, an overall response rate (ORR) of 66%, with favorable Pryma et al. 2019). Thus, identification and testing of safety and tolerability profile Courtney( et al. 2018). effective drugs to treat mPPGL remain an unmet clinical Recently, a phase 1/2 dose-escalation trial with PT2977 need. (more potent and with superior pharmacokinetics than As discussed, about 40–50% of the patients with PT2385) was performed in patients with advanced solid mPPGL carry a germline mutation in the succinate tumors. The phase 2 portion included 52 patients with dehydrogenase subunit B (SDHB) gene (Astuti et al. advanced, previously treated renal carcinoma. Interim 2001, Amar et al. 2007, Ayala-Ramirez et al. 2011). These results of this trial showed 22% patients with a confirmed mutations inhibit degradation of hypoxia inducible partial response. Based on these results, a phase 3 trial factor (HIF) transcription factor, ultimately leading to its for renal carcinoma recently started recruiting patients stabilization and constitutive activation, a phenomenon (NCT04195750). Importantly, one patient from the known as pseudohypoxia (Dahia et al. 2005, Fishbein et al. UTHSCSA cohort with metastatic paraganglioma, carrier 2017b). As described, mPPGLs associated with other of an SDHB mutation, enrolled in the phase 1 portion of mutations, including prominently other components of the PT2977 trial (Papadopoulos et al. 2018). This patient, the energy cycle, often share this pseudohypoxic profile heavily pre-treated, remained stable with sustained (Favier et al. 2015, Cascon et al. 2019). HIF target genes are reduction of plasma normetanephrines and good involved in angiogenesis, cell proliferation, metastases, tolerability to PT2977 for 30 weeks, suggesting that HIF2 metabolic reprogramming, and so on. (Kaelin & Ratcliffe inhibition may have a place in the therapeutic arsenal 2008). Thus, pseudohypoxia and HIF represent early for mPPGL. A proposal for a pilot trial with this drug is (or truncal) and critically important events for PPGL currently undergoing evaluation. initiation, and possibly also for tumor maintenance, rendering them relevant targets for mPPGL treatment Advances in therapeutics: high specific activity MIBG, (Toledo 2017). tyrosine kinase inhibitors, immunotherapy, and Transcriptionally active HIFs are heterodimers that other treatments comprise an inducible, short-lived alpha subunit and a constitutive beta-subunit (ARNT). In particular, multiple Metastases happen in approximately 15–20% of patients lines of evidence suggest that the HIF2α subunit is the most with PPGLs (Ayala-Ramirez et al. 2011). Tumors more biologically relevant of the HIF subunits for oncogenesis commonly spread to the lymph nodes, skeletal tissue,

https://erc.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/ERC-19-0435 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/25/2021 06:36:54PM via free access Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T47 Cancer paragangliomas lungs, and liver (Ayala-Ramirez et al. 2013). A metastatic methodology. I-131-MIBG has been offered since then phenotype is more commonly observed in tumors to patients with mPPGLs that express the noradrenaline associated with pseudo-hypoxia (Dahia 2014). As transporter (MIBG-avid tumors). Approximately, 60% of mentioned before, 40–50% of patients with mPPGLs carry mPPGLs are MIBG-avid (Ilias et al. 2008, Jimenez et al. germline mutations of the SDHB gene. In addition, many 2019). Close to one-third of patients treated I-131-MIBG other hereditary and apparently sporadic mPPGLs share a exhibit tumor size reduction and stabilization with similar molecular profile with the SDHB mutant tumors improvement of symptoms of catecholamine excess (Dahia et al. 2005). However, survival curves indicate (Jimenez et al. 2019). Similar to chemotherapy, only that the outcomes of patients with mPPGLs are quite rare patients achieve a complete response (Jimenez et al. heterogeneous. Some patients may have very aggressive 2019). Over the last two decades, the manufacturing of tumors with poor clinical outcomes and die shortly after I-131-MIBG has been optimized through a selective resin diagnosis, while others have very slow growing or ‘static’ (Ultratrace) (Vallabhajosula & Nikolopoulou 2011). This tumors that may not even require systemic intervention. resin prevents unlabeled MIBG from being carried from Most patients have tumors that exhibit progression the production reaction to the final solution. Thus, the over time and therefore, they need systemic therapy specific radioactivity of Ultratrace I-131-MIBG is much (Jimenez et al. 2013). higher than then simple isotope exchange I-131-MIBG Chemotherapy, mainly with a combination of (92.5 vs 1.59 MBq/kg), implying a much higher delivery of cyclophosphamide, vincristine, and dacarbazine (CVD), radioactivity to the tumor per dose (Jimenez et al. 2019). was the first therapy introduced for patients with mPPGLs. The results of a phase 2 clinical trial with Ultratrace I-131- Approximately, 30–40% of these patients respond MIBG showed that more than 90% of patients achieved to chemotherapy (Asai et al. 2017, Roman-Gonzalez tumor stabilization and reduction 1 year after the first & Jimenez 2017). Responses mainly include disease infusion; these patients had improvement of symptoms of stabilization and tumor size reduction with improvement catecholamine excess (Pryma et al. 2019). Ultratrace I-131- of symptoms of catecholamine excess and a reduction MIBG did not cause cardiovascular toxicity. Less than a of the risk for tumor burden-related complications. quarter of patients had severe bone marrow insufficiency In contrast, complete responses are exceptional that required supportive treatment (i.e. platelet and red (Niemeijer et al. 2014). It is difficult to predict which blood cell transfusion, granulocyte colony stimulating patients will benefit from chemotherapy and responsive factors). All patients recovered bone marrow function and patients may remain on treatment for a long period. no patients required bone marrow transplant (Pryma et al. Nevertheless, chemotherapy may cause severe toxicity 2019). The United States Food and Drug Administration (i.e. bone marrow suppression, neuropathy); toxicity (FDA) approved Ultratrace I-131-MIBG for the treatment becomes more obvious over time and limits its long- of patients with MIBG-avid mPPGLs in 2018. Ultratrace term use. Chemotherapy is, however, the only treatment I-131-MIBG is currently, the only FDA approved therapy available worldwide. Interestingly, SDHB mutation carriers in the United States. were noted to display better response to CVD than non- mPPGLs frequently express somatostatin receptors carriers (Fishbein et al. 2017a). Taken together with other in the cell membranes; in fact, Gallium-68-DOTATATE observations of improved outcome after sunitinib (Ayala- scintigraphy is the most sensitive study to anatomically Ramirez et al. 2012) or temozolomide (Hadoux et al. characterize these tumors (Janssen et al. 2016a). Therefore, 2014) in SDHB mutation carriers, these studies may somatostatin analogues labeled with radioactivity support the notion that an SDHB mutation, although are attractive medications to study in prospective increasing the risk of metastatic disease, may in fact be clinical trials. Lutetium-177 labeled DOTATATE is FDA- associated with better outcome and greater therapeutic approved for the treatment of gastro-enteropancreatic response. Additional, prospective studies evaluating the neuroendocrine tumors. Retrospective studies and meta progression-free survival and overall survival of SDHB- analyses suggest that this radionuclide may be an effective mutation carriers are warranted. option in mPPGLs (Satapathy et al. 2019, Taieb et al. 2019). In the 1980s, radiopharmaceutical medications This drug is currently evaluated in recently activated became a therapeutic option to consider as treatments clinical trials for patients with mPPGLs (NCT04106843 for patients with mPPGLs. The first medication was and NCT03206060). meta-iodine-benzyl-guanidine (MIBG) labeled with Angiogenesis is an important hallmark for mPPGL Iodine-131, prepared through a simple isotope exchange development. Several tyrosine kinase inhibitors that block

https://erc.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/ERC-19-0435 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/25/2021 06:36:54PM via free access Endocrine-Related P L M Dahia et al. Metastatic pheochromocytomas/ 27:8 T48 Cancer paragangliomas the vascular endothelial growth factor receptors and other Table 3 Current gaps recognized in research and clinical receptors involved in angiogenesis are currently under practice of metastatic PPGLs. evaluation in clinical trials. These drugs include axitinib, Risk assessment models cabozantinib, lenvatinib, pazopanib, and sunitinib. These Specific guidelines for care of metastatic PPGL drugs can lead to tumor stabilization and size reduction Surveillance programs for mutation carriers with improvement of symptoms of catecholamine excess Access to treatment opportunities (Jimenez 2018). Nevertheless, the positive tumor responses Limited access to genetic testing: not widely available Opportunities for communication and discussion of care/ reported by the clinical trials with axitinib, pazopanib, and surveillance of specific cases sunitinib were blunted by toxicity associated with their increasing doses (Jasim et al. 2017, O’Kane et al. 2019). Goals for the future The preliminary results of a phase 2 clinical trial with At the two-day workshop on metastatic paragangliomas, cabozantinib show a high objective response rate with extensive and productive discussions reached consensus acceptable toxicity. Different from the trials with axitinib on several relevant action items to be developed over the and pazopanib, the trial with cabozantinib was designed coming 5 years. They are summarized below: to allow for dose adjustment based on patient’s tolerability (Jimenez 2018). Cabozantinib inhibits the c-met pathway •• The group recognizes the need for a large, publicly implicated in the development of metastases and tumor accessible database of pheochromocytoma/ resistance and is arguably the most potent antiangiogenic paraganglioma as a critical resource to better drug currently available in clinical practice (Salgia et al. understand the natural history of the disease, to help 2019). Therefore, cabozantinib may become the most refine and improve risk assessment models. effective tyrosine kinase inhibitor to treat patients with •• A means to achieve this level of information will mPPGLs. Evaluation of current trials is ongoing. likely be operationalized by the creation of multi- The recognition of the hallmarks involved in institutional, international networks with well-defined the origin of mPPGLs is leading to the discovery of data entry. This will facilitate the exchange of uniform medications that benefit these patients. In addition to data points. radiopharmaceuticals and tyrosine kinase inhibitors, •• Existing infrastructure such as the European ENS@T immunotherapy is currently evaluated in clinical trials (http://www.ensat.org/) for the study of adrenal tumors (Jimenez 2018). None of these therapies is expected to be is a successful model that can be leveraged for new curative. However, the results of these clinical trials are networks. The A5 Alliance (www.a5adrenalalliance. helping to identify pathogenic complementary pathways. com) has been created in 2015 utilizing a model similar The success rate of systemic therapy for patients with to the ENS@T and can spearhead network studies mPPGLs is expected to increase in the years to come, as outside of Europe. clinical trials will likely explore combinations of therapies. •• An important point of discussion was the widely perceived need for developing guidelines specific for management of metastatic pheochromocytomas and paragangliomas. Expanding opportunities for diagnosis, •• Additional proposals involved more specific studies surveillance, and therapy of mPPGLs: for long-term surveillance to investigate the role of a global perspective and SDHB in patient outcome. Such studies would require international collaborations that genetic testing be performed routinely, a practice There has been enormous progress in our understanding which has not yet been adopted outside of the United of the genetic basis and biological stratification of PPGLs. States, parts of Europe, and Australia; the widespread Nevertheless, several important gaps remain in this standardization of SDHB immunohistochemistry disease. The symposium participants and, in particular, the as a first-level screen for patients carrying an SDHB well-attended workshop sessions (see list of participants mutation was discussed as a potential short-term in Supplementary Table 1, see section on supplementary measure to circumvent genetic testing limitations. materials given at the end of this article), identified the •• The need for development of multi-institutional most critical limitations currently perceived in the field infrastructure for the design and implementation of mPPGLs and attempted to define research areas that of pragmatic trials was recognized; for example, the should be undertaken to help narrow these gaps (Table 3). efficacy and potential genotype impact on clinical

response of existing cytotoxic systemic therapies (UL1 TR002645). R C-B is funded by grants from the National Health and (e.g CVD, temozolomide) has not yet been evaluated Medical Research Council of Australia (1108032), the Hillcrest Foundation, the Paradifference Foundation, and the Pheo-Para Alliance. M.R. receives prospectively in large cohorts. funding support from the Instituto de Salud Carlos III (ISCIII), Acción •• It has been acknowledged that the design of clinical Estratégica en Salud, confounded by FEDER (grant number PI17/01796), trials of mPPGLs should take into account the unique and the Paradifference Foundation. C J receives research funding support by the Team NAT Foundation, Progenics Pharmaceuticals, Exelixis U.S., challenges posed by rare diseases/cancers and should LLC, and Advanced Accelerator Applications, a Novartis Company. involve innovative design and operational approaches, which allow for the participation of multiple sites across countries. Acknowledgments •• In times of limited funding, research on rare diseases The authors thank all workshop participants for their contribution, exciting is particularly vulnerable. Future multi-institutional discussions, and valuable suggestions. The list of participants of the research should develop innovative funding models mPPGL workshop is presented in Supplementary Table 1. The authors also acknowledge the invitation and support provided by the Multiple to carry out studies that can have wide impact in the Endocrine Neoplasia Symposium International Organizing Committee to field. develop this program.

Due to space constraints, the authors acknowledge that there are other areas relevant to mPPGLs that have not been included in this article. For example, studies to References validate novel high-risk mutations, including MAML3 fusions, CSDE1 mutations, and SLC25A1 variants; to Amar L, Baudin E, Burnichon N, Peyrard S, Silvera S, Bertherat J, Bertagna X, Schlumberger M, Jeunemaitre X, Gimenez-Roqueplo AP, investigate the role of co-existing genetic events, for et al. 2007 Succinate dehydrogenase B gene mutations predict example, germline SDHB associated with somatic ATRX survival in patients with malignant pheochromocytomas or or TERT variants, or to characterize the contribution of paragangliomas. Journal of Clinical Endocrinology and Metabolism 92 3822–3828. (https://doi.org/10.1210/jc.2007-0709) co-existing genetic and epigenetic alterations. These areas Amin MB, Greene FL, Edge SB, Compton CC, Gershenwald JE, represent emerging fields revealed by multiple ‘omics’ Brookland RK, Meyer L, Gress DM, Byrd DR & Winchester DP 2017 studies, and their exploration may hold promise for future The Eighth Edition AJCC Cancer Staging Manual: continuing to build a bridge from a population-based to a more ‘personalized’ risk assessment and development of novel therapeutic approach to cancer staging. CA: A Cancer Journal for Clinicians 67 opportunities. 93–99. (https://doi.org/10.3322/caac.21388) Asai S, Katabami T, Tsuiki M, Tanaka Y & Naruse M 2017 Controlling tumor progression with cyclophosphamide, vincristine, and dacarbazine treatment improves survival in patients with metastatic and unresectable malignant pheochromocytomas/paragangliomas. Supplementary materials 8 108–118. (https://doi.org/10.1007/s12672- This is linked to the online version of the paper at https://doi.org/10.1530/ Hormones and Cancer 017-0284-7) ERC-19-0435. Astuti D, Latif F, Dallol A, Dahia PL, Douglas F, George E, Skoldberg F, Husebye ES, Eng C & Maher ER 2001 Gene mutations in the succinate dehydrogenase subunit SDHB cause susceptibility to familial pheochromocytoma and to familial paraganglioma. American Declaration of interest Journal of Human Genetics 69 49–54. (https://doi.org/10.1086/321282) The authors declare that there is no conflict of interest that could be Ayala-Ramirez M, Feng L, Johnson MM, Ejaz S, Habra MA, Rich T, perceived as prejudicing the impartiality of this review. Busaidy N, Cote GJ, Perrier N, Phan A, et al. 2011 Clinical risk factors for malignancy and overall survival in patients with pheochromocytomas and sympathetic paragangliomas: primary tumor size and primary tumor location as prognostic indicators. Funding Journal of Clinical Endocrinology and Metabolism 96 717–725. (https:// A P G-R is funded by grants from the European Commission FP7 Research doi.org/10.1210/jc.2010-1946) and Innovation Funding Program for 2007–2013 (n° 259735), Horizon 2020 Ayala-Ramirez M, Chougnet CN, Habra MA, Palmer JL, Leboulleux S, (n° 633983); Institut National du Cancer and Direction Générale de l’Offre de Cabanillas ME, Caramella C, Anderson P, Al Ghuzlan A, Soins (DGOS), Programme de Recherche Translationnelle en cancérologie Waguespack SG, et al. 2012 Treatment with sunitinib for patients (PRT-K 2014, COMETE-TACTIC, INCa_DGOS_8663); Agence Nationale de la with progressive metastatic pheochromocytomas and sympathetic Recherche (ANR-2011-JCJC-00701 MODEOMAPP); Alliance nationale pour paragangliomas. Journal of Clinical Endocrinology and Metabolism 97 les sciences de la vie et de la santé (AVIESAN); and Plan Cancer: Appel à 4040–4050. (https://doi.org/10.1210/jc.2012-2356) projets Epigénétique et Cancer 2013 (EPIG201303 METABEPIC). Our team Ayala-Ramirez M, Palmer JL, Hofmann MC, De La Cruz M, Moon BS, is supported by the Ligue Nationale contre le Cancer (Equipe Labellisée). Waguespack SG, Habra MA & Jimenez C 2013 Bone metastases and P L M D receives funding support from NIH (GM114102), Alex’s Lemonade skeletal-related events in patients with malignant Stand Foundation for Childhood Cancer (co-funded by Flashes of Hope pheochromocytoma and sympathetic paraganglioma. Journal of and Northwest Mutual) Innovation Award, Mays Cancer Center (CCSG-NCI Clinical Endocrinology and Metabolism 98 1492–1497. (https://doi. P30 CA054174), and National Center for Advancing Translational Sciences org/10.1210/jc.2012-4231)

Baudin E, Habra MA, Deschamps F, Cote G, Dumont F, Cabanillas M, Crona J, Lamarca A, Ghosal S, Welin S, Skogseid B & Pacak K 2019 Arfi-Roufe J, Berdelou A, Moon B, Al Ghuzlan A, et al. 2014 Therapy Genotype-phenotype correlations in pheochromocytoma and of endocrine disease: treatment of malignant pheochromocytoma paraganglioma: a systematic review and individual patient meta- and paraganglioma. European Journal of Endocrinology 171 analysis. Endocrine-Related Cancer 26 539–550. (https://doi. R111–R122. (https://doi.org/10.1530/EJE-14-0113) org/10.1530/ERC-19-0024) Buffet A, Morin A, Castro-Vega LJ, Habarou F, Lussey-Lepoutre C, Dahia PL 2014 Pheochromocytoma and paraganglioma pathogenesis: Letouze E, Lefebvre H, Guilhem I, Haissaguerre M, Raingeard I, et al. learning from genetic heterogeneity. Nature Reviews: Cancer 14 2018 Germline mutations in the mitochondrial 2-oxoglutarate/ 108–119. (https://doi.org/10.1038/nrc3648) malate carrier SLC25A11 gene confer a predisposition to metastatic Dahia PL 2017 Pheochromocytomas and paragangliomas, genetically paragangliomas. Cancer Research 78 1914–1922. (https://doi. diverse and minimalist, all at once! Cancer Cell 31 159–161. (https:// org/10.1158/0008-5472.CAN-17-2463) doi.org/10.1016/j.ccell.2017.01.009) Buffet A, Ben Aim L, Leboulleux S, Drui D, Vezzosi D, Libe R, Dahia PL, Ross KN, Wright ME, Hayashida CY, Santagata S, Barontini M, Ajzenberg C, Bernardeschi D, Cariou B, Chabolle F, et al. 2019 Kung AL, Sanso G, Powers JF, Tischler AS, et al. 2005 A HIF1alpha Positive impact of genetic test on the management and outcome of regulatory loop links hypoxia and mitochondrial signals in patients with paraganglioma and/or pheochromocytoma. Journal of pheochromocytomas. PLoS Genetics 1 72–80. (https://doi. Clinical Endocrinology and Metabolism 104 1109–1118. (https://doi. org/10.1371/journal.pgen.0010008) org/10.1210/jc.2018-02411) De Cubas AA, Korpershoek E, Inglada-Perez L, Letouze E, Curras- Busch JI, Unger TL, Jain N, Tyler Skrinak R, Charan RA & Chen- Freixes M, Fernandez AF, Comino-Mendez I, Schiavi F, Mancikova V, Plotkin AS 2016 Increased expression of the frontotemporal Eisenhofer G, et al. 2015 DNA methylation profiling in dementia risk factor TMEM106B causes C9orf72-dependent pheochromocytoma and paraganglioma reveals diagnostic and alterations in lysosomes. Human Molecular Genetics 25 2681–2697. prognostic markers. Clinical Cancer Research 21 3020–3030. (https:// (https://doi.org/10.1093/hmg/ddw127) doi.org/10.1158/1078-0432.CCR-14-2804) Cancer Genome Atlas Research Network 2013 Comprehensive molecular Dwight T, Flynn A, Amarasinghe K, Benn DE, Lupat R, Li J, characterization of clear cell renal cell carcinoma. Nature 499 43–49. Cameron DL, Hogg A, Balachander S, Candiloro ILM, et al. 2018 (https://doi.org/10.1038/nature12222) TERT structural rearrangements in metastatic pheochromocytomas. Cascon A, Comino-Mendez I, Curras-Freixes M, De Cubas AA, Endocrine-Related Cancer 25 1–9. (https://doi.org/10.1530/ERC-17- Contreras L, Richter S, Peitzsch M, Mancikova V, Inglada-Perez L, 0306) Perez-Barrios A, et al. 2015 Whole-exome sequencing identifies Eisenhofer G, Huynh TT, Pacak K, Brouwers FM, Walther MM, MDH2 as a new familial paraganglioma gene. Journal of the National Linehan WM, Munson PJ, Mannelli M, Goldstein DS & Cancer Institute 107 djv053. (https://doi.org/10.1093/jnci/djv053) Elkahloun AG 2004 Distinct gene expression profiles in Cascon A, Remacha L, Calsina B & Robledo M 2019 norepinephrine- and epinephrine-producing hereditary and sporadic Pheochromocytomas and paragangliomas: bypassing cellular pheochromocytomas: activation of hypoxia-driven angiogenic respiration. Cancers 11 E683. (https://doi.org/10.3390/ pathways in von Hippel-Lindau syndrome. Endocrine-Related Cancer cancers11050683) 11 897–911 897–911. (https://doi.org/10.1677/erc.1.00838) Castro-Vega LJ, Buffet A, De Cubas AA, Cascon A, Menara M, Khalifa E, Eisenhofer G, Lenders JW, Siegert G, Bornstein SR, Friberg P, Amar L, Azriel S, Bourdeau I, Chabre O, et al. 2014 Germline Milosevic D, Mannelli M, Linehan WM, Adams K, Timmers HJ, et al. mutations in FH confer predisposition to malignant 2012 Plasma methoxytyramine: a novel biomarker of metastatic pheochromocytomas and paragangliomas. Human Molecular Genetics pheochromocytoma and paraganglioma in relation to established 23 2440–2446. (https://doi.org/10.1093/hmg/ddt639) risk factors of tumour size, location and SDHB mutation status. Castro-Vega LJ, Letouze E, Burnichon N, Buffet A, Disderot PH, European Journal of Cancer 48 1739–1749. (https://doi.org/10.1016/j. Khalifa E, Loriot C, Elarouci N, Morin A, Menara M, et al. 2015 ejca.2011.07.016) Multi-omics analysis defines core genomic alterations in Favier J, Amar L & Gimenez-Roqueplo AP 2015 Paraganglioma and pheochromocytomas and paragangliomas. Nature Communications 6 phaeochromocytoma: from genetics to personalized medicine. Nature 6044. (https://doi.org/10.1038/ncomms7044) Reviews: Endocrinology 11 101–111. (https://doi.org/10.1038/ Cho H, Du X, Rizzi JP, Liberzon E, Chakraborty AA, Gao W, Carvo I, nrendo.2014.188) Signoretti S, Bruick RK, Josey JA, et al. 2016 On-target efficacy of a Fishbein L, Khare S, Wubbenhorst B, Desloover D, D'andrea K, Merrill S, HIF-2alpha antagonist in preclinical kidney cancer models. Nature Cho NW, Greenberg RA, Else T, Montone K, et al. 2015 Whole- 539 107–111. (https://doi.org/10.1038/nature19795) exome sequencing identifies somatic ATRX mutations in Cho YY, Kwak MK, Lee SE, Ahn SH, Kim H, Suh S, Kim BJ, Song KH, pheochromocytomas and paragangliomas. Nature Communications 6 Koh JM, Kim JH, et al. 2018 A clinical prediction model to estimate 6140. (https://doi.org/10.1038/ncomms7140) the metastatic potential of pheochromocytoma/paraganglioma: ASES Fishbein L, Ben-Maimon S, Keefe S, Cengel K, Pryma DA, Loaiza- score. Surgery 164 511–517. (https://doi.org/10.1016/j. Bonilla A, Fraker DL, Nathanson KL & Cohen DL 2017a SDHB surg.2018.05.001) mutation carriers with malignant pheochromocytoma respond better Comino-Mendez I, De Cubas AA, Bernal C, Alvarez-Escola C, Sanchez- to CVD. Endocrine-Related Cancer 24 L51–L55. (https://doi. Malo C, Ramirez-Tortosa CL, Pedrinaci S, Rapizzi E, Ercolino T, org/10.1530/ERC-17-0086) Bernini G, et al. 2013 Tumoral EPAS1 (HIF2A) mutations explain Fishbein L, Leshchiner I, Walter V, Danilova L, Robertson AG, sporadic pheochromocytoma and paraganglioma in the absence of Johnson AR, Lichtenberg TM, Murray BA, Ghayee HK, Else T, et al. erythrocytosis. Human Molecular Genetics 22 2169–2176. (https://doi. 2017b Comprehensive molecular characterization of org/10.1093/hmg/ddt069) pheochromocytoma and paraganglioma. Cancer Cell 31 181–193. Courtney KD, Infante JR, Lam ET, Figlin RA, Rini BI, Brugarolas J, (https://doi.org/10.1016/j.ccell.2017.01.001) Zojwalla NJ, Lowe AM, Wang K, Wallace EM, et al. 2018 Phase I Frezza C, Pollard PJ & Gottlieb E 2011 Inborn and acquired metabolic dose-escalation trial of PT2385, a first-in-class hypoxia-inducible defects in cancer. Journal of Molecular Medicine 89 213–220. (https:// factor-2alpha antagonist in patients with previously treated doi.org/10.1007/s00109-011-0728-4) advanced clear cell renal cell carcinoma. Journal of Clinical Oncology Gimenez-Roqueplo AP, Favier J, Rustin P, Rieubland C, Crespin M, 36 867–874. (https://doi.org/10.1200/JCO.2017.74.2627) Nau V, Van Kien PK, Corvol P, Plouin PF, Jeunemaitre X, et al. 2003

Mutations in the SDHB gene are associated with extra-adrenal and/ Job S, Draskovic I, Burnichon N, Buffet A, Cros J, Lépine C, Venisse A, or malignant phaeochromocytomas. Cancer Research 63 5615–5621. Robidel E, Verkarre V, Meatchi T, et al. 2019 Telomerase activation Hadoux J, Favier J, Scoazec JY, Leboulleux S, Al Ghuzlan A, Caramella C, and ATRX mutations are independent risk factors for metastatic Deandreis D, Borget I, Loriot C, Chougnet C, et al. 2014 SDHB pheochromocytoma and paraganglioma. Clinical Cancer Research 25 mutations are associated with response to temozolomide in patients 760–770. (https://doi.org/10.1158/1078-0432.CCR-18-0139) with metastatic pheochromocytoma or paraganglioma. International Kaelin Jr WG 2018 HIF2 inhibitor joins the kidney cancer Journal of Cancer 135 2711–2720. (https://doi.org/10.1002/ijc.28913) armamentarium. Journal of Clinical Oncology 36 908–910. (https:// Hamidi O, Young Jr WF, Iniguez-Ariza NM, Kittah NE, Gruber L, doi.org/10.1200/JCO.2017.77.5254) Bancos C, Tamhane S & Bancos I 2017 Malignant Kaelin Jr WG & Ratcliffe PJ 2008 Oxygen sensing by metazoans: the pheochromocytoma and paraganglioma: 272 patients over 55 years. central role of the HIF hydroxylase pathway. Molecular Cell 30 Journal of Clinical Endocrinology and Metabolism 102 3296–3305. 393–402. (https://doi.org/10.1016/j.molcel.2008.04.009) (https://doi.org/10.1210/jc.2017-00992) Lam AK 2017 Update on adrenal tumours in 2017 World Health Hescot S, Curras-Freixes M, Deutschbein T, Van Berkel A, Vezzosi D, Organization (WHO) of endocrine tumours. Endocrine Pathology 28 Amar L, De La Fouchardiere C, Valdes N, Riccardi F, Do Cao C, et al. 213–227. (https://doi.org/10.1007/s12022-017-9484-5) 2019 Prognosis of malignant pheochromocytoma and paraganglioma Letouze E, Martinelli C, Loriot C, Burnichon N, Abermil N, (MAPP-Prono study): a European Network for the Study of Adrenal Ottolenghi C, Janin M, Menara M, Nguyen AT, Benit P, et al. 2013 Tumors retrospective study. Journal of Clinical Endocrinology and SDH mutations establish a hypermethylator phenotype in Metabolism 104 2367–2374. (https://doi.org/10.1210/jc.2018-01968) paraganglioma. Cancer Cell 23 739–752. (https://doi.org/10.1016/j. Ilias I, Chen CC, Carrasquillo JA, Whatley M, Ling A, Lazurova I, ccr.2013.04.018) Adams KT, Perera S & Pacak K 2008 Comparison of Liu T, Brown TC, Juhlin CC, Andreasson A, Wang N, Backdahl M, 6–18F-fluorodopamine PET with 123I-metaiodobenzylguanidine and Healy JM, Prasad ML, Korah R, Carling T, et al. 2014 The activating 111in-pentetreotide scintigraphy in localization of nonmetastatic tert promoter mutation C228T is recurrent in subsets of adrenal and metastatic pheochromocytoma. Journal of Nuclear Medicine 49 tumors. Endocrine-Related Cancer 21 427–434. (https://doi. 1613–1619. (https://doi.org/10.2967/jnumed.108.052373) org/10.1530/ERC-14-0016) Janssen I, Blanchet EM, Adams K, Chen CC, Millo CM, Herscovitch P, Lopez-Jimenez E, Gomez-Lopez G, Leandro-Garcia LJ, Munoz I, Taieb D, Kebebew E, Lehnert H, Fojo AT, et al. 2015 Superiority of Schiavi F, Montero-Conde C, De Cubas AA, Ramires R, Landa I, [68Ga]-DOTATATE PET/CT to other functional imaging modalities in Leskela S, et al. 2010 Research resource: transcriptional profiling the localization of SDHB-associated metastatic pheochromocytoma reveals different pseudohypoxic signatures in SDHB and VHL-related and paraganglioma. Clinical Cancer Research 21 3888–3895. (https:// pheochromocytomas. Molecular Endocrinology 24 2382–2391. (https:// doi.org/10.1158/1078-0432.CCR-14-2751) doi.org/10.1210/me.2010-0256) Janssen I, Chen CC, Millo CM, Ling A, Taieb D, Lin FI, Adams KT, McCrary HC, Babajanian E, Calquin M, Carpenter P, Casazza G, Wolf KI, Herscovitch P, Fojo AT, et al. 2016a PET/CT comparing (68) Naumer A, Greenberg S, Kohlmann W, Cannon R, Monroe MM, Ga-DOTATATE and other radiopharmaceuticals and in comparison et al. 2019 Characterization of malignant head and neck with CT/MRI for the localization of sporadic metastatic paragangliomas at a single institution across multiple decades. JAMA pheochromocytoma and paraganglioma. European Journal of Nuclear Otolaryngology: Head and Neck Surgery 145 641–646. (https://doi. Medicine and Molecular Imaging 43 1784–1791. (https://doi. org/10.1001/jamaoto.2019.1110) org/10.1007/s00259-016-3357-x) NGS in PPGL (NGSnPPGL) Study Group, Toledo RA, Burnichon N, Janssen I, Chen CC, Taieb D, Patronas NJ, Millo CM, Adams KT, Cascon A, Benn DE, Bayley JP, Welander J, Tops CM, Firth H, Nambuba J, Herscovitch P, Sadowski SM, Fojo AT, et al. 2016b Dwight T, et al. 2017 Consensus statement on next-generation- 68Ga-DOTATATE PET/CT in the localization of head and neck sequencing-based diagnostic testing of hereditary paragangliomas compared with other functional imaging modalities phaeochromocytomas and paragangliomas. Nature Reviews and CT/MRI. Journal of Nuclear Medicine 57 186–191. (https://doi. Endocrinology 13 233–247. (https://doi.org/10.1038/nrendo.2016.185) org/10.2967/jnumed.115.161018) Niemeijer ND, Alblas G, Van Hulsteijn LT, Dekkers OM & Corssmit EP Janssen I, Chen CC, Zhuang Z, Millo CM, Wolf KI, Ling A, Lin FI, 2014 Chemotherapy with cyclophosphamide, vincristine and Adams KT, Herscovitch P, Feelders RA, et al. 2017 Functional imaging dacarbazine for malignant paraganglioma and pheochromocytoma: signature of patients presenting with polycythemia/paraganglioma systematic review and meta-analysis. Clinical Endocrinology 81 syndromes. Journal of Nuclear Medicine 58 1236–1242. (https://doi. 642–651. (https://doi.org/10.1111/cen.12542) org/10.2967/jnumed.116.187690) O’Kane GM, Ezzat S, Joshua AM, Bourdeau I, Leibowitz-Amit R, Jasim S, Suman VJ, Jimenez C, Harris P, Sideras K, Burton JK, Worden FP, Olney HJ, Krzyzanowska M, Reuther D, Chin S, Wang L, et al. 2019 Auchus RJ & Bible KC 2017 Phase II trial of pazopanib in advanced/ A phase 2 trial of sunitinib in patients with progressive progressive malignant pheochromocytoma and paraganglioma. paraganglioma or pheochromocytoma: the SNIPP trial. British Journal Endocrine 57 220–225. (https://doi.org/10.1007/s12020-017-1359-5) of Cancer 120 1113–1119. (https://doi.org/10.1038/s41416-019- Jimenez C 2018 Treatment for patients with malignant 0474-x) pheochromocytomas and paragangliomas: a perspective from the Pang Y, Lu Y, Caisova V, Liu Y, Bullova P, Huynh TT, Zhou Y, Yu D, hallmarks of cancer. Frontiers in Endocrinology 9 277. (https://doi. Frysak Z, Hartmann I, et al. 2018 Targeting NAD(+)/PARP DNA repair org/10.3389/fendo.2018.00277) pathway as a novel therapeutic approach to SDHB-mutated cluster I Jimenez C, Rohren E, Habra MA, Rich T, Jimenez P, Ayala-Ramirez M & pheochromocytoma and paraganglioma. Clinical Cancer Research 24 Baudin E 2013 Current and future treatments for malignant 3423–3432. (https://doi.org/10.1158/1078-0432.CCR-17-3406) pheochromocytoma and sympathetic paraganglioma. Current Papadopoulos KP, Jonasch E, Zojwalla NJ, Wang K & Bauer TM 2018 A Oncology Reports 15 356–371. (https://doi.org/10.1007/s11912-013- first-in-human phase 1 dose-escalation trial of the oral HIF-2a 0320-x) inhibitor PT2977 in patients with advanced solid tumors. Journal of Jimenez C, Erwin W & Chasen B 2019 Targeted radionuclide therapy for Clinical Oncology 36 2508–2508. (https://doi.org/10.1200/ patients with metastatic pheochromocytoma and paraganglioma: JCO.2018.36.15_suppl.2508) from low-specific-activity to high-specific-activity iodine-131 Papathomas TG, Oudijk L, Persu A, Gill AJ, Van Nederveen F, metaiodobenzylguanidine. Cancers 11 E1018. (https://doi. Tischler AS, Tissier F, Volante M, Matias-Guiu X, Smid M, et al. 2015 org/10.3390/cancers11071018) SDHB/SDHA immunohistochemistry in pheochromocytomas and

paragangliomas: a multicenter interobserver variation analysis using PAS-B domain of the HIF2 transcription factor. PNAS 106 450–455. virtual microscopy: a Multinational Study of the European Network (https://doi.org/10.1073/pnas.0808092106) for the Study of Adrenal Tumors (ENS@T). Modern Pathology 28 Scheuermann TH, Li Q, Ma HW, Key J, Zhang L, Chen R, Garcia JA, 807–821. (https://doi.org/10.1038/modpathol.2015.41) Naidoo J, Longgood J, Frantz DE, et al. 2013 Allosteric inhibition of Pryma DA, Chin BB, Noto RB, Dillon JS, Perkins S, Solnes L, hypoxia inducible factor-2 with small molecules. Nature Chemical Kostakoglu L, Serafini AN, Pampaloni MH, Jensen J, et al. 2019 Biology 9 271–276. (https://doi.org/10.1038/nchembio.1185) Efficacy and safety of high-specific-activity (131)I-MIBG therapy in Taieb D, Jha A, Guerin C, Pang Y, Adams KT, Chen CC, Romanet P, patients with advanced pheochromocytoma or paraganglioma. Roche P, Essamet W, Ling A, et al. 2018 18F-FDOPA PET/CT imaging Journal of Nuclear Medicine 60 623–630. (https://doi.org/10.2967/ of MAX-related pheochromocytoma. Journal of Clinical Endocrinology jnumed.118.217463) and Metabolism 103 1574–1582. (https://doi.org/10.1210/jc.2017- Rahman N 2014 Realizing the promise of cancer predisposition genes. 02324) Nature 505 302–308. (https://doi.org/10.1038/nature12981) Taieb D, Jha A, Treglia G & Pacak K 2019 Molecular imaging and Remacha L, Comino-Mendez I, Richter S, Contreras L, Curras-Freixes M, radionuclide therapy of paraganglioma and pheochromocytoma. Pita G, Leton R, Galarreta A, Torres-Perez R, Honrado E, et al. 2017 Endocrine-Related Cancer 26 R627–R652. (https://doi.org/10.1530/ Targeted exome sequencing of Krebs cycle genes reveals candidate ERC-19-0165) cancer-predisposing mutations in pheochromocytomas and Tateishi K, Wakimoto H, Iafrate AJ, Tanaka S, Loebel F, Lelic N, paragangliomas. Clinical Cancer Research 23 6315–6324. (https://doi. Wiederschain D, Bedel O, Deng G, Zhang B, et al. 2015 Extreme org/10.1158/1078-0432.CCR-16-2250) vulnerability of IDH1 mutant cancers to NAD+ depletion. Cancer Cell Remacha L, Curras-Freixes M, Torres-Ruiz R, Schiavi F, Torres-Perez R, 28 773–784. (https://doi.org/10.1016/j.ccell.2015.11.006) Calsina B, Leton R, Comino-Mendez I, Roldan-Romero JM, Montero- Tian H, Hammer RE, Matsumoto AM, Russell DW & Mcknight SL 1998 Conde C, et al. 2018 Gain-of-function mutations in DNMT3A in The hypoxia-responsive transcription factor EPAS1 is essential for patients with paraganglioma. Genetics in Medicine 20 1644–1651. catecholamine homeostasis and protection against heart failure (https://doi.org/10.1038/s41436-018-0003-y) during embryonic development. Genes and Development 12 Remacha L, Pirman D, Mahoney CE, Coloma J, Calsina B, Curras- 3320–3324. (https://doi.org/10.1101/gad.12.21.3320) Freixes M, Leton R, Torres-Perez R, Richter S, Pita G, et al. 2019 Toledo RA 2017 New HIF2alpha inhibitors: potential implications as Recurrent germline DLST mutations in individuals with multiple therapeutics for advanced pheochromocytomas and paragangliomas. pheochromocytomas and paragangliomas. American Journal of Human Endocrine-Related Cancer 24 C9–C19. (https://doi.org/10.1530/ERC- Genetics 104 1008–1010. (https://doi.org/10.1016/j.ajhg.2019.04.010) 16-0479) Richter S, Peitzsch M, Rapizzi E, Lenders JW, Qin N, De Cubas AA, Toledo RA, Qin Y, Srikantan S, Morales NP, Li Q, Deng Y, Kim SW, Schiavi F, Rao JU, Beuschlein F, Quinkler M, et al. 2014 Krebs cycle Pereira MA, Toledo SP, Su X, et al. 2013 In vivo and in vitro metabolite profiling for identification and stratification of oncogenic effects of HIF2A mutations in pheochromocytomas and pheochromocytomas/paragangliomas due to succinate paragangliomas. Endocrine-Related Cancer 20 349–359. (https://doi. dehydrogenase deficiency. Journal of Clinical Endocrinology and org/10.1530/ERC-13-0101) Metabolism 99 3903–3911. (https://doi.org/10.1210/jc.2014-2151) Turkova H, Prodanov T, Maly M, Martucci V, Adams K, Widimsky Jr J, Roman-Gonzalez A & Jimenez C 2017 Malignant pheochromocytoma- Chen CC, Ling A, Kebebew E, Stratakis CA, et al. 2016 Characteristics paraganglioma: pathogenesis, TNM staging, and current clinical and outcomes of metastatic Sdhb and sporadic pheochromocytoma/ trials. Current Opinion in Endocrinology, Diabetes, and Obesity 24 paraganglioma: an National Institutes of Health study. Endocrine 174–183. (https://doi.org/10.1097/MED.0000000000000330) Practice 22 302–314. (https://doi.org/10.4158/EP15725.OR) Roman-Gonzalez A, Zhou S, Ayala-Ramirez M, Shen C, Waguespack SG, Vallabhajosula S & Nikolopoulou A 2011 Radioiodinated Habra MA, Karam JA, Perrier N, Wood CG & Jimenez C 2018 Impact metaiodobenzylguanidine (MIBG): radiochemistry, biology, and of surgical resection of the primary tumor on overall survival in pharmacology. Seminars in Nuclear Medicine 41 324–333. (https://doi. patients with metastatic pheochromocytoma or sympathetic org/10.1053/j.semnuclmed.2011.05.003) paraganglioma. Annals of Surgery 268 172–178. (https://doi. Xu W, Yang H, Liu Y, Yang Y, Wang P, Kim SH, Ito S, Yang C, Wang P, org/10.1097/SLA.0000000000002195) Xiao MT, et al. 2011 Oncometabolite 2-hydroxyglutarate is a Salgia NJ, Dara Y, Bergerot P, Salgia M & Pal SK 2019 The changing competitive inhibitor of alpha-ketoglutarate-dependent landscape of management of metastatic renal cell carcinoma: current dioxygenases. Cancer Cell 19 17–30. (https://doi.org/10.1016/j. treatment options and future directions. Current Treatment Options in ccr.2010.12.014) Oncology 20 41. (https://doi.org/10.1007/s11864-019-0638-1) Yan Q, Bartz S, Mao M, Li L & Kaelin Jr WG 2007 The hypoxia- Satapathy S, Mittal BR & Bhansali A 2019 Peptide receptor radionuclide inducible factor 2alpha N-terminal and C-terminal transactivation therapy in the management of advanced pheochromocytoma and domains cooperate to promote renal tumorigenesis in vivo. Molecular paraganglioma: a systematic review and meta-analysis. Clinical and Cellular Biology 27 2092–2102. (https://doi.org/10.1128/ Endocrinology 91 718–727. (https://doi.org/10.1111/cen.14106) MCB.01514-06) Scheuermann TH, Tomchick DR, Machius M, Guo Y, Bruick RK & Yang M & Pollard PJ 2013 Succinate: a new epigenetic hacker. Cancer Gardner KH 2009 Artificial ligand binding within the HIF2alpha Cell 23 709–711. (https://doi.org/10.1016/j.ccr.2013.05.015)

Received in final form 16 January 2020 Accepted 5 February 2020 Accepted Manuscript published online 18 February 2020