Total loss of VHL gene function impairs neuroendocrine cancer cell fitness due to excessive HIF2α activity.

Loss-of-function germline von Hippel-Lindau (VHL) tumor suppressor mutations cause VHL disease, which predisposes individuals to kidney cancer, hemangioblastomas, and paragangliomas. The risk that a given VHL disease family will manifest some or all these tumor types is profoundly influenced by the VHL allele it carries. For example, almost all VHL disease families that develop paraganglioma have missense VHL mutations. VHL families with null VHL alleles develop kidney cancer and hemangioblastomas without a high risk of paraganglioma. The latter is surprising because the VHL gene product, pVHL, suppresses the HIF2 transcription factor and gain-of-function HIF2 mutations are also linked to paraganglioma. Paragangliomas arise from the sympathetic or parasympathetic nervous system. Given the lack of human paraganglioma cell lines, we studied the effects of inactivating VHL in neuroblastoma cell lines, which also arise from the sympathetic nervous system. We found that total loss of pVHL function profoundly impairs the fitness of neuroblastoma cell lines in a HIF2-dependent manner both ex vivo and in vivo. This fitness defect can be rescued by pVHL variants linked to paraganglioma, but not by pVHL variants associated with a low risk of paraganglioma. These findings suggest that HIF2 activity above a critical threshold prevents the development of paraganglioma.

Role of epigenetic regulation on catecholamine synthesis in pheochromocytoma and paraganglioma.

INTRODUCTION: Pheochromocytomas and paragangliomas (PPGLs) typically secrete catecholamines and their metabolites (metanephrines [MN] and normetanephrine [NMN]). Catecholamines are synthesized by several enzymes: phenylalanine hydroxylase (encoded by PAH), tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (DDC), dopamine ß-hydroxylase (DBH), and phenylethanolamine N-methyltransferase (PNMT). MN/NMN secretion varies between anatomical and molecular subgroups. The aim of this study was to assess the correlation between DNA methylation of catecholamine synthesis genes and MN/NMN secretion. METHODS: Gene promoter methylation of PAH, TH, AADC, DBH, and PNMT were extracted and calculated based on publicly available data. Comparisons and correlation analysis were performed between MN ± NMN (MN/NMN), NMN only, and neither/unknown secretion patterns. Methylation levels and MN/NMN patterns were compared by three genetic alteration subgroups: pseudohypoxia (PH), kinase signaling (KS), and others. RESULTS: A total of 178 cases were included. Methylation of PAH CpGs negatively correlated with probability for MN/NMN secretion (p < .05 for all CpGs) and positively with NMN-only secretion. NMN-only secreting tumors had significantly higher promoter methylation of PAH, DBH, and PNMT compared with MN/NMN-secreting tumors. MN/NMN-secreting PPGLs had mainly KS alterations (52.1%), whereas NMN-only PPGLs had PH alterations (41.9%). PPGLs in the PH versus KS group had gene promoter hypermethylation of PAH (p = .002), DBH (p = .02), and PNMT (p = .003). CONCLUSIONS: Promoter methylation of genes encoding catecholamine synthesis enzymes is strongly and inversely correlated with MN/NMN patterns in PPGLs. KS and PH-related tumors have distinct methylation patterns. These results imply that methylation is a key regulatory mechanism of catecholamine synthesis in PPGLs.

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.

Belzutifan, a Potent HIF2α Inhibitor, in the Pacak-Zhuang Syndrome.

The integration of genomic testing into clinical care enables the use of individualized approaches to the management of rare diseases. We describe the use of belzutifan, a potent and selective small-molecule inhibitor of the protein hypoxia-inducible factor 2α (HIF2α), in a patient with polycythemia and multiple paragangliomas (the Pacak-Zhuang syndrome). The syndrome was caused in this patient by somatic mosaicism for an activating mutation in EPAS1. Treatment with belzutifan led to a rapid and sustained tumor response along with resolution of hypertension, headaches, and long-standing polycythemia. This case shows the application of a targeted therapy for the treatment of a patient with a rare tumor-predisposition syndrome. (Funded by the Morin Family Fund for Pediatric Cancer and Alex's Lemonade Stand Foundation.).

Preoperative prediction of metastatic pheochromocytoma and paraganglioma using clinical, genetic, and biochemical markers: A cohort study.

BACKGROUND: The prevalence of metastatic pheochromocytoma and paraganglioma (PPGL) is approximately 15%-20%. Although there are indicators to assess metastatic risks, none of them predict metastasis reliably. Therefore, we aimed to develop and validate a scoring system using clinical, genetic, and biochemical risk factors to preoperatively predict the metastatic risk of PPGL. METHODS: In the cross-sectional cohort (n = 180), clinical, genetic, and biochemical risk factors for metastasis were identified using multivariate logistic regression analysis, and a novel scoring system was developed. The scoring system was validated and compared with the age, size of tumor, extra-adrenal location, and secretory type (ASES) score in the longitudinal cohort (n = 114). RESULTS: In the cross-sectional cohort, pseudohypoxia group-related gene variants (SDHB, SDHD, or VHL), methoxytyramine >0.16 nmol/L, and tumor size >6.0 cm were independently associated with metastasis after multivariate logistic regression. Using them, the gene variant, methoxytyramine, and size of tumor (GMS) score were developed. In the longitudinal cohort, Harrell's concordance index of the GMS score (0.873, 95% confidence interval [CI]: 0.738-0.941) was higher than that of the ASES score (0.713, 95% CI: 0.567-0.814, p = 0.007). In the longitudinal cohort, a GMS score ≥2 was significantly associated with a higher risk of metastasis (hazard ratio = 25.07, 95% CI: 5.65-111.20). A GMS score ≥2 (p < 0.001), but not ASES score ≥2 (p = 0.090), was associated with shorter progression-free survival. CONCLUSION: The GMS scoring system, which integrates gene variant, methoxytyramine level, and tumor size, provides a valuable preoperative approach to assess metastatic risk in PPGL.

Clinical management and outcome of head and neck paragangliomas (HNPGLs): A single centre retrospective study.

CONTEXT: Head and neck paragangliomas (HNPGLs) are rare, usually benign, slow-growing tumours arising from neural crest-derived tissue. Definitive management pathways for HNPGLs have yet to be clearly defined. OBJECTIVE: To review our experience of the clinical features and management of these tumours and to analyse outcomes of different treatment modalities. METHODS: Demographic and clinical data were obtained from The Northern Ireland Electronic Care Record (NIECR) as well from a prospectively maintained HNPGL database between January 2011 through December 2023. RESULTS: There were 87 patients; 50 females: 37 males with a mean age of 52.3 ± 14.2 years old (range 17-91 years old). 58.6% (n = 51) of patients had carotid body tumours, 25.2% (n = 22) glomus vagal tumours, 6.8% (n = 6) tumours in the middle ear, 2.2% (n = 2) in the parapharyngeal space and 1.1% (n = 1) in the sphenoid sinus. 5.7% (n = 5) of patients had multifocal disease. The mean tumour size at presentation was 3.2 ± 1.4 cm (range 0.5-6.9 cm). Pathogenic SDHD mutations were identified in 41.3% (n = 36), SDHB in 12.6% (n = 11), SDHC in 2.2% (n = 2) and SDHA in 1.1% (n = 1) of the patients. Overall treatment modalities included surgery alone in 51.7% (n = 45) of patients, radiotherapy in 14.9% (n = 13), observation in 28.7% (n = 25), and somatostatin analogue therapy with octreotide in 4.5% (n = 4) of patients. Factors associated with a significantly higher risk of recurrence included age over 60 years (p = .04), tumour size exceeding 2 cm (p = .03), positive SDHx variants (p = .01), and vagal and jugular tumours (p = .04). CONCLUSION: The majority of our patients underwent initial surgical intervention and achieved disease stability. Our results suggest that carefully selected asymptomatic or medically unfit patients can be safely observed provided lifelong surveillance is maintained. We advocate for the establishment of a UK and Ireland national HNPGL registry, to delineate optimal management strategies for these rare tumours and improve long term outcomes.

[68Ga]DOTATOC PET-derived radiomics to predict genetic background of head and neck paragangliomas: a pilot investigation.

PURPOSE: To investigate the [68Ga]DOTATOC PET radiomic profile of head and neck paragangliomas (HNPGLs) and identify radiomic characteristics useful as predictors of succinate dehydrogenase genes (SDHx) pathogenic variants. METHODS: Sporadic and SDHx HNPGL patients, who underwent [68Ga]DOTATOC PET/CT, were retrospectively included. HNPGLs were analyzed using LIFEx software, and extracted features were harmonized to correct for batch effects and confronted testing for multiple comparison. Stepwise discriminant analysis was conducted to remove redundancy and identify best discriminating features. ROC analysis was used to define optimal cut-offs. Multivariate decision-tree analysis was performed using CHAID method. RESULTS: 34 patients harboring 60 HNPGLs (51 SDHx in 25 patients) were included. Three sporadic and nine SDHx HNPGLs were metastatic. At stepwise discriminant analysis, both GLSZM-Zone Size Non-Uniformity (ZSNU, reflecting tumor heterogeneity) and IB-TLSRE (total lesion somatostatin receptor expression) were independent predictors of genetic status, with 96.4% of lesions and 91.6% of patients correctly classified after cross validation (p < 0.001). Among non-metastatic patients, GLSZM-ZSNU and IB-TLSRE were significantly higher in sporadic than SDHx HNPGLs (p < 0.001). No differences were revealed in metastatic patients. Decision-tree analysis highlights multifocality and IB-TLSRE as useful variables, correctly identifying 6/9 sporadic and 24/25 SDHx patients. Model failed to classify one SDHA and three sporadic patients (2 metastatic). CONCLUSION: Radiomics features GLSZM-ZSNU and IB-TLSRE appear to reflect HNPGLs SDHx status and tumor behavior (metastatic vs. non-metastatic). If validated, especially IB-TLSRE might represent a simple and time-efficient radiomic index for SDHx variants early screening and prediction of tumor behavior in HNPGL cases.

Prediction model for pheochromocytoma/paraganglioma using nCounter assay.

BACKGROUND: World Health Organization defined pheochromocytomas/paragangliomas (PPGL) as malignant tumors in 2017 because the existing classification system could not reflect locally aggressive behavior sufficiently. However, predicting the likelihood of metastasis remains a crucial part of the treatment strategy. METHODS: From one tertiary care hospital and one secondary hospital, 97 PPGL cases were selected. Medical records of PPGL cases with the presence of formalin-fixed and paraffin-embedded (FFPE) tissue of primary lesion were reviewed. For FFPE tissues, a nCounter assay was conducted to determine differently expressed genes between metastatic and non-metastatic PPGL groups. Performances of prediction models for the likelihood of metastasis were calculated. RESULTS: Of a total of 97 PPGL cases, 39, 20, and 38 were classified as benign, malignant, and validation, respectively. In the nCounter assay, CDK1, TYMS, and TOP2A genes showed significant differences in expression. Tumor size was positively correlated with CDK1 expression level. The Lasso regression model showed supreme performance of sensitivity 91.7% and specificity 95.5% when those significant factors were considered. CONCLUSION: Machine learning of multi-modal classifiers can be used to create a prediction model for metastasis of PPGL with high sensitivity and specificity using nCounter assay. Moreover, CDK1 inhibitors could be considered for developing drug treatment.

Pseudohypoxia in paraganglioma and pheochromocytoma is associated with an immunosuppressive phenotype.

Metastatic pheochromocytoma and paraganglioma (PPGL) have poor prognosis and limited therapeutic options. The recent advent of immunotherapies showing remarkable clinical efficacies against various cancer types offers the possibility of novel opportunities also for metastatic PPGL. Most PPGLs are pathogenically linked to inactivating mutations in genes encoding different succinate dehydrogenase (SDH) subunits. This causes activation of the hypoxia-inducible factor 2 (HIF2)-mediated transcriptional program in the absence of decreased intratumoral oxygen levels, a phenomenon known as pseudohypoxia. Genuine hypoxia in a tumor creates an immunosuppressive tumor microenvironment. However, the impact of pseudohypoxia in the immune landscape of tumors remains largely unexplored. In this study, tumoral expression of programmed death-ligand 1 (PD-L1) and HIF2α and tumor infiltration of CD8 T lymphocytes (CTLs) were examined in PPGL specimens from 102 patients. We assessed associations between PD-L1, CTL infiltration, HIF2α expression, and the mutational status of SDH genes. Our results show that high PD-L1 expression levels in tumor cells and CTL tumor infiltration were more frequent in metastatic than nonmetastatic PPGL. However, this phenotype was negatively associated with SDH mutations and high HIF2α protein expression. These data were validated by analysis of mRNA levels of genes expressing PD-L1, CD8, and HIF2α in PPGL included in The Cancer Genome Atlas database. Further, PD-L1 and CD8 expression was lower in norepinephrine than epinephrine-secreting PPGL. This in silico analysis also revealed the low PD-L1 or CD8 expression levels in tumors with inactivating mutations in VHL or activating mutations in the HIF2α-coding gene, EPAS1, which, together with SDH-mutated tumors, comprise the pseudohypoxic molecular subtype of PPGL. These findings suggest that pseudohypoxic tumor cells induce extrinsic signaling toward the immune cells promoting the development of an immunosuppressive environment. It also provides compelling support to explore the differential response of metastatic PPGL to immune checkpoint inhibitors. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

UK recommendations for SDHA germline genetic testing and surveillance in clinical practice.

SDHA pathogenic germline variants (PGVs) are identified in up to 10% of patients with paraganglioma and phaeochromocytoma and up to 30% with wild-type gastrointestinal stromal tumours. Most SDHA PGV carriers present with an apparently sporadic tumour, but often the pathogenic variant has been inherited from parent who has the variant, but has not developed any clinical features. Studies of SDHA PGV carriers suggest that lifetime penetrance for SDHA-associated tumours is low, particularly when identified outside the context of a family history. Current recommended surveillance for SDHA PGV carriers follows an intensive protocol. With increasing implementation of tumour and germline large panel and whole-genome sequencing, it is likely more SDHA PGV carriers will be identified in patients with tumours not strongly associated with SDHA, or outside the context of a strong family history. This creates a complex situation about what to recommend in clinical practice considering low penetrance for tumour development, surveillance burden and patient anxiety. An expert SDHA working group was formed to discuss and consider this situation. This paper outlines the recommendations from this working group for testing and management of SDHA PGV carriers in clinical practice.

SDHB variant type impacts phenotype and malignancy in pheochromocytoma-paraganglioma.

BACKGROUND: Traditional genotype-phenotype correlations for the succinate dehydrogenase-complex II (SDH) genes link SDHB variants to thoracic-abdominal pheochromocytoma-paraganglioma (PPGL) and SDHD variants to head and neck paraganglioma (HNPGL). However, in a recent study we found strong and specific genotype-phenotype associations for SDHD variants. In the present study we zoom in on the genotype-phenotype associations of SDHB gene variants, considering the impact of individual gene variants on disease risk and risk of malignancy. METHODS: We analysed two large independent data sets, including a total of 448 patients with PPGL and HNPGL, and studied the association of missense or truncating SDHB variants with tumour incidence, age of onset and malignancy risk using binomial testing and Kaplan-Meier analysis. RESULTS: Compared with missense variants, truncating SDHB variants were significantly and consistently more common in patients with PPGL, by a 20 percentage point margin. Malignancy was also significantly more common in truncating versus missense variant carriers. No overall differences in age of PPGL onset were noted between carriers of the two variant types, although some individual variants may differ in certain cases. Missense variants were marginally over-represented among patients with HNPGL, but the difference was not statistically significant. CONCLUSION: SDHB truncating variants convey an elevated risk for development of both PPGL and malignancy compared with missense variants. These results further support earlier robust associations between truncating variants and PPGL, and also suggest that the two variant types differ in their impact on complex II function, with PPGL/HNPGL tissues displaying differing sensitivities to changes in complex II function.

Two sisters diagnosed with familial paraganglioma syndrome type 1 (FPGL1) and multiple endocrine neoplasia type 2A (MEN2A).

BACKGROUND: In clinical practice, genetic testing has become standard for many cancerous diseases. While a diagnosis of a single hereditary syndrome is not uncommon, the coexistence of two genetic diseases, even with partially common symptoms, remains unusual. Therefore, targeted next-generation sequencing (NGS), along with genetic consultation and imaging studies, is essential for every patient with confirmed paraganglioma. In this report, we present two sisters diagnosed with multiple endocrine neoplasia type 2 (MEN2A) and familial paraganglioma syndrome type 1 (FPGL1). CASE PRESENTATION: After presenting to the clinic with neck tumors persisting for several months, both patients underwent tumor removal procedures following imaging and laboratory studies. Pathological reports confirmed the diagnosis of paragangliomas. Subsequently, genetic testing, including NGS, revealed a mutation in the rearranged during transfection (RET) gene: the heterozygous change (c.2410G > A), (p.Val804Met), and a variant of the succinate dehydrogenase complex subunit D (SDHD) gene: (c.64 C > T), (p.Arg22Ter). Subsequently, thyroidectomy procedures were scheduled in both cases. CONCLUSION: To the best of our knowledge, this is the first report presenting these two mutations in two related patients, resulting in distinctive genetic syndromes with similar manifestations. This underscores that although infrequent, multiple hereditary disorders may co-occur in the same individual.

Intratumoral Microbiome in Head and Neck Paragangliomas.

Head and neck paragangliomas (HNPGLs) are rare neoplasms arising from paraganglia of the parasympathetic nervous system. HNPGLs are characterized by high vascularity and are located in proximity to major vessels and nerves, which may be potential sources of microbial invasion in these tumors. There have been no studies in the literature on the microbiota in HNPGLs. Investigation of the microbiome associated with paragangliomas is important for understanding tumor pathogenesis. In this study, we investigated the microbiome composition in two sets of HNPGLs. First, 29 fresh frozen (FF) tissues were subjected to 16S rRNA gene sequencing; concurrently, a panel of candidate laboratory-derived contaminants was investigated. Second, we analyzed microbial reads from whole transcriptome sequencing data obtained for 82 formalin-fixed paraffin-embedded (FFPE) HNPGLs. The bacterial diversity in FF tumors was found to be significantly lower than that observed in FFPE HNPGLs. Based on 16S rRNA gene sequencing, only seven bacterial families were identified as potential tumor inhabitants: Bryobacteraceae, Enterococcaceae, Neisseriaceae, Legionellaceae, Vibrionaceae, Obscuribacteraceae, and Mycobacteriaceae. However, RNA-Seq demonstrated higher sensitivity for identifying microbiome composition and revealed abundant bacterial families that partially correlated with those previously described in pheochromocytomas and extra-adrenal paragangliomas. No viruses were found in HNPGLs. In summary, our findings indicated the presence of a microbiome in HNPGLs, comprising a number of bacterial families that overlap with those observed in pheochromocytomas/paragangliomas and glioblastomas.

Characterisation of an Adult Zebrafish Model for SDHB-Associated Phaeochromocytomas and Paragangliomas.

Phaeochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours arising from chromaffin cells. Pathogenic variants in the gene succinate dehydrogenase subunit B (SDHB) are associated with malignancy and poor prognosis. When metastases arise, limited treatment options are available. The pathomechanism of SDHB-associated PPGL remains largely unknown, and the lack of suitable models hinders therapy development. Germline heterozygous SDHB pathogenic variants predispose to developing PPGLs with a life-long penetrance of around 50%. To mimic the human disease phenotype, we characterised adult heterozygous sdhb mutant zebrafish as a potential model to study SDHB-related PPGLs. Adult sdhb mutant zebrafish did not develop an obvious tumour phenotype and were anatomically and histologically like their wild-type siblings. However, sdhb mutants showed significantly increased succinate levels, a major hallmark of SDHB-related PPGLs. While basal activity was increased during day periods in mutants, mitochondrial complex activity and catecholamine metabolite levels were not significantly different. In conclusion, we characterised an adult in vivo zebrafish model, genetically resembling human carriers. Adult heterozygous sdhb mutants mimicked their human counterparts, showing systemic elevation of succinate levels despite the absence of a tumour phenotype. This model forms a promising basis for developing a full tumour phenotype and gaining knowledge of the pathomechanism behind SDHB-related PPGLs.

Genetic and Molecular Biomarkers in Aggressive Pheochromocytomas and Paragangliomas.

Pheochromocytomas and paragangliomas (PPGLs) are rare neoplasms producing catecholamines that occur as hereditary syndromes in 25-40% of cases. To date, PPGLs are no longer classified as benign and malignant tumors since any lesion could theoretically metastasize, even if it occurs only in a minority of cases (approximately 10-30%). Over the last decades, several attempts were made to develop a scoring system able to predict the risk of aggressive behavior at diagnosis, including the risk of metastases and disease recurrence; unfortunately, none of the available scores is able to accurately predict the risk of aggressive behavior, even including clinical, biochemical, and histopathological features. Thus, life-long follow-up is required in PPGL patients. Some recent studies focusing on genetic and molecular markers (involved in hypoxia regulation, gene transcription, cellular growth, differentiation, signaling pathways, and apoptosis) seem to indicate they are promising prognostic factors, even though their clinical significance needs to be further evaluated. The most involved pathways in PPGLs with aggressive behavior are represented by Krebs cycle alterations caused by succinate dehydrogenase subunits (SDHx), especially when caused by SDHB mutations, and by fumarate hydratase mutations that lead to the activation of hypoxia pathways and DNA hypermethylation, suggesting a common pathway in tumorigenesis. Conversely, PPGLs showing mutations in the kinase cascade (cluster 2) tend to display less aggressive behavior. Finally, establishing pathways of tumorigenesis is also fundamental to developing new drugs targeted to specific pathways and improving the survival of patients with metastatic disease. Unfortunately, the rarity of these tumors and the scarce number of cases enrolled in the available studies represents an obstacle to validating the role of molecular markers as reliable predictors of aggressiveness.

[The relationship between clinical characteristics and pathological features in patients with pheochromocytomas/paragangliomas].

Objective: To explore the correlation between clinical characteristics and pathological features in patients with pheochromocytoma/paraganglioma (PPGLs). Methods: A case series study. A retrospective analysis was conducted on patients with single and primary PPGLs after postoperative pathological diagnosis who were admitted to Peking Union Medical College Hospital between January 2019 and December 2022. The patients were divided into the Ki-67<3% group and the Ki-67≥3% group with Ki-67 proliferation index of 3% as the threshold. The relationship between clinical and pathological characteristics of PPGLs was analyzed. Results: A total of 399 PPGLs patients were included, with 177 males and 222 females, aged [M(Q1, Q3)] 45.0(35.5, 53.0) years. Among them, 226 (56.6%) cases originated from the adrenal gland, while 104 cases (26.1%) from the retroperitoneum. 20.9% (27/129) of the patients were found to harbor germline mutations of susceptibility genes, with SDHB mutations being the most common (10.1%, 13/129). The Ki-67 staining was performed on 302 cases, with a Ki-67 proliferation index [M(Q1, Q3)] of 2.0% (1.0%, 3.0%). There were 194 cases in Ki-67<3% group and 108 cases in Ki-67≥3% group. Compared with the patients in Ki-67<3% group, the age of onset in Ki-67≥3% group was younger (P=0.029). Compared with the patients with paragangliomas without SDHB or Cluster 1A-related gene mutations, positive 131I-meta-iodobenzylguanidine (131I-MIBG) imaging or negative O-6-methylguanine-DNA methyltransferase (MGMT) immunohistochemistry staining, those with SDHB or Cluster 1A-related gene mutations, negative 131I-MIBG imaging or positive MGMT immunohistochemistry staining had a higher Ki-67 index (all P<0.05). Compared with adrenal pheochromocytoma, retroperitoneal paragangliomas had a higher proportion of SDHB mutations and a higher proportion of normetanephrine (NMN) secretory types (all P<0.05). Compared with adrenal pheochromocytoma, the maximum diameter of head and neck paraganglioma tumors was smaller [3.0 (1.9, 3.8) cm vs 4.7 (3.4, 6.4) cm, P<0.001] and the proportion of Ki-67≥3% was higher (61.3% vs 33.8%, P=0.007). Conclusions: PPGLs patients with earlier onset age, SDHB or Cluster 1A-related gene mutations, negative 131I-MIBG imaging, or positive MGMT immunohistochemistry staining tend to have a higher Ki-67 index. Head and neck tumors, though smaller, exhibit a higher proliferation potential.

[Clinical features of patients with metastatic pheochromocytoma/paraganglioma].

Objective: To analyze the clinical features of patients with metastatic pheochromocytoma/paraganglioma (PPGL). Methods: A follow-up study. The clinical data of 250 patients with metastatic PPGL treated at Peking Union Medical College Hospital from January 2018 to August 2023 were retrospectively analyzed, including 124 males and 126 females. The clinical features and treatment status of patients with metastatic PPGL were summarized and analyzed. Kaplan-Meier survival curve was used to evaluate patients' prognosis. Results: The age of onset, age of diagnosis, and age of tumor metastasis in patients with metastatic PPGL were (33.1±14.2) years, (35.4±15.2) years, and (40.7±15.3) years, respectively. Metastasis occurred in 26.4%(66/250) of patients at the time of initial diagnosis. Among patients without metastases at the time of initial diagnosis, the time from primary tumor resection to metastasis[M(Q1, Q3)] was 5.0 (3.0, 9.0) years, among which 20.1%(37/184) of patients had metastases more than 10 years after surgery. Most patients showed increased 24-hour urinary norepinephrine and plasma normetanephrine, accounting for 78.2%(176/225) and 78.7%(85/108), respectively. 42.3%(69/163) of patients had increased neuron specific enolase (NSE)levels. Germline mutations were screened in 201 patients, of which 55.2%(111/201) had germline pathogenic mutations. In patients with gene mutations, 76.5%(85/111) had SDHB mutations. 52.0%(130/250) of metastatic PPGL patients had primary sites outside the adrenal gland, with the Ki-67 index of 5% (3%, 8%). There were 85.6%(214/250) patients had multisystem metastasis, with bone metastasis being the most common site of metastasis, accounting for 60.8%(152/250). In terms of treatment, 32.8%(75/229) of patients underwent two treatment regimens and 8.7%(20/229) of patients underwent three treatment regimens. Most patients had a good prognosis, with a 5-year and 10-year survival rate of 88.0% and 84.0%, respectively. However, some patients had rapid disease progression, and as of August 2023, 30 patients died, and the time from diagnosis to death in deceased patients was 2.0 (1.0, 4.0) years. Conclusions: Patients with metastatic PPGL have a high rate of germline mutations, especially those with SDHB mutations. The metastatic PPGL is usually multisystem metastasis with the characteristics of mostly paraganglioma, large lesion diameter and high Ki-67 index.

[MAX germline mutation-associated pheochromocytoma-paraganglioma syndrome: multiple endocrine neoplasia type 5].

The individualized precision management of hereditary pheochromocytoma (PHEO) and paraganglioma (PGL) syndromes (PPGLs) based on molecular diagnosis and molecular subtype is becoming more popular. The newly discovered MAX germline mutation-associated PPGLs are autosomally dominant and rare. To raise awareness and explore the effective management of individual diagnosis and treatment, the relevant literature published between January 2011 and February was systematically reviewed. There were a total of 101 patients in the 77 families, involving all 5 exons, containing 44 types of MAX germline mutations and mostly concentrated in exons 3 and 4 (64.4%), the main mutations were nonsense mutations and missense mutations (72.3%), and some were large fragment deletions or insertions, intron variant, gene fusion mutations were relatively infrequent. Furthermore, about 10% of the patients had a paternal parent-of-origin effect. Among the 101 patients, 96 (95.0%) developed PHEO including 15 metastatic PHEO, 61 bilateral PHEO and 35 unilateral PHEO. The age of diagnosis was (31.7±10.9) years (range: 13 to 80 years). The male to female ratio was 1.2∶1. Eleven were accompanied with chest and abdominal PGL. Eight (7.9%) were accompanied by functional pituitary adenoma. And 12 (11.9%) developed other neuroendocrine tumors (NET), of which 8 were accompanied by PHEO, including 4 hyperparathyroidism, 1 gangliocytoma and neuroblastoma, 1 pancreatic NET, 1 medullary thyroid carcinoma and 1 C cell hyperplasia. Six presented concomitant non-NET, including 1 tongue squamous cell carcinoma, 1 papillary thyroid carcinoma, 1 prostate cancer, 1 renal oncocytoma, 1 breast cancer with renal oncocytoma, and 1 thoracic chondrosarcoma with multifocal adenocarcinoma of lung. The remaining 5 cases (5.0%), including 4 other NET (2 ganglioblastoma, 1 abdominal neuroblastoma and 1 pancreatic NET) and 1 asymptomatic child, did not present PHEO. The MAX germline mutation may cause a novel multiple endocrine neoplasia, which can be described as type 5. A comprehensive baseline assessment of neural crest cell-derived diseases such as PPGL, pituitary adenoma, hyperparathyroidism, and/or gangliocytoma (neuroblastoma) was recommended for all people with MAX germline mutations, and the risk of bilateral and/or metastatic PHEO should also be considered. In contrast, patients with PPGLs combined with other NET, such as functional pituitary adenoma, should undergo genetic testing and pedigree screening that includes at least the MAX gene.

NDUFA4 promotes the progression of head and neck paraganglioma by inhibiting ferroptosis.

NDUFA4 is a component of respiratory chain-oxidative phosphorylation pathway. NDUFA4 is highly expressed in tumor tissues, but little is known about the function of NDUFA4 in head and neck paraganglioma (HNPGL). We examined NDUFA4 expression in tissues from 10 HNPGL patients and 6 controls using qRT-PCR and Western blotting. NDUFA4 knockdown PGL-626 cells were established by using lentivirus infection and puromycin screening. Cell viability, ATP production, lipid reactive oxygen species, and mitochondrial membrane potential assays were performed to investigate the ferroptotic effects in NDUFA4 deficiency HNPGL cancer cells. Xenograft mouse model was created to detect the synergetic antitumor action between NDUFA4 deficiency and Metformin. NDUFA4 was upregulated in tumor tissues of HNPGL patients. NDUFA4 knockdown impaired the assembly of mitochondrial respiratory chain complexes and decreased the production of ATP and reduced cancer cell viability. Mechanistically, NDUFA4 knockdown increased cell ferroptosis, which further promoted Metformin-induced ferroptosis in PGL-626 cells. Therefore, NDUFA4 deficiency enhanced Metformin-mediated inhibition of the HNPGL progression in mice. In conclusion, NDUFA4 promotes the progression of HNPGL, and NDUFA4 knockdown enhances Metformin-mediated inhibition of the HNPGL progression in a mouse model.

Molecular basis of carotid body tumor and associated clinical features in Japan identified by genomic, immunohistochemical, and clinical analyses.

Carotid body tumor (CBT) is classified as a paraganglioma (PGL). Here, we report the genetic background, protein expression pattern, and clinical findings of 30 Japanese CBT cases. Germline pathogenic or likely pathogenic (P/LP) variants of genes encoding succinate dehydrogenase subunits (SDHs) were detected in 15 of 30 cases (50%). The SDHB variants were the most frequently detected, followed by SDHA and SDHD variants. One case with SDHAF2 variant was bilateral CBT, and other two multiple PGL cases were not detected P/LP variants. The three cases with germline variants that could be tested did not have somatic P/LP variants of the same genes. Immunohistochemical analysis showed negative SDHB signals in CBT tissues in five cases with germline P/LP variants of SDHB, SDHD, or SDHA. In addition, SDHB signals in CBT tissues were negative in four of nine cases without germline P/LP variants of SDHs. These findings suggest the involvement of unidentified molecular mechanisms affecting SDHs.