Multiple Endocrine Neoplasia: A Genetically Diverse Group of Familial Tumor Syndromes

Case of Recurrent Primary Hyperparathyroidism, Congenital Granular Cell Tumor and Aggressive Colorectal Cancer

We present the case of a 53-year-old African-American male with recurrent primary hyperparathyroidism (PHPT), multi-focal benign granular cell tumor (GCT) and metastatic colon adenocarcinoma. PHPT was diagnosed on routine blood testing [ionized calcium 1.66 (1.12-1.32) mmol/L, PTH 110pg/mL, Vitamin D-25-OH-D: 18ng/mL, PTHrP: undetectable]. Medical history was notable for two reoccurrences of PHPT with persistent disease after most recent parathyroidectomy. Lymph node (LN) dissection during this last surgery showed a 2-mm focus of poorly differentiated adenocarcinoma in 1/5 LNs. Additionally, patient had a history of multi-focal GCTs diagnosed at age two. On exam, there were no Lisch nodules, axillary, or inguinal freckling, neurofibromas or café-au-lait macules but a prominent abdominal wall nodule was noted. En bloc resection of a tumor in the tracheoesophageal groove, identified by sestamibi scan and excision of 4.5-cm abdominal wall nodule showed both masses having histology consistent with GCT. Serum calcium and PTH did not decrease indicating another unsuccessful surgery. Genetic testing was negative for germline variants in PHPT-associated genes, APC or genes of RAS-MAPK signaling pathway. The LN finding of metastatic adenocarcinoma prompted an endoscopy and trans-bronchial biopsy leading to the diagnosis of widely metastatic colonic adenocarcinoma, eventually resulting in his death a year later. Source of patient’s persistent PHPT remained unidentified. This is the first case with co-association of recurrent PHPT, multi-focal GCT and colon cancer. Whether the disparate tumors in this patient share common driver(s) remains unknown. Prospective surveillance of patients for similar associations may provide clues for a novel syndromic form of PHPT.

Patients' perception on the quality of care for multiple endocrine neoplasia disorders in Europe: an online survey from a patient support group

PURPOSE

European Patient Advocacy Groups (ePAGs) within the Endo-ERN identified a lack of knowledge about quality of care (QoC) of patients with multiple endocrine neoplasia (MEN). The aim of this study was to identify inequalities in care and to encourage improvements.

METHODS

The European MEN Alliance (EMENA) developed and conducted a survey, using the European Commissions' EUSurvey platform. Patient groups and healthcare professionals (HCPs) distributed the survey.

RESULTS

A total of 288 participants completed the survey (MEN1 n = 203, MEN2 n = 67, MEN3 n = 18) from 18 European countries. The majority of respondents were recruited via patient groups (58%), aged between 41 and 60 years (53%) and were female (67%). All participants reported having been diagnosed on average 5.58 years (95%-CI: 4.45-6.60) after first symptoms occurred. This timeframe was lower in the group with MEN2 (2.97 years, 95%-CI: 1.37-4.57). Most of the participants (67%) received their diagnosis by a positive gene test after presenting with one or more MEN-related tumours. Overall QoC was rated as either "good" (43%) or "excellent" (36%).

CONCLUSION

The results of this unique Europe-wide, patient-driven survey on QoC of patients with MEN show that ratings for overall QoC were lower than ratings for different aspects of care. This may be because of the complex nature of care for genetic syndromes. Furthermore, patients who connect with patient groups may be deemed "expert patients" whose answers are not representative of the overall MEN patient community. We hope that Endo-ERN can support further education and training for HCPs based on these results.

Clinical and genetic features of pediatric PCCs/PGLs patients: a single-center experience in China

Background

Although 40% to 80% of pediatric patients with pheochromocytoma (PCC) and paraganglioma (PGL) have been reported to carry germline mutations, the genetic and clinical features are poorly understood, and few such patients have undergone genetic testing. In this series, we aimed to investigate the clinical and genetic features of Han Chinese pediatric patients with PCC/PGL.

Methods

The medical records of 15 pediatric patients with PCC/PGL who presented to our hospital between 2006 and 2018 were retrospectively studied. DNAs isolated from leukocytes of the patients were analyzed using whole-exome sequencing (WES).

Results

The patients were nine girls and six boys with a mean age of 14.9 (range, 6–18) years. All were alive after a follow-up from 1 to 12 years, although two were diagnosed with pulmonary metastatic PGLs. Four patients were diagnosed with bilateral PCCs. Four patients were diagnosed with tumor syndromes. Among the 15 patients, nine were identified carrying germline mutations, of which seven were VHL and one each of RET and SDHB. In addition, a de novo mutation, VHL c.193T>A, was identified in a patient clinically diagnosed with a VHL syndrome.

Conclusions

Among 15 pediatric patients studied, nine were identified carrying germline genetic mutations, four were diagnosed with bilateral PCCs, and four were diagnosed with other syndromic tumors in addition to PCC, which underscores the importance of genetic testing and managing treatment accordingly.

Parathyroid Pathology

Proliferative pathologic lesions of parathyroid glands encompass a spectrum of entities ranging from benign hyperplastic processes to malignant neoplasia. This review article outlines the pathophysiologic classification of parathyroid disorders and describes histologic, immunohistochemical, and molecular features that can be assessed to render accurate diagnoses.

Cryo-EM structure of the activated RET signaling complex reveals the importance of its cysteine-rich domain

Signaling through the receptor tyrosine kinase RET is essential during normal development. Both gain- and loss-of-function mutations are involved in a variety of diseases, yet the molecular details of receptor activation have remained elusive. We have reconstituted the complete extracellular region of the RET signaling complex together with Neurturin (NRTN) and GFRα2 and determined its structure at 5.7-Å resolution by cryo-EM. The proteins form an assembly through RET-GFRα2 and RET-NRTN interfaces. Two key interaction points required for RET extracellular domain binding were observed: (i) the calcium-binding site in RET that contacts GFRα2 domain 3 and (ii) the RET cysteine-rich domain interaction with NRTN. The structure highlights the importance of the RET cysteine-rich domain and allows proposition of a model to explain how complex formation leads to RET receptor dimerization and its activation. This provides a framework for targeting RET activity and for further exploration of mechanisms underlying neurological diseases.

Discoveries beyond BRCA1/2: Multigene testing in an Asian multi-ethnic cohort suspected of hereditary breast cancer syndrome in the real world

BACKGROUND

Due to historically low uptake of genetic testing, the mutational spectrum of Asians with Hereditary Breast Cancer (HBC) is not well understood. This study sought to understand the incidence and spectrum of germline mutations in Asian patients with suspected HBC in a clinic setting.

METHODS

1056 patients with suspected HBC were seen in our Cancer (CA) Genetics Clinic from 2000-2017, of which 460 underwent genetic testing.

RESULTS

Of 460 probands tested, 93% were female, 61% Chinese, 90% had prior CA, with 19% (77/414) having ≥2 primary CA. Median age at CA-diagnosis was 43y (17-83); 70% had Breast CA (BC) and 25% Ovarian CA (OC). 34% had young-onset BC, 8% bilateral BC, and 4% BC/OC. Majority had family history of BC (53%) or OC (20%). 57% underwent multigene testing (14-49 genes), 34% targeted testing, and 8% predictive testing. 30% were found to have a pathogenic mutation: 80% in BRCA1/2 (8 novel mutations noted). Of 33 non-BRCA1/2 pathogenic mutations detected, 61% were in 11 BC genes while 39% were in non-BC genes suggestive of alternative CA syndromes. Testing beyond BRCA1/2 impacted management for 15.9% (22/138) of carriers, but extensive testing identified variants of uncertain significance (VUS) in up to 44.5% of probands. Restricting multigene panel testing to a guideline-based 20-gene panel including Lynch Syndrome genes was found to be most optimal, detecting 94.6% of mutation carriers while reducing VUS rate to 21.5%.

CONCLUSIONS

Evolution of CA Genetics testing strategy to a multigene approach facilitated detection of pathogenic mutations in non-BRCA1/2 genes and aided management. Guideline-based panel testing is feasible and can be offered in Asians with suspected HBC.

Multiple endocrine neoplasia-like syndrome in 24 baboons (Papio spp.)

Multiple endocrine neoplasia (MEN) has not been reported in baboons, but this condition is well described in humans. An internal database was searched for all cases of concurrent endocrine hyperplasia and neoplasia in baboons. Twenty-four baboons (Papio spp.) with concurrent endocrine hyperplasia and neoplasia were identified. Twenty-one baboons had lesions in two endocrine organs, two baboons had lesions in three organs, and one baboon had lesions in four organs. Ten baboons aligned with the MEN1 classification; 14 baboons did not match any current human MEN classification. We report 24 cases of MEN-like syndrome in baboons. MEN1-like lesions accounted for nearly half (41%) of the affected animals. Genetic analysis of baboons with MEN-like syndrome could further elucidate the mechanisms of MEN and support the use of baboons as animal models for human MEN.

Mouse models in endocrine tumors

Endocrine and neuroendocrine tumors comprise a highly heterogeneous group of neoplasms that can arise from (neuro)endocrine cells, either from endocrine glands or from the widespread diffuse neuroendocrine system, and, consequently, are widely distributed throughout the body. Due to their diversity, heterogeneity and limited incidence, studying in detail the molecular and genetic alterations that underlie their development and progression is still a highly elusive task. This, in turn, hinders the discovery of novel therapeutic options for these tumors. To circumvent these limitations, numerous mouse models of endocrine and neuroendocrine tumors have been developed, characterized and used in pre-clinical, co-clinical (implemented in mouse models and patients simultaneously) and post-clinical studies, for they represent powerful and necessary tools in basic and translational tumor biology research. Indeed, different in vivo mouse models, including cell line-based xenografts (CDXs), patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMs), have been used to delineate the development, progression and behavior of human tumors. Results gained with these in vivo models have facilitated the clinical application in patients of diverse breakthrough discoveries made in this field. Herein, we review the generation, characterization and translatability of the most prominent mouse models of endocrine and neuroendocrine tumors reported to date, as well as the most relevant clinical implications obtained for each endocrine and neuroendocrine tumor type.

Thyroid cancer in adolescents and young adults

In adolescents and young adults, thyroid cancer accounts for 13% of all invasive neoplasms, being three times more frequent in females, but overdiagnosis and overtreatment are common. There are two therapeutic approaches, one radical and no longer preferred in all instances, and the other conservative. Permanent complications of surgery and metabolic irradiation can affect quality of life and carry an economic burden. The overall survival rate approaches 100% for patients with differentiated thyroid cancer regardless of the extent of treatment. Medullary thyroid carcinoma is a very different entity, occurring most frequently in the context of hereditary tumor susceptibility syndromes.

Inherited lung cancer syndromes targeting never smokers

Lung cancer is the leading cause of cancer death worldwide. Most of lung cancers develop sporadically and thus inherited lung cancers are rare. Several reports show that germline mutations in the kinase domain of epidermal growth factor receptor (EGFR) such as R776G, R776H, T790M, V843I and P848L, predispose to develop lung cancer. Most lung cancer cases with germline EGFR T790M mutations had secondary EGFR somatic mutations. Never smokers with germline EGFR T790M mutations develop lung cancer more frequently than ever smokers. In addition, germline EGFR T790M mutations favored female gender. Therefore, germline EGFR T790M mutations result in a unique inherited lung cancer syndrome targeting never smokers. The authors previously reported a Japanese familial lung cancer pedigree with germline mutations in the transmembrane domain of human epidermal growth factor receptor 2 (HER2). The female proband and her mother in this pedigree, who were light or never smokers, developed multiple lung adenocarcinomas, and had germline HER2 G660D mutations. They had no EGFR somatic mutations or other genes known to cause lung cancers. Although we know only one pedigree with germline HER2 mutations, these mutations may also cause inherited lung cancers targeting female never smokers. Based on our in vitro analyses, we administered HER2 inhibitor afatinib to the proband and achieved partial response. These lung cancers arising from germline mutations of receptor tyrosine kinases such as EGFR and HER2 may have different features from those with sporadic mutations.

Identification of diverse target RNAs that are functionally regulated by human Pumilio proteins

Human Pumilio proteins, PUM1 and PUM2, are sequence specific RNA-binding proteins that regulate protein expression. We used RNA-seq, rigorous statistical testing and an experimentally derived fold change cut-off to identify nearly 1000 target RNAs-including mRNAs and non-coding RNAs-that are functionally regulated by PUMs. Bioinformatic analysis defined a PUM Response Element (PRE) that was significantly enriched in transcripts that increased in abundance and matches the PUM RNA-binding consensus. We created a computational model that incorporates PRE position and frequency within an RNA relative to the magnitude of regulation. The model reveals significant correlation of PUM regulation with PREs in 3' untranslated regions (UTRs), coding sequences and non-coding RNAs, but not 5' UTRs. To define direct, high confidence PUM targets, we cross-referenced PUM-regulated RNAs with all PRE-containing RNAs and experimentally defined PUM-bound RNAs. The results define nearly 300 direct targets that include both PUM-repressed and, surprisingly, PUM-activated target RNAs. Annotation enrichment analysis reveal that PUMs regulate genes from multiple signaling pathways and developmental and neurological processes. Moreover, PUM target mRNAs impinge on human disease genes linked to cancer, neurological disorders and cardiovascular disease. These discoveries pave the way for determining how the PUM-dependent regulatory network impacts biological functions and disease states.

Multiple Oral Mucosal Hamartomas in a 34-Year Old Female

A case of Cowden syndrome (CS) is described in a 34-year-old African American female who reported a history of breast and thyroid malignancies. Clinical examination demonstrated multiple soft, white-pink papules across multiple mucosal surfaces of the oral cavity. Microscopy of the lesions revealed hyperkeratotic surface squamous epithelium with papillomatosis and acanthosis along with elongated rete processes. A genomic polymerase chain reaction direct sequencing using the patient's blood was positive for mutations of the PTEN gene typical of CS.