Faculty Bibliography

Hotspot mutations in the promoter of the telomerase reverse transcriptase (TERT) gene have been recently reported in human cancers and proposed as a novel mechanism of telomerase activation. To explore TERT promoter mutations in tumors originating from the adrenal gland and extra-adrenal paraganglia, a set of 253 tumors (38 adrenocortical carcinomas (ACCs), 127 pheochromocytomas (PCCs), 18 extra-adrenal paragangliomas (ea PGLs), 37 head and neck PGLs (HN PGLs), and 33 peripheral neuroblastic tumors) was selected along with 16 human neuroblastoma (NBL) and two ACC cell lines to assess TERT promoter mutations by the Sanger sequencing method. All mutations detected were confirmed by a SNaPshot assay. Additionally, 36 gastrointestinal stromal tumors (GISTs) were added to explore an association between TERT promoter mutations and SDH deficiency. TERT promoter mutations were found in seven out of 289 tumors and in three out of 18 human cell lines; four C228T mutations in 38 ACCs (10.5%), two C228T mutations in 18 ea PGLs (11.1%), one C250T mutation in 36 GISTs (2.8%), and three C228T mutations in 16 human NBL cell lines (18.75%). No mutation was detected in PCCs, HN PGLs, neuroblastic tumors as well as ACC cell lines. TERT promoter mutations preferentially occurred in a SDH-deficient setting (P=0.01) being present in three out of 47 (6.4%) SDH-deficient tumors vs zero out of 171 (0%) SDH-intact tumors. We conclude that TERT promoter mutations occur in ACCs and ea PGLs. In addition, preliminary evidence indicates a potential association with the acquisition of TERT promoter mutations in SDH-deficient tumors.

CONTEXT/BACKGROUND:Only a small number of case reports has been published on patients with PTHrP-hypersecreting metastatic gastroenteropancreatic (GEP) neuroendocrine tumors (NETs). OBJECTIVE:The objective of this study was to evaluate the clinical, biochemical, and radiological features, management, and treatment outcome of patients with PTHrP-hypersecreting GEP-NETs. DESIGN/METHODS:Retrospective case series. SETTING/METHODS:Tertiary referral hospital. MAIN OUTCOME MEASURES/METHODS:Clinical, biochemical, and radiological features were measured, as well as response to therapy and survival. PATIENTS/METHODS:Ten patients with PTHrP-secreting GEP-NETs (nine pancreatic and one unknown primary) with a median age of 50.4 years (range, 38.3-61.1) were studied. Multiple endocrine neoplasia type 1 patients were excluded. RESULTS:The median follow-up was 57.2 months (range, 11.6-204.5 mo). Median overall survival was 86.0 months. In total, 51 different treatment interventions and combinations were applied. In seven of the 10 patients, somatostatin analog (SSA) treatment resulted in a temporary normalization of serum calcium levels with a long-term response observed in two patients (up to 35.2 mo). Peptide receptor radiotherapy (PRRT) with radiolabeled SSAs induced long-term responses ranging from 9.0-49.0 months in four of six patients treated with PRRT. CONCLUSIONS:Hypersecretion of PTHrP by metastatic GEP-NETs is very rare and seems to be exclusively associated with metastatic pancreatic NETs. PTHrP production has major clinical impact because poorly controllable hypercalcemia is associated with increased morbidity and mortality. The most successful treatment options for PTHrP-producing GEP-NETs are SSAs and PRRT using radiolabeled SSAs. Isotonic saline and bisphosphonates can be considered as supportive therapies.

Adrenocortical carcinoma (ACC) is a rare, but highly malignant tumor of unknown origin. Inhibin α-subunit (Inha) knockout mice develop ACCs following gonadectomy. In man, INHA expression varies widely within ACC tissues and its circulating peptide inhibin pro-αC has been described as a novel tumor marker for ACC. We investigated whether genetic and epigenetic changes of the INHA gene in human ACC cause loss or variation of INHA expression. To this end, analyses of INHA sequence, promoter methylation and mRNA expression were performed in human adrenocortical tissues. Serum inhibin pro-αC levels were also measured in ACC patients. INHA genetic analysis in 37 unique ACCs revealed 10 novel, heterozygous rare variants. Of the 3 coding bases affected, one variant was synonymous and two were missense variants: S72F and S184F. The minor allele of rs11893842 at -124 bp was observed at a low frequency (24%) in ACC samples and was associated with decreased INHA mRNA levels: 4.7±1.9 arbitrary units for AA, compared to 26±11 for AG/GG genotypes (P = 0.034). The methylation of four proximal INHA promoter CpGs was aberrantly increased in five ACCs (47.7±3.9%), compared to normal adrenals (18.4±0.6%, P = 0.0052), whereas the other 14 ACCs studied showed diminished promoter methylation (9.8±1.1%, P = 0.020). CpG methylation was inversely correlated to INHA mRNA levels in ACCs (r = -0.701, p = 0.0036), but not associated with serum inhibin pro-αC levels. In conclusion, aberrant methylation and common genetic variation in the INHA promoter occur in human ACCs and are associated with decreased INHA expression.

BACKGROUND:Adrenocortical carcinoma (ACC) is a rare disease with a poor prognosis and limited therapeutic options. Mitotane is considered the standard first-line therapy with only 30% of the patients showing objective tumour response. Defining predictive factors for response is therefore of clinical importance. The epidermal growth factor receptor (EGFR) has been implicated in the development of one-third of all malignancies. EGFR pathway members in ACC have been investigated, however, without available clinical data and relation to survival. METHODS:In this study, mutation status of EGFR and downstream signalling pathways was evaluated in 47 ACC patients on mitotane using direct sequencing, a TaqMan allele-specific assay and immunohistochemistry. Archival formalin-fixed paraffin-embedded tumour tissue was used for all analyses. Patient data were obtained anonymously, after coupling with the collected tumour tissue. RESULTS:One BRAF, two EGFR TK domain (c.2590> A, p.864A>T) and 11 TP53, but no PIK3CA or KRAS, mutations were found. No relationship was found between mutation status, immunostaining and mitotane response or survival. CONCLUSION/CONCLUSIONS:In conclusion, our data suggest that the role of EGFR tyrosine kinase inhibitors in ACC is limited. Treatment with EGFR monoclonal antibodies on the other hand might be beneficial for a larger group of patients. The possible efficacy of this therapy in ACC should be evaluated in future trials.

OBJECTIVE:The widespread application of abdominal computerized tomography (CT) imaging has revealed that 0.98-4.0% of individuals harbour adrenal lesions (incidentalomas). There is, however, paucity of information regarding the prevalence of adrenal lesions in patients with gastroenteropancreatic neuroendocrine tumours (GEP-NETS). Purpose of this study was to estimate the prevalence of adrenal lesions in patients with GEP-NETS and identify their radiological features and clinical significance. DESIGN/METHODS:The prevalence of adrenal lesions was estimated retrospectively in 438 patients with GEP-NETS who underwent abdominal imaging. Secretory status and changes in size were documented during subsequent follow-up. MEN-1 patients and ectopic ACTH-secreting tumours were excluded. RESULTS:Adrenal lesions were detected in 32 (8.4%) of 383 patients included. The majority (22 patients - 69%) were located at the left adrenal gland and the mean size was 23.6 mm. In two patients, one with a well and another with a poorly differentiated tumour, clinicopathological features suggested adrenal metastases. During a mean follow-up period of 69.5 months, no subsequent growth of any adrenal lesion was observed. Endocrine evaluation documented subclinical glucocorticoid hypersecretion in 4 cases (14%). The presence of adrenal lesions did not correlate to distant metastases, however, they were observed more frequently in patients with G3 tumours. CONCLUSION/CONCLUSIONS:The prevalence of adrenal lesions in patients with GEP-NETs was found to be higher than the general population and mostly represent benign adrenal adenomas (except patients with G3 tumours). Nevertheless, individualized assessment of imaging characteristics should be still considered.