Study of the Value of hPG80 (Circulating Progastrin) for the Diagnosis of Neuroendocrine Tumours in Patients With an MEN1 Mutation

Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal dominant disease with a high degree of penetrance (\>80% of patients). It is caused by the presence of the MEN1 mutation located on chromosome 11q13. The prevalence of this mutation is estimated at approximately 1/30,000. This hereditary syndrome is characterized by the presence of tumours of the endocrine system (adenoma of the parathyroid, pituitary and adrenal glands, neuroendocrine tumors - NETs - of the endocrine pancreas, duodenum, lung or thymus), which threaten the health of these patients. Other malignant tumors such as breast cancer are also more common in patients with MEN1. The clinical manifestations of MEN1 are linked to the location of the adenomas and NETs and their secretory products. Indeed, most NETs produce and secrete numerous peptide hormones (in the case of Insulinomas, Gastrinomas, VIPomas, Glucagonomas or PPomas for example). This causes a specific clinical syndrome, which can be detected in the blood serum. However, most NETs are "non-functional" tumors, which do not have specific secretions. Among general tumor markers, chromogranin A (CgA) is widely used as a biomarker for monitoring NETs. CgA is a secretory protein released into the blood by neuroendocrine cells. However, the performance of CgA as a diagnostic biomarker is too limited to be used for the early identification of NETs, particularly in patients with MEN1. This is why patients with MEN1 undergo regular biological and morphological examinations, at least once a year, to screen for the development of adenomas and NETs. However, CgA or hormone secretions assays, and imaging examinations (MRI, CT scan, or duodenopancratic endoscopic ultrasound (EUS)) are tedious and stressful for patients; in addition, they all have their limitations (poor performance for biological tests; irradiation for CT scan; need for anesthesia for endoscopic ultrasound, etc.). Consequently, there is a need for new markers to identify NETs in thi