Chemoprevention with Somatuline© Delays the Progression of Pancreatic Neuroendocrine Neoplasms in a Mouse Model of Multiple Endocrine Neoplasia Type 1 (MEN1)

[Individualized approach for MEN1-associated duodenopancreatic neuroendocrine neoplasms]

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1)-associated duodenopancreatic neuroendocrine neoplasms (dpNEN) represent the most frequent syndrome-associated cause of death, but the adequate treatment is sometimes considered controversial.

OBJECTIVE

Presentation of possible diagnostic and therapeutic options for MEN1-associated dpNENs.

MATERIAL AND METHODS

In this review article retrospective case studies, expert recommendations, national and international guidelines as well as personal experiences were analyzed and evaluated.

RESULTS

Due to early detection programs and the use of the most modern imaging techniques, dpNEN are nowadays diagnosed much earlier. Nonfunctional pNENs currently represent the most frequent dpNENs with about 70%, followed by gastrinomas and insulinomas. Regardless of their functional activity, dpNENs with a size of > 2 cm are generally an indication for surgery. The choice of the optimal treatment strategy, however, in most cases remains the subject of controversial discussions, although nowadays surgery should always be performed in an organ-preserving and minimally invasive way when feasible. Recurrences or new dpNENs are expected in more than 60% of cases, necessitating a reoperation in up to 40% of these cases. Duodenopancreatic resections and reoperations can be carried out safely by experienced practitioners and with an acceptable level of risk.

CONCLUSION

The planning of treatment requires careful consideration of the suitable timing, the extent of the operation, the risk of recurrence and potential morbidities. Furthermore, preserving pancreatic function and the quality of life is of utmost importance. In view of the complexity of the disease, MEN1 patients should be treated in specialized centers.

Status of Surveillance and Nonsurgical Therapy for Small Nonfunctioning Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) occur in < 1/100,000 patients and most are nonfunctioning (NF). Approximately 5% occur as part of multiple endocrine neoplasia type 1. Anatomic and molecular imaging have a pivotal role in the diagnosis, staging and active surveillance. Surgery is generally recommended for nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) >2 cm to prevent metastases. For tumors ≤2 cm, active surveillance is a viable alternative. Tumor size and grade are important factors to guide management. Assessment of death domain-associated protein 6/alpha-thalassemia/mental retardation X-linked and alternative lengthening of telomeres are promising novel prognostic markers. This review summarizes the status of surveillance and nonsurgical management for small NF-PNETs, including factors that can guide management.

A New Medical Therapy for Multiple Endocrine Neoplasia Type 1?

Pancreatic neuroendocrine tumours (pNETs) are a major manifestation of multiple endocrine neoplasia type 1 (MEN1), and the most significant cause of morbidity and mortality in this disorder. There is some evidence that the early use of somatostatin analogues can retard progression, especially of small non-functioning tumours, but there are no other prophylactic therapies for patients, and the treatment of metastatic disease is similar to that for sporadic pNETs. A recent study has shown that in cell line and animal models, MEN1 mutations lead to an upregulation of the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in increasing precursor metabolites for the synthesis of pyrimidines. In these studies, blockade of this pathway by various means, including the DHODH inhibitor leflunomide, attenuates cell growth and tumour progression, suggesting a critical dependence on DHODH specifically in MEN1-mutated tissue. Preliminary clinical studies in three patients with MEN1 and pNETs have indicated some therapeutic potential of this drug, which has previously been used for some years in patients with rheumatoid arthritis. It is suggested that further clinical trials of this re-purposed drug are indicated to evaluate its potential for the treatment of patients with MEN1 and pNETS. This article describes the clinical problem of MEN1 and pNETs, and reviews the recent publication reporting on these initial results.

Multiple Endocrine Neoplasia Type 1: Latest Insights

Multiple endocrine neoplasia type 1 (MEN1), a rare tumor syndrome that is inherited in an autosomal dominant pattern, is continuing to raise great interest for endocrinology, gastroenterology, surgery, radiology, genetics, and molecular biology specialists. There have been 2 major clinical practice guidance papers published in the past 2 decades, with the most recent published 8 years ago. Since then, several new insights on the basic biology and clinical features of MEN1 have appeared in the literature, and those data are discussed in this review. The genetic and molecular interactions of the MEN1-encoded protein menin with transcription factors and chromatin-modifying proteins in cell signaling pathways mediated by transforming growth factor β/bone morphogenetic protein, a few nuclear receptors, Wnt/β-catenin, and Hedgehog, and preclinical studies in mouse models have facilitated the understanding of the pathogenesis of MEN1-associated tumors and potential pharmacological interventions. The advancements in genetic diagnosis have offered a chance to recognize MEN1-related conditions in germline MEN1 mutation-negative patients. There is rapidly accumulating knowledge about clinical presentation in children, adolescents, and pregnancy that is translatable into the management of these very fragile patients. The discoveries about the genetic and molecular signatures of sporadic neuroendocrine tumors support the development of clinical trials with novel targeted therapies, along with advancements in diagnostic tools and surgical approaches. Finally, quality of life studies in patients affected by MEN1 and related conditions represent an effort necessary to develop a pharmacoeconomic interpretation of the problem. Because advances are being made both broadly and in focused areas, this timely review presents and discusses those studies collectively.

Lanreotide Therapy vs Active Surveillance in MEN1-Related Pancreatic Neuroendocrine Tumors < 2 Centimeters

PURPOSE

Pancreatic neuroendocrine tumors (pNETs) are frequent in multiple endocrine neoplasia type 1 (MEN1) syndrome. They are usually not surgically treated unless larger than 1 to 2 cm or a growth rate > 0.5 cm per year. Somatostatin analogues represent one of the main therapeutic options in pNETs, but they have never been prospectively investigated in MEN1-related pNETs. The aim of this study was to prospectively evaluate the effectiveness of lanreotide in patients with MEN1-related pNETs < 2 cm.

METHODS

MEN1 patients with 1 or more pNETs < 2 cm of maximal diameter were considered. Study design was prospective observational, comparing patients treated with lanreotide autogel 120 mg every 28 days (LAN group) and patients in active surveillance, not receiving any therapy (AS group).

RESULTS

Forty-two patients were enrolled: 23 in LAN and 19 in AS group. Median follow-up was 73 months. Initial imaging identified a total of 91 pNETs. The median progression-free survival was significantly longer in the LAN than in the AS group (median not reached vs 40 months, P < 0.001). In the LAN group, 4 patients had an objective tumor response, 15 patients had stable disease, while 4 had tumor progression. In the AS group, 13 patients had pNET progression, while 6 were stable.

CONCLUSIONS

This is the first prospective study evaluating the efficacy of somatostatin analogues in MEN1-related pNETs. These findings highlight that lanreotide autogel is effective as antiproliferative therapy in MEN1-related pNETs < 2cm, suggesting the utility of somatostatin analogues to arrest the development of tumor lesions as well as to delay or avoid pancreatic surgery.