Perspectives on the current pharmacotherapeutic strategies for management of functional neuroendocrine tumor syndromes

All you need to know about VIPoma: Review on the latest studies

Vasoactive intestinal peptide secreting tumor (VIPoma) is a rare mostly malignant neuroendocrine tumor that is characterized by watery diarrhea, hypokalemia and achlorhydria due to the nonregulated increased secretion of VIP. VIPomas ar diagnosed by the presence of the most common symptoms, laboratory analysis of blood and stool, radiological imaging and immunohistochemical findings. Primary treatment includes fluid replacement, electrolyte balance correction, pharmacological treatment with somatostatin analogs, surgical resection and chemotherapy. This review aims to provide an insight into the latest research on VIPoma epidemiology, pathophysiology, diagnostics and treatment.

Management of Functional Pancreatic Neuroendocrine Neoplasms

OPINION STATEMENT

Functional pancreatic neuroendocrine neoplasms (pNENs) are rare and heterogeneous diseases in terms of both clinical and pathological aspects. These tumors secrete hormones or peptides, which may cause a wide variety of symptoms related to a clinical syndrome. The management of functional pNENs is still challenging for clinicians due to the need to control both tumor growth and specific symptoms. Surgery remains the cornerstone in the management of local disease because it can definitively cure the patient. However, when the disease is not resectable, a broad spectrum of therapeutic options, including locoregional therapy, somatostatin analogs (SSAs), targeted therapies, peptide-receptor radionuclide therapy (PRRT), and chemotherapy, are available. The present review summarizes the main key issues regarding the clinical management of these tumors, providing a specific highlight on their therapeutic approach.

Successful Lifetime/Long-Term Medical Treatment of Acid Hypersecretion in Zollinger-Ellison Syndrome (ZES): Myth or Fact? Insights from an Analysis of Results of NIH Long-Term Prospective Studies of ZES

Analysis of the efficacy/pharmacology of long-term/lifetime medical treatment of acid hypersecretion in a large cohort of ZES patients in a prospective study. This study includes the results from all 303 patients with established ZES who were prospectively followed and received acid antisecretory treatment with either H2Rs or PPIs, with antisecretory doses individually titrated by the results of regular gastric acid testing. The study includes patients treated for short-term periods (<5 yrs), patients treated long-term (>5 yrs), and patients with lifetime treatment (30%) followed for up to 48 years (mean 14 yrs). Long-term/lifelong acid antisecretory treatment with H2Rs/PPIs can be successfully carried out in all patients with both uncomplicated and complicated ZES (i.e., with MEN1/ZES, previous Billroth 2, severe GERD). This is only possible if drug doses are individually set by assessing acid secretory control to establish proven criteria, with regular reassessments and readjustments. Frequent dose changes both upward and downward are needed, as well as regulation of the dosing frequency, and there is a primary reliance on the use of PPIs. Prognostic factors predicting patients with PPI dose changes are identified, which need to be studied prospectively to develop a useful predictive algorithm that could be clinically useful for tailored long-term/lifetime therapy in these patients.

An Insight on Functioning Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (PanNENs) are rare neoplasms arising from islets of the Langerhans in the pancreas. They can be divided into two groups, based on peptide hormone secretion, functioning and nonfunctioning PanNENs. The first group is characterized by different secreted peptides causing specific syndromes and is further classified into subgroups: insulinoma, gastrinoma, glucagonoma, somatostatinoma, VIPoma and tumors producing serotonin and adrenocorticotrophic hormone. Conversely, the second group does not release peptides and is usually associated with a worse prognosis. Today, although the efforts to improve the therapeutic approaches, surgery remains the only curative treatment for patients with PanNENs. The development of high-throughput techniques has increased the molecular knowledge of PanNENs, thereby allowing us to understand better the molecular biology and potential therapeutic vulnerabilities of PanNENs. Although enormous advancements in therapeutic and molecular aspects of PanNENs have been achieved, there is poor knowledge about each subgroup of functioning PanNENs.Therefore, we believe that combining high-throughput platforms with new diagnostic tools will allow for the efficient characterization of the main differences among the subgroups of functioning PanNENs. In this narrative review, we summarize the current landscape regarding diagnosis, molecular profiling and treatment, and we discuss the future perspectives of functioning PanNENs.

Severe ectopic Cushing syndrome in a transgender man with a metastatic gastrinoma and an adrenal tumor-A case report and review of the literature

A 38-year-old transgender man with advanced metastatic functional pancreatic neuroendocrine neoplasm (PanNEN) gastrinoma was admitted to the Department of Endocrinology due to severe ACTH-dependent hypercortisolemia. An ectopic production of ACTH by PanNEN was suspected. The patient qualified for bilateral adrenalectomy after preoperative treatment with metyrapone. Finally, the patient underwent resection of the left adrenal gland with the tumor only, which surprisingly resulted in a significant decrease in ACTH and cortisol levels, leading to clinical improvement. Pathology report revealed an adenoma of the adrenal cortex with positive ACTH staining. The result of the simultaneous liver lesion biopsy confirmed a metastatic NEN G2 with positive ACTH immunostaining as well. We looked for a correlation between gender-affirming hormone treatment and the onset of the disease and its rapid progression. This may be the first case describing the coexistence of gastrinoma and ectopic Cushing disease in a transsexual patient.

Intestinal secretory mechanisms and diarrhea

One of the primary functions of the intestinal epithelium is to transport fluid and electrolytes to and from the luminal contents. Under normal circumstances, absorptive and secretory processes are tightly regulated such that absorption predominates, thereby enabling conservation of the large volumes of water that pass through the intestine each day. However, in conditions of secretory diarrhea, this balance becomes dysregulated, so that fluid secretion, driven primarily by Cl- secretion, overwhelms absorptive capacity, leading to increased loss of water in the stool. Secretory diarrheas are common and include those induced by pathogenic bacteria and viruses, allergens, and disruptions to bile acid homeostasis, or as a side effect of many drugs. Here, we review the cellular and molecular mechanisms by which Cl- and fluid secretion in the intestine are regulated, how these mechanisms become dysregulated in conditions of secretory diarrhea, currently available and emerging therapeutic approaches, and how new strategies to exploit intestinal secretory mechanisms are successfully being used in the treatment of constipation.

Predictive Factors for Resistant Disease with Medical/Radiologic/Liver-Directed Anti-Tumor Treatments in Patients with Advanced Pancreatic Neuroendocrine Neoplasms: Recent Advances and Controversies

Simple Summary

Tumor resistance, both primary and acquired, is leading to increased complexity in the nonsurgical treatment of patients with advanced panNENs, which would be greatly helped by reliable prognostic/predictive factors. The importance in identifying resistance is being contributed to by the increased array of possible treatments available for treating resistant advanced disease; the variable clinical course as well as response to any given treatment approach of patients within one staging or grading system, the advances in imaging which are providing increasing promising results/parameters that correlate with grading/outcome/resistance, the increased understanding of the molecular pathogenesis providing promising prognostic markers, all of which can contribute to selecting the best treatment to overcome resistance disease. Several factors have been identified that have prognostic/predictive value for identifying development resistant disease and affecting overall survival (OS)/PFS with various nonsurgical treatments of patients with advanced panNENs. Prognostic factors identified for patients with advanced panNENs for both OS/PFSs include various clinically-related factors (clinical, laboratory/biological markers, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors. Particularly important prognostic factors for the different treatment modalities studies are the recent grading systems. Most prognostic factors for each treatment modality for OS/PFS are not specific for a given treatment option. These advances have generated several controversies and new unanswered questions, particularly those related to their possible role in predicting the possible sequence of different anti-tumor treatments in patients with different presentations. Each of these areas is reviewed in this paper.

Abstract

Purpose: Recent advances in the diagnosis, management and nonsurgical treatment of patients with advanced pancreatic neuroendocrine neoplasms (panNENs) have led to an emerging need for sensitive and useful prognostic factors for predicting responses/survival. Areas covered: The predictive value of a number of reported prognostic factors including clinically-related factors (clinical/laboratory/imaging/treatment-related factors), pathological factors (histological/classification/grading), and molecular factors, on therapeutic outcomes of anti-tumor medical therapies with molecular targeting agents (everolimus/sunitinib/somatostatin analogues), chemotherapy, radiological therapy with peptide receptor radionuclide therapy, or liver-directed therapies (embolization/chemoembolization/radio-embolization (SIRTs)) are reviewed. Recent findings in each of these areas, as well as remaining controversies and uncertainties, are discussed in detail, particularly from the viewpoint of treatment sequencing. Conclusions: The recent increase in the number of available therapeutic agents for the nonsurgical treatment of patients with advanced panNENs have raised the importance of prognostic factors predictive for therapeutic outcomes of each treatment option. The establishment of sensitive and useful prognostic markers will have a significant impact on optimal treatment selection, as well as in tailoring the therapeutic sequence, and for maximizing the survival benefit of each individual patient. In the paper, the progress in this area, as well as the controversies/uncertainties, are reviewed.