Treatment Options For Neuroendocrine Tumors Research Articles

Management of Gastrointestinal Carcinoid Tumors: An Overview

Gastrointestinal Carcinoid Tumors are neoplasms that originate in the lining of the gastrointestinal (GI) tract and are derived from the neuroendocrine cells. It is rare for these tumors to be detected before they develop metastases, and they are often discovered incidentally during surgery for other abdominal conditions. Currently, various treatment options are available for managing these tumors, such as surgery, which is usually the most effective treatment. The type of surgery depends on several factors, including the size and location of the tumor, the patient's comorbidities, and the presence of carcinoid syndrome. As a result of the low probability of metastasizing, surgery is typically the best treatment option for neuroendocrine tumors of type I. NETs of type II and III are the most aggressive and require a formal gastrostomy, whereas NETs of type IV are treated with local ablation or cytotoxic chemotherapy. The first line of pharmacological treatment is somatostatin analogs (SSAs); they inhibit hormone production and tumor cell proliferation by binding to G-protein-coupled somatostatin receptors (SSTRs). Another option is Telotristat, which inhibits tryptophan hydroxylase - 1 (TPH-1) in the digestive tract, thereby reducing serotonin production. The treatment of patients with carcinoid syndrome who are refractory to SSAs could be improved by peptide receptor radionuclide therapy (PRRT), which uses radiolabeled somatostatin analogs to target overexpressed somatostatin receptors in well-differentiated NETs.

Health-related quality of life in patients with advanced well-differentiated pancreatic and extrapancreatic neuroendocrine tumors treated with surufatinib versus placebo: Results from two randomized, double-blind, phase III trials (SANET-p and SANET-ep)

AimTo investigate the health-related quality of life (HRQoL) of patients who had neuroendocrine tumors (NETs) from SANET trials. MethodsEligible patients were randomized in a 2:1 ratio to receive surufatinib or placebo. HRQoL questionnaires, including the European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-G.I.NET21, were collected. The prespecified HRQoL outcome was the mean change of scores from baseline to the last available visit for each domain. Time until definitive deterioration (TUDD) was defined as the time from randomization to deterioration of ≥10 points from baseline in domain score, disease progression, or death. Results370 patients were enrolled and randomly assigned to surufatinib (n = 242) or placebo (n = 128). No significant difference in mean scores change from baseline to the last available visit was observed for QLQ-C30 and QLQ- G.I.NET21 domains, with the exception of diarrhea. The mean score of diarrhea increased 11.7 points from baseline in the surufatinib arm and decreased 1.2 points in the placebo arm, and the between-group difference was 12.9 points. Compared with placebo, surufatinib treated patients had a significantly longer TUDD for dyspnea (hazard ratio [HR] 0.58; 95% confidence interval [CI], 0.39–0.86; P = 0.0058) and a significantly shorter TUDD for diarrhea (HR 2.91; 95% CI, 1.66–5.10; P < 0.0001). There were no significant differences in TUDD for the remaining domains of QLQ-C30 and G.I.NET-21. ConclusionsHRQoL was similar in patients treated with surufatinib and placebo except for diarrhea. The preservation of HRQoL supports surufatinib as a treatment option for NETs. Clinical trial informationClinicalTrials.gov: NCT02589821, NCT02588170.

Emerging Treatment Options for Gastroenteropancreatic Neuroendocrine Tumors.

Treatment options for neuroendocrine tumors (NETs) and carcinomas (NECs) are expanding. Early-phase studies have shown preliminary evidence of the antitumor activity of alpha-emitting peptide receptor radionuclide therapy (PRRT), and novel radiopeptides incorporating somatostatin receptor antagonists (rather than agonists) have been developed. Several tyrosine kinase inhibitors (TKIs) with antiangiogenic potential have been evaluated in patients with NETs, including lenvatinib, axitinib, cabozantinib and pazopanib. Recently, two phase 3 clinical trials have demonstrated the efficacy and safety of surufatinib, an inhibitor of vascular endothelial growth factor receptor (VEGFR)-1, -2, -3, fibroblast growth factor receptor (FGFR)-1 and colony stimulating factor-1 receptor (CSF-1R), in patients with pancreatic and extra-pancreatic NETs. Multiple clinical trials of combination immunotherapy have been recently completed, but interpretation of the results is hampered by small samples sizes and discordant outcomes. This review summarizes recent data on emerging treatments for neuroendocrine neoplasms.

Metformin and Everolimus: A Promising Combination for Neuroendocrine Tumors Treatment.

Introduction: Treatment options for neuroendocrine tumors (NETs) are rarely curative, as NETs frequently show resistance to medical therapy. The use of everolimus, an mTOR inhibitor, is limited by the development of resistance, probably due to the activation of Akt signaling. In this context, the antidiabetic drug metformin is able to inhibit mTOR, providing a rationale for the use of metformin and everolimus in combination. Methods: We investigated the effects of the metformin and everolimus combination on NET cell proliferation, apoptosis, colony formation, cell viability, NET spheroids growth and the involvement of the Akt and mTOR pathways, and also developed everolimus-resistant NET cells to further study this combination. Results: Metformin and everolimus in combination are more effective than monotherapy in inhibiting pancreatic NET (PAN-NET) cell proliferation (−71% ± 13%, p < 0.0001 vs. basal), whereas no additive effects were observed on pulmonary neuroendocrine tumor (PNT) cell proliferation. The combinatorial treatment is more effective than monotherapy in inhibiting colony formation, cell viability, NET spheroids growth rate and mTOR phosphorylation in both NET cell lines. In a PAN-NET cell line, metformin did not affect Akt phosphorylation; conversely, it significantly decreased Akt phosphorylation in a PNT cell line. Using everolimus-resistant NET cells, we confirmed that metformin maintained its effects, acting by two different pathways: Akt-dependent or independent, depending on the cell type, with both leading to mTOR suppression. Conclusions: Considering the promising effects of the everolimus and metformin combination in NET cells, our results provide a rationale for its use in NET patients.

Chemotherapy and Targeted Therapy beyond Adenocarcinoma of the Lung: Neuroendocrine Carcinoma

Neuroendocrine carcinoma (NEC) has been reported to comprise 25% of lung cancer cases. NEC is classified as typical carcinoid, atypical carcinoid, large-cell neuroendocrine carcinoma, and small-cell lung cancer. Carcinoid tumors are less aggressive and surgery is the mainstay of treatment; however, patients with metastatic or inoperable disease need systemic therapy to control carcinoid symptoms and improve survival. Somatostain analogues, targeted agents including everolimus, sunitinib, bevacizumab, and conventional chemotherapy have emerged as treatment options for such patients. Large-cell neuroendocrine carcinoma exhibits more aggressive behavior and has a poorer prognosis than carcinoid tumors. No standard adjuvant and palliative chemotherapeutic agents have yet been established. This review sets out the treatment options for neuroendocrine tumors. (Korean J Med 2016;90:7-14)

Profiling of 1,350 neuroendocrine tumors for identification of multiple potential drug targets.

4113 Background: Identification of new drug targets may extend treatment options for neuroendocrine tumors (NET) regardless of histologic classification or primary organ site. Methods: 1,350 cases ...

Current Scientific Rationale for the Use of Somatostatin Analogs and mTOR Inhibitors in Neuroendocrine Tumor Therapy

Among the innovative molecules used to manage neuroendocrine tumors, there is growing interest in combining the somatostatin analogs octreotide or pasireotide (SOM230) and everolimus (RAD001), an inhibitor that targets the protein kinase mammalian target of rapamycin (mTOR). The aims of this review were to describe the signaling pathways targeted independently by somatostatin analogs and everolimus and to summarize the scientific rationale for the potential additive or synergistic antitumor effects of combined therapy. The somatostatin analogs (octreotide and lanreotide) have potent inhibitory effects on hypersecretion, thereby alleviating the symptoms associated with neuroendocrine tumors. Furthermore, the antitumor potential of octreotide is now well documented. Pasireotide, a somatostatin analog, has the advantage of targeting a wider range of somatostatin receptors (subtypes 1, 2, 3, and 5) than the analogs previously used in clinical practice (which preferentially target subtype 2) and thus has a broader spectrum of activity. Everolimus is a rapamycin analog that inhibits mTOR, but it is more soluble than rapamycin and can be administered orally. mTOR is a protein kinase involved in many signaling pathways, primarily those initiated by tyrosine kinase receptors. Sustained mTOR activity leads to the induction of cell growth, proliferation, and cell survival. Everolimus therefore has obvious potential in cancer therapy. The combination of somatostatin analogs and everolimus in therapeutic trials offers a promising treatment option for neuroendocrine tumors.

Current treatment options for neuroendocrine tumors

Neuroendocrine tumors are heterogeneous in their clinical behavior and require therapies specially tailored according to staging and grading, origin and expression of peptide receptors. Somatostatin analogues act as antisecretory and antiproliferative agents. Chemotherapy is mandatory for poorly differentiated neuroendocrine carcinomas and is also effective in neuroendocrine tumors of the pancreas and of the bronchial system. For localized neuroendocrine tumors, surgery should be performed with curative intent and is also an option in advanced or metastasized neuroendocrine tumors with the goal to debulk tumor masses. Local ablative therapies may be applied to decrease tumor load in the liver; however, results are often of short duration. Peptide receptor radiotherapy is a new treatment method applying radionuclide-targeted somatostatin receptor agonists for internal cytotoxic radiotherapy in somatostatin receptor-expressing neuroendocrine tumors. Retrospective and prospective clinical studies indicate prolonged progression-free survival and overall survival of patients responding by stable disease or any kind of remission with this innovative treatment, which is, however, available only in a few specialized centers. Finally, small-molecule inhibitors of vascular endothelial growth factor and serine/threonine-protein kinase mTOR pathways have been shown to delay progression in patients with neuroendocrine tumors. In summary, treatment options for neuroendocrine tumors have expanded considerably in the last years leading to prolonged overall survival.

Management of neuroendocrine tumors: current and future therapies

Neuroendocrine tumors (NETs) are a genetically diverse group of malignancies that sometimes produce peptides that cause characteristic hormonal syndromes. NETs can be clinically symptomatic (functioning) or silent (nonfunctioning); both types frequently synthesize more than one peptide, although often these are not associated with specific syndromes. Based on data from various sources, the incidence and prevalence of NETs is increasing. The primary treatment goal for patients with NETs is curative, with symptom control and the limitation of tumor progression as secondary goals. Surgery is the only possible curative approach and so represents the traditional first-line therapy. However, as most patients with NETs are diagnosed once metastases have occurred, curative surgery is generally not possible. Patients therefore require chronic postoperative medical management with the aim of relieving symptoms and, in recent years, suppressing tumor growth and spread. Somatostatin analogues, such as octreotide long-acting repeatable (LAR), can improve the symptoms of carcinoid syndrome and stabilize tumor growth in many patients. Results from the placebo-controlled, double-blind, prospective randomized study on the effect of octreotide LAR in the control of tumor growth in patients with metastatic neuroendocrine midgut tumors (PROMID study) demonstrate that octreotide LAR 30 mg is an effective antiproliferative treatment in patients with newly diagnosed, functionally active or inactive, well-differentiated metastatic midgut NETs. An antiproliferative effect can also be achieved with everolimus, and combination therapy with octreotide LAR has shown synergistic antiproliferative activity. Sunitinib, a tyrosine kinase inhibitor, is active in pancreatic NETs. In the future, pasireotide, the multireceptor targeted somatostatin analogue, has the potential to be an effective therapy for de novo or octreotide-refractory carcinoid syndrome and for inhibiting tumor cell proliferation. Peptide receptor radiotherapy with 90Yttrium-DOTATOC or 177Lutetium-DOTATE is also a new interesting treatment option for NETs.

Does the Expression of c‐kit (CD117) in Neuroendocrine Tumors Represent a Target for Therapy?

Neuroendocrine tumors are very heterogeneous, develop from a variety of tissues, and can be difficult to diagnose. Without the clinical manifestation of metastases, it is often difficult to characterize them as malignant. Even so-called completely (R0) resected tumors can spread clinically visible metastases within a few months after initial surgery. Treatment options for neuroendocrine tumors including pheochromocytoma are limited. Molecular targeted therapies using tyrosine kinase inhibitors might prove to be helpful in patients with these tumors. In an immunohistochemical study, we examined KIT in 26 pheochromocytomas, 8 of which were malignant (3 adrenal pheochromocytomas, 5 paragangliomas). KIT expression was found in one of these 8 malignant tumors. This 2.5-cm-large adrenal pheochromocytoma originated from a woman with neurofibromatosis type 1 and spread into spine, skull, and lung. KIT expression could be demonstrated in 5% of tumor cells. On the basis of KIT expression immunohistochemically, we treated patients with neuroendocrine (i.e., medullary thyroid cancer) and other tumors with imatinib 400 mg per day, but without efficacy after 2 months of therapy. Similar results were shown by other investigators. Therefore, monotherapy with imatinib may not be efficacious in patients with neuroendocrine tumors that express KIT. Tyrosine kinase inhibitors such as sorafenib that targets several receptors in addition to KIT may be more efficacious in treating patients with neuroendocrine tumors.