The Expanding Role of Somatostatin Analogs in Gastroenteropancreatic and Lung Neuroendocrine Tumors

Efficacy and tolerability of somatostatin analogues according to gender in patients with neuroendocrine tumors

As the incidence of neuroendocrine tumors has been rising, gender differences in epidemiology and clinical behavior have emerged, and interest into a gender-driven management of these tumors has grown with the aim to improve survival and quality of life of these patients. Somatostatin Analogues represent the first line of systemic treatment of both functional and non-functional neuroendocrine tumors, through the expression of somatostatin receptors (SSTRs) in the tumor cells, and proved effective in controlling hormonal hypersecretion and inhibiting tumor growth, improving progression-free survival and overall survival of these patients. Aim of the present review is to investigate any differences by gender in efficacy and safety of SSTS-targeted therapies, that represent the mainstay treatment of neuroendocrine tumors, as they emerge from studies of varying design and intent. Although preclinical studies have provided evidence in favor of differences by gender in tumor expression of SSTR, as well as of the role of sex hormones and related receptors in modulating SSTRs expression and function, the clinical studies conducted so far have not shown substantial differences between males and females in either efficacy or toxicity of SSTR-targeted therapies, even if with sometimes inconsistent results. Moreover, in most studies gender was not a predictor of response to treatment. Studies specifically designed to address this issue are needed to develop gender-specific therapeutic algorithms, improving patients' prognosis and quality of life.

Concomitant inhibition of PI3K/mTOR signaling pathways boosts antiproliferative effects of lanreotide in bronchopulmonary neuroendocrine tumor cells

Introduction: Somatostatin analogues (SSAs) are commonly used in the treatment of hormone hypersecretion in neuroendocrine tumors (NETs), however the extent to which they inhibit proliferation is much discussed. Objective: We studied the antiproliferative effects of novel SSA lanreotide in bronchopulmonary NETs (BP-NETs). We focused on assessing whether pretreating cells with inhibitors for phosphatidylinositol 3-kinase (PI3K) and mammalian target for rapamycin (mTOR) could enhance the antiproliferative effects of lanreotide. Methods: BP-NET cell lines NCI-H720 and NCI-H727 were treated with PI3K inhibitor BYL719 (alpelisib), mTOR inhibitor everolimus and SSA lanreotide to determine the effect on NET differentiation markers, cell survival, proliferation and alterations in cancer-associated pathways. NT-3 cells, previously reported to express somatostatin receptors (SSTRs) natively, were used as control for SSTR expression. Results: SSTR2 was upregulated in NCI-H720 and NT-3 cells upon treatment with BYL719. Additionally, combination treatment consisting of BYL719 and everolimus plus lanreotide tested in NCI-H720 and NCI-H727 led to diminished cell proliferation in a dose-dependent manner. Production of proteins activating cell death mechanisms was also induced. Notably, a multiplexed gene expression analysis performed on NCI-H720 revealed that BYL719 plus lanreotide had a stronger effect on the downregulation of mitogens than lanreotide alone. Discussion/Conclusion: We report a widespread analysis of changes in BP-NET cell lines at the genetic/protein expression level in response to combination of lanreotide with pretreatment consisting of BYL719 and everolimus. Interestingly, SSTR expression reinduction could be exploited in therapeutic and diagnostic applications. The overall results of this study support the evaluation of combination-based therapies using lanreotide in preclinical studies to further increase its antiproliferative effect and ultimately facilitate its use in high-grade tumors.

The nerve cells in gastrointestinal cancers: from molecular mechanisms to clinical intervention

Gastrointestinal (GI) cancer is a formidable malignancy with significant morbidity and mortality rates. Recent studies have shed light on the complex interplay between the nervous system and the GI system, influencing various aspects of GI tumorigenesis, such as the malignance of cancer cells, the conformation of tumor microenvironment (TME), and the resistance to chemotherapies. The discussion in this review first focused on exploring the intricate details of the biological function of the nervous system in the development of the GI tract and the progression of tumors within it. Meanwhile, the cancer cell-originated feedback regulation on the nervous system is revealed to play a crucial role in the growth and development of nerve cells within tumor tissues. This interaction is vital for understanding the complex relationship between the nervous system and GI oncogenesis. Additionally, the study identified various components within the TME that possess a significant influence on the occurrence and progression of GI cancer, including microbiota, immune cells, and fibroblasts. Moreover, we highlighted the transformation relationship between non-neuronal cells and neuronal cells during GI cancer progression, inspiring the development of strategies for nervous system-guided anti-tumor drugs. By further elucidating the deep mechanism of various neuroregulatory signals and neuronal intervention, we underlined the potential of these targeted drugs translating into effective therapies for GI cancer treatment. In summary, this review provides an overview of the mechanisms of neuromodulation and explores potential therapeutic opportunities, providing insights into the understanding and management of GI cancers.

Tumour Heterogeneity and the Consequent Practical Challenges in the Management of Gastroenteropancreatic Neuroendocrine Neoplasms

Tumour heterogeneity is a common phenomenon in neuroendocrine neoplasms (NENs) and a significant cause of treatment failure and disease progression. Genetic and epigenetic instability, along with proliferation of cancer stem cells and alterations in the tumour microenvironment, manifest as intra-tumoural variability in tumour biology in primary tumours and metastases. This may change over time, especially under selective pressure during treatment. The gastroenteropancreatic (GEP) tract is the most common site for NENs, and their diagnosis and treatment depends on the specific characteristics of the disease, in particular proliferation activity, expression of somatostatin receptors and grading. Somatostatin receptor expression has a major role in the diagnosis and treatment of GEP-NENs, while Ki-67 is also a valuable prognostic marker. Intra- and inter-tumour heterogeneity in GEP-NENS, however, may lead to inaccurate assessment of the disease and affect the reliability of the available diagnostic, prognostic and predictive tests. In this review, we summarise the current available evidence of the impact of tumour heterogeneity on tumour diagnosis and treatment of GEP-NENs. Understanding and accurately measuring tumour heterogeneity could better inform clinical decision making in NENs.

Predicting Novel Drug Candidates for Pancreatic Neuroendocrine Tumors via Gene Signature Comparison and Connectivity Mapping

INTRODUCTION

There is a paucity of effective treatment options for advanced pancreatic neuroendocrine tumors (pNETs). Genome-wide analyses may allow for potential drugs to be identified based on differentially expressed genes (DEGs).

METHODS

Oligo microarray data of RNA expression profiling of pNETs and normal pancreas tissues were downloaded from the Gene Expression Omnibus. Functional and pathway enrichment information of the DEGs was obtained using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. Corresponding homologous proteins were analyzed and potential therapeutic drugs for pNETs were identified using the Connectivity Map and Drug-Gene Interaction Database.

RESULTS

Assessment of raw data from 12,610 pNET genes demonstrated that 1082 and 380 genes were upregulated and downregulated, respectively, compared with normal pancreas tissue. Upregulated pathways were associated with nitrogen metabolism (i.e., GABAergic synapse, and graft-versus-host disease), whereas downregulated pathways included C-type leptin receptor signaling pathway, pertussis and AMPK signaling pathway. In particular, the protein-protein interaction analysis revealed 10 upregulated hub genes (DYNLL1, GNB5, GNB2, GNG4, GNAI2, GNAI1, HIST2H2BE, NUP107, NUP133, and SNAP25) and 10 downregulated hub genes (CXCL8, F2, CXCL2, GCG, SST, INS, GALR3, CCL20, ADRA2B, and CXCL6). Using the Drug-Gene Interaction Database, candidate drugs for pNETs treatment included 3 EGFR inhibitors (canertinib, erlotinib, WZ-4-145), as well as other cell-signaling pathway inhibitors such as AG-592, acarbose, lonidamine, azacytidine, rottlerin, and HU-211.

CONCLUSION

Using available genetic atlas data, potential drug candidates for treatment of pNETs were identified based on differentially expressed genes. These results may help focus efforts on identifying targeted agents with therapeutic efficacy to treat patients with pNETs.

Development of anti-somatostatin receptors CAR T cells for treatment of neuroendocrine tumors

Background

Neuroendocrine tumors (NETs) overexpress somatostatin receptors (SSTRs).

Methods

We developed a second-generation, ligand-based, anti-SSTR chimeric antigen receptor (CAR) incorporating the somatostatin analog octreotide in its extracellular moiety.

Results

Anti-SSTR CAR T cells exerted antitumor activity against SSTR+NET cell linesin vitro. The killing activity was highly specific, as demonstrated by the lack of CAR T cell reactivity against NET cells engineered to express mutated variants of SSTR2/5 by CRISPR/Cas9. When adoptively transferred in NSG mice, anti-SSTR CAR T cells induced significant antitumor activity against human NET xenografts. Although anti-SSTR CAR T cells could recognize the murine SSTRs as shown by their killing ability against murine NET cells, no obvious deleterious effects on SSTR-expressing organs such as the brain or the pancreas were observed in mice.

Conclusions

Taken together, our results establish anti-SSTR CAR T cells as a potential candidate for early phase clinical investigations in patients with NETs. More broadly, the demonstration that a known peptide drug can direct CAR T cell targeting may streamline the potential utility of multiple peptide motifs and provide a blueprint for therapeutic applications in a variety of cancers.

Recent advances in diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are a rare group of tumors originating from neuroendocrine cells of the digestive system. Their incidence has increased over the last decades. The specific pathogenetic mechanisms underlying GEP-NEN development have not been completely revealed. Unfunctional GEP-NENs are usually asymptomatic; some grow slowly and thus impede early diagnosis, which ultimately results in a high rate of misdiagnosis. Therefore, many GEP-NEN patients present with later staged tumors. Motivated hereby, research attention for diagnosis and treatment for GEP-NENs increased in recent years. The result of which is great progress in clinical diagnosis and treatment. According to the most recent clinical guidelines, improved grading standards can accurately define poorly differentiated grade 3 neuroendocrine tumors and neuroendocrine carcinomas (NECs), which are subclassified into large and small cell NECs. Combining different functional imaging methods facilitates precise diagnosis. The expression of somatostatin receptors helps to predict prognosis. Genetic analyses of mutations affecting death domain associated protein (DAXX), multiple endocrine neoplasia type 1 (MEN 1), alpha thalassemia/intellectual disability syndrome X-linked (ATRX), retinoblastoma transcriptional corepressor 1 (RB 1), and mothers against decapentaplegic homolog 4 (SMAD 4) help distinguishing grade 3 NENs from poorly differentiated NECs. The aim of this review is to summarize the latest research progress on diagnosis and treatment of GEP-NENs.

Somatostatin receptors in congenital hyperinsulinism: Biology to bedside

Congenital hyperinsulinism (CHI), although a rare disease, is an important cause of severe hypoglycemia in early infancy and childhood, causing preventable morbidity and mortality. Prompt diagnosis and appropriate treatment is necessary to prevent hypoglycaemia mediated brain damage. At present, the medical treatment of CHI is limited to diazoxide as first line and synthetic somatostatin receptor ligands (SRLs) as second line options; therefore understanding somatostatin biology and treatment perspectives is important. Under healthy conditions, somatostatin secreted from pancreatic islet δ-cells reduces insulin release through somatostatin receptor induced cAMP-mediated downregulation and paracrine inhibition of β- cells. Several SRLs with extended duration of action are now commercially available and are being used off-label in CHI patients. Efficacy remains variable with the present generation of SRLs, with treatment effect often being compromised by loss of initial response and adverse effects such as bowel ischaemia and hepatobiliary dysfunction. In this review we have addressed the biology of the somatostatin system contexualised to CHI. We have discussed the clinical use, limitations, and complications of somatostatin agonists and new and emerging therapies for CHI.

Somatostatin and Somatostatin Receptors: From Signaling to Clinical Applications in Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) are heterogeneous neoplasms which arise from neuroendocrine cells that are distributed widely throughout the body. Although heterogenous, many of them share their ability to overexpress somatostatin receptors (SSTR) on their cell surface. Due to this, SSTR and somatostatin have been a large subject of interest in the discovery of potential biomarkers and treatment options for the disease. The aim of this review is to describe the molecular characteristics of somatostatin and somatostatin receptors and its application in diagnosis and therapy on patients with NENs as well as the use in the near future of somatostatin antagonists.

177Lu-Dotatate plus long-acting octreotide versus high‑dose long-acting octreotide in patients with midgut neuroendocrine tumours (NETTER-1): final overall survival and long-term safety results from an open-label, randomised, controlled, phase 3 trial

BACKGROUND

The primary analysis of the phase 3 NETTER-1 trial showed significant improvement in progression-free survival with ¹⁷⁷Lu-Dotatate plus long-acting octreotide versus high-dose long-acting octreotide alone in patients with advanced midgut neuroendocrine tumours. Here, we report the prespecified final analysis of overall survival and long-term safety results.

METHODS

This open-label, randomised, phase 3 trial enrolled patients from 41 sites in eight countries across Europe and the USA. Patients were 18 years and older with locally advanced or metastatic, well differentiated, somatostatin receptor-positive midgut neuroendocrine tumours (Karnofsky performance status score ≥60) and disease progression on fixed-dose long-acting octreotide. Patients were randomly assigned (1:1) via an interactive web-based response system to intravenous ¹⁷⁷Lu-Dotatate 7·4 GBq (200 mCi) every 8 weeks (four cycles) plus intramuscular long-acting octreotide 30 mg (¹⁷⁷Lu-Dotatate group) or high-dose long-acting octreotide 60 mg every 4 weeks (control group). The primary endpoint of progression-free survival has been previously reported; here, we report the key secondary endpoint of overall survival in the intention-to-treat population. Final overall survival analysis was prespecified to occur either after 158 deaths or 5 years after the last patient was randomised, whichever occurred first. During long-term follow-up, adverse events of special interest were reported in the ¹⁷⁷Lu-Dotatate group only. This trial is registered with ClinicalTrials.gov, NCT01578239.

FINDINGS

From Sept 6, 2012, to Jan 14, 2016, 231 patients were enrolled and randomly assigned for treatment. The prespecified final analysis occurred 5 years after the last patient was randomly assigned (when 142 deaths had occurred); median follow-up was 76·3 months (range 0·4-95·0) in the ¹⁷⁷Lu-Dotatate group and 76·5 months (0·1-92·3) in the control group. The secondary endpoint of overall survival was not met: median overall survival was 48·0 months (95% CI 37·4-55·2) in the ¹⁷⁷Lu-Dotatate group and 36·3 months (25·9-51·7) in the control group (HR 0·84 [95% CI 0·60-1·17]; two-sided p=0·30). During long-term follow-up, treatment-related serious adverse events of grade 3 or worse were recorded in three (3%) of 111 patients in the ¹⁷⁷Lu-Dotatate group, but no new treatment-related serious adverse events were reported after the safety analysis cutoff. Two (2%) of 111 patients given ¹⁷⁷Lu-Dotatate developed myelodysplastic syndrome, one of whom died 33 months after randomisation (this person was the only the only reported ¹⁷⁷Lu-Dotatate treatment-related death). No new cases of myelodysplastic syndrome or acute myeloid leukaemia were reported during long-term follow-up.

INTERPRETATION

¹⁷⁷Lu-Dotatate treatment did not significantly improve median overall survival versus high-dose long-acting octreotide. Despite final overall survival not reaching statistical significance, the 11·7 month difference in median overall survival with ¹⁷⁷Lu-Dotatate treatment versus high-dose long-acting octreotide alone might be considered clinically relevant. No new safety signals were reported during long-term follow-up.

FUNDING

Advanced Accelerator Applications, a Novartis company.

Targeted Cancer Therapy: What's New in the Field of Neuroendocrine Neoplasms?

Neuroendocrine tumors (NETs) are a heterogeneous family of neoplasms of increasing incidence and high prevalence due to their relatively indolent nature. Their wide anatomic distribution and their characteristic ability to secrete hormonally active substances pose unique challenges for clinical management. They are also characterized by the common expression of somatostatin receptors, a target that has been extremely useful for diagnosis and treatment (i.e., somatostatin analogues (SSAs) and peptide-receptor radionuclide therapy (PRRT)). Chemotherapy is of limited use for NETs of non-pancreatic origin, and the only approved targeted agents for advanced progressive NETs are sunitinib for those of pancreatic origin, and everolimus for lung, gastrointestinal and pancreatic primaries. Despite recent therapeutic achievements, thus, systemic treatment options remain limited. In this review we will discuss the state-of-the-art targeted therapies in the field of NETs, and also future perspectives of novel therapeutic drugs or strategies in clinical development, including recently presented results from randomized trials of yet unapproved antiangiogenic agents (i.e., pazopanib, surufatinib and axitinib), PRRT including both approved radiopharmaceuticals (177Lu-Oxodotreotide) and others in development (177Lu-Edotreotide, 177Lu-Satoreotide Tetraxetan), immunotherapy and other innovative targeted strategies (antibody-drug conjugates, bites,…) that shall soon improve the landscape of personalized treatment options in NET patients.

Treatment personalization in gastrointestinal neuroendocrine tumors

OPINION STATEMENT

The clinical scenario of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) is continuously changing due to significant improvements in the definition of their molecular landscapes and the introduction of innovative therapeutic approaches. Many efforts are currently employed in the integration of the genetics/epigenetics and clinical information. This is leading to an improvement of tumor classification, prognostic stratification and ameliorating the management of patients based on a personalized approach.

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

OBJECTIVE

Long-acting synthetic somatostatin analogues (SSA) are an essential part of the treatment of neuroendocrine neoplasms. We evaluated the chemopreventive effects of a long-acting somatostatin analogue on the development of pancreatic neuroendocrine neoplasms (pNENs) in a genetically engineered MEN1 knockout mouse model.

MATERIALS AND METHODS

Heterozygote MEN1 knockout mice were injected every 28 days subcutaneously with the somatostatin analogue lanreotide (Somatuline Autogel©; Ipsen Pharma) or a placebo starting at day 35 after birth. Mice were euthanized after 6, 9, 12, 15 and 18 months, and the size and number of pNENs were measured due histological analysis and compared to the placebo group.

RESULTS

The median tumor size of pNENs was statistically significantly smaller after 9 (control group vs. SSA group; 706.476 µm² vs. 195.271 µm²; p = 0.0012), 12 (placebo group vs. SSA group 822.022 vs. 255.482; p ≤ 0.001), 15 (placebo group vs. SSA group 1192.568 vs. 273.533; p ≤ 0.001) and after 18 months (placebo group vs. SSA group 1328.299 vs. 864.587; p ≤ 0.001) in the SSA group. Comparing the amount of tumors in both groups, a significant reduction was achieved in treated Men1^(+/-) mice (41%, p = 0.002). Immunostaining showed, however, no significant difference in the expression of the apoptosis marker caspase-3, but a significant difference in Ki67 index as a marker for tumor cell proliferation (p ≤ 0.005).

CONCLUSION

Long-acting somatostatin analogues may be an effective chemopreventive approach to delay the progression of MEN1-associated pNENs. After our preclinical results, we would recommend to evaluate the effects of long-acting SSA in a prospective clinical trial.

Somatostatin Receptor Expression Is Associated With Metastasis and Patient Outcome in Pulmonary Carcinoid Tumors

CONTEXT

Pulmonary carcinoids (PCs) belong to neuroendocrine tumors that often overexpress somatostatin receptors (SSTRs). This overexpression provides a molecular basis for tumor imaging and treatment with somatostatin analogs.

OBJECTIVE

To evaluate SSTR1 to SSTR5 distribution in a large set of PC tumors and to investigate whether the expression is associated with clinicopathological and outcome data.

DESIGN, SETTING, AND PATIENTS

This retrospective study was conducted at Helsinki University Hospital and University of Helsinki. It included 178 PC tumors coupled with patients' clinical data retrieved through Finnish biobanks. After histological reclassification, tissue specimens were processed into next-generation tissue microarray format and stained immunohistochemically with monoclonal SSTR1 to SSTR5 antibodies.

MAIN OUTCOME MEASURE

SSTR1 to SSTR5 expression in PC tumors.

RESULTS

Expression of SSTR1 to SSTR5 was detected in 52%, 75%, 56%, 16%, and 32% of the tumors, respectively. Membrane-bound staining was observed for all receptors. SSTR2 negativity and SSTR4 positivity was associated with lymph node involvement at the time of surgery (P = 0.014 and P = 0.017, respectively) and with distant metastasis (P = 0.027 and P = 0.015, respectively). SSTR3 and SSTR4 expression was associated with increased risk of shorter survival [P = 0.046, hazard ratio (HR) 4.703, 95% CI 1.027 to 21.533; and P = 0.013, HR 6.64, 95% CI 1.48 to 29.64, respectively], whereas expression of SSTR1 and SSTR2 was associated with improved outcome (P = 0.021, HR 0.167, 95% CI 0.037 to 0.765; and P = 0.022, HR 0.08, 95% CI 0.01 to 0.70, respectively).

CONCLUSION

SSTR1 to SSTR5 expression is observed in PCs. As SSTR expression is associated with the tumor's metastatic potential and patient outcome, these receptors may offer the possibility for individualized prognosis estimation.

Neuroendocrine Tumors (NETs) of the Minor Papilla/Ampulla: Analysis of 16 Cases Underlines Homology With Major Ampulla NETs and Differences From Extra-Ampullary Duodenal NETs

Neuroendocrine tumors (NETs) of the minor papilla/ampulla (MIPA) are rare and poorly studied. Only individual case reports and no comprehensive analysis are available from the literature. We collected 16 MIPA NETs and investigated their clinicopathologic and immunohistochemical features, including markers such as somatostatin, pancreatic polypeptide, gastrin, serotonin, MUC1, cytokeratin 7, and somatostatin receptors type 2A and 5. The median age at diagnosis was 57.5 years, and the female-to-male ratio was 2.2:1. The median NET size was 1.45 cm, and most (94%) were low-grade (G1) tumors. Similarly to what was observed in the major ampulla, 3 histotypes were found: (i) ampullary-type somatostatin-producing tumors (ASTs, 10 cases), characterized by somatostatin expression in most tumor cells, focal-to-extensive tubulo-acinar structures, often with psammoma bodies, MUC1 reactivity, and no or rare membranous reactivity for somatostatin receptor type 2A; (ii) gangliocytic paragangliomas (3 cases), characterized by the coexistence of 3 tumor cell types: epithelioid, often reactive for pancreatic polypeptide, ganglion-like cells, and S100 reactive sustentacular/stromal cells; and (iii) ordinary nonfunctioning NETs (3 cases), resembling those more commonly observed in the extra-ampullary duodenum. Comparable histotypes could also be recognized among the 30 MIPA NETs from the literature. No NET-related patient death among MIPA cases was observed during a median follow-up of 38 months; however, MIPA ASTs showed lymph node metastases and invasion of the duodenal muscularis propria or beyond in 44% and 40% of cases, respectively. In conclusion, MIPA NETs closely resemble tumors arising in the major ampulla, with predominance of ASTs.

Peptide receptor radionuclide therapy with 177Lu-DOTA-TATE as a promising treatment of malignant insulinoma: a series of case reports and literature review

INTRODUCTION

Insulinomas are a rare type of pancreatic neuroendocrine tumours characterized by insulin hypersecretion. They are considered malignant when metastases are present. Traditional therapies often promote only temporarily symptomatic relief and may be associated with severe adverse effects. There is scarce experience in treating malignant insulinomas with peptide receptors radionuclide therapy (PRRNT).

PATIENTS AND METHODS

We describe PRRNT results in four patients with inoperable malignant insulinomas with poorly controllable hypoglycaemia. All patients received therapy with ¹⁷⁷Lu-DOTA-TATE after conventional therapies failed in controlling disease progression and symptoms. The activity administered per cycle was 4.8-7.4 GBq. The interval between cycles was 10-16 weeks. Haematology, liver and kidney function tests were performed before treatment initiation and 5 and 10 weeks after each cycle.

RESULTS

Patient 1 presented significant clinical benefit for 13 months after PRRNT, with imaging improvement. Patient 2 obtained reduction of the number and severity of hypoglycaemic episodes during 15 months after therapy. Patient 3 is asymptomatic since PRRNT first cycle performed 23 months ago and revealed significant imaging improvement. Patient 4 had resolution of hypoglycaemia only 3 days after PRRNT first cycle and today, 16 months after therapy, the disease seems to be in remission and the patient maintains euglycaemic state. PRRNT was well tolerated, with only hematologic grade 2 toxicity in patient 1 and mild kidney toxicity in patient 3.

CONCLUSIONS

After the start of ¹⁷⁷Lu-DOTA-TATE all patients achieved hypoglycaemia symptomatic control and had evident improvement of their quality of life. Three patients showed imagiological improvement suggesting reduced tumour load.

Evaluation of Spheroid 3D Culture Methods to Study a Pancreatic Neuroendocrine Neoplasm Cell Line

Pancreatic Neuroendocrine Neoplasms (pNEN) are rare tumors which treatment still represent an important clinical problem, due to the paucity of medical treatments. Due to tumor complexity, techniques as 3D cultures are important to study drug activity in a more realistic model. This study aims to compare three different 3D culture methods in order to understand which one can be considered the best option in terms of experimental easiness and reproducibility in studying the efficacy of a target drug on pNEN. The BON1 cell line was used as a pNEN model and the well-known Receptor Tyrosine Kinase inhibitor Sunitinib was used in order to better investigate the different features of each method. The investigated methods are: (1) 96-well hanging drop plates (HD plates), (2) 24-well plates with a cell-repellent surface, and (3) ultra-low attachment 96-well plates with clear round bottom (ULA plates). The evaluated parameters during the study were: cell seeding, easiness in spheroids formation, morphology, culture maintenance, medium change, spheroids monitoring, picture quality, spheroid perimeter measurement reproducibility error, possibility to perform assays into the seeding plate, overall time of the experiment. Moreover, we investigated how culture methods can influence experimental outcomes evaluating perimeter changes, cell viability and immunohistochemistry of spheroids treated with different Sunitinib concentrations. Results showed that each method has weak and strong points but, considering the easiness of spheroids maintenance and reproducibility results, ULA plates method appears to be the best approach to culture BON1 spheroids and, therefore, to study pNEN.

Variable somatostatin receptor subtype expression in 151 primary pheochromocytomas and paragangliomas

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are neuroendocrine tumors that express somatostatin receptors (SSTRs), a phenomenon that constitutes a basis for tumor imaging and treatment with somatostatin analogues and peptide receptor radionuclide therapy. We studied the immunohistochemical expression of SSTR1-5 in 151 primary tumors, including 14 metastasized and 16 SDHB-deficient tumors. SSTR2 and SSTR3 were most abundantly present in these tumors, whereas the tumors were mostly negative for SSTR1, SSTR4, and SSTR5. All metastasized PGLs (9/9), but only one metastasized PHEO (1/5), were strongly SSTR2 positive. SSTR3 expression was lower in metastatic tumors and tumors with a high proliferation rate (MIB1 ≥ 5%), but tumors had variable individual SSTR profiles. No correlation was found between SDHB status and SSTR expression. Our results suggest that new SSTR analogues with affinity for several SSTRs could be relevant for a subgroup of patients with these tumors. Better knowledge of tumor SSTR profiles could open the door for personalized imaging and treatment in the future. Because SSTR profiles vary in PHEOs and PGLs, individual analysis is required for each tumor.

Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are heterogeneous malignancies arising from the diffuse neuroendocrine system. They frequently originate in the gastroenteropancreatic (GEP) tract and the bronchopulmonary tree, and their incidence has steadily increased in the last 3 decades. Fundamental biologic and genomic differences underlie the clinical heterogeneity of NETs, and distinct molecular features characterize NETs of different grades and different primary sites. Although surgery remains the cornerstone of treatment for localized tumors, systemic treatment options for patients with metastatic NETs have expanded considerably. Somatostatin analogs have demonstrated both antisecretory and antitumor efficacy. Peptide receptor radionuclide therapy with lutetium-177 dotatate (¹⁷⁷ Lu-DOTATATE) has been approved for advanced GEP-NETs. The antitumor activity of everolimus has been demonstrated across a wide spectrum of NETs, and the antiangiogenic agent sunitinib has been approved for pancreatic NETs (pNETs). Chemotherapy with temozolomide and capecitabine has recently demonstrated an unprecedented prolongation of progression-free survival in a randomized trial of pNETs. Multiple retrospective series have reported the efficacy of liver-directed therapies both for palliating symptoms of hormone excess and for controlling tumor growth. Telotristat, an oral inhibitor of tryptophan hydroxylase, has been shown to reduce diarrhea in patients with carcinoid syndrome. Defining the therapeutic algorithm and identifying biomarkers predictive of response to treatments are among the main priorities for the next decade of research in the NET field.

Treatment with Lanreotide Depot Following Octreotide Long-Acting Release Among Patients with Gastroenteropancreatic Neuroendocrine Tumors

Objective: To examine patients with metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs) who receive sequential treatment with somatostatin analogs. Materials and Methods: This retrospective chart review examined lanreotide depot/autogel tolerability and efficacy among GEP-NET patients who received lanreotide after octreotide long-acting release (LAR) at Tufts University Medical Center. Information obtained included background patient characteristics, dosing, adverse events (AEs), radiologic response, and biochemical markers. Results: Patients (n = 16; 43-81 years; mean age, 64.25 years; 11 female) with nonfunctional, low-grade GEP-NETs receiving octreotide LAR 30-60 mg were transitioned to lanreotide because of patient decision (n = 6), disease progression (n = 6), AEs (n = 2), poor tolerance (n = 1), and injection discomfort/pain (n = 1). Lanreotide doses started at 120 mg (n = 13), 90 mg (n = 1), or 60 mg (n = 2); 8 patients received concomitant therapies, mostly liver-directed (radiofrequency ablation/radioembolization). AEs associated with lanreotide experienced by ≥2 patients were fatigue, diarrhea, nausea, hypertension, pancreatic enzyme deficiency, and hyperglycemia. Radiologic treatment responses of the combination of lanreotide with other therapeutic modalities included complete response (n = 1), partial response (n = 5), and stable disease (n = 9). One patient had radiologic progression. Serum serotonin and chromogranin levels decreased, but urinary 5-hydroxyindoleacetic acid levels appeared relatively unchanged. Conclusion: Among post-octreotide GEP-NET patients, including those with disease progression or poor octreotide tolerance, lanreotide alone or with concomitant therapies was well tolerated and associated with radiologic responses.

Paraneoplastic Cushing syndrome, case-series and review of the literature

OBJECTIVES

Paraneoplastic Cushing syndrome is a rare condition, representing a small fraction of the adrenocorticotropic hormone (ACTH)-dependent cases of Cushing syndrome Methods: Four case descriptions and literature review, highlighting the diagnostic challenges and treatment options are presented.

RESULTS

Different tumor types can be associated with ectopic ACTH secretion. The most common types are bronchial carcinoids and small cell lung carcinoma (SCLC). However, in approximately 10 to 20% of the cases, no overt tumor (occult tumor) can be found. The diagnosis is made in a multistep process. Firstly, hypercortisolemia and adrenocorticotropin hormone dependency have to be confirmed. Distinction between a pituitary or ectopic cause can be cumbersome. MRI of the pituitary gland, a corticotropin releasing hormone stimulation test and a sinus petrosus sampling can be used. Treatment options consist of tumor management, somatostatin analogs, steroidogenesis inhibitors, and bilateral adrenalectomy.

CONCLUSION

Clinicians should consider the diagnosis, and opt for specific treatment, especially in patients with a history of neuroendocrine tumors.

Ex vivo activity of cytotoxic drugs and targeted agents in small intestinal neuroendocrine tumors

Small intestinal neuroendocrine tumors (SI-NETs) are generally considered resistant to systemic treatment. To date, predictive markers for drug activity are lacking. Tumor samples from 27 patients with SI-NETs were analyzed ex vivo for sensitivity to a panel of cytotoxic drugs and targeted agents using a short-term total cell kill assay. Samples of renal cancer, colorectal cancer (CRC), ovarian cancer and chronic lymphocytic leukemia (CLL) were included for comparison. For the SI-NET subset, drug sensitivity was analyzed in relation to clinicopathological variables and pre-treatment biomarkers. For cytotoxic drugs, SI-NETs demonstrated similar or higher sensitivity to 5-FU, platinum, gemcitabine and doxorubicin compared with CRC. For several of the targeted kinase inhibitors, SI-NET was among the most sensitive solid tumor types. CLL and ovarian cancer were generally the most sensitive tumor types to both cytotoxic drugs and protein kinase inhibitors. SI-NET was more sensitive to the mTOR inhibitor sirolimus than the other solid tumor types tested. Individual SI-NET samples demonstrated great variability in ex vivo sensitivity for most drugs. Cross-resistance between different drugs also varied considerably, being higher among protein kinase inhibitors. Age, stage, grade, peritoneal carcinomatosis and extra-abdominal metastases as well as serum chromogranin A and urine 5-HIAA concentrations at diagnosis did not correlate to drug sensitivity ex vivo SI-NETs exhibit intermediate sensitivity ex vivo to cytotoxic and targeted drugs. Clinicopathological factors and currently used biomarkers are not clearly associated to ex vivo sensitivity, challenging these criteria for treatment decisions in SI-NET. The great variability in drug sensitivity calls for individualized selection of therapy.

Efficacy and safety of long-acting pasireotide or everolimus alone or in combination in patients with advanced carcinoids of the lung and thymus (LUNA): an open-label, multicentre, randomised, phase 2 trial

BACKGROUND

There are no data from prospective studies focused exclusively on patients with advanced lung and thymic carcinoids. We aimed to assess the efficacy and safety of long-acting pasireotide and everolimus, administered alone or in combination, in patients with advanced carcinoids of the lung or thymus.

METHODS

LUNA was a prospective, multicentre, randomised, open-label, phase 2 trial of adult patients (aged >18 years) with advanced (unresectable or metastatic), well differentiated carcinoid tumours of the lung or thymus, with radiological progression within 12 months before randomisation, and a WHO performance status of 0-2. At each centre, the investigator or their designee registered each patient using an interactive voice recognition system into one of the three treatment groups. The randomisation allocation sequence was generated by an external company; patients were randomly assigned (1:1:1) to receive treatment with long-acting pasireotide (60 mg intramuscularly every 28 days), everolimus (10 mg orally once daily), or both in combination, for the core 12-month treatment period. Patients were stratified by carcinoid type (typical vs atypical) and line of study treatment (first line vs others). The primary endpoint was the proportion of patients progression-free at month 9, defined as the proportion of patients with overall lesion assessment at month 9 showing a complete response, partial response, or stable disease according to local Response Evaluation Criteria in Solid Tumors, version 1.1, assessed in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study drug and had at least one post-baseline safety assessment. The trial is registered with ClinicalTrials.gov, number NCT01563354. The extension phase of the study is ongoing.

FINDINGS

Between Aug 16, 2013, and Sept 30, 2014, 124 patients were enrolled from 36 centres in nine countries: 41 were allocated to the long-acting pasireotide group, 42 to the everolimus group, and 41 to the combination group. At month 9, the proportion of patients with an overall lesion assessment of complete response, partial response, or stable disease was 16 of 41 patients (39·0%, 95% CI 24·2-55·5) in the long-acting pasireotide group, 14 of 42 patients (33·3%, 19·6-49·5) in the everolimus group, and 24 of 41 patients (58·5%, 42·1-73·7) in the combination group. The most common grade 1-2 adverse events with a suspected association with long-acting pasireotide monotherapy were diarrhoea (15 [37%] of 41), hyperglycaemia (17 [41%]), and weight loss (8 [20%]); those with a suspected association with everolimus monotherapy were stomatitis (26 [62%] of 42) and diarrhoea (16 [38%]); and those suspected to be associated with combination treatment were hyperglycaemia (27 [66%] of 41]), diarrhoea (19 [46%]), and asthenia (8 [20%]). The most common grade 3-4 adverse events with a suspected association with long-acting pasireotide monotherapy were γ-glutamyltransferase increased (four [10%] of 41 patients), diarrhoea (three [7%]), and hyperglycaemia (three [7%]); those for everolimus were hyperglycaemia (seven [17%] of 42 patients), stomatitis (four [10%]), and diarrhoea (three [7%]); those for combination treatment were hyperglycaemia (nine [22%] of 41 patients) and diarrhoea (four [10%]). 11 patients died during the core 12-month treatment phase or up to 56 days after the last study treatment exposure date: two (5%) of 41 in the long-acting pasireotide group, six (14%) of 42 in the everolimus group, and three (7%) of 41 in the combination group. No deaths were suspected to be related to long-acting pasireotide treatment. One death in the everolimus group (acute kidney injury associated with diarrhoea), and two deaths in the combination group (diarrhoea and urinary sepsis in one patient, and acute renal failure and respiratory failure in one patient) were suspected to be related to everolimus treatment. In the latter patient, acute renal failure was not suspected to be related to everolimus treatment, but respiratory failure was suspected to be related.

INTERPRETATION

The study met the primary endpoint in all three treatment groups. Safety profiles were consistent with the known safety profiles of these agents. Further studies are needed to confirm the antitumour efficacy of the combination of a somatostatin analogue with everolimus in lung and thymic carcinoids.

FUNDING

Novartis Pharma AG.

Treatment Strategies for Metastatic Neuroendocrine Tumors of the Gastrointestinal Tract

OPINION STATEMENT

The therapeutic landscape of gastroenteropancreatic-neuroendocrine tumors (GEP-NETs) has evolved significantly in recent years. Current and emerging treatment options include somatostatin analogs, radiolabeled somatostatin analogs, the mTOR inhibitor everolimus, and the tyrosine kinase inhibitor sunitinib. Although high-quality data from phase III trials are lacking, cytotoxic agents are commonly used for the treatment of poorly differentiated neuroendocrine carcinomas and well-differentiated NETs originating in the pancreas. Hepatic-directed therapies are recommended for patients with slow-growing, liver-predominant disease but have never been compared to systemic agents. Telotristat ethyl, a novel serotonin synthesis inhibitor, has recently demonstrated efficacy in palliating diarrhea in patients with poorly controlled carcinoid syndrome. In the absence of definite predictive biomarkers, therapeutic decisions in most cases rely on clinical and pathological criteria. However, navigating the current therapeutic algorithm may be challenging, and future trials need to address several important questions: what is the best sequence of treatment? Is there a role for combination therapies in GEP-NETs? Are neoadjuvant, adjuvant, or maintenance strategies safe and effective? Do all NET patients require active treatment? What new molecular targets can be clinically exploited? A tight integration between basic and clinical research is needed to further advance the field of NETs.

Will clinical heterogeneity of neuroendocrine tumors impact their management in the future? Lessons from recent trials

PURPOSE OF REVIEW

Neuroendocrine tumors (NETs) are a group of biologically and clinically heterogeneous neoplasms arising from the diffuse neuroendocrine system. In the last few years, advances in our understanding of the biology of these tumors have translated into an expansion of treatment options for patients with NETs. Current treatment modalities include somatostatin analogs (SSAs), radiolabeled SSAs, targeted agents, cytotoxic drugs and liver-directed therapies for the management of metastatic disease.

RECENT FINDINGS

Recent studies have expanded the role of SSAs in gastroenteropancreatic (GEP)-NETs, and everolimus has shown robust antitumor activity across a broad range of NETs of the lung and GEP tract. The radiolobeled SSA Lu-DOTATATE has been investigated in a randomized phase III trial, and has demonstrated exceptional efficacy and tolerability in patients with progressive midgut NETs. The new serotonin inhibitor telotristat etiprate has shown significant activity in the palliation of symptoms of carcinoid syndrome, and its approval by regulatory authorities is expected soon.

SUMMARY

The field of NETs has been transformed from one dominated by limited treatment options to one characterized by an increasing number of therapeutic agents and active clinical trials. Navigating the current therapeutic algorithm may be challenging, and requires an understanding both of the heterogeneity of NETs and of characteristics that are shared by NETs across tumor subtypes.

Pharmacotherapeutic Targeting of G Protein-Coupled Receptors in Oncology: Examples of Approved Therapies and Emerging Concepts

G protein-coupled receptors (GPCRs) are involved in numerous physio-pathological processes, including the stimulation of cancer progression. In this regard, it should be mentioned that although GPCRs may represent major pharmaceutical targets, only a few drugs acting as GPCR inhibitors are currently used in anti-tumor therapies. For instance, certain pro-malignancy effects mediated by GPCRs are actually counteracted by the use of small molecules and peptides that function as receptor antagonists or inverse agonists. Recently, humanized monoclonal antibodies targeting GPCRs have also been developed. Here, we review the current GPCR-targeted therapies for cancer treatment, summarizing the clinical studies that led to their official approval. We provide a broad overview of the mechanisms of action of the available anti-cancer drugs targeting gonadotropin-releasing hormone, somatostatin, chemokine, and Smoothened receptors. In addition, we discuss the anti-tumor potential of novel non-approved molecules and antibodies able to target some of the aforementioned GPCRs in different experimental models and clinical trials. Likewise, we focus on the repurposing in cancer patients of non-oncological GPCR-based drugs, elucidating the rationale behind this approach and providing clinical evidence on their safety and efficacy.

Theoretical analysis of somatostatin receptor 5 with antagonists and agonists for the treatment of neuroendocrine tumors

We report on SSTR5 receptor modeling and its interaction with reported antagonist and agonist molecules. Modeling of the SSTR5 receptor was carried out using multiple templates with the aim of improving the precision of the generated models. The selective SSTR5 antagonists, agonists and native somatostatin SRIF-14 were employed to propose the binding site of SSTR5 and to identify the critical residues involved in the interaction of the receptor with other molecules. Residues Q2.63, D3.32, Q3.36, C186, Y7.34 and Y7.42 were found to be highly significant for their strong interaction with the receptor. SSTR5 antagonists were utilized to perform a 3D quantitative structure-activity relationship study. A comparative molecular field analysis (CoMFA) was conducted using two different alignment schemes, namely the ligand-based and receptor-based alignment methods. The best statistical results were obtained for ligand-based ([Formula: see text], [Formula: see text] = 0.988, noc = 4) and receptor-guided methods (docked mode 1:[Formula: see text], [Formula: see text], noc = 5), (docked mode 2:[Formula: see text] = 0.555, [Formula: see text], noc = 5). Based on CoMFA contour maps, an electropositive substitution at [Formula: see text], [Formula: see text] and [Formula: see text] position and bulky group at [Formula: see text] position are important in enhancing molecular activity.

Theoretical analysis of somatostatin receptor 5 with antagonists and agonists for the treatment of neuroendocrine tumors

We report on SSTR5 receptor modeling and its interaction with reported antagonist and agonist molecules. Modeling of the SSTR5 receptor was carried out using multiple templates with the aim of improving the precision of the generated models. The selective SSTR5 antagonists, agonists and native somatostatin SRIF-14 were employed to propose the binding site of SSTR5 and to identify the critical residues involved in the interaction of the receptor with other molecules. Residues Q2.63, D3.32, Q3.36, C186, Y7.34 and Y7.42 were found to be highly significant for their strong interaction with the receptor. SSTR5 antagonists were utilized to perform a 3D quantitative structure-activity relationship study. A comparative molecular field analysis (CoMFA) was conducted using two different alignment schemes, namely the ligand-based and receptor-based alignment methods. The best statistical results were obtained for ligand-based ([Formula: see text], [Formula: see text] = 0.988, noc = 4) and receptor-guided methods (docked mode 1:[Formula: see text], [Formula: see text], noc = 5), (docked mode 2:[Formula: see text] = 0.555, [Formula: see text], noc = 5). Based on CoMFA contour maps, an electropositive substitution at [Formula: see text], [Formula: see text] and [Formula: see text] position and bulky group at [Formula: see text] position are important in enhancing molecular activity.

Somatostatin receptor expression on von Hippel-Lindau-associated hemangioblastomas offers novel therapeutic target

Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX – caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat ⁶⁸Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy.

Four Neuroendocrine Tumor Types and Neuroendocrine Carcinoma of the Duodenum: Analysis of 203 Cases

BACKGROUND

Several types of neuroendocrine neoplasms (NENs) have been described in the duodenal tract, from low-grade tumors (NETs) to high-grade neuroendocrine carcinomas (NECs). A comprehensive analysis of histology, hormonal profile and prognostic parameters of a sufficiently large duodenal NEN series to cover all main kinds of neoplasms is however lacking.

METHODS

We collected a retrospective series of 203 duodenal wall and ampullary region NENs, from six specialized endocrine pathology centers. All were characterized histopathologically and histochemically, and 190 were followed for a median of 9 years.

RESULTS

Twenty-seven poorly differentiated NECs, mostly from the ampullary region, were identified and shown to lead to patient demise in a median of 10 months. Among 176 NETs, four subtypes were characterized, including 20 gastrinomas, 37 ampullary-type somatostatin-producing NETs (ASTs), 12 gangliocytic paragangliomas (GPs) and 106 nonfunctioning NETs (nfNETs). ASTs and GPs were mostly localized in the ampullary/periampullary region, while gastrinomas and nfNETs were mainly from the proximal duodenum. ASTs and gastrinomas showed high rates of local infiltration (especially lymphoinvasion and deep duodenal wall/pancreatic tissue invasion) and lymph node metastasis, while nfNETs had significantly lower and more size-dependent local invasive potential. Disease-specific survival differed significantly between NETs and NECs, though not among NET subtypes. NET cases with distant metastases (n = 23) were significantly associated with larger size, higher proliferative grade, lymphovascular invasion, deep invasion and local lymph node metastasis.

CONCLUSION

Our careful analysis of a large series of duodenal NENs identified five histologically and prognostically different histotypes of potential clinical relevance.

Notch Signaling in Neuroendocrine Tumors

Carcinoids and neuroendocrine tumors (NETs) are a heterogeneous group of tumors that arise from the neuroendocrine cells of the GI tract, endocrine pancreas, and the respiratory system. NETs remain significantly understudied with respect to molecular mechanisms of pathogenesis, particularly the role of cell fate signaling systems such as Notch. The abundance of literature on the Notch pathway is a testament to its complexity in different cellular environments. Notch receptors can function as oncogenes in some contexts and tumor suppressors in others. The genetic heterogeneity of NETs suggests that to fully understand the roles and the potential therapeutic implications of Notch signaling in NETs, a comprehensive analysis of Notch expression patterns and potential roles across all NET subtypes is required.

AAVP displaying octreotide for ligand-directed therapeutic transgene delivery in neuroendocrine tumors of the pancreas

Patients with inoperable or unresectable pancreatic neuroendocrine tumors (NETs) have limited treatment options. These rare human tumors often express somatostatin receptors (SSTRs) and thus are clinically responsive to certain relatively stable somatostatin analogs, such as octreotide. Unfortunately, however, this tumor response is generally short-lived. Here we designed a hybrid adeno-associated virus and phage (AAVP) vector displaying biologically active octreotide on the viral surface for ligand-directed delivery, cell internalization, and transduction of an apoptosis-promoting tumor necrosis factor (TNF) transgene specifically to NETs. These functional attributes of AAVP-TNF particles displaying the octreotide peptide motif (termed Oct-AAVP-TNF) were confirmed in vitro, in SSTR type 2-expressing NET cells, and in vivo using cohorts of pancreatic NET-bearing Men1 tumor-suppressor gene KO mice, a transgenic model of functioning (i.e., insulin-secreting) tumors that genetically and clinically recapitulates the human disease. Finally, preclinical imaging and therapeutic experiments with pancreatic NET-bearing mice demonstrated that Oct-AAVP-TNF lowered tumor metabolism and insulin secretion, reduced tumor size, and improved mouse survival. Taken together, these proof-of-concept results establish Oct-AAVP-TNF as a strong therapeutic candidate for patients with NETs of the pancreas. More broadly, the demonstration that a known, short, biologically active motif can direct tumor targeting and receptor-mediated internalization of AAVP particles may streamline the potential utility of myriad other short peptide motifs and provide a blueprint for therapeutic applications in a variety of cancers and perhaps many nonmalignant diseases as well.