Octreotide attenuates intestinal barrier damage by maintaining basal autophagy in Caco2 cells

The intestinal mucosal barrier is of great importance for maintaining the stability of the internal environment, which is closely related to the occurrence and development of intestinal inflammation. Octreotide (OCT) has potential applicable clinical value for treating intestinal injury according to previous studies, but the underlying molecular mechanisms have remained elusive. This article is based on a cell model of inflammation induced by lipopolysaccharide (LPS), aiming to explore the effects of OCT in protecting intestinal mucosal barrier function. A Cell Counting Kit‑8 assay was used to determine cell viability and evaluate the effectiveness of OCT. Gene silencing technology was used to reveal the mediated effect of somatostatin receptor 2 (SSTR2). The changes in intestinal permeability were detected through trans‑epithelial electrical resistance and fluorescein isothiocyanate‑dextran 4 experiments, and the alterations in tight junction proteins were detected using immunoblotting and reverse transcription fluorescence‑quantitative PCR technology. Autophagosomes were observed by electron microscopy and the dynamic changes of the autophagy process were characterized by light chain (LC)3‑II/LC3‑I conversion and autophagic flow. The results indicated that SSTR2‑dependent OCT can prevent the decrease in cell activity. After LPS treatment, the permeability of monolayer cells decreased and intercellular tight junctions were disrupted, resulting in a decrease in tight junction protein zona occludens 1 in cells. The level of autophagy‑related protein LC3 was altered to varying degrees at different times. These abnormal changes gradually returned to normal levels after the combined application of LPS and SSTR2‑dependent OCT, confirming the role of OCT in protecting intestinal barrier function. These experimental results suggest that OCT maintains basal autophagy and cell activity mediated by SSTR2 in intestinal epithelial cells, thereby preventing the intestinal barrier dysfunction in inflammation injury.

The Novel SSTR3 Agonist ITF2984 Exerts Antimitotic and Proapoptotic Effects in Human Non-Functioning Pituitary Neuroendocrine Tumor (NF-PitNET) Cells

Somatostatin receptor ligands (SRLs) with high affinity for somatostatin receptors 2 and 5 (SSTR2 and SSTR5) are poorly efficacious in NF-PitNETs, expressing high levels of SSTR3. ITF2984 is a pan-SSTR ligand with high affinity for SSTR3, able to induce SSTR3 activation and to exert antitumoral activity in the MENX rat model. The aim of this study was to test ITF2984's antiproliferative and proapoptotic effects in NF-PitNET primary cultured cells derived from surgically removed human tumors and to characterize their SSTR expression profile. We treated cells derived from 23 NF-PitNETs with ITF2984, and a subset of them with octreotide, pasireotide (SRLs with high affinity for SSTR2 or 5, respectively), or cabergoline (DRD2 agonist) and we measured cell proliferation and apoptosis. SSTR3, SSTR2, and SSTR5 expression in tumor tissues was analyzed by qRT-PCR and Western blot. We demonstrated that ITF2984 reduced cell proliferation (-40.8 (17.08)%, p < 0.001 vs. basal, n = 19 NF-PitNETs) and increased cell apoptosis (+41.4 (22.1)%, p < 0.001 vs. basal, n = 17 NF-PitNETs) in all tumors tested, whereas the other drugs were only effective in some tumors. In our model, SSTR3 expression levels did not correlate with ITF2984 antiproliferative nor proapoptotic effects. In conclusion, our data support a possible use of ITF2984 in the pharmacological treatment of NF-PitNET.

Does Telotristat Have a Role in Preventing Carcinoid Heart Disease?

Carcinoid heart disease (CHD) is a frequent and life-threatening complication in patients with carcinoid tumors. Its clinical management is challenging is some cases since serotonin-induced valve fibrosis leads to heart failure. Telotristat is an inhibitor of tryptophan-hydroxylase (TPH), a key enzyme in serotonin production. Telotristat use in patients with carcinoid syndrome and uncontrollable diarrhea under somatostatin analogs is approved, but its specific role in patients with CHD is still not clear. IN this context, we aimed to explore the effect of telotristat in heart fibrosis using a mouse model of serotonin-secreting metastasized neuroendocrine neoplasm (NEN). To this aim, four treatment groups (n = 10/group) were evaluated: control, monthly octreotide, telotristat alone, and telotristat combined with octreotide. Plasma serotonin and NT-proBNP levels were determined. Heart fibrosis was histologically evaluated after 6 weeks of treatment or when an individual mouse's condition was close to being terminal. Heart fibrosis was observed in all groups. Non-significant reductions in primary tumor growth were observed in all of the treated groups. Feces volume was increased in all groups. A non-significant decrease in feces volume was observed in the octreotide or telotristat-treated groups, while it was significantly reduced with the combined treatment at the end of the study compared with octreotide (52 g reduction; p < 0.01) and the control (44.5 g reduction; p = 0.05). Additionally, plasma NT-proBNP decreased in a non-significant, but clinically relevant, manner in the octreotide (28.2% reduction), telotristat (45.9% reduction), and the octreotide + telotristat (54.1% reduction) treatment groups. No significant changes were observed in plasma serotonin levels. A similar non-significant decrease in heart valve fibrosis was observed in the three treated groups. In conclusion, Telotristat alone and especially in combination with octreotide decreases NT-proBNP levels in a mouse model of serotonin-secreting metastasized NEN, when compared with the control and octreotide, but its effect on heart valve fibrosis (alone and in combination) was not superior to octreotide in monotherapy.

Octreotide improves human lymphatic fluid transport a translational trial

OBJECTIVES

Chylothorax is a complex condition and many different pharmacological agents have been tried as treatment. Octreotide is used off-label to treat chylothorax, but the efficacy of octreotide remains unclear. A decrease in lymph production is suggested as the mechanism. In this cross-over study, we explore the direct effect of octreotide on human lymphatic drainage.

METHODS

Pre-clinical: the effect of octreotide on force generation was assessed during acute and prolonged drug incubation on human lymphatic vessels mounted in a myograph. Clinical: in a double-blinded, randomized, cross-over trial including 16 healthy adults, we administered either octreotide or saline as an intravenous infusion for 2.5 h. Near-infrared fluorescence imaging was used to examine spontaneous lymphatic contractions and lymph pressure in peripheral lymphatic vessels and plethysmography was performed to assess the capillary filtration rate, capillary filtration coefficient and isovolumetric pressures of the lower leg.

RESULTS

Pre-clinical: human thoracic duct (n = 12) contraction rate was concentration-dependently stimulated by octreotide with a maximum effect at 10 and 100 nmol/l in the myograph chamber. Clinical: spontaneous lymphatic contractions and lymph pressure evaluated by near-infrared fluorescence did not differ between octreotide or placebo (P = 0.36). Plethysmography revealed similar capillary filtration coefficients (P = 0.057), but almost a doubling of the isovolumetric pressures (P = 0.005) during octreotide infusion.

CONCLUSIONS

Octreotide stimulated lymphatic contractility in the pre-clinical setup but did not affect the spontaneous lymphatic contractions or lymph pressure in healthy individuals. Plethysmography revealed a doubling in the isovolumetric pressure. These results suggest that octreotide increases lymphatic drainage capacity in situations with high lymphatic afterload.

Primary weight loss failure after Roux-en-Y gastric bypass is characterized by impaired gut-hormone mediated regulation of food intake

BACKGROUND/OBJECTIVES

After Roux-en-Y gastric bypass (RYGB) a subset of patients never obtain excess BMI loss (EBMIL) > 50% and are categorized as having primary weight loss (WL) failure. We hypothesized that postprandial concentrations of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) would be lower in patients with primary WL failure compared with patients with successfully maintained WL. Furthermore, that inhibition of gut hormone secretions would increase ad libitum food intake less in patients with primary WL failure.

SUBJECTS/METHODS

Twenty women with primary WL failure (LowEBMIL < 50%) were individually matched to twenty women with successful WL (HighEBMIL > 60%) on age, preoperative BMI and time from RYGB. On separate days performed in a random order, patient-blinded subcutaneous injections of octreotide or saline (placebo) were followed by a fixed breakfast and an ad libitum lunch with blood sampling for appetite regulating hormones and Visual-Analogue-Scale (VAS)-scoring of hunger/satiety. Furthermore, participants underwent gene variant analysis for GLP-1, PYY and their receptors, indirect calorimetry, dual-energy X-ray absorptiometry (DXA)-scans, 4-days at-home food registration and 14-days step counting.

RESULTS

On placebo days, postprandial GLP-1, PYY and cholecystokinin (CCK) concentrations were similar between groups after breakfast. Fasting ghrelin was lower in LowEBMIL, but the postprandial suppression was similar. LowEBMIL had lower satiety VAS-scores and less suppression of hunger VAS-scores. Gene variants did not differ between groups. Octreotide diminished GLP-1, PYY, CCK and ghrelin concentrations in both groups. Octreotide did not affect ad libitum food intake in LowEBMIL (-1% [-13, 12], mean [95%CI]), while food intake increased in HighEBMIL (+23% [2,44]).

CONCLUSIONS

Primary WL failure after RYGB was not characterized by impaired secretions of appetite regulating gut hormones. Interestingly, inhibition of gut hormone secretions with octreotide only increased food intake in patients with successful WL post-RYGB. Thus, an impaired central anorectic response to gut hormones may contribute to primary WL failure after RYGB.

Pantoprazole-Induced Bone Loss through Gastrin Secretion: A Stereological Study

Background

Recent researches have failed to uncover a clear explanation for proton pump inhibitors' bone-loss effects. In light of pantoprazole's effects on gastrin secretion, the goal of this study was to see if it caused bone loss through gastrin secretion.

Methods

Forty male rats were divided into control, octreotide (Oct), pantoprazole (Pan), and pantoprazole plus octreotide (Pan+Oct) groups. Serum calcium, phosphorous, alkaline phosphatase, parathyroid hormone, and gastrin were measured before and three months after the treatment, and bone densitometry was examined. The rats' femoral bones were examined stereologically at the end of the investigation.

Results

The Pan group had considerably greater levels of serum alkaline phosphatase, parathyroid hormone (PTH), and gastrin, but this was prevented in the presence of Oct, a gastrin secretion inhibitor. All parameters of femoral bone densitometry in the Pan group were significantly lower than the control after treatment which was considerably inhibited in the presence of Oct. Furthermore, when compared to the control and Oct groups, the rats in the Pan group had a lower trabecular volume, femur bone weight, and volume, as well lower number of osteocytes. The amount of osteoclasts, on the other hand, was much higher in the Pan group than in the other groups.

Conclusion

Overall findings revealed that pantoprazole caused bone loss, which could be prevented by adding octreotide. Because these detrimental effects were not detected in rats given both Oct and Pan, it was suggested that the effect of Pan on bone was produced by a hypergastrinemic condition.

Effects of GLP-1 Infusion Upon Whole-body Glucose Uptake and Skeletal Muscle Perfusion During Fed-state in Older Men

INTRODUCTION

Ageing skeletal muscles become both insulin resistant and atrophic. The hormone glucagon-like peptide 1 (GLP-1) facilitates postprandial glucose uptake as well as augmenting muscle perfusion, independent of insulin action. We thus hypothesized exogenous GLP-1 infusions would enhance muscle perfusion and positively affect glucose metabolism during fed-state clamps in older people.

METHODS

Eight men (71 ± 1 years) were studied in a randomized crossover trial. Basal blood samples were taken before postprandial (fed-state) insulin and glucose clamps, accompanied by amino acid infusions, for 3 hours. Reflecting this, following insertions of peripheral and femoral vessels cannulae and baseline measurements, peripheral IV infusions of octreotide, insulin (Actrapid), 20% glucose, and mixed amino acids; Vamin 14-EF with or without a femoral arterial GLP-1 infusion were started. GLP-1, insulin, and C-peptide were measured by ELISA. Muscle microvascular blood flow was assessed via contrast enhanced ultrasound. Whole-body glucose handling was assayed by assessing glucose infusion rate parameters.

RESULTS

Skeletal muscle microvascular blood flow significantly increased in response to GLP-1 vs feeding alone (5.0 ± 2.1 vs 1.9 ± 0.7 fold-change from basal, respectively; P = 0.008), while also increasing whole-body glucose uptake (area under the curve 16.9 ± 1.7 vs 11.4 ± 1.8 mg/kg-1/180 minutes-1, P = 0.02 ± GLP, respectively).

CONCLUSIONS

The beneficial effects of GLP-1 on whole-body glycemic control are evident with insulin clamped at fed-state levels. GLP-1 further enhances the effects of insulin on whole-body glucose uptake in older men, underlining its role as a therapeutic target. The effects of GLP-1 in enhancing microvascular flow likely also affects other glucose-regulatory organs, reflected by greater whole-body glucose uptake.

Resistance of neuroendocrine tumours to somatostatin analogs

INTRODUCTION

A common feature shared by most neuroendocrine tumors (NETs) is the expression on their surface of somatostatin receptors (SSTRs) that are essential for their pathophysiological regulation, diagnosis, and management. The first-generation synthetic somatostatin analogs (SSAs), octreotide and lanreotide, constitute the cornerstone of treatment for growth hormone secreting pituitary adenomas and functioning, progressive functioning, and non-functioning gastro-entero-pancreatic (GEP-NETs). SSAs exert their mechanism of action through binding to the SSTRs; however, their therapeutic response is frequently attenuated or diminished by the development of resistance. The phenomenon of resistance is complex implicating the presence of additional epigenetic and genetic mechanisms.

AREAS COVERED

We aim to analyze the molecular, genetic, and epigenetic mechanisms of resistance to SSA treatment. We also summarize recent clinical data related to the development of resistance on conventional and non-conventional modes of administration of the first-generation SSAs and the second-generation SSA pasireotide. We explore mechanisms used to counteract the resistance to SSAs using higher doses or more frequent mode of administration of SSAs and/or combination treatments.

EXPERT OPINION

There is considerable heterogeneity in the development of resistance to SSAs that is tumor-specific necessitating the delineation of the underlying pathophysiological processes to further expand their therapeutic applications.

Differential Effects of Somatostatin, Octreotide, and Lanreotide on Neuroendocrine Differentiation and Proliferation in Established and Primary NET Cell Lines: Possible Crosstalk with TGF-β Signaling

GEP-NETs are heterogeneous tumors originating from the pancreas (panNET) or the intestinal tract. Only a few patients with NETs are amenable to curative tumor resection, and for most patients, only palliative treatments to successfully control the disease or manage symptoms remain, such as with synthetic somatostatin (SST) analogs (SSAs), such as octreotide (OCT) or lanreotide (LAN). However, even cells expressing low levels of SST receptors (SSTRs) may exhibit significant responses to OCT, which suggests the possibility that SSAs signal through alternative mechanisms, e.g., transforming growth factor (TGF)-β. This signaling mode has been demonstrated in the established panNET line BON but not yet in other permanent (i.e., QGP) or primary (i.e., NT-3) panNET-derived cells. Here, we performed qPCR, immunoblot analyses, and cell counting assays to assess the effects of SST, OCT, LAN, and TGF-β1 on neuroendocrine marker expression and cell proliferation in NT-3, QGP, and BON cells. SST and SSAs were found to regulate a set of neuroendocrine genes in all three cell lines, with the effects of SST, mainly LAN, often differing from those of OCT. However, unlike NT-3 cells, BON cells failed to respond to OCT with growth arrest but paradoxically exhibited a growth-stimulatory effect after treatment with LAN. As previously shown for BON, NT-3 cells responded to TGF-β1 treatment with induction of expression of SST and SSTR2/5. Of note, the ability of NT-3 cells to respond to TGF-β1 with upregulation of the established TGF-β target gene SERPINE1 depended on cellular adherence to a collagen-coated matrix. Moreover, when applied to NT-3 cells for an extended period, i.e., 14 days, TGF-β1 induced growth suppression as shown earlier for BON cells. Finally, next-generation sequencing-based identification of microRNAs (miRNAs) in BON and NT-3 revealed that SST and OCT impact positively or negatively on the regulation of specific miRNAs. Our results suggest that primary panNET cells, such as NT-3, respond similarly as BON cells to SST, SSA, and TGF-β treatment and thus provide circumstantial evidence that crosstalk of SST and TGF-β signaling is not confined to BON cells but is a general feature of panNETs.

Understanding the Radiobiological Mechanisms Induced by 177Lu-DOTATATE in Comparison to External Beam Radiation Therapy

Radionuclide Therapy (RNT) with ¹⁷⁷Lu-DOTATATE targeting somatostatin receptors (SSTRs) in neuroendocrine tumours (NET) has been successfully used in routine clinical practice, mainly leading to stable disease. Radiobiology holds promise for RNT improvement but is often extrapolated from external beam radiation therapy (EBRT) studies despite differences in these two radiation-based treatment modalities. In a panel of six human cancer cell lines expressing SSTRs, common radiobiological endpoints (i.e., cell survival, cell cycle, cell death, oxidative stress and DNA damage) were evaluated over time in ¹⁷⁷Lu-DOTATATE- and EBRT-treated cells, as well as the radiosensitizing potential of poly (ADP-ribose) polymerase inhibition (PARPi). Our study showed that common radiobiological mechanisms were induced by both ¹⁷⁷Lu-DOTATATE and EBRT, but to a different extent and/or with variable kinetics, including in the DNA damage response. A higher radiosensitizing potential of PARPi was observed for EBRT compared to ¹⁷⁷Lu-DOTATATE. Our data reinforce the need for dedicated RNT radiobiology studies, in order to derive its maximum therapeutic benefit.

A Randomized Trial Evaluating Patient Experience and Preference Between Octreotide Long-Acting Release and Lanreotide for Treatment of Well-Differentiated Neuroendocrine Tumors

PURPOSE

Somatostatin analogs octreotide long-acting release (octLAR) and lanreotide are equally acceptable in National Comprehensive Cancer Network guidelines for neuroendocrine tumors (NETs). Lanreotide is more expensive and given by deep subcutaneous injection, whereas octLAR is given intramuscularly. We evaluated patient preference between these agents in terms of injection site pain.

MATERIALS AND METHODS

Randomized, single-blinded study. Patients with NETs received injections every 4 weeks. Arm 1: octLAR × 3, then lanreotide × 3; arm 2: reverse order. Self-reported injection site pain scores (range, 0-10) were obtained after each of the first three injections. Primary end point was comparison of mean pain scores over the first three injections. Secondary end points included patient-reported preference.

RESULTS

Fifty-one patients enrolled (26 in arm 1 and 25 arm 2), all evaluable for primary end point. No significant difference was identified in the mean pain score over the first three injections (2.4 ± 1.9 v 1.9 ± 1.5, P = .5). Thirty-four of 51 (67%) patients (15 in arm 1 and 19 in arm 2) completed post-therapy questionnaires and were evaluable for secondary end points. Seven patients (47%) in arm 1 and eight patients (42%) in arm 2 indicated no drug preference at the end of treatment. In the other 19 patients, more patients indicated mild or strong preference for octLAR over lanreotide.

CONCLUSION

We found minimal pain with octLAR and lanreotide and no significant pain score differences between the two. Patients indicating a drug preference trended toward favoring octLAR.

Direct effects of octreotide on osteoblast cell proliferation and function

PURPOSE

Octreotide (OCT) is a first-generation somatostatin analog (SSA) used in the treatment of acromegaly and neuroendocrine tumors (NETs). In both diseases, OCT interacts with somatostatin receptors 2 and 5 (SSTR2 and SSTR5), inhibiting hormone hypersecretion and cell proliferation. Skeletal health is an important clinical concern in acromegaly and NETs, since acromegalic osteopathy and NET bone metastasis occur in a remarkable number of patients. While OCT's effect on NET and pituitary cells has been extensively investigated, its direct action on bone cells remains unknown.

METHODS

Here, we investigated OCT direct effects on cell proliferation, differentiation, mineralization, and chemoattractant capacity of murine primary osteoblasts and osteoblast cell line MC3T3-E1.

RESULTS

OCT inhibited osteoblasts and MC3T3-E1 cell proliferation (- 30 ± 16%, and - 22 ± 4%, both p < 0.05 vs control) and increased MC3T3-E1 cell apoptosis (+ 76 ± 32%, p < 0.05 vs control). The anti-proliferative action of OCT was mediated by SSTR2 and SSTR5 in MC3T3-E1, while its pro-apoptotic effect was abrogated in SSTR2-silenced cells. The analysis of genes related to the early and late phases of osteoblast differentiation showed that OCT did not affect Alp, Runx2, Bglap, Spp1, and Sost levels in MC3T3-E1 cells. Similarly, OCT did not affect ALP activity, mineralization, and osteoclastogenic induction. Finally, Vegfa expression decreased in OCT-treated MC3T3-E1 cells and OCT inhibited pancreatic NET cell migration toward the osteoblast-conditioned medium.

CONCLUSION

This study provides the first evidence of the direct action of OCT on osteoblasts which may have clinically relevant implications for the management of skeletal health in subjects with acromegaly and metastatic NETs.

Octreotide-based therapies effectively protect mice from acute and chronic gastritis

Gastritis is a common inflammation of stomach with multiple pathogenesis. This study was designed to investigate the protective effects of oral octreotide (OCT) against ethanol-induced acute gastric injury and H. pylori-induced chronic gastritis via promoting gastric mucosa restoration, reducing gastric acid secretion and inflammation. Male C57BL/6J mice were randomly divided and treated with three doses of OCT (0.5, 2.5, 10 mg/kg) alone or combined respectively with 10 mg/kg omeprazole (OME), 0.2 g/L metronidazole (MTZ)/0.1 g/L clarithromycin (CLR) in drinking water. Oxidative stress analysis, bacterial load analysis, qPCR, gastric histopathology examinations were performed in our study. Ethanol-induced acute gastric ulcer was restored by OCT alone at doses of 2.5 mg/kg, or combined with OME as indicated by markedly reducing Gastrin, Il-6 and Il1b expression through induction of Muc5ac and Occludin, significantly improving hyperacidity and gastric bleeding. As well, OCT combined with MTZ/CLR restored the integrity of gastric mucosa damaged by H. pylori via elevating the expression of Muc5ac and somatostatin receptor 2, decreasing inflammation and increasing the number of chorionic or glands. Besides, OCT is more suitable for long-term medication in the treatment of chronic gastritis than OME. In conclusion, our results proved that the newly developed oral OCT-based therapies were more effective to reverse gastric mucosa damage and inflammation in ethanol and H. pylori infection-induced gastric injury, it is of great significance for supplementing new clinical regimens for the treatment of acute and chronic gastritis.

Long-term effects of somatostatin analogues in rat GH-secreting pituitary tumor cell lines

PURPOSE

First-generation somatostatin analogs, octreotide (OCT) and lanreotide, are the cornerstone for the medical treatment of growth hormone (GH)-secreting pituitary tumors. A new multireceptor analog, such as pasireotide (PAS), showed better activity than OCT in long-term treatment of patients with acromegaly, but modulation of intracellular key processes is still unclear in vitro. In this study, we evaluated the antitumor activity of OCT and PAS in two GH-secreting pituitary tumor cell lines, GH3 and GH4C1, after a long-term incubation.

METHODS

The effects of PAS and OCT on the cell viability, cell cycle, apoptosis, GH secretion, and tumor-induced angiogenesis have been evaluated through a colorimetric method (MTS Assay), DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, ELISA assay and zebrafish platform, respectively.

RESULTS

PAS showed a more potent antitumor activity compared to OCT in GH3 cell line exerted through inhibition of cell viability, perturbation of cell cycle progression, and induction of apoptosis after 6 days of incubation. A concomitant decrease in GH secretion has been observed after 2 days of incubation only with PAS. No effect on tumor-induced angiogenesis has been reported after treatment with OCT or PAS in zebrafish/tumor xenograft model.

CONCLUSION

Long-term incubation with PAS showed a more potent antitumor activity than that reported after OCT in GH3 cells, mainly modulated by a cell cycle perturbation and a relevant induction in apoptosis.

Short-term protective effect of octreotide on the lungs of rats with experimentally induced sepsis

BACKGROUND

Acute respiratory distress syndrome is a devastating complication of severe sepsis. Preclinical models suggest that direct lung injury begins with attack to the lung epithelium, but indirect lung injury results from systemic endothelial damage due to inflammatory mediators. The aim of the present study was to explore the effect of octreotide on lungs in a surgically induced sepsis model in rats.

METHODS

We used 32 male Sprague Dawley rats and divided into four groups. Group 1: Normal (non-operative and orally fed control, n=8); Group 2: Sham operated (n=8); Group 3: Cecal ligation and puncture (CLP) (untreated group, n=8); and Group 4: CLP and 100 µg/kg octreotide i.p. (n=8). For sepsis, CLP procedure was performed on 16 rats to induce a sepsis model. All groups were analyzed, their blood was taken for arterial blood gas analysis. For histological examination, lung tissues were removed and sections were prepared.

RESULTS

In histological examination, if we compare CLP + Octreotide with only CLP group in CLP + Octreotide group decreased inflammatory cell infiltration in alveolar and interstitial area as well as edema, bleeding, when CLP group was compared with octreotide group, all histopathological parameters improved significantly and the severity index decreased from 3 to 1. For arterial blood gas, when CLP and octreotide groups were compared with CLP group, it was observed that there was a significant change in favor of healing and that they almost came up to controls and sham group.

CONCLUSION

It could be hypothesized that it would be beneficial to administer octreotide for ameliorate lung injury state in sepsis patients.

Dimerization of GPCRs: Novel insight into the role of FLNA and SSAs regulating SST2 and SST5 homo- and hetero-dimer formation

The process of GPCR dimerization can have profound effects on GPCR activation, signaling, and intracellular trafficking. Somatostatin receptors (SSTs) are class A GPCRs abundantly expressed in pituitary tumors where they represent the main pharmacological targets of somatostatin analogs (SSAs), thanks to their antisecretory and antiproliferative actions. The cytoskeletal protein filamin A (FLNA) directly interacts with both somatostatin receptor type 2 (SST₂) and 5 (SST₅) and regulates their expression and signaling in pituitary tumoral cells. So far, the existence and physiological relevance of SSTs homo- and hetero-dimerization in the pituitary have not been explored. Moreover, whether octreotide or pasireotide may play modulatory effects and whether FLNA may participate to this level of receptor organization have remained elusive. Here, we used a proximity ligation assay (PLA)-based approach for the in situ visualization and quantification of SST₂/SST₅ dimerization in rat GH3 as well as in human melanoma cells either expressing (A7) or lacking (M2) FLNA. First, we observed the formation of endogenous SST₅ homo-dimers in GH3, A7, and M2 cells. Using the PLA approach combined with epitope tagging, we detected homo-dimers of human SST₂ in GH3, A7, and M2 cells transiently co-expressing HA- and SNAP-tagged SST₂. SST₂ and SST₅ can also form endogenous hetero-dimers in these cells. Interestingly, FLNA absence reduced the basal number of hetero-dimers (-36.8 ± 6.3% reduction of PLA events in M2, P < 0.05 vs. A7), and octreotide but not pasireotide promoted hetero-dimerization in both A7 and M2 (+20.0 ± 11.8% and +44.1 ± 16.3% increase of PLA events in A7 and M2, respectively, P < 0.05 vs. basal). Finally, immunofluorescence data showed that SST₂ and SST₅ recruitment at the plasma membrane and internalization are similarly induced by octreotide and pasireotide in GH3 and A7 cells. On the contrary, in M2 cells, octreotide failed to internalize both receptors whereas pasireotide promoted robust receptor internalization at shorter times than in A7 cells. In conclusion, we demonstrated that in GH3 cells SST₂ and SST₅ can form both homo- and hetero-dimers and that FLNA plays a role in the formation of SST₂/SST₅ hetero-dimers. Moreover, we showed that FLNA regulates SST₂ and SST₅ intracellular trafficking induced by octreotide and pasireotide.

External Validity of Somatostatin Analogs Trials in Advanced Neuroendocrine Neoplasms: The GETNE-TRASGU Study

INTRODUCTION

Somatostatin analogs (SSA) prolong progression-free survival (PFS) in patients with well-differentiated gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). However, the eligibility criteria in randomized clinical trials (RCTs) have been restricted, which contrasts with the vast heterogeneity found in NENs.

METHODS

We identified patients with well-differentiated (Ki-67% ≤20%), metastatic GEP-NENs treated in first line with SSA monotherapy from the Spanish R-GETNE registry. The therapeutic effect was evaluated using a Bayesian Cox model. The objective was to compare survival-based outcomes from real-world clinical practice versus RCTs.

RESULTS

The dataset contained 535 patients with a median age of 62 years (range: 26-89). The median Ki-67% was 4 (range: 0-20). The most common primary tumor sites were as follows: midgut, 46%; pancreas, 34%; unknown primary, 10%; and colorectal, 10%. Half of the patients received octreotide LAR (n = 266) and half, lanreotide autogel (n = 269). The median PFS was 28.0 months (95% CI: 22.1-32.0) for octreotide versus 30.1 months (95% CI: 23.1-38.0) for lanreotide. The overall hazard ratio for lanreotide versus octreotide was 0.90 (95% credible interval: 0.71-1.12). The probability of effect sizes >30% with lanreotide versus octreotide was 2 and 6% for midgut and foregut NENs, respectively.

CONCLUSION

Our study evaluated the external validity of RCTs examining SSAs in the real world, as well as the main effect-modifying factors (progression status, symptoms, tumor site, specific metastases, and analytical data). Our results indicate that both octreotide LAR and lanreotide autogel had a similar effect on PFS. Consequently, both represent valid alternatives in patients with well-differentiated, metastatic GEP-NENs.

TGF-β1/Smad2/3 signaling pathway modulates octreotide antisecretory and antiproliferative effects in pituitary somatotroph tumor cells

Octreotide (OCT) is used to inhibit hormone secretion and growth in somatotroph tumors, although a significant percentage of patients are resistant. It has also been tested in nonfunctioning (NF) tumors but with poor results, with these outcomes having been associated with SSTR2 levels and impaired signaling. We investigated whether OCT inhibitory effects can be improved by TGF-β1 in functioning and nonfunctioning somatotroph tumor cells. OCT effects on hormone secretion and proliferation were analyzed in the presence of TGF-β1 in WT and SSTR2-overexpressing secreting GH3 and silent somatotroph tumor cells. The mechanism underlying these effects was assessed by studying SSTR and TGFβR signaling pathways mediators. In addition, we analyzed the effects of OCT/TGF-β1 treatment on tumor growth and cell proliferation in vivo. The inhibitory effects of OCT on GH- and PRL-secretion and proliferation were improved in the presence of TGF-β1, as well as by SSTR2 overexpression. The OCT/TGF-β1 treatment induced downregulation of pERK1/2 and pAkt, upregulation of pSmad3, and inhibition of cyclin D1. In vivo experiments showed that OCT in the presence of TGF-β1 blocked tumor volume growth, decreased cell proliferation, and increased tumor necrosis. These results indicate that SSTR2 levels and the stimulation of TGF-β1/TGFβR/Smad2/3 pathway are important for strengthening the antiproliferative and antisecretory effects of OCT.

Target therapies plus somatostatin analogs in NETs: a network meta-analysis

Although combination therapy is not recommended in patients with gastro-entero-pancreatic (GEP) neuroendocrine tumors (NETs), this strategy is widely used in clinical practice. This network meta-analysis of randomized trials evaluates targeted therapies and somatostatin analogues in GEP-advanced NETs, either alone or in combination, comparing the efficacy of different, single or combined treatment strategies in terms of progression-free survival (PFS). Interventions were grouped as analogs, everolimus, everolimus plus SSAs, sunitinib and placebo. In a secondary analysis, we also assessed the efficacy of individual-specific pharmacological treatments vs placebo or each other. From 83 studies identified, 8 randomized controlled trials were selected, with a total of 1849 patients with either functioning or non-functioning NETs. The analysis confirmed the superiority of all treatments over placebo (HR ranging from 0.34, 95% CI: 0.24-0.37 with the combination of everolimus plus SSAs to 0.42, 0.31-0.57 with the analogs; moderate quality of evidence). On ranking analysis, the combination of everolimus plus SSA (P score = 0.86) and then everolimus alone (P score = 0.65) ranked highest in increasing PFS. On comparative evaluation of different interventions, pasireotide (P score = 0.96) and everolimus + octreotide (P score = 0.82) ranked as the best pharmacological treatment options. Our findings support the use of combination therapy in the treatment of functioning and non-functioning GEP NETs. The role of pasireotide should be explored in selected subgroups of patients. Lastly, the combination of everolimus and octreotide appears promising and should be more widely considered in clinical practice.

Characterization of the ability of a, second-generation SST-DA chimeric molecule, TBR-065, to suppress GH secretion from human GH-secreting adenoma cells

CONTEXT

Somatostatin (SST) and dopamine (DA) inhibit growth hormone (GH) secretion and proliferation of GH-secreting pituitary adenomas (GHomas) through binding to SSTR2 and D2R receptors. Chimeric SST-DA compounds (Dopastatins) display increased potency in inhibiting GH secretion, as compared with individual SST or DA analogs (alone or combined).

OBJECTIVE

To assess the efficacy of a second-generation dopastatin, TBR-065, in suppressing GH secretion from human GH- and GH/prolactin(PRL)-omas.

DESIGN

We compared the ability of TBR-065 to inhibit GH secretion from primary cultures of human GH- or GH/PRLoma cells to that of the first generation dopastatin, TBR-760 (formerly BIM-23A760), octreotide (OCT) and cabergoline (CAB), the later either alone or combined. We investigated whether there was any impact of BIM-133, the metabolite of TBR-065, on the ability of TBR-065 to inhibit GH in these cultures.

METHODS

17 GH- and GH/PRLomas were included in this study. Inhibition of GH secretion by TBR-065, TBR-760, OCT and CAB (0.1 pM to 0.1 µM) was assessed over a period of 8 h.

RESULTS

All tumors expressed SSTR2 and D2R mRNAs. GH suppression was higher with TBR-065 as compared with TBR-760 (E_max = 57 ± 5.6% vs. 41.1 ± 12.5%, respectively, p < 0.001) or with OCT + CAB (E_max = 56.8 ± 7.2% vs. 44.4 ± 9.4%, p < 0.001). BIM-133 did not have any impact on the activity of TBR-065.

CONCLUSION

TBR-065 has significantly improved efficacy in suppressing GH secretion as compared to current available therapies and may represent a new promising option for the treatment of acromegaly.

Octreotide inhibits secretion of IGF-1 from orbital fibroblasts in patients with thyroid-associated ophthalmopathy via inhibition of the NF-κB pathway

PURPOSE

We investigated the effect of octreotide, a long-acting somatostatin (SST) analogue, on IGF-1 secretion and its possible mechanism of action in orbital fibroblasts (OFs) from patients with thyroid-associated ophthalmopathy (TAO).

MATERIALS AND METHODS

OFs were isolated from the orbital fat of patients with TAO or healthy individuals. The expression level of insulin-like growth factor (IGF)-1, at the protein and mRNA level, was determined with ELISA and quantitative RT-PCR, respectively. The expression pattern of somatostatin receptor (SSTR) 2, which has the highest affinity for octreotide, was examined by flow cytometry. The activity of NF-κB pathway was determined by examining the levels of phosphorylation of IKKα/β and p65, and degradation of IκB via western blot analysis, and by measuring the activity of NF-kB-dependent luciferase via transfection with plasmids containing luciferase and NF-κB binding site.

RESULTS

OFs from patients with TAO showed significantly higher levels of IGF-1 secretion and NF-κB activity even in the absence of stimulation, compared to those from controls. Treatment with octreotide reduced the level of IGF-1 secretion in OFs from patients with TAO, but not in OFs from controls. OFs from patients with TAO expressed higher levels of SSTR2 on the cell surface, compared to controls. In addition, the expression of IGF-1 at the protein and mRNA level was dependent on the activity of NF-κB pathway in OFs from patients with TAO. Furthermore, treatment with octreotide reduced on the activity of NF-κB pathway in OFs from patients with TAO.

CONCLUSION

OFs from patients with TAO showed significantly higher levels of IGF-1 secretion via up-regulation of NF-κB activity. Treatment with octreotide inhibited the secretion of IGF-1 by reducing the NF-κB pathway in OFs, which expressed higher levels of SSRT2 on the cell surface, from patients with TAO.

Octreotide and pasireotide effects on medullary thyroid carcinoma (MTC) cells growth, migration and invasion

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine neoplasm of the parafollicular thyroid C cells. Although somatostatin receptors are expressed by MTCs, treatment with octreotide has shown poor efficacy, whereas recently pasireotide has demonstrated antiproliferative effects in persistent postoperative MTCs. Aim of this study was to test the effects of octreotide and pasireotide on MTC cells proliferation, cell cycle proteins expression, MAPK activation, apoptosis, calcitonin secretion, migration and invasion in TT cell line as well as in primary MTC cultured cells. Our results showed that both octreotide and pasireotide reduced TT cell proliferation (-35.2 ± 12.1%, p < 0.001, and -25.3 ± 24.8%, p < 0.05, at 10^-8 M, respectively), with concomitant inhibition of ERK phosphorylation and cyclin D1 expression. This cytostatic effect was accompanied by a proapoptotic action, with an increase of caspase3/7 activity of 1.5-fold. Moreover, both octreotide and pasireotide inhibited cell migration (-50.9 ± 11.3%, p < 0.01, and -40.5 ± 17%, p < 0.05, respectively) and invasion (-61.3 ± 35.1%, p < 0.05, and -49.7 ± 18%, p < 0.01, respectively). No effect was observed on calcitonin secretion. We then tried to extend these observations to primary cultures (n = 5). Octreotide and/or pasireotide were effective in reducing cells proliferation in 3 out of 5 tumors, and to induce cell apoptosis in 1 out of 3 MTCs. Both octreotide and pasireotide were able to reduce cell migration in all MTC tested. SST2, SST3 and SST5 were expressed in all MTC, with a tendency to increased expression of SST2 in RET mutated vs wild type MTCs. In agreement, inhibition of mutated RET in TT cells reduced SST2 expression. In conclusion, we demonstrated that octreotide and pasireotide inhibited cell proliferation and invasiveness in a subset of MTC, supporting their potential use in the control of tumor growth.

Somatostatin receptor 2 expression in nasopharyngeal cancer is induced by Epstein Barr virus infection: impact on prognosis, imaging and therapy

Nasopharyngeal cancer (NPC), endemic in Southeast Asia, lacks effective diagnostic and therapeutic strategies. Even in high-income countries the 5-year survival rate for stage IV NPC is less than 40%. Here we report high somatostatin receptor 2 (SSTR2) expression in multiple clinical cohorts comprising 402 primary, locally recurrent and metastatic NPCs. We show that SSTR2 expression is induced by the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) via the NF-κB pathway. Using cell-based and preclinical rodent models, we demonstrate the therapeutic potential of SSTR2 targeting using a cytotoxic drug conjugate, PEN-221, which is found to be superior to FDA-approved SSTR2-binding cytostatic agents. Furthermore, we reveal significant correlation of SSTR expression with increased rates of survival and report in vivo uptake of the SSTR2-binding 68Ga-DOTA-peptide radioconjugate in PET-CT scanning in a clinical trial of NPC patients (NCT03670342). These findings reveal a key role in EBV-associated NPC for SSTR2 in infection, imaging, targeted therapy and survival.

Antiproliferative Effect of Above-Label Doses of Somatostatin Analogs for the Management of Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

Above-label doses of somatostatin analogs (SSAs) are increasingly utilized in the management of inoperable/metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs), progressing on standard 4-weekly regimens.

OBJECTIVE

To evaluate the antiproliferative effect of 3-weekly SSA administration in a retrospective GEP-NET cohort.

METHODS

Patients with advanced GEP-NET, treated with long-acting release (LAR) octreotide 30 mg or lanreotide Autogel 120 mg at a 3-weekly interval, after disease progression on standard 4-weekly doses, were retrospectively identified. Clinicopathologic and treatment response data were collected. Progression-free survival (PFS; dose escalation to radiographic progression or death) was estimated with the Kaplan-Meier method. Factors associated with PFS were identified with the Cox proportional-hazards model.

RESULTS

The inclusion criteria were fulfilled by 105 patients. Octreotide LAR was administered to 60 (57%) and lanreotide Autogel to 45 (43%). Indications for dose escalation were breakthrough carcinoid symptoms (58%), radiographic progression (35%) and/or increasing biomarkers (11%). Diarrheal and/or flushing symptomatic improvement was identified in 37/67 cases (55%) and 30/55 cases (55%) with available data, respectively. The disease control rate (radiographic partial response or stable disease) was achieved in 53 patients (50%). Median PFS was 25.0 months (95% CI 16.9-33.1). Patients with radiographic progression <12 months from 4-weekly SSA initiation had worse PFS after dose escalation (7.0 vs. 17.0 months, p = 0.002). In multivariate analysis, pancreatic NETs, a Ki-67 index ≥5% and multiple extrahepatic metastases were independently associated with inferior PFS.

CONCLUSIONS

Above-label doses of SSAs may offer a considerable prolongation of PFS and could be utilized as a bridge to other more toxic treatments. Patients with small bowel/colorectal primaries, a Ki-67 index <5% and absence of/limited extrahepatic metastases are more likely to benefit from this approach.

Pharmacological Acromegaly Treatment: Cost-Utility and Value of Information Analysis

OBJECTIVES

To conduct a cost-utility analysis comparing drug strategies involving octreotide, lanreotide, pasireotide, and pegvisomant for the treatment of patients with acromegaly who have failed surgery, from a Brazilian public payer perspective.

METHODS

A probabilistic cohort Markov model was developed. One-year cycles were employed. The patients started at 45 years of age and were followed lifelong. Costs, efficacy, and quality of life parameters were retrieved from the literature. A discount rate (5%) was applied to both costs and efficacy. The results were reported as costs per quality-adjusted life year (QALY), and incremental cost-effectiveness ratios (ICERs) were calculated when applicable. Scenario analyses considered alternative dosages, discount rate, tax exemption, and continued use of treatment despite lack of response. Value of information (VOI) analysis was conducted to explore uncertainty and to estimate the costs to be spent in future research.

RESULTS

Only lanreotide showed an ICER reasonable for having its use considered in clinical practice (R$ 112,138/US$ 28,389 per QALY compared to no treatment). Scenario analyses corroborated the base-case result. VOI analysis showed that much uncertainty surrounds the parameters, and future clinical research should cost less than R$ 43,230,000/US$ 10,944,304 per year. VOI also showed that almost all uncertainty that precludes an optimal strategy choice involves quality of life.

CONCLUSIONS

With current information, the only strategy that can be considered cost-effective in Brazil is lanreotide treatment. No second-line treatment is recommended. Significant uncertainty of parameters impairs optimal decision-making, and this conclusion can be generalized to other countries. Future research should focus on acquiring utility data.

177Lu-DOTATATE Therapy of Advanced Pancreatic Neuroendocrine Tumors Heavily Pretreated with Chemotherapy: Analysis of Outcome, Safety, and Their Determinants

OBJECTIVE

To retrospectively analyze toxicity, progression-free survival (PFS), overall survival (OS), and their determinants in patients with advanced pancreatic neuroendocrine tumors (PanNETs), previously pretreated with chemothe-r-apy, undergoing peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE.

METHODS

A total of 102 patients with advanced PanNETs, previously pretreated with one (67%) or several (33%) lines of chemotherapy, were included, of whom 90% had progressive disease and the majority (74.5%) had grade 2 tumors. 177Lu-DOTATATE, 7.4 GBq per cycle, was administered with 6- to 8-week intervals in 88% of patients utilizing a dosimetry-guided protocol until an absorbed dose of 23 Gy to the kidneys was reached.

RESULTS

A mean dose of 32 ± 10.9 GBq per patient was administered in 1-10 cycles starting a median of 36 months after PanNET diagnosis. The median follow-up was 34 months, the median PFS was 24 months, and the median OS was 42 months from start of PRRT. Independent risk factors for both progression and death were liver tumor burden >50%, more than one line of previous chemotherapy, and elevated alkaline phosphatase. Resection of the primary tumor was linked to longer survival. Bone marrow toxicity grade 3-4 occurred in 10.8%. One patient (1.0%) developed acute myeloid leukemia. Bone marrow toxicity was unrelated to type and length of previous chemotherapy, amount of administered activity, and absorbed dose to the bone marrow.

CONCLUSION

177Lu-DOTATATE therapy was feasible, highly effective, and safe in patients with advanced PanNETs heavily pretreated with chemotherapy. More than one line of chemotherapy was a therapy-related independent risk factor for shorter PFS and OS.

Octreotide alleviates pancreatic damage caused by paraquat in rats by reducing inflammatory responses and oxidative stress

This study explores the efficacy and mechanism by which octreotide (OCT) alleviates paraquat (PQ)-induced pancreatic injury. Twenty-four adult male rats were randomly divided into three groups: the normal control (NC), PQ poisoning, and OCT treatment groups. The PQ-induced pancreatic injury rat model was established by administering PQ (120 mg/kg). Treatment group rats received OCT (8 μg/kg body weight) every 8 h by subcutaneous injection, 1 h after PQ administration. Rats were euthanized 24 h after PQ injection. Serum amylase, lipase, tumor necrosis factor-α, and interleukin-6 levels were markedly increased in the PQ group versus the NC group. In pancreatic tissue, PQ poisoning drastically induced necrosis and increased inflammatory cytokine and oxidative stress marker levels. Compared with the PQ group, OCT reduced pancreatic damage and histological scores, serum amylase, lipase, and inflammatory cytokine levels, as well as oxidative stress. OCT demonstrates protective effects against PQ-induced pancreatic damage through anti-inflammatory and antioxidant actions.

Elevated miR-16-5p induces somatostatin receptor 2 expression in neuroendocrine tumor cells

Somatostatin analogs, which are used to treat neuroendocrine tumors, inhibit hormone secretion or promote tumor shrinkage; however, their efficacy varies between patients, possibly because of differential expression of somatostatin receptors (SSTRs) in tumors. In this study, we evaluated the regulatory mechanism underlying the expression of SSTR2, the main octreotide target. Thirty miRNAs were found to be dysregulated in neuroendocrine cells (INS-1 cells) incubated with octreotide compared to that in placebo-treated cells. Among the upregulated miRNAs, miR-16-5p was elevated after short-term octreotide treatment. We conducted in vitro experiments to determine whether the expression of miR-16-5p was associated with the regulation of SSTR2 expression and affected octreotide sensitivity in INS-1 cells. Overexpression of miR-16-5p by transfected mimics induced upregulation of SSTR2 expression. Additionally, the expression of miR-16-5p further enhanced octreotide-induced reduction in cell proliferation in both two- and three-dimensional culture of INS-1 cells. Thus, our results reveal the mechanism underlying SSTR2 expression regulation and may aid in developing therapeutic approaches for enhancing the response to octreotide, particularly in patients unresponsive to SSTR2-targeted somatostatin analog treatment.

Enhancing the anti-tumour activity of 177Lu-DOTA-octreotate radionuclide therapy in somatostatin receptor-2 expressing tumour models by targeting PARP

Peptide receptor radionuclide therapy (PRRT) is an important treatment option for patients with somatostatin receptor-2 (SSTR2)-expressing neuroendocrine tumour (NET) though tumour regression occurs in only a minority of patients. Therefore, novel PRRT regimens with improved therapeutic activity are needed. Radiation induced DNA damage repair is an attractive therapeutic target to increase PRRT efficacy and consequently, we have characterised a panel of preclinical models for their SSTR2 expression, in vivo growth properties and response to 177Lu-DOTA-octreotate (LuTate) PRRT to identify models with features suitable for evaluating novel therapeutic combinations. In vitro studies using the SSTR2 expressing AR42J model demonstrate that the combination of LuTate and the small molecule Poly(ADP-ribose) polymerase-1 (PARP) inhibitor, talazoparib led to increased DNA double strand breaks, as assessed by γ-H2AX foci formation, as compared to LuTate alone. Furthermore, using the AR42J tumour model in vivo we demonstrate that the combination of LuTate and talazoparib significantly improved the anti-tumour efficacy of LuTate alone. These findings support the clinical evaluation of the combination of LuTate and PARP inhibition in SSTR2-expressing NET.

A novel insight into the anticancer mechanism of metformin in pancreatic neuroendocrine tumor cells

The antidiabetic drug metformin displays anticancer properties in several neoplasms. In pituitary NETs, aryl hydrocarbon receptor-interacting protein (AIP) is up-regulated by the somatostatin analog octreotide. Metformin inhibited QGP-1 cell proliferation in a dose- and time-dependent manner, at concentrations similar to those achievable in treated patients (-31 ± 12%, p < 0.05 vs basal at 100 μM). Moreover, metformin decreased pancreatic neuroendocrine tumors (PAN-NETs) cell proliferation (-62 ± 15%, p < 0.0001 vs basal at 10 mM), without any additive effect when combined with octreotide. Both octreotide and metformin induced AIP up-regulation. AIP silencing abolished the reduction of mTOR phosphorylation induced by metformin and octreotide. Moreover, metformin decreased HSP70, increased Zac1 and AhR expression; these effects were abolished in AIP silenced QGP-1 cells. In conclusion, metformin acts as an anticancer agent in PAN-NET cells, its activity is mediated by AIP and its interacting proteins. These findings provide a novel insight into the antitumorigenic mechanism of metformin.

Effects of octreotide on autophagy markers and cell viability markers related to metabolic activity in rat pituitary tumor cells

PURPOSE

The aim of this work was to investigate possible direct effects of the somatostatin analog octreotide on autophagy markers and markers of cellular metabolic activity using in vitro cultured rat pituitary tumor cells (GH3 cell line).

METHODS

We measured two markers of the autophagic flux in cell lysates by Western blot and MTT reductive activity, total cellular ATP levels, pyruvate dehydrogenase (PDH) complex activity in cells lysates as markers of cell viability related to metabolic activity.

RESULTS

Octreotide (100 nM) treatment induced autophagy activation (increased LC3-I protein lipidation) and enhanced the autophagic flux (SQSTM1/p62 protein downregulation) in GH3 cells in different incubation media, in detail in Hank's balanced salt solution (HBSS) as well as in maintenance medium with serum. We did not observe any decrease of redox activity and energy production related to the induction of autophagy by octreotide. On the other hand, short-term treatments with octreotide in HBSS tended to enhance MTT reduction activity and to increase PDH complex enzymatic activity and ATP levels measured in GH3 cell lysates.

CONCLUSIONS

We provided evidence that octreotide can affect autophagy in pituitary tumor cells. The observed effects of octreotide were not related to a decrease of cellular metabolic activity. Finally, the induction of autophagy was either short-lived or overshadowed by other factors in the long term and this limit does not help clarifying their real impact on the pharmacological activity of somatostatin analogs.

Abundant expression of the membrane-anchored protease-regulator RECK in the anterior pituitary gland and its implication in the growth hormone/insulin-like growth factor 1 axis in mice

The tumor suppressor gene Reversion-inducing cysteine-rich protein with Kazal motifs (Reck) encodes a membrane-anchored protease regulator expressed in multiple tissues in mouse embryos and is essential for embryonic development. In postnatal mice, however, physiological roles for the RECK protein remain unclear. We found in this study that Reck is abundantly expressed in growth hormone (GH)-producing cells (somatotrophs) in the anterior pituitary gland (AP). We also found that two types of viable Reck mutant mice, one with reduced RECK expression (Hypo mice) and the other with induced Reck deficiency from 10 days after birth (iKO mice treated with tamoxifen), exhibit common phenotypes including decreases in body size and plasma levels of insulin-like growth factor-1 (IGF1). To gain insights into the function of RECK in the AP, we characterized several somatotroph-associated molecules in the AP of these mice. Immunoreactivity of GH was greatly reduced in tamoxifen-treated iKO mice; in these mice, two membrane receptors involved in the stimulation of GH secretion [growth hormone secretagogue receptor (GHSR) and growth hormone releasing hormone receptor (GHRHR)] were decreased, however, their mRNAs were increased. Decrease in GHSR immunoreactivity and concomitant increase in its mRNA were also found in the other mutant line, Hypo. Furthermore, reduced immunoreactivity of growth hormone receptor (GHR) and concomitant increase in its mRNA was also found in the liver of Hypo mice. These results raise the possibility that RECK supports proper functioning of the GH/IGF1 axis in mice, thereby affecting their growth and metabolism.

Cytoskeleton Protein Filamin A Is Required for Efficient Somatostatin Receptor Type 2 Internalization and Recycling through Rab5 and Rab4 Sorting Endosomes in Tumor Somatotroph Cells

The high expression of somatostatin receptor 2 (SST2) in growth hormone (GH)-secreting tumors represents the rationale for the clinical use of somatostatin analogs (SSAs) in acromegaly. Recently, the cytoskeletal protein Filamin A (FLNA) has emerged as key modulator of the responsiveness of GH-secreting pituitary tumors to SSAs by regulating SST2 signaling and expression. The aim of this study was to explore FLNA involvement in SST2 intracellular trafficking in tumor somatotroph cells. By biotinylation assay, we found that FLNA silencing abolished octreotide-mediated SST2 internalization in rat GH3 cell line (28.0 ± 2.7 vs. 4 ± 4.3% SST2 internalization, control versus FLNA small interfering RNAs (siRNA) cells, respectively, p < 0.001) and human GH-secreting primary cultured cells (70.3 ± 21.1 vs. 24 ± 19.2% SST2 internalization, control versus FLNA siRNA cells, respectively, p < 0.05). In addition, confocal imaging revealed impaired SST2 recycling to the plasma membrane in FLNA silenced GH3 cells. Coimmunoprecipitation and immunofluorescence experiments showed that FLNA, as well as β-arrestin2, is timely dependent recruited to octreotide-stimulated SST2 receptors both in rat and human tumor somatotroph cells. Although FLNA expression knock down did not prevent the formation of β-arrestin2-SST2 complex in GH3 cells, it significantly impaired efficient SST2 loading into cytosolic vesicles positive for the early endocytic and recycling markers Rab5 and 4, respectively (33.7 ± 8.9% down to 25.9 ± 6.9%, p < 0.05, and 28.4 ± 7.4% down to 17.6 ± 5.7%, p < 0.01, for SST2-Rab5 and SST2-Rab4 colocalization, respectively, in control versus FLNA siRNA cells). Altogether these data support an important role for FLNA in the mediation of octreotide-induced SST2 trafficking in GH-secreting pituitary tumor cells through Rab5 and 4 sorting endosomes.

Gemcitabine potentiates the anti-tumour effect of radiation on medullary thyroid cancer

Patients with medullary thyroid cancer (MTC) are often diagnosed with spread tumour disease and the development of better systemic treatment options for these patients is important. Treatment with the radiolabelled somatostatin analogue ¹⁷⁷Lu-octreotate is already a promising option but can be optimised. For example, combination treatment with another substance could increase the effect on tumour tissue. Gemcitabine is a nucleoside analogue that has been shown to sensitise tumour cells to radiation. The aim of this study was to investigate potentially additive or synergistic effects of combining radiation with gemcitabine for treatment of MTC. Nude mice transplanted with patient-derived MTC tumours (GOT2) were divided into groups and treated with radiation and/or gemcitabine. Radiation treatment was given as ¹⁷⁷Lu-octreotate or external beam radiotherapy (EBRT). The volume of treated and untreated tumours was followed. The absorbed dose and amount of gemcitabine were chosen to give moderate tumour volume reduction when given as monotherapy to enable detection of increased effects from combination treatment. After follow-up, the mice were killed and tumours were immunohistochemically (IHC) analysed. Overall, the animals that received a combination of EBRT and gemcitabine showed the largest reduction in tumour volume. Monotherapy with EBRT or gemcitabine also resulted in a clear detrimental effect on tumour volume, while the animals that received ¹⁷⁷Lu-octreotate monotherapy showed similar response as the untreated animals. The GOT2 tumour was confirmed in the IHC analyses by markers for MTC. The IHC analyses also revealed that the proliferative activity of tumour cells was similar in all tumours, but indicated that fibrotic tissue was more common after EBRT and/or gemcitabine treatment. The results indicate that an additive, or even synergistic, effect may be achieved by combining radiation with gemcitabine for treatment of MTC. Future studies should be performed to evaluate the full potential of combining ¹⁷⁷Lu-octreotate with gemcitabine in patients.

Antibody array strategy for human growth factor secretome profiling of GH-secreting adenomas

PURPOSES

To test if the antibody array strategy could be utilized to simultaneously detect the secretion of multiple growth factors by human pituitary GH-adenomas and to measure octreotide-induced alterations.

METHODS

Specimens of human pituitary adenomas were cultured and incubated with or without octreotide for 24 h. Conditional media were analyzed by human growth factor antibody array and VEGF concentrations were measured by ELISA. Media were also analyzed for GH concentrations. p21 expression levels were examined by Western blot of the specimens lysates.

RESULTS

The antibody arrays successfully identified growth factors secreted by GH-adenomas in vitro. Octreotide treatment induced both elevations and reductions in growth factors secretion. GH response to octreotide was measured, and in this small-sized study resistant and sensitive GH-adenomas presented with no unique secretome pattern of each of the groups. Octreotide-induced VEGF alterations analyzed by the antibody array and by ELISA were not fully matched.

CONCLUSIONS

This study suggests that the broad proteomic strategy of antibody arrays may be utilized to study the growth factors secretion pattern of GH-adenomas and its regulation by somatostatin analogs or other compounds.

Somatostatin Analogues in the Treatment of Neuroendocrine Tumors: Past, Present and Future

In recent decades, the incidence of neuroendocrine tumors (NETs) has steadily increased. Due to the slow-growing nature of these tumors and the lack of early symptoms, most cases are diagnosed at advanced stages, when curative treatment options are no longer available. Prognosis and survival of patients with NETs are determined by the location of the primary lesion, biochemical functional status, differentiation, initial staging, and response to treatment. Somatostatin analogue (SSA) therapy has been a mainstay of antisecretory therapy in functioning neuroendocrine tumors, which cause various clinical symptoms depending on hormonal hypersecretion. Beyond symptomatic management, recent research demonstrates that SSAs exert antiproliferative effects and inhibit tumor growth via the somatostatin receptor 2 (SSTR2). Both the PROMID (placebo-controlled, prospective, randomized study in patients with metastatic neuroendocrine midgut tumors) and the CLARINET (controlled study of lanreotide antiproliferative response in neuroendocrine tumors) trial showed a statistically significant prolongation of time to progression/progression-free survival (TTP/PFS) upon SSA treatment, compared to placebo. Moreover, the combination of SSA with peptide receptor radionuclide therapy (PRRT) in small intestinal NETs has proven efficacy in the phase 3 neuroendocrine tumours therapy (NETTER 1) trial. PRRT is currently being tested for enteropancreatic NETs versus everolimus in the COMPETE trial, and the potential of SSTR-antagonists in PRRT is now being evaluated in early phase I/II clinical trials. This review provides a synopsis on the pharmacological development of SSAs and their use as antisecretory drugs. Moreover, this review highlights the clinical evidence of SSAs in monotherapy, and in combination with other treatment modalities, as applied to the antiproliferative management of neuroendocrine tumors with special attention to recent high-quality phase III trials.

Effects of novel somatostatin-dopamine chimeric drugs in 2D and 3D cell culture models of neuroendocrine tumors

Control of symptoms related to hormonal hypersecretion by functioning neuroendocrine tumors (NETs) is challenging. New therapeutic options are required. Since novel in vitro tumor models seem to better mimic the tumor in vivo conditions, we aimed to study the effect of somatostatin and dopamine receptor agonists (octreotide and cabergoline, respectively) and novel somatostatin-dopamine chimeric multi-receptor drugs (BIM-065, BIM-23A760) using 2D (monolayer) and 3D (spheroids) cultures. Dose-response studies in 2D and 3D human pancreatic NET cell cultures (BON-1 and QGP-1) were performed under serum-containing and serum-deprived conditions. Cell proliferation, somatostatin and dopamine receptor expression (SSTs and D2R), apoptosis, lactate dehydrogenase, as well as serotonin and chromogranin A (CgA) release were assessed. The following results were obtained. 3D cultures of BON-1/QGP-1 allowed better cell survival than 2D cultures in serum-deprived conditions. SSTs and D2R mRNA levels were higher in the 3D model vs 2D model. Octreotide/cabergoline/BIM-065/BIM-23A760 treatment did not affect cell growth or spheroid size. In BON-1 2D-cultures, only BIM-23A760 significantly inhibited CgA release -this effect being more pronounced in 3D cultures. In BON-1 2D cultures, cabergoline/BIM-065/BIM-23A760 treatment decreased serotonin release (maximal effect up to 40%), being this effect again more potent in 3D cultures (up to 67% inhibition; with BIM-23A760 having the most potent effects). In QGP-1, cabergoline/BIM-065 treatment decreased serotonin release only in the 3D model. In conclusion, cultures of NET 3D spheroids represent a promising method for evaluating cell proliferation and secretion in NET cell-line models. Compared to 2D models, 3D models grow relatively serum independent. In 3D model, SST-D2R multi-receptor targeting drugs inhibit CgA and serotonin secretion, but not NET cell growth.

Octreotide-Conjugated Core-Cross-Linked Micelles with pH/Redox Responsivity Loaded with Etoposide for Neuroendocrine Neoplasms Therapy and Bioimaging with Photoquenching Resistance

The study of multifunctional polymer micelles combined with chemotherapy due to reduced systemic toxicity and enhanced efficacy has attracted intensive attention. Herein, a multifunctional core-cross-linked hybrid micelle system based on mPEG- b-PGu(BA-TPE) and OCT-PEG- b-PGu(DA-TPE) with pH- and redox-triggered drug release and aggregation-induced emission (AIE) active imaging has been developed for active targeting of neuroendocrine neoplasms (NENs), especially neuroendocrine carcinomas (NECs) with poor prognosis. These micelles showed excellent biocompatibility and stability. After the formation of borate ester bonds, core-cross-linked micelles (CCLMs) showed enhanced emission properties. In addition, etoposide (ETO), one of the most important anticancer drugs of NECs, was loaded into the hydrophobic core of micelles by self-assembly with an average diameter of 274.6 nm and spherical morphology. Octreotide (OCT) conjugated onto the micelles enhanced cellular uptake by receptor-mediated endocytosis. ETO-loaded micelles demonstrated the dual-responsive triggered intracellular drug release and great tumor suppression ability in vitro. Compared with free ETO, ETO-loaded CCLMs exhibited a considerable antitumor effect and significantly reduced side effects. Considering the active tumor targeting, dual-responsive drug release and the AIE effect, the polymer micelle system will be a potential candidate for diagnosis and oncotherapy of NENs.

Clinical Characteristics of Acromegalic Patients With Paradoxical GH Response to Oral Glucose Load

CONTEXT

A paradoxical GH response to oral glucose (OG) is often found in acromegaly. However, the clinical characteristics of patients with acromegaly and a paradoxical GH response to OG (OG responders) remain unclear.

OBJECTIVE

The aim of the present study was to define the clinical characteristics of OG responders with acromegaly.

DESIGN

Retrospective study.

SETTING

Hospitalized care at Osaka University Hospital.

PATIENTS AND METHODS

Of 63 patients with acromegaly admitted to our hospital from January 2006 to January 2017, 19 were classified as OG responders and 44 as nonresponders. The clinical characteristics of these groups were compared.

RESULTS

Before surgery, OG responders had substantially greater IGF-1 SD scores than nonresponders (P < 0.05), although no difference was found in basal GH levels between the two groups (P = 0.46). Regarding glucose metabolism, 120-minute plasma glucose and immunoreactive insulin after OG administration and hemoglobin A1c were significantly greater in OG responders than in nonresponders (P < 0.01, P < 0.05, P < 0.05, respectively). GH levels during octreotide or bromocriptine testing were decreased more significantly in OG responders than in nonresponders (P < 0.05, P < 0.05, respectively). The proportion of pituitary tumors with hypointensity on T2-weighted MRI was significantly greater in OG responders than in nonresponders (P < 0.05). The difference in IGF-1 and parameters of glucose metabolism described disappeared between the two groups after surgery.

CONCLUSIONS

The paradoxical GH response reflected the clinical characteristics, especially IGF-I level, glucose metabolism, and drug efficacy in acromegaly. A paradoxical GH response, in addition to the nadir GH levels, to OG load is potentially useful for evaluation of the clinical characteristics of acromegaly.

177Lu-octreotate therapy for neuroendocrine tumours is enhanced by Hsp90 inhibition

177Lu-octreotate is an FDA-approved radionuclide therapy for patients with gastroenteropancreatic neuroendocrine tumours (NETs) expressing somatostatin receptors. The 177Lu-octreotate therapy has shown promising results in clinical trials by prolonging progression-free survival, but complete responses are still uncommon. The aim of this study was to improve the 177Lu-octreotate therapy by means of combination therapy. To identify radiosensitising inhibitors, two cell lines, GOT1 and P-STS, derived from small intestinal neuroendocrine tumours (SINETs), were screened with 1,224 inhibitors alone or in combination with external radiation. The screening revealed that inhibitors of Hsp90 can potentiate the tumour cell-killing effect of radiation in a synergistic fashion (GOT1; false discovery rate <3.2×10-11). The potential for Hsp90 inhibitor ganetespib to enhance the anti-tumour effect of 177Lu-octreotate in an in vivo setting was studied in the somatostatin receptor-expressing GOT1 xenograft model. The combination led to a larger decrease in tumour volume relative to monotherapies and the tumour-reducing effect was shown to be synergistic. Using patient-derived tumour cells from eight metastatic SINETs, we could show that ganetespib enhanced the effect of 177Lu-octreotate therapy for all investigated patient tumours. Levels of Hsp90 protein expression were evaluated in 767 SINETs from 379 patients. We found that Hsp90 expression was upregulated in tumour cells relative to tumour stroma in the vast majority of SINETs. We conclude that Hsp90 inhibitors enhance the tumour-killing effect of 177Lu-octreotate therapy synergistically in SINET tumour models and suggest that this potentially promising combination should be further evaluated.

Risk Factors for Post-Endoscopic Retrograde Cholangiopancreatography (ERCP) Pancreatitis and the Effect of Octreotide Combined with Nonsteroidal Anti-Inflammatory Drugs on Preventing Its Occurrence

BACKGROUND The aim of this study was to explore the risk factors for post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis and investigate the effect of octreotide combined with nonsteroidal anti-inflammatory drugs on preventing its occurrence. MATERIAL AND METHODS A total of 139 patients undergoing ERCP in our hospital from May 2016 to April 2017 were retrospectively analyzed, and divided into an observation group (n=67) (octreotide + indomethacin) and a control group (n=72) (no preventive drugs). The preoperative and postoperative inflammatory cytokines such as tumor necrosis factor-α (TNF)-α, interleukin-6 (IL-6) and IL-8, and serum amylase levels were measured, and the incidence of pancreatitis and hyper amylasemia were monitored. RESULTS Serum amylase level was increased significantly 3 hours after operation in both groups with significantly higher level in the control group compared to the observation group. After 24 hours, serum amylase in the observation group was decreased to preoperative level, whereas it was still higher than preoperative in the control group (P<0.05). Regarding the levels of TNF-α, IL-6, IL-8, and visual analogue scale, they were significantly increased in both groups after operation with significantly higher levels in the control group compared to the observation group (P<0.05). Furthermore, logistic regression analysis showed that difficult intubation, pancreatic duct angiography, surgery for a long time, and the history of previous pancreatitis were risk factors for post-ERCP pancreatitis (P<0.05). CONCLUSIONS Difficult intubation, pancreatic duct angiography, surgery for a long time, and the history of previous pancreatitis were risk factors for post-ERCP pancreatitis. Octreotide combined with non-steroidal anti-inflammatory drugs can reduce the pain of patients with abdominal pain as well as the incidence of postoperative pancreatitis, indicating that they might be effective preventative approaches for pancreatitis.

Somatostatin analogue, Octreotide, improves restraint stress-induced liver injury by ameliorating oxidative stress, inflammatory response, and activation of hepatic stellate cells

The aim of this study is to investigate the effect of somatostatin (SST) analogue, Octreotide, on some features of liver injury induced by immobilization stress (IS) in adult male albino rats. Eighteen adult male albino rats were randomly divided into three equal groups: control, IS, and Octreotide-treated stressed groups. Octreotide (40 μg/kg body weight, subcutaneously) was administrated twice daily for 8 days during the exposure to IS. Octreotide was found to reduce the IS significantly and induce elevations in the plasma level of corticosterone, liver transaminases, and tumor necrosis factor α (TNF-α) as compared with IS group. Furthermore, Octreotide administration has significantly elevated the decline in the total antioxidant capacities (TAC) and lowered the elevated malondialdehyde (MDA) levels observed with IS in the hepatic tissue. Additionally, Octreotide treatment provided protection against the histopathological changes in the stressed liver in the form of significant reduction in the mean number of degenerated hepatocytes, the area % of collagen fibers, and glial fibrillary acid protein (GFAP) immunostaining with a significant increase in the mean number of normal hepatocytes. In conclusion, stressed rats showed disturbed liver functions and its oxidant-antioxidant status with highly expression hepatic stellate cells (HSCs), which were all improved by Octreotide administration, SST analogue.

E4206: AMG 706 and Octreotide in Patients with Low-Grade Neuroendocrine Tumors

LESSONS LEARNED

Rate of progression-free survival at a particular point in time, i.e., a landmark analysis, is a difficult endpoint for a heterogenous malignancy such as neuroendocrine cancer.Landmark analyses can also be complicated by evolution in the standard of care during the conduct of a clinical trial.Improvements in biomarker development would be useful in developing future clinical trials in NET to better tailor individualized therapies and assess for possible efficacy endpoints.

BACKGROUND

Neuroendocrine tumors (NETs) are rare malignancies of the gastrointestinal (GI) tract that are highly vascularized and overexpress vascular-endothelial growth factor (VEGF). Sunitinib has demonstrated efficacy in the pancreatic subset of NET. This study explored the activity of another oral VEGF inhibitor, AMG 706 or motesanib, a multikinase inhibitor that targets receptor tyrosine kinases, including VEGFR1, VEGFR2, VEGFR3, KIT, RET, and PDGFR (IC50s = 2, 3, 6, 8, 59, and 84 nM, respectively).

METHODS

This was a single-arm, first-line, phase II study run through the Eastern Cooperative Oncology Group. Patients with low-grade NET (as defined by central confirmation of Ki-67 of 0%-2%) were administered a flat dose of 125 mg per day orally combined with octreotide long acting-repeatable (LAR) for patients who had been on a stable dose. The primary objective was to determine the 4-month progression-free survival (PFS).

RESULTS

Forty-four patients were evaluated per protocol. The 4-month PFS was 78.5%. The partial response rate was 13.6% (6/44), stable disease was 54.5% (24/44), 9.1% (4/44) had progressive disease, and 10/44 were not evaluable for response. Common toxicities included fatigue, hypertension, nausea, and headache, and most were grade 1-2. Median PFS was 8.7 months, and overall survival was 27.5 months.

CONCLUSION

Motesanib (AMG 706) demonstrated a 4-month PFS that met the per-protocol definition of efficacy. Fatigue and hypertension were the most common toxicities, and few grade 3-4 toxicities were encountered. The progression-free survival of 8.7 months in all NETs merits further study.

Octreotide ameliorates dermal fibrosis in bleomycin-induced scleroderma

Background/aim

Insulin-like growth factor (IGF)-I is a differentiation and growth factor. Antifibrotic action of octreotide has been reported in pulmonary fibrosis. The present study aimed to research the prophylactic and therapeutic potential of octreotide on a bleomycin (BLM)-induced experimental scleroderma model.

Materials and methods

Sixty Balb/c female mice were divided into 6 groups. Daily subcutaneous BLM (100 μg) was injected for 3 weeks in groups II and III and for 6 weeks in groups V and VI. Octreotide (100 μg/kg per day) was injected subcutaneously for the first 3 weeks in group III (prophylactic) and the second 3 weeks in group VI (therapeutic). Mice in groups I, II, and III were sacrificed at the end of the third week, while mice in groups IV, V, and VI were sacrificed at the end of the sixth week.

Results

Repeated BLM applications increased dermal inflammatory cell counts and dermal thickness, and led to dermal fibrosis at both the third and sixth weeks. Moreover, mRNA expressions of TGF-β1 and IGF binding protein (IGFBP)-3 and -5 were higher in the BLM- injected sham groups. On the other hand, IGFBP-3 and -5 mRNA expressions were significantly decreased in both the prophylactic and therapeutic octreotide groups. Similarly, octreotide decreased dermal inflammatory infiltrations and dermal thickness.

Conclusion

Octreotide has antifibrotic actions on experimentally induced dermal fibrosis. It can be suggested that IGF-I plays pathogenic roles, and octreotide is a candidate for research in the treatment of scleroderma.

The effect of Resveratrol and Octreotide on peritoneal adhesions in a rat model

INTRODUCTION

The aim of this study was to investigate the efficacy of resveratrol and octreotide, agents that are used to prevent intra-abdominal adhesions in experimental models, in preventing intraperitoneal adhesions when used alone or in combination.

MATERIALS AND METHODS

The study employed 28 young female Wistar albino rats weighing 250-300 grams. An experimental adhesion model was created in each rat using serosal abrasion and peritoneal excision. They were divided into four groups, each comprising seven rats: Group 1, adhesion induction only; Group 2, resveratrol administration only; Group 3, octreotide administration only; and Group 4, administration of resveratrol and octreotide combination. The rats were monitored under appropriate conditions for 14 days and then underwent laparotomy. Macroscopic intensity and extensiveness of adhesions and microscopic changes in the granulation tissue (cellular intensity, reticular and collagen fibers, capillaries, elastic and smooth muscle fibers, fibrosis) were evaluated and graded. Kruskal-Wallis and Mann-Whitney U-test were used in statistical analysis and the level of statistical significance was established as p <0.05.

RESULTS

There was no significant difference between the groups in terms of the intensity and extensiveness of macroscopic adhesions (p=0.377 and p=0.319). There was a statistically significant difference between the microscopic scores of the groups according to Zühlke's classification (p=0.026). The Bonferroni correction used to test for the differences revealed that the rats in Group 1 achieved significantly higher scores than the rats in Group 3 (p=0.016).

CONCLUSION

Octreotide showed higher efficiency compared to the control group in microscopic classification; however, the two agents were not superior to each other or their combination was not superior in preventing intra-abdominal adhesions.

Phase II Study of Everolimus and Octreotide LAR in Patients with Nonfunctioning Gastrointestinal Neuroendocrine Tumors: The GETNE1003_EVERLAR Study

BACKGROUND

Antitumor activity of the combination of somatostatin analogues (SSAs) and the mammalian target of rapamycin (mTOR) inhibitor everolimus in patients with neuroendocrine tumors (NETs) has been reported but not confirmed in prospective trials.

MATERIALS AND METHODS

This prospective, multicenter, single-arm phase II EVERLAR study evaluated everolimus 10 mg/day and the SSA octreotide 30 mg every 28 days in patients with advanced nonfunctioning well-differentiated gastrointestinal NETs (GI-NETs) that progressed in the last 12 months (ClinicalTrials.gov NCT01567488). Prior treatment with SSAs and any systemic or locoregional therapy was allowed except for mTOR inhibitors. Patients continued treatment until disease progression or unacceptable adverse events (AEs). The primary endpoint was progression-free survival (PFS) at 12 months; secondary endpoints included early biochemical response, objective response rate (ORR) by RECIST v1.0, overall survival (OS), AEs, activation of mTOR pathway (insulin-like growth factor 1 receptor [IGF1R] and phosphoS6 [pS6] expression).

RESULTS

Forty-three patients were included in the intent-to-treat analyses. After 12 months of treatment, 62.3% (95% confidence interval [CI] 48%-77%) of patients had not progressed or died. The 24-month PFS rate was 43.6% (95% CI 29%-58%). The confirmed ORR was 2.3%, and stable disease was 58.1%. Median OS was not reached after 24 months of median follow-up. Dose reductions and temporary interruptions due to AEs were required in 14 (33%) and 33 (77%) patients, respectively. The most frequent AEs were diarrhea, asthenia, mucositis, rash, and hyperglycemia. No correlation was observed between IGFR1 and pS6 expression and PFS/OS.

CONCLUSION

The everolimus-octreotide combination provided clinically relevant efficacy in nonfunctioning GI-NETs, similar to the results of RADIANT-2 in functioning setting.

IMPLICATIONS FOR PRACTICE

The EVERLAR study reports prospective data of somatostatin analogue in combination with everolimus in nonfunctioning gastrointestinal neuroendocrine tumors suggesting meaningful activity and favorable toxicity profile that supports drug combination in this setting.

Effect of Octreotide on Neuroenolase Levels in Patients with Small Cell Lung Cancer

Aims and Background

The somatostatin analog octreotide has an antiproliferative effect on small cell lung cancer lines in vitro and in experimental xenograft transplantation systems in vivo. Thus it is worth investigating octreotide activity in the clinical setting.

Methods

We studied the effect of octreotide (200 μg three times a day subcutaneously for seven days) on serum levels of the tumor marker neuroenolase in 13 patients with small cell lung cancer.

Results

A decrease in neuroenolase levels was observed at day 7 during octreotide treatment, with a mean ± SD of 32.6 ± 42.0 ng/ml compared to basal values of 44.4 ± 57.7 ng/ml and to washout values of 50.3 ± 65.7 ng/ml ( P < 0.03).

Conclusions

Our results indicate that octreotide is effective in reducing neuroenolase levels in small cell lung cancer patients. These data suggest a possible role for octreotide in the treatment of this kind of tumor.

The Role of Somatostatin and Octreotide in Bowel Obstruction: Pre-Clinic Al and Clinical Results

Malignant bowel obstruction is a common complication in patients with advanced abdominal or pelvic cancer. Whereas surgery should be considered in all cases of malignant bowel obstruction, many advanced and terminal cancer patients are considered unfit for surgery. In such patients with a short life expectancy, gastrointestinal symptoms such as nausea, vomiting, continuous and/or colicky pain, can be controlled by using a pharmacologic approach made up of analgesics, antiemetics and antisecretory drugs, without the use of a venting nasogastric tube. Among the antisecretory drugs, octreotide has been shown to reduce nausea and vomiting in bowel-obstructed patients owing to a reduction of gastrointestinal secretions, thus allowing in most patients removal of the nasogastric tube and the associated distress. Preclinical and clinical studies that demonstrated the role of somatostatin and octreotide in bowel obstruction are reviewed.

Cardiovascular magnetic resonance imaging and clinical performance of somatostatin receptor positron emission tomography in cardiac sarcoidosis

AIMS

Cardiac affection constitutes a major limiting condition in systemic sarcoidosis. The primary objective of this study was to investigate the persistence rate of cardiac sarcoid involvement by cardiovascular magnetic resonance (CMR) imaging in patients diagnosed with cardiac sarcoidosis (CS). Moreover, we examined the additional insights into myocardial damage's characteristics gained by somatostatin receptor scintigraphy.

METHODS AND RESULTS

In a pilot study, we had previously identified cardiac involvement-diagnosed by CMR imaging-to be present in 29 of 188 patients (15.4%) with histologically proven, extra-CS. Out of these initial 29 CS-positive patients, 27 patients (49.9 ± 11.8 years, 59.3% male) were presently re-examined and underwent a second CMR study and complementary standard clinical testing. Somatostatin receptor scintigraphy using the ligand 68 Ga-DOTATOC was additionally performed when clinically indicated (17 patients). Within a median follow-up period of 2.6 years, none of the initial 29 patients deceased or experienced aborted sudden cardiac death. However, two patients developed third-degree atrioventricular block that required device therapy. Among the 27 re-examined CS patients, pathological CMR findings persisted in 14 of 27 patients (51.9%). CS remission was primarily due to a resolution of acute inflammatory processes. 68 Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) identified one patient with regions of raised tracer uptake that concorded with acute inflammatory changes, as assessed by CMR; this patient received no immunosuppressive medication at the time of PET/CT execution.

CONCLUSIONS

Within follow-up, CS persisted in barely half the patients, and the patients were not afflicted with cardiac death. Additional 68 Ga-DOTATOC PET/CT allowed for visualization of acute myocardial inflammation.