Expression of vascular endothelial growth factor in growth hormone-secreting pituitary adenomas: special reference to the octreotide treatment

Current role of pasireotide in the treatment of acromegaly

"First-generation" somatostatin receptor agonists (SSTRAs) octreotide and lanreotide are the most commonly used first-line pharmacological therapy for patients with acromegaly. A subset of patients respond only partially or not at all to the first-generation SSTRA, necessitating the use of additional pharmacological agents or other modes of therapy. Pasireotide is a "second-generation" SSTRA that has multi-receptor activity. Prospective studies have shown promise in the use of pasireotide in patients with poor response to first-generation SSTRA. Here we elucidate the molecular pathways of resistance to first-generation SSTRA, the mechanism of action, pre-clinical and clinical evidence of the use of pasireotide in patients having incomplete / lack of response to first-generation SSTRA. We also discuss the clinical, pathological, and radiological markers predicting response to pasireotide, and the difference in side-effect profiles of pasireotide, compared to first-generation SSTRA.

Aggressive PitNETs and Potential Target Therapies: A Systematic Review of Molecular and Genetic Pathways

Recently, advances in molecular biology and bioinformatics have allowed a more thorough understanding of tumorigenesis in aggressive PitNETs (pituitary neuroendocrine tumors) through the identification of specific essential genes, crucial molecular pathways, regulators, and effects of the tumoral microenvironment. Target therapies have been developed to cure oncology patients refractory to traditional treatments, introducing the concept of precision medicine. Preliminary data on PitNETs are derived from preclinical studies conducted on cell cultures, animal models, and a few case reports or small case series. This study comprehensively reviews the principal pathways involved in aggressive PitNETs, describing the potential target therapies. A search was conducted on Pubmed, Scopus, and Web of Science for English papers published between 1 January 2004, and 15 June 2023. 254 were selected, and the topics related to aggressive PitNETs were recorded and discussed in detail: epigenetic aspects, membrane proteins and receptors, metalloprotease, molecular pathways, PPRK, and the immune microenvironment. A comprehensive comprehension of the molecular mechanisms linked to PitNETs' aggressiveness and invasiveness is crucial. Despite promising preliminary findings, additional research and clinical trials are necessary to confirm the indications and effectiveness of target therapies for PitNETs.

Small bowel angioectasia-The clinical and cost impact of different management strategies

BACKGROUND

The management of patients with recurrent anaemia and small bowel angioectasia (SBA) is costly and challenging.

AIMS/METHODS

In this retrospective cohort study, we examined the clinical and cost implication of a combination therapy of Somatostatin analogues (SA) and endoscopic ablation, endoscopic therapy alone, and conservative management.

RESULTS

Median number of bleeding episodes reduced from 3.5 (IQR 4) in the year before, to 1 (IQR 2) in the year after starting combination therapy with SA (p = 0.002). There were no differences in number of bed days (13.7 vs. 15.3, p = 0.66) and cost (£10,835 vs £11,653, p = 0.73) in the year before and after starting combination therapy. There was a trend towards a reduction in median number of blood transfusions episodes (17 vs 5, p = 0.07) and therapeutic endoscopies (1 vs. 0, p = 0.05) after starting SA. In patients suitable for endoscopic therapy alone, time spent in hospital was reduced (-3.5 days, p = 0.004), but bleeding episodes, transfusions and cost of treatment were not different. Patients requiring a combination therapy were significantly more co-morbid with a mean (± sd) Charlson comorbidity index (CCI) of 7.1 (± 2.7). Higher CCI (OR 2.1, 95% CI 1.1-3.9) and presence of chronic renal failure (OR 4.1, 95% CI 1.4-12.4) predicted escalation to combination therapy.

CONCLUSIONS

SAs may be a useful adjunct to endoscopic therapy for transfusion dependent comorbid patients. In the first year they reduce bleeding episodes. Cost in the 1-year before and after adding on SA are no different suggesting additional clinical benefit can be gained without additional cost.

Small Bowel Bleeding: Clinical Diagnosis and Management in the Elderly

INTRODUCTION

With the global increase in life expectancy, there is an increase in gastrointestinal presentations in the elderly. Small bowel bleeding (SBB) is a cause of significant morbidity in the elderly requiring multiple hospital visits, investigations and potentially expensive therapy.

AREAS COVERED

In this review we will outline the different modalities which are used for the diagnosis and management of SBB. We will also discuss the common causes of SBB in the elderly.

EXPERT OPINION

SBB in elderly has a significant impact on the quality of life of the elderly. Larger randomized studies in the elderly are urgently required to help guide clinicians on the best and most cost-effective treatment algorithm in this challenging cohort.

Cathepsin D Inhibits Angiogenesis in Pituitary Neuroendocrine Tumors

Prolactin and growth hormone can acquire anti-angiogenic properties after undergoing proteolytic cleavage by Cathepsin D and bone morphogenetic protein 1 (BMP-1) into fragments known as vasoinhibins. Little is known about the effect of vasoinhibins on angiogenesis through the involvement of key cleavage enzymes Cathepsin D and BMP-1 in pituitary neuroendocrine tumors (PitNETs, formerly pituitary adenomas). The purpose of this study was to investigate the mechanism of action of Cathepsin D and BMP-1 on angiogenesis in PitNETs compared with that of pro-angiogenic factors, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor-2 (FGF2). A total of 43 patients were enrolled in a retrospective analysis and 22 samples were suitable for RNA extraction, including 16 nonfunctional PitNETs and six somatotroph tumors. The mRNA and protein levels of Cathepsin D, BMP-1, VEGF, and FGF2 were compared with those of von Willebrand factor, which was assessed to determine the vascularization of PitNETs. Cathepsin D and FGF2 were significantly correlated with vascularization in PitNETs. Both Cathepsin D and FGF2 are highly involved in angiogenesis in PitNETs, although the effect of Cathepsin D as an anti-angiogenic factor is dominant over that of FGF2 as a pro-angiogenic factor.

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.

Anti-VEGF Therapy in Refractory Pituitary Adenomas and Pituitary Carcinomas: A Review

Most pituitary tumors are considered benign adenomas, and only 0.1%–0.2% of them present metastasis and are defined as pituitary carcinomas (PCs). Refractory pituitary adenomas (PAs) lie between benign adenomas and true malignant PCs and are defined as aggressive-invasive PAs, characterized by a high Ki-67 index, rapid growth, frequent recurrence, and resistance to conventional treatments. Refractory PAs and PCs are notoriously difficult to manage because of limited therapeutic options. Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis not only during development but also during pathological processes in pituitary tumors. Recently, increasing numbers of preclinical studies and clinical research have demonstrated that anti-VEGF therapy plays an important role in pituitary tumors. The purpose of this review is to report the role of VEGF in the development and pathology of pituitary tumors and the progress of anti-VEGF therapy in pituitary tumors, including refractory PAs and PCs. Previous preclinical studies indicated that cyclin-dependent kinase 5 (CDK5)-mediated VEGF expression might play a crucial role in the development of PAs. Vascular endothelial growth inhibitors have been reported as independent predictors of invasion in human PAs and have been indicated as markers for poor outcome. Furthermore, several studies have reported that angiogenesis decreases tumor sizes in experimental animal models of pituitary tumors. The expression of VEGF is relatively high in PAs; therefore, anti-VEGF therapy has been used in some refractory PAs and PCs. To date, anti-VEGF has been reported as monotherapy, in combination with temozolomide (TMZ), TMZ and radiotherapy, and with pasireotide, which might be a promising alternative therapy for refractory PAs and PCs resistant to conventional treatments. However, the role of anti-VEGF therapy in pituitary tumors is still controversial due to a lack of large-scale clinical trials. In summary, the results from preclinical studies and clinical trials indicated that anti-VEGF therapy monotherapy or in combination with other treatments may be a promising alternative therapy for refractory PAs and PCs resistant to conventional treatments. More preclinical studies and clinical trials are needed to further evaluate the exact efficacy of anti-VEGF in refractory PAs and PCs.

Primary and Secondary Prevention Strategies for Gastrointestinal Bleeding in Patients with Left Ventricular Assist Device: A Systematic Review and Network Meta-analysis

Recurrent gastrointestinal bleeding (GIB) is a common complication following left ventricular assist device (LVAD) implantation. Our study aimed to estimate the comparative efficacy of different pharmacologic interventions for the prevention of GIB, through a network meta-analysis (NMA). A total of 13 observational studies comparing six strategies. Among those, 4 were for primary, and 9 were for secondary prevention of GIB. On NMA, thalidomide (Hazard ratio [HR]: 0.016, Credible interval [CrI]I: 0.00053-0.12), omega-3-fatty acid (HR:0.088, CrI: 0.026-0.77), octreotide (HR: 0.17, CrI: 0.0589-0.41) and danazol (HR:0.17, CrI: 0.059-0.41) reduced the risk of GIB. The use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blocker (ACEi/ARB) and digoxin were not associated with any significant reduction. Based on NMA, combining indirect treatment comparisons, thalidomide, danazol, and octreotide treatments were associated with decreased risk of recurrent GIB. Additionally, Omega 3 fatty acids were associated with a lower risk of the primary episode of GIB in the LVAD patient population.

Pharmacokinetic analysis of [68Ga]Ga-DOTA-TOC PET in meningiomas for assessment of in vivo somatostatin receptor subtype 2

PURPOSE

DOTA-D-Phe¹-Tyr³-octreotide with gallium-68 ([⁶⁸Ga]Ga-DOTA-TOC) is one of the PET tracers that forms the basis for peptide receptor radionuclide therapy based on somatostatin receptor subtype 2 (SSTR2) expression in meningiomas. Yet, the quantitative relationship between [⁶⁸Ga]Ga-DOTA-TOC accumulation and SSTR2 is unknown. We conducted a correlative analysis of a range of [⁶⁸Ga]Ga-DOTA-TOC PET metric(s) as imaging surrogate(s) of the receptor binding in meningiomas by correlating the PET results with SSTR2 expression from surgical specimens. We additionally investigated possible influences of secondary biological factors such as vascularization, inflammation and proliferation.

METHODS

Fifteen patients with MRI-presumed or recurrent meningiomas underwent a 60-min dynamic [⁶⁸Ga]Ga-DOTA-TOC PET/CT before surgery. The PET data comprised maximum and mean standardized uptake values (SUV_max, SUV_mean) with and without normalization to reference regions, and quantitative measurements derived from kinetic modelling using a reversible two-tissue compartment model with the fractional blood volume (V_B). Expressions of SSTR2 and proliferation (Ki-67, phosphohistone-H3, proliferating cell nuclear antigen) were determined by immunohistochemistry and/or quantitative polymerase chain reaction (qPCR), while biomarkers of vascularization (vascular endothelial growth factor A (VEGFA), endothelial marker CD34) and inflammation (cytokine interleukin-18, microglia/macrophage-specific marker CD68) by qPCR.

RESULTS

Histopathology revealed 12 World Health Organization (WHO) grade I and three WHO grade II meningiomas showing no link to SSTR2. The majority of [⁶⁸Ga]Ga-DOTA-TOC PET metrics showed significant associations with SSTR2 protein, while all PET metrics were positively correlated with SSTR2 mRNA with the best results for mean tumour-to-blood ratio (TBR_mean) (r = 0.757, P = 0.001) and SUV_mean (r = 0.714, P = 0.003). Significant positive correlations were also found between [⁶⁸Ga]Ga-DOTA-TOC PET metrics, and VEGFA and V_B. SSTR2 mRNA was moderately correlated with VEGFA (r = 0.539, P = 0.038). Neither [⁶⁸Ga]Ga-DOTA-TOC PET metrics nor SSTR2 were correlated with proliferation or inflammation.

CONCLUSION

[⁶⁸Ga]Ga-DOTA-TOC accumulation in meningiomas is associated with SSTR2 binding and vascularization with TBR_mean being the best PET metric for assessing SSTR2.

Exploring the Role of Novel Medical Therapies for Aggressive Pituitary Tumors: A Review of the Literature-"Are We There Yet?"

Aggressive pituitary tumors account for up to 10% of pituitary tumors and are characterized by resistance to medical treatment and multiple recurrences despite standard therapies, including surgery, radiotherapy, and chemotherapy. They are associated with increased morbidity and mortality, particularly pituitary carcinomas, which have mortality rates of up to 66% at 1 year after diagnosis. Novel targeted therapies under investigation include mammalian target of rapamycin (mTOR), tyrosine kinase, and vascular endothelial growth factor (VEGF) inhibitors. More recently, immune checkpoint inhibitors have been proposed as a potential treatment option for pituitary tumors. An increased understanding of the molecular pathogenesis of aggressive pituitary tumors is required to identify potential biomarkers and therapeutic targets. This review discusses novel approaches to the management of aggressive pituitary tumors and the role of molecular profiling.

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.

A Risk Assessment of Factors for the Presence of Angiodysplasias During Endoscopy and Factors Contributing to Symptomatic Bleeding and Rebleeds

BACKGROUND

Few studies have assessed factors associated with angiodysplasias during endoscopy or factors associated with symptomatic disease.

AIMS

To evaluate risk factors for the presence of and contribution to symptomatic disease in patients with angiodysplasias.

METHODS

We performed a systematic MEDLINE, EMBASE and Cochrane Library search according to the PRISMA guidelines for studies assessing risk factors involved in angiodysplasias detected during endoscopy and factors that lead to anemia or overt bleeding. Study quality was assessed with the Newcastle-Ottawa scale. A risk assessment was performed by selecting risk factors identified by two independent studies and/or by a large effect size.

RESULTS

Twenty-three studies involving 92,634 participants were included. The overall quality of the evidence was moderate. Risk factors for the diagnosis of angiodysplasias during endoscopy confirmed by at least two studies were increasing age (OR 1.09 per year, 95% CI 1.04-1.1), chronic kidney disease (OR 4.5, 95% CI 1.9-10.5) and cardiovascular disease (2.9, 95% CI 1.4-6.2). The risk of rebleeds was higher in the presence of multiple lesions (OR 4.2, 95% CI 1.1-16.2 and 3.8, 95% CI 1.3-11.3 and 8.6, 95% CI 1.4-52.6), liver cirrhosis (OR 4.0, 95% 1.1-15.0) and prothrombin time < 30% (OR 4.2, 95% 1.1-15.4) with a moderate effect size. Multiple comorbidities were associated with an increased in-hospital mortality (OR 2.29, 95% CI 1.2-4.3).

CONCLUSIONS

This systematic review identified age, chronic kidney disease and cardiovascular disease as the most important risk factors for the diagnosis of angiodysplasias during endoscopy. Multiple lesions increase the risk of recurrent bleeding.

An overview of angiodysplasia: management and patient prospects

Gastrointestinal angiodysplasias (GIADs) have a wide variety of presentations, which can be significant and debilitating in a subset of patients. Endoscopic ablation is currently the most effective treatment for GIADs, however re-bleeding rates are high. Several medical have been used for GIADs and reported in the literature, however these medications have significant side effect profiles and randomized controlled trials are lacking. A relatively poor understanding of the pathophysiology of GIAD formation has limited the development of more effective treatments and improved diagnostic and prognostic markers for GIAD. However, recent advances in research in the area of angiogenesis have identified a potential role for certain angiogenic factors including Angiopoeitin 1 and 2, in the pathophysiology of GIAD. Areas covered: We performed an extensive pubmed search of all articles mentioning GIAD and summarized our findings focussing on patient management and prospects. We summarize the available literature regarding the medical, endoscopic, and radiological management of GIAD and the value of clinical prognostic factors. Expert commentary: Although the area of angiogenesis is a novel area of research in GIAD, it represents an exciting avenue for development with the potential to improve diagnostic and prognostic tools to improve patient outcome.

Small bowel bleeding: cause and the role of endoscopy and medical therapy

PURPOSE OF REVIEW

The objective is to provide an overview on the cause of small bowel bleeding. We discuss the role of small bowel endoscopy in the management of small bowel bleeding and provide an outline of pharmacotherapy that can be additionally beneficial.

RECENT FINDINGS

Small bowel capsule endoscopy (SBCE) is the initial diagnostic investigation of choice in small bowel bleeding. Computed tomography (CT) can be helpful in the context of small bowel tumours. Device-assisted enteroscopy (DAE) enables several therapeutic procedures such as argon plasma coagulation (APC) and haemoclip application. It can also guide further management with histology or by marking culprit lesions with India ink. A persistent rate of rebleeding despite APC is increasingly being reported. Pharmacotherapy has an emerging role in the management of small bowel bleeding. Somatostatin analogues are a well tolerated class of drugs that can play an additional role in the management of refractory bleeding secondary to small bowel angioectasias.

SUMMARY

SBCE is useful in determining the cause of small bowel bleeding. DAE offers an endoscopic therapeutic approach to small bowel bleeding replacing surgery and intraoperative enteroscopy. Pharmacotherapy, in addition to endotherapy, can play an important role in the management of multifocal, recurring bleeding small bowel lesions.

Overview of small bowel angioectasias: clinical presentation and treatment options

Elderly patients with multiple co-morbidities are at an increased risk of developing small bowel angioectasias. Treating these lesions can be both challenging and costly with patients requiring extensive investigations and recurrent admissions for iron infusions and blood transfusions as well as invasive procedures. This review presents treatment options and describes in detail drugs that should be considered whilst taking into account their effectiveness and their safety profile. Areas covered: A PubMed search was carried out using the following keywords: small bowel angiodysplasias, small bowel angioectasias, small bowel bleeding and obscure gastrointestinal bleeding to assess existing evidence. The pathophysiology and risk factors are covered in this review together with appropriate methods of investigation and management. Treatment options discussed are endoscopic measures, surgical options and pharmacotherapy. The role of serum biomarkers is also discussed. Expert commentary: Future work should be directed at alternative drugs with a good safety profile that target biomarkers. Novel pharmacotherapy directed at biomarkers could potentially provide a non-invasive treatment option for angioectasias particularly in the elderly where management can be challenging.

Lanreotide in the management of small bowel angioectasias: seven-year data from a tertiary centre

BACKGROUND AND AIMS

Haemorrhage from small bowel angioectasias (SBAs) can be debilitating to patients who are very often elderly and have multiple comorbidities. Our aim was to assess the use of lanreotide in addition to endotherapy in patients with SBAs.

METHOD

Patients with SBAs on capsule endoscopy (CE) who received lanreotide injections from January 2010 to till the present day at the Royal Hallamshire Hospital in Sheffield were included. Baseline demographics were recorded. Efficacy was evaluated in terms of improvement in mean haemoglobin, transfusion requirements and bleeding episodes.

RESULTS

Twelve patients (67% males, mean age 74 SD ± 15.5 years) were included. All patients had multiple comorbidities. Lanreotide was given at a dosage of 60 mg (42%), 90 mg (33%) or 120 mg (25%). It was given at a four-week interval in 75% of patients and at a six-week interval in 17% of patients. One patient (8%) received a single dose. The mean duration of treatment was 19 months SD ± 14.5. Only 17% of patients had their lanreotide stopped due to cholelithiasis. There was a significant improvement in mean haemoglobin: 86.8 versus 98.0 (131-166 g/L, p = .012). The mean number of bleeding episodes (4.18 versus 1.09, p = .010) and packed red cells (323 versus 152, p = .006) received improved. Patients required less DBEs ± APCs after starting lanreotide (19 versus 11 p = .048).

CONCLUSION

Lanreotide is a useful adjuvant treatment to therapeutic enteroscopy in patients with refractory obscure gastrointestinal bleeding due to SBAs. It improves haemoglobin levels, reduces transfusion requirements, bleeding episodes and number of DBEs. Overall, it has a good safety profile.

Pasireotide Long-Acting Release Treatment for Diabetic Cats with Underlying Hypersomatotropism

BACKGROUND

Long-term medical management of hypersomatotropism (HS) in cats has proved unrewarding. Pasireotide, a novel somatostatin analogue, decreases serum insulin-like growth factor 1 (IGF-1) and improves insulin sensitivity in cats with HS when administered as a short-acting preparation.

OBJECTIVES

Assess once-monthly administration of long-acting pasireotide (pasireotide LAR) for treatment of cats with HS.

ANIMALS

Fourteen cats with HS, diagnosed based on diabetes mellitus, pituitary enlargement, and serum IGF-1 > 1000 ng/mL.

METHODS

Uncontrolled, prospective cohort study. Cats received pasireotide LAR (6-8 mg/kg SC) once monthly for 6 months. Fructosamine and IGF-1 concentrations, and 12-hour blood glucose curves (BGCs) were assessed at baseline and then monthly. Product of fructosamine concentration and insulin dose was calculated as an indicator of insulin resistance (Insulin Resistance Index). Linear mixed-effects modeling assessed for significant change in fructosamine, IGF-1, mean blood glucose (MBG) of BGCs, insulin dose (U/kg) and Insulin Resistance Index.

RESULTS

Eight cats completed the trial. Three cats entered diabetic remission. Median IGF-1 (baseline: 1962 ng/mL [range 1051-2000 ng/mL]; month 6: 1253 ng/mL [524-1987 ng/mL]; P < .001) and median Insulin Resistance Index (baseline: 812 μmolU/L kg [173-3565 μmolU/L kg]; month 6: 135 μmolU/L kg [0-443 μmolU/L kg]; P = .001) decreased significantly. No significant change was found in mean fructosamine (baseline: 494 ± 127 μmol/L; month 6: 319 ± 113.3 μmol/L; P = .07) or MBG (baseline: 347.7 ± 111.0 mg/dL; month 6: 319.5 ± 113.3 mg/dL; P = .11), despite a significant decrease in median insulin dose (baseline: 1.5 [0.4-5.2] U/kg; 6 months: 0.3 [0.0-1.4] U/kg; P < .001). Adverse events included diarrhea (n = 11), hypoglycemia (n = 5), and worsening polyphagia (n = 2).

CONCLUSIONS AND CLINICAL IMPORTANCE

Pasireotide LAR is the first drug to show potential as a long-term management option for cats with HS.

Octreotide therapy in meningiomas: in vitro study, clinical correlation, and literature review

OBJECTIVE Meningiomas express somatostatin receptor subtype 2 (SST2), which is targeted by the somatostatin analog octreotide. However, to date, using somatostatin analog therapy for the treatment of these tumors in clinical practice has been debated. This study aims to clarify the in vitro effects of octreotide on meningiomas for precise clinical applications. METHODS The effects of octreotide were analyzed in a large series of 80 meningiomas, including 31 World Health Organization (WHO) Grade II and 4 WHO Grade III tumors, using fresh primary cell cultures to study the impact on cell viability, apoptosis, and signal transduction pathways. RESULTS SST2 mRNA was detected in 100% of the tested meningiomas at levels similar to those observed in other SST2-expressing tumors, neuroendocrine tumors, or pituitary adenomas. Octreotide significantly decreased cell proliferation in 88% of meningiomas but did not induce cell death. On average, cell proliferation was more inhibited in the meningioma group expressing a high level of SST2 than in the low-SST2 group. Moreover, octreotide response was positively correlated to the level of merlin protein and inversely correlated to the level of phosphorylated p70-S6 kinase, a downstream effector of the PI3K/Akt/mammalian target of rapamycin (mTOR) pathway. Octreotide inhibited Akt phosphorylation and activated tyrosine phosphatase without impacting the extracellular regulated kinase (ERK) pathway. CONCLUSIONS Octreotide acts exclusively as an antiproliferative agent and does not promote apoptosis in meningioma in vitro. Therefore, in vivo, octreotide is likely to limit tumor growth rather than induce tumor shrinkage. A meta-analysis of the literature reveals an interest in octreotide for the treatment of WHO Grade I tumors, particularly those in the skull base for which the 6-month progression-free survival level reached 92%. Moreover, somatostatin analogs, which are well-tolerated drugs, could be of interest for use as co-targeting therapies for aggressive meningiomas.

Multicentre, open-label, randomised, parallel-group, superiority study to compare the efficacy of octreotide therapy 40 mg monthly versus standard of care in patients with refractory anaemia due to gastrointestinal bleeding from small bowel angiodysplasias: a protocol of the OCEAN trial

INTRODUCTION

Gastrointestinal angiodysplasias are an important cause of difficult-to-manage bleeding, especially in older patients. Endoscopic coagulation of angiodysplasias is the mainstay of treatment, but may be difficult for small bowel angiodysplasias because of the inability to reach them for endoscopic intervention. Some patients are red blood cell (RBC) transfusion dependent due to frequent rebleeding despite endoscopic treatment. In small cohort studies, octreotide appears to decrease the number of bleeding episodes in patients with RBC transfusion dependency due to gastrointestinal angiodysplasias. This trial will assess the efficacy of octreotide in decreasing the need for RBC transfusions and parenteral iron in patients with anaemia due to gastrointestinal bleeding of small bowel angiodysplasias despite endoscopic intervention.

STUDY DESIGN

Randomised controlled, superiority, open-label multicentre trial.

PARTICIPANTS

62 patients will be included with refractory anaemia due to small bowel angiodysplasias, who are RBC transfusion or iron infusion dependent despite endoscopic intervention and oral iron supplementation.

INTERVENTION

Patients will be randomly assigned (1:1) to standard care or 40 mg long-acting octreotide once every 4 weeks for 52 weeks, in addition to standard care. The follow-up period is 8 weeks.

MAIN OUTCOME MEASURES

The primary outcome is the difference in the number of blood and iron infusions between the year prior to inclusion and the treatment period of 1 year. Important secondary outcomes are the per cent change in the number of rebleeds from baseline to end point, adverse events and quality of life.

ETHICS AND DISSEMINATION

The trial received ethical approval from the Central Committee on Research Involving Human Subjects and from the local accredited Medical Research Ethics Committee of the region Arnhem-Nijmegen, the Netherlands (reference number: 2014-1433). Results will be published in a peer-reviewed journal and presented at international conferences.

TRIAL REGISTRATION NUMBER

NCT02384122; Pre-results.

The effects of somatostatin analogue therapy on pituitary tumor volume in patients with acromegaly

INTRODUCTION

In nearly all cases, acromegaly is caused by excess GH from a pituitary adenoma, resulting in elevated circulating levels of GH and, subsequently, IGF-1. Treatment goals are to eliminate morbidity and restore the increased mortality to normal rates. Therapeutic strategies aim to minimize tumor mass and normalize GH and IGF-1 levels. Somatostatin analogues are the medical treatment of choice in acromegaly, as first-line or post-surgical therapy, and have proven efficacy in pituitary tumor volume reduction (TVR).

METHODS

Here we review the effects of somatostatin analogue therapy on pituitary tumor volume in patients with acromegaly.

RESULTS

TVR with somatostatin analogues may be mediated by direct anti-proliferative effects via activation of somatostatin receptors, or by indirect effects, such as angiogenesis inhibition, and is more pronounced when they are administered as first-line therapy. Various studies of first-line treatment with octreotide LAR have shown significant TVR in ≥73% of patients. First-line treatment with lanreotide Autogel has shown evidence of TVR, although more studies are needed. In a recent randomized, double-blind, 12-month trial in 358 medical-treatment-naïve acromegaly patients, significant TVR was achieved by 81% of patients administered pasireotide LAR and 77% administered octreotide LAR. Pre-operative somatostatin analogue therapy may also induce TVR and improve post-operative disease control compared with surgery alone. TVR is progressive with prolonged treatment, and decreased IGF-1 levels may be its best predictor, followed by age and degree of GH decrease. However, TVR does not always correlate with degree of biochemical control.

CONCLUSION

Somatostatin analogues (first- or second-line treatment) are the mainstay of medical therapy and, as first-line medical therapy, are associated with significant pituitary TVR in most patients.

Pituitary gigantism: update on molecular biology and management

PURPOSE OF REVIEW

To provide an update on the mechanisms leading to pituitary gigantism, as well as to familiarize the practitioner with the implication of these genetic findings on treatment decisions.

RECENT FINDINGS

Prior studies have identified gigantism as a feature of a number of monogenic disorders, including mutations in the aryl hydrocarbon receptor interacting protein gene, multiple endocrine neoplasia types 1 and 4, McCune Albright syndrome, Carney complex, and the paraganglioma, pheochromocytoma, and pituitary adenoma association because of succinate dehydrogenase defects. We recently described a previously uncharacterized form of early-onset pediatric gigantism caused by microduplications on chromosome Xq26.3 and we termed it X-LAG (X-linked acrogigantism). The age of onset of increased growth in X-LAG is significantly younger than other pituitary gigantism cases, and control of growth hormone excess is particularly challenging.

SUMMARY

Knowledge of the molecular defects that underlie pituitary tumorigenesis is crucial for patient care as they guide early intervention, screening for associated conditions, genetic counseling, surgical approach, and choice of medical management. Recently described microduplications of Xq26.3 account for more than 80% of the cases of early-onset pediatric gigantism. Early recognition of X-LAG may improve outcomes, as successful control of growth hormone excess requires extensive anterior pituitary resection and are difficult to manage with medical therapy alone.

Octreotide in the management of recurrent gastrointestinal bleed in patients supported by continuous flow left ventricular assist devices

Gastrointestinal (GI) bleeding is the most common cause of readmission in patients supported by continuous flow left ventricular assist devices (CF-LVAD). We describe our experience in the off-label use of octreotide in the management of recurrent GI bleed in this population. Of 116 patients implanted with a CF-LVAD at our institution, seven had recurrent GI bleeding unresponsive to conventional management and were started in chronic octreotide injections. Hospitalizations due to GI bleeding, number of packed red blood cells transfused, and number of endoscopic procedures were compared 3 months before and after octreotide treatment. In the overall cohort, there were no differences in these three endpoints. When one patient with differing characteristics was excluded from the analysis there was a trend (p = 0.06) to a reduction of hospitalizations due to GI bleeding, number of blood transfusions, and number of endoscopic procedures. Octreotide exhibit a favorable trend in the frequency of admissions, blood transfusions, and endoscopic procedures in most patients with recurrent GI bleed. Further prospective studies are needed to clarify its benefits in this population.

Molecular genetic advances in pituitary tumor development

Pituitary adenomas are a heterogeneous group of tumors that may occur as part of a complex syndrome or as an isolated endocrinopathy and both forms can be familial or non-familial. Studies of syndromic and non-syndromic pituitary adenomas have yielded important insights about the molecular mechanisms underlying tumorigenesis. Thus, syndromic forms, including multiple endocrine neoplasia type 1 (MEN1), MEN4, Carney Complex and McCune Albright syndrome, have been shown to be due to mutations of the tumor-suppressor protein menin, a cyclin-dependent kinase inhibitor (p27Kip1), the protein kinase A regulatory subunit 1-α, and the G-protein α-stimulatory subunit (Gsα), respectively. Non-syndromic forms, which include familial isolated pituitary adenoma (FIPA) and sporadic tumors, have been shown to be due to abnormalities of: the aryl hydrocarbon receptor-interacting protein; Gsα; signal transducers; cell cycle regulators; transcriptional modulators and miRNAs. The roles of these molecular abnormalities and epigenetic mechanisms in pituitary tumorigenesis, and their therapeutic implications are reviewed.

The expression profile of Dopamine D2 receptor, MGMT and VEGF in different histological subtypes of pituitary adenomas: a study of 197 cases and indications for the medical therapy

BACKGROUND

To study the expression of D2R, MGMT and VEGF for clinical significance in pituitary adenomas, and to predict the potential curative medical therapy of dopamine agonists, temozolomide and bevacizumab on pituitary adenomas.

METHODS

Immunohistochemistry and western blot were performed to detect the expression of expression of D2R, MGMT and VEGF in pituitary adenoma tissue samples. The ratio of high expression of D2R, MGMT or VEGF in different subtypes of PA was compared by the use of chi-squared tests. The relationships between D2R, MGMT and VEGF expression were assessed by the Spearman rank correlation test. The association between their expression and clinical parameters was analyzed using a chi-squared test, or Fisher's exact probability test when appropriate.

RESULTS

The data showed that in 197 different histological subtypes of pituitary adenomas (PAs), 64.9% of them were D2R high expression, 86.3% were MGMT low expression and 58.9% were VEGF high expression. D2R high expression existed more frequently in PRL- and GH- secreting PAs. MGMT low expression existed in all PA subtypes. VEGF high expression existed more frequently in PRL, ACTH, FSH secreting and non-functioning PAs. The data of western blot also support the results. Spearman's rank correlation analysis showed that expression of MGMT was positively associated with D2R (r = 0.154, P = 0.031) and VEGF (r = 0.161, P = 0.024) in PAs, but no correlation was showed between D2R and VEGF expression (r = -0.025, P = 0.725 > 0.05). The association between their expression and clinical parameters was analyzed using a chi-squared test, or Fisher's exact probability test when appropriate, but the result showed no significant association.

CONCLUSIONS

PRL-and GH-secreting PAs exist high expression of D2R, responding to dopamine agonists; Most PAs exist low expression of MGMT and high expression of VEGF, TMZ or bevacizumab treatment could be applied under the premise of indications.

Over-expression of vascular endothelial growth factor in pituitary adenomas is associated with extrasellar growth and recurrence

Some pituitary adenomas (PA) demonstrate aggressive behavior with local invasion and recurrences. Angiogenesis is regarded as an essential step in the formation of solid tumors. The aim of this study is to find out whether angiogenic factors may have information about the aggressiveness of PA that could be useful in determining the frequency of follow-up and whether adjuvant therapy is necessary. In this retrospective descriptive study, we evaluated vascular endothelial growth factors (VEGF) and VEGF receptor (KDR) mRNA expression by RT-PCR analysis on 46 human PA samples. Clinical data, histological subtype and radiologic characteristics were studied to determine the associations between the variables and the pre-operative behavior of the tumor. In addition, we monitored 12 patients without adjuvant post-operative therapies over 46 months after surgery, determining progression of tumor remnants and its association with these markers. VEGF expression correlates with KDR expression (r = 0.40, p = 0.006). VEGF demonstrates different expression between histological subtypes (p = 0.036). The extension at magnetic resonance imaging showed that VEGF expression was related to suprasellar extension (p = 0.007), being expressed more on tumors with extrasellar growth than intrasellar ones (p = 0.008). Our results demonstrate a 27.5 times increased risk of extrasellar growth when VEGF expression exceeds 0.222 normalized copy number (NCN) (p = 0.002). Likewise, tumors with KDR greater than 0.750 NCN had less recurrence-free survival time (p = 0.032). Our results suggest that the expression of VEGF and its receptor could be a marker for poor outcome after partial tumor resection. These data should be considered in future studies evaluating angiogenic factors as therapeutic targets in patients with PA.

Clinicopathological investigation of vascular endothelial growth factor and von Hippel-Lindau gene-related protein expression in immunohistochemically negative pituitary adenoma--possible involvement in tumor aggressiveness

OBJECTIVES

Immunohistochemically negative pituitary adenoma is known to be relatively indolent, but a few aggressive and highly vascular cases have been reported, which sometimes show high expression of vascular endothelial growth factor (VEGF).

METHODS

The present study investigated the relationship between high expression of VEGF and the clinical character of pituitary adenomas in 30 cases of immunohistochemically negative pituitary adenomas using immunohistochemical staining with monoclonal VEGF antibody and related upstream factors, including von Hippel-Lindau gene-related protein (pVHL). Correlations between the histological findings and the clinical characteristics were investigated.

RESULTS

Immunohistochemical staining using VEGF antibody showed high expression in 7 (23.3%) and low expression in 23 (76.7%) cases, and pVHL staining showed high expression in 24 (80%) and low expression in 6 (20%) cases. The pVHL low expression group showed significantly higher expression of VEGF (p = 0.005019), and significantly higher recurrence or regrowth rate (p = 0.04535) than the pVHL high expression group, whereas Ki-67 labeling index of >3% also showed significant correlation with recurrence or regrowth rate (p = 0.01745). However, there was no significant correlation between pVHL staining and Ki-67 labeling index (p = 0.49978).

CONCLUSION

Low expression of pVHL with high expression of VEGF may be involved in the unusual aggressive clinical course in some pituitary adenomas.

Pituitary-directed medical therapy with pasireotide for a corticotroph macroadenoma: pituitary volume reduction and literature review

Hypercortisolism due to an ACTH-secreting pituitary adenoma (Cushing's disease) is a chronic condition associated with high morbidity and mortality if inadequately managed. Pasireotide is a multireceptor-targeted somatostatin analogue and is the only approved medical therapy for Cushing's disease that treats the underlying cause of the disorder. This paper reviews the available literature for medical-therapy-induced adenoma volume reduction in patients with Cushing's disease and reports the experience of a 53-year-old surgically, radiologically and medically naïve (de novo) female with a pituitary macroadenoma who declined surgery. This patient was treated with pasireotide as first-line therapy as part of the largest randomized Phase III study evaluating a medical therapy in patients with Cushing's disease (SOM230B2305 trial). Subcutaneous pasireotide significantly decreased tumor volume, suppressed cortisol secretion, and improved clinical signs and symptoms of Cushing's disease in this patient. Based on this experience, first-line pasireotide has the potential to achieve substantial tumor volume reduction in addition to significant improvements in cortisol levels and signs and symptoms in patients with Cushing's disease for whom surgery is not an option.

Long-acting somatostatin analogues decrease blood transfusion requirements in patients with refractory gastrointestinal bleeding associated with angiodysplasia

BACKGROUND

Gastrointestinal angiodysplasias (GIADs) may be the cause of recurrent bleeding, despite endoscopic treatment.

AIM

To evaluate the effect of long-acting somatostatin analogues on blood transfusion requirements, in patients with refractory bleeding due to GIADs.

METHODS

Consecutive patients with recurrent bleeding from GIADs were enrolled. They received somatostatin analogue treatment for at least 6 months. The efficacy was evaluated in terms of blood transfusions, frequency of bleeding episodes and haemoglobin level during 6 months of treatment (Period During) compared to a 6-months' period before treatment (Period Before).

RESULTS

Fifteen patients were enrolled from 2007 to 2010. The median duration of somatostatin analogue treatment was 12 months (range: 6-36). The number of transfusions significantly decreased in Period During compared with Period Before [median number: 2 (0-14) vs. 10 (6-24); P < 0.001]. The percentage of patients who experienced a bleeding event was lower during somatostatin analogues treatment (20% vs. 73%; P = 0.01). The mean haemoglobin level was significantly higher when somatostatin analogues were offered [median: 10 g/dL (9-13) vs. 7 (5-8.5); P < 0.001]. None of the patients discontinued treatment due to side effects.

CONCLUSIONS

Long-acting somatostatin analogues treatment decreased transfusion needs in patients with refractory bleeding from gastrointestinal angiodysplasias. Bleeding episodes were limited and haemoglobin improved during treatment. Long-acting somatostatin analogues may represent an option for the management of patients with chronic bleeding due to gastrointestinal angiodysplasias.

Von Hippel-Lindau disease and aggressive GH-PRL pituitary adenoma in a young boy

Von Hippel-Lindau disease is an autosomal dominant disorder involving the development of specific tumours in multiple organs, both benign and malignant. In the CNS, the syndrome is characterized by haemangioblastomas of the retina, spinal cord and brain. We report the case of a 15-year-old boy with the diagnosis of aggressive GH-PRL pituitary macroadenoma and a family history of VHL disease. Pituitary resection was performed, although complete excision of the lesion could not be confirmed by the neurosurgeon. A control MRI was done 6 months after surgery and the pituitary lesion was similar to the presurgical image. A second operation allowed partial resection of the tumour followed by targeted radiotherapy. Pituitary adenomas are rare benign tumours in children with macroadenomas observed mainly in boys. These tumours in adolescents often occur in a familial setting or in the context of known genetic defects. Angiogenesis is an important feature of pituitary adenomas and a possible inhibitory role of pVHL in pituitary angiogenesis has been suggested. This GH-PRL pituitary macroadenoma with a VHL mutation might be of particular aggressiveness. Pituitary adenomas are not classically described in VHL syndrome and the medical community should be alerted to its rare occurrence in this location.

Potential synergies for combined targeted therapy in the treatment of neuroendocrine cancer

Well differentiated neuroendocrine tumours (WDNET) are a diverse group of cancers that are often advanced at the time of diagnosis and generally do not respond significantly to traditional chemotherapy. A number of intriguing therapeutic targets have emerged, including somatostatin receptors, insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R), the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, and vascular endothelial growth factor receptor. Functional somatostatin receptors and IGF-1R as well as dysregulated mTOR--a key pathway component for both growth factor signalling and protein synthesis--have been identified in human neuroendocrine tumour (NET) cell lines. Somatostatin analogues (SSA) and mTOR inhibitors have exhibited in vitro and in vivo antitumour activity against NET and have shown effects on the IGF-1 pathway in preclinical studies. SSA inhibit PI3K/Akt signalling upstream of mTOR, suggesting that the combination of an SSA and an mTOR inhibitor may have greater efficacy than either as single agents. Recent clinical trial experience has provided some encouraging findings and prompted the design of additional studies of this dual-targeted approach to treating advanced WDNET. Results of ongoing trials of dual-targeted therapy combinations will define future therapies for advanced WDNET.

Somatostatin analogues in the treatment of recurrent bleeding from gastrointestinal vascular malformations: an overview and systematic review of prospective observational studies

BACKGROUND

Vascular malformation of the gastrointestinal tract is an uncommon cause for gastrointestinal bleeding. Traditionally, gastroenterologists prefer to use endoscopic modalities like argon plasma coagulation and electrocoagulation to treat accessible lesions. The role of somatostatin analogues (octreotide) in preventing recurrent bleeding in these patients is unclear. The use of pharmacological treatments would be useful especially in refractory bleeding, inaccessible lesions and in patients who are at high risk for invasive interventions.

AIMS

To systematically review pooled clinical response rates from prospective studies using somatostatin analogues for prevention of recurrent bleeding from gastrointestinal angiodysplasia and quantify the effects that therapy has on the use of blood transfusions.

METHODS

We searched several electronic databases including Pubmed for full journal articles published after 1966 reporting on the use of somatostatin analogues in the treatment of gastrointestinal angiodyplasia. We hand searched the reference lists of all retrieved articles. Prospective studies involving ten or more patients were included in the analysis. We calculated the pooled proportion of patients who had a clinical response to therapy in the selected studies and the weighted mean difference in transfusion requirements before and after therapy. Heterogeneity between the studies was assessed using the I2 statistic.

RESULTS

A total of three studies involving 62 patients met the inclusion criteria. The proportional meta-analysis showed a clinical response to treatment of 0.76 (95% CI 0.64-0.85). The weighted mean difference in transfusion requirements before starting therapy (control group) and after treatment initiation (treatment group) was -2.2 (95% CI -3.9 to -0.5). No significant heterogeneity was seen between the studies.

CONCLUSIONS

A significant number of patients with bleeding gastrointestinal angiodysplasia respond to treatment with octreotide by reducing the need for blood products. As all the included studies had small sample sizes, multicenter randomized trials are needed to confirm these findings. However, it seems reasonable to administer octreotide especially in patients with refractory bleeding, inaccessible lesions and in patients at high risk for other interventions.