From somatostatin to octreotide LAR: evolution of a somatostatin analogue

Radiolabeled Somatostatin Analogs for Cancer Imaging

Somatostatin receptors (SSTR) are expressed by many tumours especially those related to neuro-endocrine origin and molecular functional imaging of SSTR expression using radiolabelled somatostatin analogs have revolutionized imaging of patients with these group of malignancies. Coming a long way from the first radiolabelled somatostatin analog 123I-Tyr-3-octreotide, there has been significant developments in terms of radionuclides used, the ligands and somatostatin derivatives. 111In-Pentetreotide extensively employed for imaging NETs at the beginning has now been replaced by 68Ga-SSA based PET-CT. SSA-PET/CT performs superior to conventional imaging modalities and has evolved in the mainframe for NET imaging. The advantages were multiple: (i) superior spatial resolution of PET versus SPECT, (ii) quantitative capabilities of PET aiding in disease activity and treatment response monitoring with better precision, (iii) shorter scan time and (iv) less patient exposure to radiation. The modality is indicated for staging, detecting the primary in CUP-NETs, restaging, treatment planning (along with FDG: the concept of dual-tracer PET-CT) as well as treatment response evaluation and follow-up of NETs. SSA PET/CT has also been incorporated in the guidelines for imaging of Pheochromocytoma-Paraganglioma, Medullary carcinoma thyroid, Meningioma and Tumor induced osteomalacia. At present, there is rising interest on (a) 18F-labelled SSA, (b) 64Cu-labelled SSA, and (c) somatostatin antagonists. 18F offers excellent imaging properties, 64Cu makes delayed imaging feasible which has implications in dosimetry and SSTR antagonists bind with the SST receptors with high affinity and specificity, providing high contrast images with less background, which can be translated to theranostics effectively. SSTR have been demonstrated in non-neuroendocrine tumours as well in the peer-reviewed literature, with studies demonstrating the potential of SSA PET/CT in Neuroblastoma, Nasopharyngeal carcinoma, carcinoma prostate (neuroendocrine differentiation) and lymphoma. This review will focus on the currently available SSAs and their history, different SPECT/PET agents, SSTR antagonists, comparison between the various imaging tracers, and their utility in both neuroendocrine and non-neuroendocrine tumors.

Targeting Nrf2 by bioactive peptides alleviate inflammation: expanding the role of gut microbiota and metabolites

Inflammation is a complex process that usually refers to the general response of the body to the harmful stimuli of various pathogens, tissue damage, or exogenous pollutants. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates cellular defense against oxidative damage and toxicity by expressing genes related to oxidative stress response and drug detoxification. In addition to its antioxidant properties, Nrf2 is involved in many other important physiological processes, including inflammation and metabolism. Nrf2 can bind the promoters of antioxidant genes and upregulates their expressions, which alleviate oxidation-induced inflammation. Nrf2 has been shown to upregulate heme oxygenase-1 expression, which promotes NF-κB activation and is closely related with inflammation. Nrf2, as a key factor in antioxidant response, is closely related to the expressions of pro-inflammatory factors, NF-κB pathway and cell metabolism. Bioactive peptides come from a wide range of sources and have many biological functions. Increasing evidence indicates that bioactive peptides have potential anti-inflammatory activities. This article summarized the sources, absorption and utilization of bioactive peptides and their role in alleviating inflammation via Nrf2 pathway. Bioactive peptides can also regulate gut microbiota and alter metabolites, which regulates the Nrf2 pathway through novel pathway and supplement the anti-inflammatory mechanisms of bioactive peptides. This review provides a reference for further study on the anti-inflammatory effect of bioactive peptides and the development and utilization of functional foods.

Quantitative uptake in 99m Tc-EDDA/HYNIC-TOC somatostatin receptor imaging - the effect of long-acting release somatostatin analogue therapy

PURPOSE

Withdrawal of long-acting release somatostatin analogue (LAR-SSA) treatment before somatostatin receptor imaging is based on empirical reasoning that it may block uptake at receptor sites. This study aims to quantify differences in uptake of 99m Tc-EDDA/HYNIC-TOC between patients receiving LAR-SSA and those who were not.

METHODS

Quantification of 177 patients (55 on LAR-SSA) imaged with 99m Tc-EDDA/HYNIC-TOC was performed, with analysis of pathological tissue and organs with physiological uptake using thresholded volumes of interest. Standardised uptake values (SUVs) and tumour/background (T/B) ratios were calculated and compared between the two patient groups.

RESULTS

SUVs were significantly lower for physiological organ uptake for patients on LAR-SSA (e.g. spleen: SUV max 13.3 ± 5.9 versus 33.9 ± 9.0, P  < 0.001); there was no significant difference for sites of pathological uptake (e.g. nodal metastases: SUV max 19.2 ± 13.0 versus 17.4 ± 11.5, P  = 0.552) apart from bone metastases (SUV max 14.1 ± 13.5 versus 7.7 ± 8.0, P  = 0.017) where it was significantly higher.

CONCLUSION

LAR-SSA has an effect only on physiological organ uptake of 99m Tc-EDDA/HYNIC-TOC, reducing uptake. It has no significant effect on pathological uptake for most sites of primary and metastatic disease. This should be taken into account if making quantitative measurements, calculating T/B ratios or assigning Krenning Scores. There is the potential for improved dosimetric results in Peptide Receptor Radionuclide Therapy by maintaining patients on LAR-SSA.

Molecular simulations of SSTR2 dynamics and interaction with ligands

The cyclic peptide hormone somatostatin regulates physiological processes involved in growth and metabolism, through its binding to G-protein coupled somatostatin receptors. The isoform 2 (SSTR2) is of particular relevance for the therapy of neuroendocrine tumours for which different analogues to somatostatin are currently in clinical use. We present an extensive and systematic computational study on the dynamics of SSTR2 in three different states: active agonist-bound, inactive antagonist-bound and apo inactive. We exploited the recent burst of SSTR2 experimental structures to perform μs-long multi-copy molecular dynamics simulations to sample conformational changes of the receptor and rationalize its binding to different ligands (the agonists somatostatin and octreotide, and the antagonist CYN154806). Our findings suggest that the apo form is more flexible compared to the holo ones, and confirm that the extracellular loop 2 closes upon the agonist octreotide but not upon the antagonist CYN154806. Based on interaction fingerprint analyses and free energy calculations, we found that all peptides similarly interact with residues buried into the binding pocket. Conversely, specific patterns of interactions are found with residues located in the external portion of the pocket, at the basis of the extracellular loops, particularly distinguishing the agonists from the antagonist. This study will help in the design of new somatostatin-based compounds for theranostics of neuroendocrine tumours.

Discovery of TP0597850: A Selective, Chemically Stable, and Slow Tight-Binding Matrix Metalloproteinase-2 Inhibitor with a Phenylbenzamide-Pentapeptide Hybrid Scaffold

Matrix metalloproteinase-2 (MMP2) is a zinc-dependent endopeptidase and a promising target for various diseases, including cancer and fibrosis. Herein, we report the discovery of a novel MMP2-selective inhibitor with high chemical stability and slow tight-binding features. Based on the degradation mechanism of our small-molecule-peptide hybrid 1, the tripeptide linker {5-aminopentanoic acid [Ape(5)]-Glu-Asp} of 1 was replaced by a shorter linker (γ-D-Glu). Phenylbenzamide was suitable for the new generation of MMP2 inhibitors as an S1' pocket-binding group. The introduction of (4S)-aminoproline dramatically increased the chemical stability while maintaining high subtype selectivity because of its interaction with Glu130. TP0597850 (18) exhibited high stability over a wide range of pH values as well as potent MMP2 inhibition (K_i = 0.034 nM) and ≥2000-fold selectivity determined using the inhibition constants. A kinetic analysis revealed that it possesses slow tight-binding nature with a long MMP2 dissociative half-life (t_1/2 = 265 min).

Somatostatin venom analogs evolved by fish-hunting cone snails: From prey capture behavior to identifying drug leads

Somatostatin (SS) is a peptide hormone with diverse physiological roles. By investigating a deep-water clade of fish-hunting cone snails, we show that predator-prey evolution has generated a diverse set of SS analogs, each optimized to elicit specific systemic physiological effects in prey. The increased metabolic stability, distinct SS receptor activation profiles, and chemical diversity of the venom analogs make them suitable leads for therapeutic application, including pain, cancer, and endocrine disorders. Our findings not only establish the existence of SS-like peptides in animal venoms but also serve as a model for the synergy gained from combining molecular phylogenetics and behavioral observations to optimize the discovery of natural products with biomedical potential.

Peptide receptor radionuclide therapy implementation and results in a predominantly gastrointestinal neuroendocrine tumor population: A two-year experience in a nonuniversity setting

Neuroendocrine tumors (NETs) are rare, but the incidence and prevalence of NETs are increasing in the United States. While surgery is the preferred treatment for NETs, it is not a viable option for metastatic disease. Lutathera (177Lu-DOTATATE) is approved by the United States Food and Drug Administration and the European Medicines Agency for the treatment of gastroenteropancreatic (GEP)-NETs in adults. There is limited information on GEP-NET treatment responses to Lutathera.Our institution launched a peptide receptor radionuclide therapy (PRRT) service line using Lutathera with involvement from a multidisciplinary team and complete collaboration between hospital administration and clinical providers. A prospective registry study was also established in order to collect patient demographics and clinical data regarding the treatment of GEP primary NETs with Lutathera.Between August 2018 and July 2020, 35 GEP-NET patients were treated with Lutathera, of which 65.71% received 4 complete cycles and 25.71% received 3 cycles; 5.71% and 2.86% received 2 and 1 cycles of PRRT, respectively. Most adverse events during the course of our study were low grade using the common terminology criteria for adverse events system. Of the patients who completed all 4 cycles: 22% showed partial response to Lutathera, 44% showed stable disease, and 13% showed disease progression based on a qualitative assessment of positron emission tomography/computed tomography imaging.From our experience, Lutathera was well tolerated in patients with GEP-NET. Additional studies are needed to examine long-term clinical and patient-reported outcomes associated with GEP-NET treatment as well as financial considerations for hospitals embarking on a PRRT program.

Chylothorax in the neonate-A stepwise approach algorithm

BACKGROUND

Chylothorax in neonates results from leakage of lymph from thoracic lymphatic ducts and is mainly congenital or posttraumatic. The clinical course of the effusion is heterogeneous, and consensus on treatment, timing, and modalities of measures has not yet been established. This review aims to present, along with levels of evidence and recommendation grades, all current therapeutic possibilities for the treatment of chylothorax in neonates.

METHODS

An extensive search of publications between 1970 and 2020 was performed in the PubMed, Cochrane Database of Systematic Reviews, and UpToDate databases. A stepwise approach algorithm was proposed for both congenital and traumatic conditions to guide the clinician in a rational and systematic way for approaching the treatment of neonates with chylothorax.

DISCUSSION AND CONCLUSION

The treatment strategy for neonatal chylothorax generally involves supportive care and includes drainage and procedures to reduce chyle flow. A stepwise approach starting with the least invasive method is advocated. Progression in the invasiveness of treatment options is determined by the response to previous treatments. A practical stepwise approach algorithm is proposed for both, congenital and traumatic chylothoraces.

Opportunities to Improve Symptom Control with Somatostatin Congeners in GEP-NETs: A Review of Key Issues

Octreotide acetate (octreotide) is the most prescribed and most studied somatostatin congener, or analog, for gastroenteropancreatic neuroendocrine tumors (GEP‐NETs) and carcinoid syndrome, the latter of which may be characterized by debilitating diarrhea and flushing. Approved in the U.S. more than 30 years ago, octreotide is widely used to control the symptoms of carcinoid syndrome and has been shown to demonstrate antiproliferative activity. The two formulations available in the U.S. include a subcutaneous immediate‐release (IR) injection introduced in 1989 and a long‐acting repeatable (LAR) intramuscular injection approved in 1999. Lanreotide depot (lanreotide), a more recent somatostatin congener, has been available in the U.S. since 2014.

Despite widespread use of octreotide LAR, several key challenges exist with the current depot‐based treatment paradigm. Studies indicate that LAR formulations are associated with continued unmet patient needs, owing in part to a loss of bioactivity over time that may necessitate progressive supplemental treatment with IR octreotide to adequately control symptoms. Clinicians should understand the key differences in the pharmacokinetic profiles of the LAR and IR formulations that may contribute to bioactivity loss and somatostatin receptor desensitization. In addition, there is a need to re‐evaluate the role of IR octreotide in combination with depot therapy to provide consistent bioavailability and better control of carcinoid syndrome symptoms.

The purpose of this review is to explore all these issues and to re‐establish a rationale for the IR formulation, particularly with respect to novel use cases and its use during the COVID‐19 pandemic.

This review explores key challenges with depot‐based treatment of gastroenteropancreatic neuroendocrine tumors with octreotide and the key differences between the LAR and IR formulations.

Minireview: Mas-related G protein-coupled receptor X2 activation by therapeutic drugs

Symptoms that resemble allergic reactions, such as pruritus, flushing, and hypotension, are common side effects of therapeutic drugs. In a true allergic reaction, Immunoglobulin E (IgE) antibodies recognize the drug and trigger mediator release from mast cells through cross-linking of IgE receptors. However, many drugs can bypass this pathway and can activate mast cells directly through MRGPRX2, a G protein-coupled receptor that responds to a wide range of small molecules, peptides, and proteins that have little in common except for a net positive charge. This review will provide an overview of MRGPRX2, including its expression pattern, studies of its pharmacology, and its orthologs. It also will review evidence for MRGPRX2 activation by many drugs closely associated with these reactions.

Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia

Hyperinsulinaemic hypoglycaemia (HH) is a biochemical finding of low blood glucose levels due to the dysregulation of insulin secretion from pancreatic β-cells. Under normal physiological conditions, glucose metabolism is coupled to β-cell insulin secretion so that blood glucose levels are maintained within the physiological range of 3.5-5.5 mmol/L. However, in HH this coupling of glucose metabolism to insulin secretion is perturbed so that insulin secretion becomes unregulated. HH typically occurs in the neonatal, infancy and childhood periods and can be due to many different causes. Adults can also present with HH but the causes in adults tend to be different. Somatostatin (SST) is a peptide hormone that is released by the delta cells (δ-cells) in the pancreas. It binds to G protein-coupled SST receptors to regulate a variety of location-specific and selective functions such as hormone inhibition, neurotransmission and cell proliferation. SST plays a potent role in the regulation of both insulin and glucagon secretion in response to changes in glucose levels by negative feedback mechanism. The half-life of SST is only 1-3 min due to quick degradation by peptidases in plasma and tissues. Thus, a direct continuous intravenous or subcutaneous infusion is required to achieve the therapeutic effect. These limitations prompted the discovery of SST analogues such as octreotide and lanreotide, which have longer half-lives and therefore can be administered as injections. SST analogues are used to treat different forms of HH in children and adults and therapeutic effect is achieved by suppressing insulin secretion from pancreatic β-cells by complex mechanisms. These treatments are associated with several side effects, especially in the newborn period, with necrotizing enterocolitis being the most serious side effect and hence SS analogues should be used with extreme caution in this age group.

Overview of Radiolabeled Somatostatin Analogs for Cancer Imaging and Therapy

Identified in 1973, somatostatin (SST) is a cyclic hormone peptide with a short biological half-life. Somatostatin receptors (SSTRs) are widely expressed in the whole body, with five subtypes described. The interaction between SST and its receptors leads to the internalization of the ligand-receptor complex and triggers different cellular signaling pathways. Interestingly, the expression of SSTRs is significantly enhanced in many solid tumors, especially gastro-entero-pancreatic neuroendocrine tumors (GEP-NET). Thus, somatostatin analogs (SSAs) have been developed to improve the stability of the endogenous ligand and so extend its half-life. Radiolabeled analogs have been developed with several radioelements such as indium-111, technetium-99 m, and recently gallium-68, fluorine-18, and copper-64, to visualize the distribution of receptor overexpression in tumors. Internal metabolic radiotherapy is also used as a therapeutic strategy (e.g., using yttrium-90, lutetium-177, and actinium-225). With some radiopharmaceuticals now used in clinical practice, somatostatin analogs developed for imaging and therapy are an example of the concept of personalized medicine with a theranostic approach. Here, we review the development of these analogs, from the well-established and authorized ones to the most recently developed radiotracers, which have better pharmacokinetic properties and demonstrate increased efficacy and safety, as well as the search for new clinical indications.

Evaluation of Nurses' and Patients' Overall Satisfaction with New and Previous Formulations of Octreotide Long-acting Release (Sandostatin LAR®): A French Observational Study

INTRODUCTION

The first long-acting release (LAR) formulation of octreotide was marketed in France in the late 1990s. An injectable formulation of Sandostatin LAR^® (Novartis SAS) with a new diluent has been developed to facilitate its preparation and administration and to improve its use in practice.

METHODS

We conducted an observational, cross-sectional and multicenter study in France whose main outcome was to compare nurses' satisfaction with the preparation and administration of both previous and new formulations of octreotide LAR. Secondary outcomes included assessment of patient satisfaction (quality of life and pain felt during the injection) and product tolerance. Data were collected at two time points (one for the first formulation group and one for the second formulation group) through paper questionnaires administered to physicians, patients and nurses including a visual analog scale (VAS) from 0 (unsatisfied) to 10 (very satisfied).

RESULTS

Results showed that overall nurse satisfaction improved from 5.3 (95% CI 4.9-5.8) with the previous formulation to 7.5 (95% CI 7-7.9) with the new formulation (p < 0.0001). Regarding secondary outcomes, the simplicity of the injection increased (84% for the previous formulation and 94% for the new formulation) and the purge problem disappeared (36% for the previous formulation and 4% for the new formulation).

CONCLUSION

The improvement due to the new formulation of Sandostatin LAR^® was reported in terms of handling, ease of use and overall nurse satisfaction. The new formulation greatly reduced treatment administration problems associated with the previous formulation, while maintaining low injection site pain and an equivalent safety profile in both indications.

Targeting and therapeutic peptide-based strategies for polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by progressive cyst growth and is a leading cause of renal failure worldwide. Currently, there are limited therapeutic options available to PKD patients, and only one drug, tolvaptan, has been FDA-approved to slow cyst progression. Similar to other small molecule drugs, however, tolvaptan is costly, only moderately effective, and causes adverse events leading to high patient dropout rates. Peptides may mitigate many drawbacks of small molecule drugs, as they can be highly tissue-specific, biocompatible, and economically scaled-up. Peptides can function as targeting ligands that direct therapies to diseased renal tissue, or be potent as therapeutic agents themselves. This review discusses various aberrant signaling pathways in PKD and renal receptors that can be potential targets of peptide-mediated strategies. Additionally, peptides utilized in other kidney applications, but may prove useful in the context of PKD, are highlighted. Insights into novel peptide-based solutions that have potential to improve clinical management of PKD are provided.

Advances in therapeutic peptides targeting G protein-coupled receptors

Dysregulation of peptide-activated pathways causes a range of diseases, fostering the discovery and clinical development of peptide drugs. Many endogenous peptides activate G protein-coupled receptors (GPCRs) - nearly 50 GPCR peptide drugs have been approved to date, most of them for metabolic disease or oncology, and more than 10 potentially first-in-class peptide therapeutics are in the pipeline. The majority of existing peptide therapeutics are agonists, which reflects the currently dominant strategy of modifying the endogenous peptide sequence of ligands for peptide-binding GPCRs. Increasingly, novel strategies are being employed to develop both agonists and antagonists, to both introduce chemical novelty and improve drug-like properties. Pharmacodynamic improvements are evolving to allow biasing ligands to activate specific downstream signalling pathways, in order to optimize efficacy and reduce side effects. In pharmacokinetics, modifications that increase plasma half-life have been revolutionary. Here, we discuss the current status of the peptide drugs targeting GPCRs, with a focus on evolving strategies to improve pharmacokinetic and pharmacodynamic properties.

Somatostatin analogues and the risk of post-operative pancreatic fistulas after pancreatic resection - A systematic review & meta-analysis

BACKGROUND

Post-operative pancreatic fistula (POPF) is a common complication of pancreatic resection. Somatostatin analogues (SA) have been used as prophylaxis to reduce its incidence. The aim of this study is to appraise the current literature on the effects of SA prophylaxis on the prevention of POPF following pancreatic resection.

METHODS

The review of the literature was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data from studies that reported the effects of SA prophylaxis on POPF following pancreatic resection were extracted, to determine the effect of SA on POPF morbidity and mortality.

RESULTS

A total of 15 studies, involving 2221 patients, were included. Meta-analysis revealed significant reductions in overall POPF (Odds ratio: 0.65 (95% CI 0.53-0.81, p < 0.01)), clinically significant POPF (Odds ratio: 0.53 (95% CI 0.34-0.83, p < 0.01)) and overall morbidity (OR: 0.69 (95% CI: 0.50-0.95, p = 0.02)) following SA prophylaxis. There is no evidence that SA prophylaxis reduces mortality (OR: 1.10 (95%CI: 0.68-1.79, p = 0.68)).

CONCLUSION

SA prophylaxis following pancreatic resection reduces the incidence of POPF. However, mortality is unaffected.

203/212Pb Theranostic Radiopharmaceuticals for Image-guided Radionuclide Therapy for Cancer

Receptor-targeted image-guided Radionuclide Therapy (TRT) is increasingly recognized as a promising approach to cancer treatment. In particular, the potential for clinical translation of receptor-targeted alpha-particle therapy is receiving considerable attention as an approach that can improve outcomes for cancer patients. Higher Linear-energy Transfer (LET) of alpha-particles (compared to beta particles) for this purpose results in an increased incidence of double-strand DNA breaks and improved-localized cancer-cell damage. Recent clinical studies provide compelling evidence that alpha-TRT has the potential to deliver a significantly more potent anti-cancer effect compared with beta-TRT. Generator-produced 212Pb (which decays to alpha emitters 212Bi and 212Po) is a particularly promising radionuclide for receptor-targeted alpha-particle therapy. A second attractive feature that distinguishes 212Pb alpha-TRT from other available radionuclides is the possibility to employ elementallymatched isotope 203Pb as an imaging surrogate in place of the therapeutic radionuclide. As direct non-invasive measurement of alpha-particle emissions cannot be conducted using current medical scanner technology, the imaging surrogate allows for a pharmacologically-inactive determination of the pharmacokinetics and biodistribution of TRT candidate ligands in advance of treatment. Thus, elementally-matched 203Pb labeled radiopharmaceuticals can be used to identify patients who may benefit from 212Pb alpha-TRT and apply appropriate dosimetry and treatment planning in advance of the therapy. In this review, we provide a brief history on the use of these isotopes for cancer therapy; describe the decay and chemical characteristics of 203/212Pb for their use in cancer theranostics and methodologies applied for production and purification of these isotopes for radiopharmaceutical production. In addition, a medical physics and dosimetry perspective is provided that highlights the potential of 212Pb for alpha-TRT and the expected safety for 203Pb surrogate imaging. Recent and current preclinical and clinical studies are presented. The sum of the findings herein and observations presented provide evidence that the 203Pb/212Pb theranostic pair has a promising future for use in radiopharmaceutical theranostic therapies for cancer.

Antibacterial properties of snake venom components

An increasing problem in the field of health protection is the emergence of drug-resistant and multi-drug-resistant bacterial strains. They cause a number of infections, including hospital infections, which currently available antibiotics are unable to fight. Therefore, many studies are devoted to the search for new therapeutic agents with bactericidal and bacteriostatic properties. One of the latest concepts is to search for this type of substances among toxins produced by venomous animals. In this approach, however, special attention is paid to snake venom because it contains molecules with antibacterial properties. Thorough investigations have shown that the phospholipases A2 (PLA2) and l-amino acids oxidases (LAAO), as well as fragments of these enzymes, are mainly responsible for the bactericidal properties of snake venoms. Some preliminary research studies also suggest that fragments of three-finger toxins (3FTx) are bactericidal. It has also been proven that some snakes produce antibacterial peptides (AMP) homologous to human defensins and cathelicidins. The presence of these proteins and peptides means that snake venoms continue to be an interesting material for researchers and can be perceived as a promising source of antibacterial agents.

Systemic treatment for lung carcinoids: from bench to bedside

In the huge spectrum of lung neuroendocrine neoplasms, typical and atypical carcinoids should be considered as a separate biological entity from poorly differentiated forms, harboring peculiar molecular alterations. Despite their indolent behavior, lung carcinoids correlate with a worse survival. To date, only limited therapeutic options are available and novel drugs are strongly needed. In this work, we extensively reviewed scientific literature exploring available therapeutic options, new molecular targets and future perspectives in the management of well differentiated neoplasms of bronchopulmonary tree. Systemic therapy represents the main option in advanced and unresectable disease; accepted choices are somatostatin analogs, peptide receptor radionuclide therapy, everolimus and chemotherapy. To date, an univocal treatment strategy has not been identified yet, thus tailored therapeutic algorithms should consider treatment efficacy as well as safety profiles. Several molecular alterations found in carcinoid tumors might act as molecular targets leading to development of new therapeutic options. Further studies are necessary to identify new potential “druggable” molecular targets in the selected subset of low-grade lung carcinoids. Furthermore, evaluating the available therapies in more homogeneous population might improve their efficacy through a perfect tailoring of treatment options.

Photonuclear production, chemistry, and in vitro evaluation of the theranostic radionuclide 47Sc

Background

In molecular imaging and nuclear medicine, theranostic agents that integrate radionuclide pairs are successfully being used for individualized care, which has led to rapidly growing interest in their continued development. These compounds, which are radiolabeled with one radionuclide for imaging and a chemically identical or similar radionuclide for therapy, may improve patient-specific treatment and outcomes by matching the properties of different radionuclides with a targeting vector for a particular tumor type. One proposed theranostic radionuclide is scandium-47 (⁴⁷Sc, T_1/2 = 3.35 days), which can be used for targeted radiotherapy and may be paired with the positron emitting radionuclides, ⁴³Sc (T_1/2 = 3.89 h) and ⁴⁴Sc (T_1/2 = 3.97 h) for imaging. The aim of this study was to investigate the photonuclear production of ⁴⁷Sc via the ⁴⁸Ti(γ,p)⁴⁷Sc reaction using an electron linear accelerator (eLINAC), separation and purification of ⁴⁷Sc, the radiolabeling of somatostatin receptor-targeting peptide DOTATOC with ⁴⁷Sc, and in vitro receptor-mediated binding of [⁴⁷Sc]Sc-DOTATOC in AR42J somatostatin receptor subtype two (SSTR2) expressing rat pancreatic tumor cells.

Results

The rate of ⁴⁷Sc production in a stack of natural titanium foils (n = 39) was 8 × 10⁷ Bq/mA·h (n = 3). Irradiated target foils were dissolved in 2.0 M H₂SO₄ under reflux. After dissolution, trivalent ⁴⁷Sc ions were separated from natural Ti using AG MP-50 cation exchange resin. The recovered ⁴⁷Sc was then purified using CHELEX 100 ion exchange resin. The average decay-corrected two-step ⁴⁷Sc recovery (n = 9) was (77 ± 7)%. A radiolabeling yield of > 99.9% of [⁴⁷Sc]Sc-DOTATOC (0.384 mg in 0.3 mL) was achieved using 1.7 MBq of ⁴⁷Sc. Blocking studies using Octreotide illustrated receptor-mediated uptake of [⁴⁷Sc]Sc-DOTATOC in AR42J cells.

Conclusions

⁴⁷Sc can be produced via the ⁴⁸Ti(γ,p)⁴⁷Sc reaction and separated from natural Ti targets with a yield and radiochemical purity suitable for radiolabeling of peptides for in vitro studies. The data in this work supports the potential use of eLINACs for studies of photonuclear production of medical radionuclides and the future development of high-intensity eLINAC facilities capable of producing relevant quantities of carrier-free radionuclides currently inaccessible via routine production pathways or limited due to costly enriched targets.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0515-8) contains supplementary material, which is available to authorized users.

Paraneoplastic syndromes and other systemic disorders associated with neuroendocrine neoplasms

Neuroendocrine paraneoplastic syndromes (PNS) consist of metabolic disorders that accompany benign and malignant neoplasms but remain unrelated to mass effects or invasion by the primary tumor or its metastases. The underlying pathogenesis responsible for PNS usual clinical presentation relies on aberrant production of protein hormones, proteins and other substances by the tumor. Prompt recognition of characteristic signs and symptoms combined with serological identification of key substances may result in early diagnosis of PNS and its underlying malignancy. For these reasons, healthcare professionals should familiarize themselves with tumor-induced hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid syndrome, virilisation syndrome, gynecomastia, acromegaly, Cushing syndrome, osteogenic osteomalacia, tumor-induced hypoglycemia, necrolytic migratory erythema, and watery diarrhea, hypokalemia and achlorydria syndrome. Medical awareness for PNS can improve patient outcomes through earlier administration of cancer therapy and treatment, better symptomatic relief and prolong overall survival.

Inoperable Giant Growth Hormone-secreting Pituitary Adenoma: Radiological Aspects, Clinical Management and Pregnancy Outcome

Methods:

We report on a young woman with acromegaly due to an inoperable giant GH-secreting pituitary adenoma extending to right cavernous sinus, right orbital cavity, ethmoid, right maxillary sinus, sphenoid sinus, clivus and right temporal fossa, in which medical treatment with Octreotide- LAR was able to promptly relieve headache and bilateral hemianopsia due to optic chiasm involvement, improve acromegaly symptoms and, over the time, control tumor expansion, improving fertility and therefore allowing the patient to become pregnant.

Results:

Octreotide-LAR therapy was withdrawn during pregnancy and the patient did not experience complications and gave birth to a healthy son. On magnetic resonance, the size of the tumor at the end of pregnancy and in the subsequent follow up was not increased.

Conclusion:

The history we report, therefore, confirms previous experiences reporting a possible favourable outcome of pregnancy in patients affected by acromegaly and adds further information about the behaviour of giant pituitary tumors in patients underwent pregnancy.

New Treatments for the Carcinoid Syndrome

Neuroendocrine tumors, including carcinoids, are rare and insidiously growing tumors. Related to their site of origin, tumors can be functional, causing various forms of the carcinoid syndrome, owing to the overproduction of serotonin, histamine, or other bioactive substances. They often invade adjacent structures or metastasize to the liver and elsewhere. Treatment includes multimodal approaches, including cytoreductive surgery, locoregional embolization, cytotoxic therapy, peptide receptor radionuclide therapy, and various targeted therapies with goals of symptom relief and control of tumor growth. This article summarizes current and emerging approaches to management and reviews several promising future therapies.

Partial hepatic resections for metastatic neuroendocrine tumors: perioperative outcomes

STUDY OBJECTIVE

Partial hepatic resection reduces tumor burden in patients with metastatic neuroendocrine tumors, thereby improving quality and length of life. These procedures can be challenging as well as life-threatening. Our aim was to evaluate our patients' perioperative outcomes and propose a definition for an intraoperative carcinoid crisis relevant to this surgery, given its unique surgical considerations.

DESIGN

Retrospective study.

SETTING

Mayo Clinic, Rochester, Minnesota.

PATIENTS

One hundred sixty-nine patients undergoing partial hepatic resection for metastatic neuroendocrine tumors between 1997 and 2015 were identified retrospectively from a surgical database at Mayo Clinic Rochester.

INTERVENTIONS

None.

MEASUREMENTS

Intraoperative carcinoid crisis for patients undergoing hepatic resection of neuroendocrine tumors was defined. Patients' medical records were reviewed and data were abstracted describing patient and procedural characteristics and perioperative outcomes.

MAIN RESULTS

There were no documented cases of carcinoid crisis (0.0%, 95% C.I. 0.0% to 2.2%). One patient developed clinical findings of an emerging carcinoid crisis, but was successfully treated with doses of octreotide and findings resolved in <10 min. Prophylactically 500 μg octreotide was given subcutaneously in 77% (130/169) of patients preoperatively.

CONCLUSIONS

There were no documented cases of carcinoid crisis (0.0%, 95% C.I. 0.0% to 2.2%). Adverse events were infrequent.

Entering the third decade of experience with octreotide LAR in neuroendocrine tumors: A review of current knowledge

Gastroenteropancreatic neuroendocrine tumors (NETs) are a relatively rare group of heterogeneous neoplasms. The most significant advance in therapy of NETs has been the advent of the somatostatin analog octreotide, which represents a cornerstone in their management and dramatically changed the therapeutic landscape. Octreotide long-acting release (LAR) was developed to overcome some of the limitations of octreotide. Several clinical studies, including PROMID and RADIANT-2, have validated the clinical benefits of octreotide LAR in NETs, with tumor shrinkage in about 10% of patients and tumor stabilization in roughly half of cases. While the use of octreotide LAR is well-consolidated in NETs, some open questions remain. These include the use of high-dose octreotide LAR, as there is evidence that higher dose may provide longer disease control, and nonstandard treatment schedules, with administration every 21 days instead of 28 days, as well as their use in combination with targeted agents or peptide receptor radiotherapy in clinical practice. After 3 decades of clinical experience with octreotide LAR, the drug has a well-established safety profile. It is well-tolerated and treatment discontinuations due to adverse events are uncommon. One exception is cholelithiasis, which may increase with longer duration of treatment. According to the literature data, octreotide LAR is currently recommended in both functioning and nonfunctioning advanced NETs. This review summarizes the available clinical data with octreotide LAR and also provides future perspectives on its possible uses in patients with NETs.

Octreotide-Associated Neutropenia

Drug-induced neutropenia and agranulocytosis are rare adverse events but can be fatal. Neutropenia can be induced by a myriad of drugs from almost every pharmacologic class. Octreotide is a somatostatin analog that has been used to treat variceal bleeding, acromegaly, and severe diarrhea associated with metastatic tumors, and to reduce symptoms in the setting of malignant bowel obstruction and pseudoobstruction. The most common adverse effects associated with octreotide include pain at the injection site and gastrointestinal effects such as loose stools, cramping, and nausea; neutropenia is not currently listed as an adverse effect of the drug. We describe the case of an 87-year-old man who developed neutropenia immediately after administration of three doses of subcutaneous octreotide. He presented to the hospital with a history of constipation and straining for 3 days. He was admitted, and laxatives, suppositories, and enemas were administered over the next 3 days to induce a bowel movement; however, they were ineffective. Bowel obstruction secondary to a mass was confirmed by computed tomography; the mass was eventually diagnosed as colon cancer. Octreotide 100 µg subcutaneously every 8 hours was started for the obstruction on the evening of hospital day 4. After the patient had received 3 doses of octreotide, his white blood cell count (WBC) had decreased from 4.1 × 10³ /mm³ (neutrophils 75.4%, absolute neutrophil count [ANC] 3.1 × 10³ /mm³ ) on admission to 1.6 × 10³ /mm³ (neutrophils 62%, ANC 0.99 × 10³ /mm³ ) on day 5. Given the temporal relationship of octreotide and neutropenia as well as the lack of a reasonable alternative cause, it was suspected that octreotide was the most likely culprit of the patient's neutropenia. Octreotide was subsequently discontinued, and his WBC increased to 4.9 × 10³ /mm³ (neutrophils 66.3%, ANC 3.2 × 10³ /mm³ ) the next day. The remainder of the patient's hospitalization was not significant for any further hematologic abnormalities. His WBC and ANC (WBC 6.7 × 10³ /mm³ , neutrophils 83.2%, ANC 5.6 × 10³ /mm³ ) remained stable 30 days after the incident. Use of the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship (score of 5) between the patient's development of neutropenia and octreotide therapy. To our knowledge, this report highlights the first case of octreotide-associated neutropenia. Although the frequency of drug-induced neutropenia remains rare outside of cytotoxic chemotherapy, the importance of recognizing this adverse effect cannot be understated given the mortality risks for neutropenic patients.

Long-term safety of long-acting octreotide in patients with diabetic retinopathy: results of pooled data from 2 randomized, double-blind, placebo-controlled phase 3 studies

PURPOSE

Octreotide (OCT) has been successfully used for treatment of acromegaly and neuroendocrine tumors for more than 30 years. However, long-term safety of OCT has not been documented in placebo-controlled setting. This present analysis pooled safety data from two similarly-designed, randomized, and placebo-controlled studies to evaluate long-term safety of long-acting OCT (20, 30 mg); targeted post-hoc analyzes focused on cardiac, hepatic, and renal safety.

METHODS

Two studies (NCT00131144, NCT001308450) were conducted in patients with diabetic retinopathy (OCT20 = 191, OCT30 = 348, placebo = 347). In this analysis, patients were stratified based on baseline glomerular filtration rate. Hepatic, cardiac, and renal adverse events (AEs) were identified by standardized MedDRA queries.

RESULTS

Median duration of exposure was >3.5 years. Most common AEs reported with OCT were diarrhea, cholelithiasis, hypoglycemia, nasopharyngitis, and hypertension. Incidence of cardiac events (QT prolongation and arrhythmia) with OCT20 and OCT30 were comparable to placebo (OCT20, RR = 1.11 [95% CI, 0.61-2.03]; OCT30, RR = 1.09 [95% CI, 0.70-1.68]). For ECG findings, changes in QTcF were similar in treatment groups, and outliers did not exceed 480 ms. Incidence of cardiac ischemia was lower with OCT than placebo (OCT20 = 12.6%, OCT30 = 10.6%, placebo = 15.3%). Incidence of liver-related AEs was higher with OCT30 than placebo (RR = 2.04 [95% CI, 1.28-3.26]); incidences were comparable with OCT20 and placebo (RR = 1.50 [95% CI, 0.69-3.25]). Overall incidences of renal AEs were comparable between treatment groups (OCT20 = 5.8%; OCT30 = 6.3%; placebo = 7.2%). Drug-related SAEs were reported more frequently with OCT (OCT20 = 7.9%; OCT30 = 10.1%; placebo = 3.5%); predominantly gallbladder-related, GI-related, and hypoglycemia.

CONCLUSIONS

The results from these long-term placebo-controlled studies confirm the established safety profile of long-acting OCT, in particular low risk of cardiac, hepatic and renal toxicity in a high-risk population.

Novel Somatostatin Receptor Ligands Therapies for Acromegaly

Surgery is considered the treatment of choice in acromegaly, but patients with persistent disease after surgery or in whom surgery cannot be considered require medical therapy. Somatostatin receptor ligands (SRLs) octreotide (OCT), lanreotide, and the more recently approved pasireotide, characterized by a broader receptor ligand binding profile, are considered the mainstay in the medical management of acromegaly. However, in the attempt to offer a more efficacious and better tolerated medical approach, recent research has been aimed to override some limitations related to the use of currently approved drugs and novel SRLs therapies, with potential attractive features, have been proposed. These include both new formulation of older molecules and new molecules. Novel OCT formulations are aimed in particular to improve patients' compliance and to reduce injection discomfort. They include an investigational ready-to-use subcutaneous depot OCT formulation (CAM2029), delivered via prefilled syringes and oral OCT that uses a "transient permeability enhancer" technology, which allows for OCT oral absorption. Another new delivery system is a long-lasting OCT implant (VP-003), which provide stable doses of OCT throughout a period of several months. Finally, a new SRL DG3173 (somatoprim) seems to be more selective for GH secretion, suggesting possible advantages in the presence of hyperglycemia or diabetes. How much these innovations will actually be beneficial to acromegaly patients in real clinical practice remains to be seen.

Systemic Octreotide Therapy in Prevention of Gastrointestinal Bleeds Related to Arteriovenous Malformations and Obscure Etiology in Atrial Fibrillation

OBJECTIVES

The present study describes the use of octreotide (OCT) in patients with atrial fibrillation (AF) receiving oral anticoagulation (OAC) who have gastrointestinal (GI) bleeding related to arteriovenous malformations (AVMs), as well as its effect on OAC tolerance and subsequent rebleeding.

BACKGROUND

AVMs cause significant GI bleeding, especially in patients with AF who are receiving OAC for stroke prevention. OCT has been shown to minimize recurrent GI bleeds related to AVMs.

METHODS

In a multicenter, observational study, 38 AF patients with contraindications to OAC because of AVM-related GI bleeding were started on 100 μg of subcutaneous OCT twice daily. OAC was resumed in all patients within 48 h. Incidence of recurrent GI bleeds was calculated, and hemoglobin levels were recorded at enrollment and at 3 and 6 months' follow-up.

RESULTS

After a median follow-up of 8 months, 36 patients (mean age 69 ± 8.0 years; mean CHA₂DS₂-VASc score 3 ± 1 and mean HAS-BLED score 3 ± 1) were available for analysis. All were able to successfully resume OAC, and 28 of 36 (78%) remained on OAC at the conclusion of the study, whereas 8 underwent left atrial appendage closure with subsequent OAC discontinuation. No systemic thromboembolic events occurred in follow-up. Of the 28 patients who continued receiving OAC, 19 (68%) were free of recurrent GI bleed, 4 had minor GI bleeds, 4 required transfusion, and 1 required colectomy for GI bleeding. Mean hemoglobin levels in all patients receiving OAC were significantly higher at 3- and 6-month follow-up than at baseline (p < 0.001).

CONCLUSIONS

Subcutaneous OCT therapy is an attractive option in AF patients receiving OAC who have AVM-related GI bleeds. It allows successful reinitiation of OAC as a bridge to left atrial appendage exclusion or short-term relief from bleeding.

The Current State of Peptide Drug Discovery: Back to the Future?

Over the past decade, peptide drug discovery has experienced a revival of interest and scientific momentum, as the pharmaceutical industry has come to appreciate the role that peptide therapeutics can play in addressing unmet medical needs and how this class of compounds can be an excellent complement or even preferable alternative to small molecule and biological therapeutics. In this Perspective, we give a concise description of the recent progress in peptide drug discovery in a holistic manner, highlighting enabling technological advances affecting nearly every aspect of this field: from lead discovery, to synthesis and optimization, to peptide drug delivery. An emphasis is placed on describing research efforts to overcome the inherent weaknesses of peptide drugs, in particular their poor pharmacokinetic properties, and how these efforts have been critical to the discovery, design, and subsequent development of novel therapeutics.

Efficacy of long-acting release octreotide for preventing chemotherapy-induced diarrhoea: protocol for a systematic review

INTRODUCTION

Diarrhoea is a common adverse effect induced by chemotherapy that can reduce the dose of chemotherapeutic drugs or interrupt the chemotherapy schedule. The current treatment strategies have various limitations. It has been shown that long-acting release octreotide (octreotide LAR) can decrease the occurrence and severity of diarrhoea, yet the efficacy of octreotide LAR in preventing chemotherapy-induced diarrhoea (CID) remains to be assessed. The main objective of this paper was to draw up a protocol for systematic review to evaluate the protective effects of octreotide LAR on CID.

METHODS AND ANALYSIS

We searched Medline, EMBASE, the Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang Data and the VIP Database without language restrictions from inception until 1 September 2016. The references of relevant studies were also manually searched. Two investigators independently accessed the selected studies, extracted data and assessed the reliability of the studies. Any discrepancies were resolved by a third investigator. The effect size of the selected studies was assessed by different measures based on the type of data. The selected studies were descriptively analysed. We then chose a fixed-effect model or a random-effect model based on statistical homogeneity, and pooled data from the studies for meta-analysis, if possible. The primary outcome was the incidence of diarrhoea. The secondary outcomes were the duration of diarrhoea, incidence of diarrhoea-associated symptoms, physical function and quality of life. All statistical analyses were performed by Review Manager V.5.3.

ETHICS AND DISSEMINATION

This systematic review did not require ethics approval, because it included aggregated published data, and not individual patient data. The review was published in a peer-reviewed journal.

TRIAL REGISTRATION

This systematic review protocol was registered with PROSPERO (registration number: CRD 42016048573).

Treatment with long-acting lanreotide autogel in early infancy in patients with severe neonatal hyperinsulinism

BACKGROUND

Treatment of severe diffuse congenital hyperinsulinism (CHI) without sufficient response to diazoxide is complicated by the lack of approved drugs. Therefore, patients are often hospitalized long-term or have to undergo pancreatic surgery if episodes of severe hypoglycaemia cannot be prevented. A long-acting somatostatin analogue, octreotide, has been reported to be an effective treatment option that prevents severe hypoglycaemia in children with CHI, and its off-label use is common in CHI. However, octreotide requires continuous i.v. or s.c. infusion or multiple daily injections. Here, we report our experiences with the use of a monthly application of a long-acting somatostatin analogue, lanreotide autogel® (LAN-ATG), in early infancy.

RESULTS

The mean blood glucose concentration within 7 days before the first LAN-ATG administration were compared to 7 days after the first LAN-ATG administration and increased by 0.75 mmol/L (range 0.39-1.19 mmol/L). In the following weeks intravenous glucose infusions, octreotide, and glucagon treatment could be successfully stopped in all patients 3-20 days after the first LAN-ATG injection without substantial worsening of the hypoglycaemia rate. Increased carbohydrate requirements could be normalized with an average reduction in the carbohydrate-intake of 7 g/kg body weight/d (range 1.75-12.8 g/kg body weight/d). Over a total of 52 treatment months, no serious adverse effects occurred.

CONCLUSION

Long-term LAN-ATG treatment improved blood glucose concentrations, lowered the frequency of hypoglycaemia or allowed for normalization of oral carbohydrate intake in infants with CHI younger than 6 months of age. No severe side effects were observed. LAN-ATG might be an alternative treatment option in infants with severe CHI who lack risk factors for necrotizing enterocolitis and are not responding to current treatment regimens as an alternative to surgery after careful individual evaluation.

Clinical Importance of Somatostatin Receptor 2 (SSTR2) and Somatostatin Receptor 5 (SSTR5) Expression in Thyrotropin-Producing Pituitary Adenoma (TSHoma)

Background

Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism. Somatostatin analogs have proved to be effective for inhibiting pituitary hormones secretion, working via interactions with somatostatin receptors (SSTRs). Moreover, antiproliferative activity of somatostatin analog is now demonstrated in several studies. In the present study, we determined the relative predominance of SSTR2 and SSTR5 subtypes among the different types of adenomas, especially TSHoma, and investigated the relationship between efficacy of short-term octreotide (OCT) treatment and SSTR expression.

Material/Methods

Serum hormone determinations and histological findings in resected tissue resulted in 5 diagnoses: 16 TSHomas, 8 acromegaly, 3 prolactinomas, 3 corticotropinomas, 4 clinically nonfunctioning adenomas (NFPAs), and 4 normal pituitary specimens. IHC was performed on formalin-fixed and paraffin-embedded tissue in tissue microarrays.

Results

IHC of SSTR subtypes in the different cohorts showed SSTR2 staining intensity scores higher than SSTR5 in TSHoma, acromegaly and prolactinoma, whereas the expression of SSTR5 was stronger than SSTR2 in corticotropinoma and NFPA. SSTR2 and SSTR5 expressions were significantly higher in TSHoma than in other pituitary adenomas. OCT treatment for a median of 8.4 days (range: 3–18 days) and with a total median dose of 1.9 mg (range: 0.9–4.2 mg) showed a significant decrease of thyroid hormone levels (TSH [μIU/ml] in all patients. Patients with low SSTR5 expression presented a significantly higher TSH suppression rate (P values <0.05).

Conclusions

The present data confirm that somatostatin analogs should be considered as a medical alternative to surgical treatment, especially in patients with TSHoma, and short-term response to OCT therapy may be related to the expression of SSTR5.

Nano-encapsulation of a novel anti-Ran-GTPase peptide for blockade of regulator of chromosome condensation 1 (RCC1) function in MDA-MB-231 breast cancer cells

Ran is a small ras-related GTPase and is highly expressed in aggressive breast carcinoma. Overexpression induces malignant transformation and drives metastatic growth. We have designed a novel series of anti-Ran-GTPase peptides, which prevents Ran hydrolysis and activation, and although they display effectiveness in silico, peptide activity is suboptimal in vitro due to reduced bioavailability and poor delivery. To overcome this drawback, we delivered an anti-Ran-GTPase peptide using encapsulation in PLGA-based nanoparticles (NP). Formulation variables within a double emulsion solvent evaporation technique were controlled to optimise physicochemical properties. NP were spherical and negatively charged with a mean diameter of 182-277nm. Peptide integrity and stability were maintained after encapsulation and release kinetics followed a sustained profile. We were interested in the relationship between cellular uptake and poly(ethylene glycol) (PEG) in the NP matrix, with results showing enhanced in vitro uptake with increasing PEG content. Peptide-loaded, pegylated (10% PEG)-PLGA NP induced significant cytotoxic and apoptotic effects in MDA-MB-231 breast cancer cells, with no evidence of similar effects in cells pulsed with free peptide. Western blot analysis showed that encapsulated peptide interfered with the proposed signal transduction pathway of the Ran gene. Our novel blockade peptide prevented Ran activation by blockage of regulator of chromosome condensation 1 (RCC1) following peptide release directly in the cytoplasm once endocytosis of the peptide-loaded nanoparticle has occurred. RCC1 blockage was effective only when a nanoparticulate delivery approach was adopted.

Peptidomimetic therapeutics: scientific approaches and opportunities

Natural endogenously occurring peptides exhibit desirable medicinal properties, but are often limited in application by rapid proteolysis and inadequate membrane permeability. However, editing naturally occurring peptide sequences to develop peptidomimetic analogs created a promising class of therapeutics that can augment or inhibit molecular interactions. Here, we discuss a variety of chemical modifications, including l to d isomerization, cyclization, and unnatural amino acid substitution, as well as design strategies, such as attachment to cell-penetrating peptides, which are used to develop peptidomimetics. We also provide examples of approved peptidomimetics and discuss several compounds in clinical trials.

The pivotal role of mammalian target of rapamycin inhibition in the treatment of patients with neuroendocrine tumors

Significant advances have been made toward understanding the biology of neuroendocrine tumors (NET) in terms of defining prognosis and improving clinical management; however, many unmet needs remain. The treatment landscape for NET has evolved, with the approval of the targeted agents everolimus and sunitinib for the treatment of advanced pancreatic NET in 2011 followed by the approval of everolimus for the treatment of advanced nonfunctional gastrointestinal and lung NET in 2016. Mammalian target of rapamycin (mTOR) and components of the mTOR pathway play pivotal roles in NET pathogenesis. Effects of the mTOR inhibitor everolimus have been well documented in preclinical and clinical studies, both as monotherapy and combination therapy. mTOR inhibition as backbone therapy within the NET treatment landscape is a focus of continuing research, which includes evaluation of the growing armamentarium of approved and investigational agents as potential combination partners. Data evaluating the clinical benefits of agents targeting mTOR and related pathways (alone and in combination) in the treatment of patients with NET continue to increase. Many of the findings to date are encouraging.

Photochemically re-bridging disulfide bonds and the discovery of a thiomaleimide mediated photodecarboxylation of C-terminal cysteines

Described in this work is a novel method for photochemically manipulating peptides and proteins via the installation of cysteine-selective photoactive tags. Thiomaleimides, generated simply by the addition of bromomaleimides to reduced disulfide bonds, undergo [2 + 2] photocycloadditions to reconnect the crosslink between the two cysteine residues. This methodology is demonstrated to enable photoactivation of a peptide by macrocyclisation, and reconnection of the heavy and light chains in an antibody fragment to form thiol stable conjugates. Finally we report on an intriguing thiomaleimide mediated photochemical decarboxylation of C-terminal cysteines, discovered during this study.

Systemic therapies for advanced gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors are a heterogeneous group of malignancies, characterised by production of hormones and vasoactive peptides. The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NET) is rising, and they have the highest prevalence amongst upper gastro-intestinal tumors. Diagnosis remains challenging due to wide variations in presentation and slow onset of symptoms. A multi-disciplinary approach is vital in appropriately managing the diverse spectrum of GEP-NET. Areas covered: Investigations in GEP-NET and biomarkers are described. Moreover, all available therapeutic options for GEP-NET including surgery, somatostatin analogues, targeted agents, Peptide Receptor Radionuclide Therapy and chemotherapy are also discussed. Expert commentary: The landscape of management has changed significantly in the last decade as a result of many practice-changing clinical trials. Long- acting somatostatin analogues are used not only for symptom control but also for their anti-proliferative effect. Targeted agents, such as everolimus and sunitinib, have improved PFS in GEP-NET. The recently presented NETTER-1 trial confirms the place of peptide receptor radionuclide treatment (PRRT) in treating NET. While chemotherapy remained an important option for high grade tumors. Despite promising results from recent trials, challenges include establishing the optimal sequencing of therapies to optimize outcome and preserve the quality of life.

Octreotide LAR Dosage and Survival Among Elderly Patients With Distant-Stage Neuroendocrine Tumors

INTRODUCTION

Octreotide long-acting repeatable (LAR) is approved for the management of carcinoid syndromes and may improve progression-free survival of patients with well-differentiated neuroendocrine tumors (NETs). It is unknown whether the dosage of octreotide LAR affects survival. This paper evaluates the association between initial octreotide LAR dosage and overall survival of elderly patients with NETs.

PATIENTS AND METHODS

Patients with distant-stage NET diagnosed between January 1999 and December 2009 who received octreotide LAR treatment within 12 months of diagnosis were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Those under age 65 years, enrolled in health maintenance organizations, or without continuous enrollment in Medicare Parts A and B were excluded. We compared the 5-year survival of patients with NET based on dose per 28 days averaged over the initial 3 months: low (≤20 mg); medium (21-30 mg); high (>30 mg). Kaplan-Meier estimations and Cox proportional hazard modeling were used to examine the association between octreotide LAR dose and survival.

RESULTS

Among 222 patients with distant-stage NET who received octreotide LAR treatment, 81 (36%) received a low dosage, 82 (37%) received a medium dosage, and only 59 (27%) received a high dosage. Multivariate analysis showed that compared with a medium octreotide LAR dose, a low dosage was associated with significantly worse survival (hazard ratio [HR]: 2.00; p = .001), whereas a high initial dosage (HR: 1.09; p = .719) did not show additional survival benefits over that observed with a medium dosage.

CONCLUSION

This population-based study suggests potential survival benefits for octreotide LAR provided within 12 months of diagnosis at a dosage of 21-30 mg among elderly patients with distant-stage NET.

Anti-parasitic Peptides from Arthropods and their Application in Drug Therapy

Africa, Asia, and Latin America are regions highly affected by endemic diseases, such as Leishmaniasis, Malaria, and Chagas' disease. They are responsible for the death of 1000s of patients every year, as there is not yet a cure for them and the drugs used are inefficient against the pathogenic parasites. During the life cycle of some parasitic protozoa, insects become the most important host and disseminator of the diseases triggered by these microorganisms. As infected insects do not develop nocive symptoms, they can carry the parasites for long time inside their body, enabling their multiplication and life cycle completion. Eventually, parasites infect human beings after insect's transmission through their saliva and/or feces. Hence, host insects and general arthropods, which developed a way to coexist with such parasites, are a promising source for the prospection of anti-parasitic compounds, as alternative methods for the treatment of protozoa-related diseases. Among the molecules already isolated and investigated, there are proteins and peptides with high activity against parasites, able to inhibit parasite activity in different stages of development. Although, studies are still taking their first steps, initial results show new perspectives on the treatment of parasitic diseases. Therefore, in this report, we describe about peptides from host insect sources with activity against the three most endemic parasites: Leishmania sp., Plasmodium sp., and Trypanosomes. Moreover, we discuss the future application insect peptides as anti-parasitic drugs and the use of non-hosts insect transcriptomes on the prospection of novel molecules for the treatment of parasitic neglected diseases.

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2014

The annual Eastern Canadian Colorectal Cancer Consensus Conference was held in Montreal, Quebec, 23-25 October 2014. Expert radiation, medical, and surgical oncologists and pathologists involved in the management of patients with gastrointestinal malignancies participated in presentations and discussions resulting in consensus statements on such hot topics as management of neuroendocrine tumours, advanced and metastatic pancreatic cancer, and metastatic colorectal cancer.

Octreotide s.c. depot provides sustained octreotide bioavailability and similar IGF-1 suppression to octreotide LAR in healthy volunteers

Aims

The aim was to assess the pharmacokinetics, pharmacodynamics, safety and tolerability of octreotide subcutaneous (s.c.) depot, a novel octreotide formulation.

Methods

This was a phase I, randomized, open label study. After a single dose of octreotide immediate release (IR) 200 µg, subjects were randomized to one of eight groups to receive three monthly injections of octreotide s.c. depot A 10, 20 or 30 mg, B 30 mg, C 10, 20 or 30 mg or long acting octreotide (octreotide LAR) 30 mg.

Results

One hundred and twenty-two subjects were randomized. For all depot variants, onset of octreotide release was rapid and sustained for up to 4 weeks. The relative octreotide bioavailability of depot variants vs. octreotide IR ranged from 0.68 (90% confidence interval [CI] 0.61, 0.76) to 0.91 (90% CI 0.81, 1.02) and, vs. octreotide LAR, was approximately four- to five-fold greater: 3.97 (90% CI 3.35, 4.71) to 5.27 ng ml^–1 h (90% CI 4.43, 6.27). All depot variants showed relatively rapid initial reductions of insulin-like growth factor 1 (IGF-1) compared with octreotide LAR. A trend of octreotide dose dependence was also indicated from the plasma concentrations and suppression of IGF-1. Maximum inhibition of IGF-1 at steady-state was highest for depot B and C. All depot treatments were well tolerated. The most frequent adverse events were gastrointestinal related.

Conclusions

Octreotide s.c. depot provides greater octreotide bioavailability with a more rapid onset and stronger suppression of IGF-1 than octreotide LAR in healthy volunteers.