An ingestible self-orienting system for oral delivery of macromolecules

Biomacromolecules have transformed our capacity to effectively treat diseases; however, their rapid degradation and poor absorption in the gastrointestinal (GI) tract generally limit their administration to parenteral routes. An oral biologic delivery system must aid in both localization and permeation to achieve systemic drug uptake. Inspired by the leopard tortoise's ability to passively reorient, we developed an ingestible self-orienting millimeter-scale applicator (SOMA) that autonomously positions itself to engage with GI tissue. It then deploys milliposts fabricated from active pharmaceutical ingredients directly through the gastric mucosa while avoiding perforation. We conducted in vivo studies in rats and swine that support the applicator's safety and, using insulin as a model drug, demonstrated that the SOMA delivers active pharmaceutical ingredient plasma levels comparable to those achieved with subcutaneous millipost administration.

Transcellular stomach absorption of a derivatized glucagon-like peptide-1 receptor agonist

Oral administration of therapeutic peptides is hindered by poor absorption across the gastrointestinal barrier and extensive degradation by proteolytic enzymes. Here, we investigated the absorption of orally delivered semaglutide, a glucagon-like peptide-1 analog, coformulated with the absorption enhancer sodiumN-[8-(2-hydroxybenzoyl) aminocaprylate] (SNAC) in a tablet. In contrast to intestinal absorption usually seen with small molecules, clinical and preclinical dog studies revealed that absorption of semaglutide takes place in the stomach, is confined to an area in close proximity to the tablet surface, and requires coformulation with SNAC. SNAC protects against enzymatic degradation via local buffering actions and only transiently enhances absorption. The mechanism of absorption is shown to be compound specific, transcellular, and without any evidence of effect on tight junctions. These data have implications for understanding how highly efficacious and specific therapeutic peptides could be transformed from injectable to tablet-based oral therapies.

Zwitterionically modified alginates mitigate cellular overgrowth for cell encapsulation

Foreign body reaction (FBR) to implanted biomaterials and medical devices is common and can compromise the function of implants or cause complications. For example, in cell encapsulation, cellular overgrowth (CO) and fibrosis around the cellular constructs can reduce the mass transfer of oxygen, nutrients and metabolic wastes, undermining cell function and leading to transplant failure. Therefore, materials that mitigate FBR or CO will have broad applications in biomedicine. Here we report a group of zwitterionic, sulfobetaine (SB) and carboxybetaine (CB) modifications of alginates that reproducibly mitigate the CO of implanted alginate microcapsules in mice, dogs and pigs. Using the modified alginates (SB-alginates), we also demonstrate improved outcome of islet encapsulation in a chemically-induced diabetic mouse model. These zwitterion-modified alginates may contribute to the development of cell encapsulation therapies for type 1 diabetes and other hormone-deficient diseases.

A microneedle platform for buccal macromolecule delivery

Alternative means for drug delivery are needed to facilitate drug adherence and administration. Microneedles (MNs) have been previously investigated transdermally for drug delivery. To date, drug loading into MNs has been limited by drug solubility in the polymeric blend. We designed a highly drug-loaded MN patch to deliver macromolecules and applied it to the buccal area, which allows for faster delivery than the skin. We successfully delivered 1-mg payloads of human insulin and human growth hormone to the buccal cavity of swine within 30 s. In addition, we conducted a trial in 100 healthy volunteers to assess potential discomfort associated with MNs when applied in the oral cavity, identifying the hard palate as the preferred application site. We envisage that MN patches applied on buccal surfaces could increase medication adherence and facilitate the painless delivery of biologics and other drugs to many, especially for the pediatric and elderly populations.

Animal models of gastrointestinal and liver diseases. Animal models of infant short bowel syndrome: translational relevance and challenges

Intestinal failure (IF), due to short bowel syndrome (SBS), results from surgical resection of a major portion of the intestine, leading to reduced nutrient absorption and need for parenteral nutrition (PN). The incidence is highest in infants and relates to preterm birth, necrotizing enterocolitis, atresia, gastroschisis, volvulus, and aganglionosis. Patient outcomes have improved, but there is a need to develop new therapies for SBS and to understand intestinal adaptation after different diseases, resection types, and nutritional and pharmacological interventions. Animal studies are needed to carefully evaluate the cellular mechanisms, safety, and translational relevance of new procedures. Distal intestinal resection, without a functioning colon, results in the most severe complications and adaptation may depend on the age at resection (preterm, term, young, adult). Clinically relevant therapies have recently been suggested from studies in preterm and term PN-dependent SBS piglets, with or without a functional colon. Studies in rats and mice have specifically addressed the fundamental physiological processes underlying adaptation at the cellular level, such as regulation of mucosal proliferation, apoptosis, transport, and digestive enzyme expression, and easily allow exogenous or genetic manipulation of growth factors and their receptors (e.g., glucagon-like peptide 2, growth hormone, insulin-like growth factor 1, epidermal growth factor, keratinocyte growth factor). The greater size of rats, and especially young pigs, is an advantage for testing surgical procedures and nutritional interventions (e.g., PN, milk diets, long-/short-chain lipids, pre- and probiotics). Conversely, newborn pigs (preterm or term) and weanling rats provide better insights into the developmental aspects of treatment for SBS in infants owing to their immature intestines. The review shows that a balance among practical, economical, experimental, and ethical constraints will determine the choice of SBS model for each clinical or basic research question.

Glucagon-like peptide-2 induces rapid digestive adaptation following intestinal resection in preterm neonates

Short bowel syndrome (SBS) is a frequent complication after intestinal resection in infants suffering from intestinal disease. We tested whether treatment with the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) increases intestinal volume and function in the period immediately following intestinal resection in preterm pigs. Preterm pigs were fed enterally for 48 h before undergoing resection of 50% of the small intestine and establishment of a jejunostomy. Following resection, pigs were maintained on total parenteral nutrition (TPN) without (SBS, n = 8) or with GLP-2 treatment (3.5 μg/kg body wt per h, SBS+GLP-2, n = 7) and compared with a group of unresected preterm pigs (control, n = 5). After 5 days of TPN, all piglets were fed enterally for 24 h, and a nutrient balance study was performed. Intestinal resection was associated with markedly reduced endogenous GLP-2 levels. GLP-2 increased the relative absorption of wet weight (46 vs. 22%), energy (79 vs. 64%), and all macronutrients (all parameters P < 0.05). These findings were supported by a 200% increase in sucrase and maltase activities, a 50% increase in small intestinal epithelial volume (P < 0.05), as well as increased DNA and protein contents and increased total protein synthesis rate in SBS+GLP-2 vs. SBS pigs (+100%, P < 0.05). Following intestinal resection in preterm pigs, GLP-2 induced structural and functional adaptation, resulting in a higher relative absorption of fluid and macronutrients. GLP-2 treatment may be a promising therapy to enhance intestinal adaptation and improve digestive function in preterm infants with jejunostomy following intestinal resection.

Targeting gut microbiota and barrier function with prebiotics to alleviate autoimmune manifestations in NOD mice

AIMS/HYPOTHESIS

Adopting a diet containing indigestible fibre compounds such as prebiotics to fuel advantageous bacteria has proven beneficial for alleviating inflammation. The effect of the microbial changes on autoimmunity, however, remains unknown. We studied the effects of prebiotic xylooligosaccharides (XOS) on pancreatic islet and salivary gland inflammation in NOD mice and tested whether these were mediated by the gut microbiota.

METHODS

Mother and offspring mice were fed an XOS-supplemented diet until diabetes onset or weaning and were compared with a control-fed group. Diabetes incidence was monitored, insulitis and sialadenitis were scored in histological sections from adult mice, and several metabolic and immune variables were analysed in mice before the development of diabetes. Gut barrier function was assessed using an in vivo FITC-dextran permeability test. The importance of XOS-mediated gut microbial changes were evaluated in antibiotic-treated mice fed either XOS or control diet or given a faecal microbiota transplant from test animals.

RESULTS

Diabetes onset was delayed in the XOS-fed mice, which also had fewer cellular infiltrations in their pancreatic islets and salivary glands. Interestingly, insulitis was most reduced in the XOS-fed groups when the mice were also treated with an antibiotic cocktail. There was no difference in sialadenitis between the dietary groups treated with antibiotics; the mice were protected by microbiota depletion regardless of diet. Faecal microbiota transplantation was not able to transfer protection. No major differences in glucose-insulin regulation, glucagon-like peptide-1, or short-chain fatty acid production were related to the XOS diet. The XOS diet did, however, reduce gut permeability markers in the small and large intestine. This was accompanied by a more anti-inflammatory environment locally and systemically, dominated by a shift from M1 to M2 macrophages, a higher abundance of activated regulatory T cells, and lower levels of induction of natural killer T cells and cytotoxic T cells.

CONCLUSIONS/INTERPRETATION

Prebiotic XOS have microbiota-dependent effects on salivary gland inflammation and microbiota-independent effects on pancreatic islet pathology that are accompanied by an improved gut barrier that seems able to heighten control of intestinal diabetogenic antigens that have the potential to penetrate the mucosa to activate autoreactive immune responses.

Distribution and neurochemical characterization of neurons within the nucleus of the solitary tract responsive to serotonin agonist-induced hypophagia

Pharmacological compounds enhancing serotonergic tone significantly decrease food intake and are among the most clinically efficacious treatments for obesity. However, the central mechanisms through which serotonergic compounds modulate feeding behavior have not been fully defined. The primary relay center receiving visceral gastrointestinal information in the central nervous system is the nucleus of the solitary tract (NTS) in the caudal brainstem. Here we investigated whether the classic anorectic serotonin receptor agonist m-chloro-phenylpiperazine (mCPP) enhances the activity of metabolically sensitive NTS neurons. Using c-fos immunoreactivity (FOS-IR) as a marker of neuronal activation in rats, we observed that mCPP significantly and dose-dependently activated a discrete population of caudal NTS neurons at the level of the area postrema (AP). In particular, this pattern of FOS-IR induction was consistent with the location of catecholamine-containing neurons. Dual-labeling performed with FOS-IR and the catecholamine biosynthetic enzyme tyrosine hydroxylase (TH) revealed that mCPP induced FOS-IR in 83.7% of TH-IR containing neurons in the NTS at the level of the AP. The degree of activation of TH neurons was strongly negatively correlated with food intake. Moreover, this activation was specific to catecholamine neurons, with negligible induction of cocaine- and amphetamine-regulated transcript (CART), cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1), or neurotensin neurons. NTS catecholaminergic neurons relay visceral gastrointestinal signals to both the lateral hypothalamus (LHA) and paraventricular nucleus of the hypothalamus (PVH), where these signals are integrated into autonomic and hormonal responses regulating food intake. The data presented here identify a novel mechanism through which a serotonin receptor agonist acting in the caudal brainstem may regulate ingestive behavior.

Immunometabolic parameters in overweight dogs during weight loss with or without an exercise program

The influence of physical activity on metabolic health in overweight dogs is unknown. This study was conducted to evaluate biomarkers of immunometabolic health in relation to changes in physical activity and adiposity. Client-owned overweight dogs participated in a 12-wk intervention based on caloric restriction combined with a training program (fitness and diet [FD] group, n = 8), or caloric restriction alone (diet-only [DO] group, n = 8). Physical activity was monitored by accelerometry. All dogs were fed the same diet and achieved similar weight loss. Fasting blood samples were collected before and after 6- and 12-wk intervention. Insulin resistance was evaluated from plasma insulin and C-peptide as well as homeostasis model assessment. Inflammation and dyslipidemia were evaluated from circulating leptin, adiponectin, C-reactive protein (CRP), monocyte chemoattractant factor-1 (MCP-1), interleukin-8 (IL-8), and cholesterol. Accelerometer counts in both groups were high compared with previous reports of physical activity in overweight dogs. No difference in blood parameters was evident between groups, evaluated by linear mixed-effects model (P > 0.05). Within the groups, the following changes were significant by t-test (P < 0.05): leptin decreased in both groups. Within the FD group, IL-8, MCP-1, and CRP decreased at 6 wk and IL-8 and cholesterol at 12 wk. Within the DO group, C-peptide and HOMA decreased at 6 wk and C-peptide at 12 wk. We conclude that, for both groups, weight loss resulted in minor indications of improved immunometabolic health, whereas this level of physical activity did not add further benefits.

Parenteral lipids and partial enteral nutrition affect hepatic lipid composition but have limited short term effects on formula-induced necrotizing enterocolitis in preterm piglets

BACKGROUND & AIMS

Rapid transition from total parenteral nutrition (TPN) to enteral feeding is a risk factor for necrotizing enterocolitis (NEC) in preterm infants. We hypothesized that partial enteral nutrition with colostrum, increased proportion of n-3 polyunsaturated fatty acids (PUFA), or exclusion of lipid in TPN would affect short term NEC sensitivity and liver function.

METHODS

Preterm piglets were fed for three days after birth: 1) TPN with a standard lipid emulsion (Nutriflex Lipid Plus, TPN control group, n = 19), 2) PN plus bovine colostrum as partial enteral nutrition (PN/COL, n = 18), 3) TPN with fish oil (FO) lipids (Omegaven, TPN/FO, n = 19), or 4) TPN with no lipid (TPN/NL, n = 22). After TPN, piglets were fed formula for two days before tissue collection.

RESULTS

None of the treatments had consistent effect on NEC incidence (∼40-50% across all groups), intestinal morphology and function, relative to TPN. In the liver, there were no signs of steatosis but PN/COL decreased the n-6 PUFA levels, leading to higher n-3/n-6 ratio, GGT activity, and plasma cholesterol and albumin levels, relative to TPN (all p < 0.05). TPN/FO increased the hepatic n-3 levels and n-3/n-6 ratio. TPN/NL treatment led to decreased hepatic n-6 level, n-3/n-6 ratio and bilirubin, albumin and triglycerides, and lowered blood clotting strength (-30%, TPN/NL vs. TPN/COL, p < 0.05).

CONCLUSION

Partial enteral nutrition with colostrum, increased n-3 PUFAs in TPN, or removal of lipid from the TPN, all affect hepatic lipids and proteins in preterm neonates. These effects do not translate into improved hepatic function or NEC resistance, at least not short term.

18F-FDG PET/MR-imaging in a Göttingen Minipig model of atherosclerosis: Correlations with histology and quantitative gene expression

BACKGROUND AND AIMS

The advantage of combining molecular and morphological imaging, e.g. positron emission tomography and magnetic resonance imaging (PET/MRI), is reflected in the increased use of these modalities as surrogate end-points in clinical trials. This study aimed at evaluating plaque inflammation using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)-PET/MRI, and gene expression in a minipig model of atherosclerosis.

METHODS

Göttingen Minipigs were fed for 60 weeks with fat/fructose/cholesterol-rich diet (FFC), chow (Control) or FFC-diet changed to chow midway (diet normalization group; DNO). In all groups, ¹⁸F-FDG-PET/MRI of the abdominal aorta was assessed midway and at study-end. The aorta was analyzed using histology and gene expression.

RESULTS

At study-end, FFC had significantly higher FDG-uptake compared to Control (target-to-background maximal uptake, TBR_Max (95% confidence interval) CI_TBRMax: 0.092; 7.32) and DNO showed significantly decreased uptake compared to FFC (CI_TBRMax: -5.94;-0.07). No difference was observed between DNO and Control (CI_TBRMax: -2.71; 4.11). FFC displayed increased atherosclerosis and gene expression of inflammatory markers, including vascular cell adhesion molecule 1 (VCAM-1), cluster of differentiation 68 (CD68), matrix metalloproteinase 9 (MMP9), cathepsin K (CTSK) and secreted phosphoprotein 1 (SPP1) compared to Control and DNO (all, p < 0.05). FDG-uptake correlated with gene expression of inflammatory markers, including CD68, ρ_s = 0.58; MMP9, ρ_s = 0.46; SPP1, ρ_s = 0.44 and CTSK, ρ_s = 0.49; (p ≤ 0.01 for all).

CONCLUSIONS

In a model of atherosclerosis, ¹⁸F-FDG-PET/MRI technology allows for detection of inflammation in atherosclerotic plaques, consistent with increased inflammatory gene expression. Our findings corroborate clinical data and are important in pre-clinical drug development targeting plaque inflammation.

Minimal Enteral Nutrition to Improve Adaptation After Intestinal Resection in Piglets and Infants

BACKGROUND

Minimal enteral nutrition (MEN) may induce a diet-dependent stimulation of gut adaptation following intestinal resection. Bovine colostrum is rich in growth factors, and we hypothesized that MEN with colostrum would stimulate intestinal adaptation, compared with formula, and would be well tolerated in patients with short bowel syndrome.

METHODS

In experiment 1, 3-day-old piglets with 50% distal small intestinal resection were fed parenteral nutrition (PN, n = 10) or PN plus MEN given as either colostrum (PN-COL, n = 5) or formula (PN-FORM, n = 9) for 7 days. Intestinal nutrient absorption and histomorphometry were performed. In experiment 2, tolerance and feasibility of colostrum supplementation were tested in a pilot study on 5 infants who had undergone intestinal resection, and they were compared with 5 resected infants who served as controls.

RESULTS

In experiment 1, relative wet-weight absorption and intestinal villus height were higher in PN-COL vs PN (53% vs 23% and 362 ± 13 vs 329 ± 7 µm, P < .05). Crypt depth and tissue protein synthesis were higher in PN-COL (233 ± 7 µm, 22%/d) and PN-FORM (262 ± 13 µm, 22%/d) vs PN (190 ± 4 µm, 9%/d, both P < .05). In experiment 2, enteral colostrum supplementation was well tolerated, and no infants developed clinical signs of cow's milk allergy.

CONCLUSION

Minimal enteral nutrition feeding with bovine colostrum and formula induced similar intestinal adaptation after resection in piglets. Colostrum was well tolerated by newly resected infants, but the clinical indication for colostrum supplementation to infants subjected to intestinal resection remains to be determined.

Modelling severe Staphylococcus aureus sepsis in conscious pigs: are implications for animal welfare justified?

BACKGROUND

A porcine model of haematogenous Staphylococcus aureus sepsis has previously been established in our research group. In these studies, pigs developed severe sepsis including liver dysfunction during a 48 h study period. As pigs were awake during the study, animal welfare was challenged by the severity of induced disease, which in some cases necessitated humane euthanasia. A pilot study was therefore performed in order to establish the sufficient inoculum concentration and application protocol needed to produce signs of liver dysfunction within limits of our pre-defined humane endpoints.

METHODS

Four pigs received 1 × 10(8) cfu/kg BW of S. aureus, and two controls were sham inoculated with saline. A fixed infusion rate of 3 mL/min was used, while the inoculum concentration, i.e., the dose volume, was changed between the pigs. The following dose volumes were used: 10 mL (n = 1), 20 mL (n = 2), and 30 mL (n = 1), corresponding to infusion durations of 3.33, 6.66, and 10 min at dose rates of 3 × 10(7), 1.5 × 10(7), and 1 × 10(7) cfu/min/kg BW, respectively. Blood samples were drawn for complete blood count, clinical chemistry, and inflammatory markers before and every 6 h after inoculation. Prior to euthanasia, a galactose elimination capacity test was performed to assess liver function. Pigs were euthanised 48 h post inoculation for necropsy and histopathological evaluation.

RESULTS

While infusion times of 6.66 min, and higher, did not induce liver dysfunction (n = 3), the infusion time of 3.33 min (n = 1) caused alterations in parameters similar to what had been seen in our previous studies, i.e., increasing bilirubin and aspartate aminotransferase, as well as histopathological occurrence of intravascular fibrin split products in the liver. This pig was however euthanised after 30 h, according to humane endpoints.

CONCLUSIONS

A usable balance between scientific purpose and animal welfare could not be achieved, and we therefore find it hard to justify further use of this conscious porcine sepsis model. In order to make a model of translational relevance for human sepsis, we suggest that future model versions should use long-term anaesthesia.

Single port laparoscopic long-term tube gastrostomy in Göttingen minipigs

Oral dosing by gavage is often used to test compounds in minipigs. This method is also used for certain nutritional studies that require exact dosing. This procedure may be stressful for the animal and requires the assistance of more than one technician. We investigated whether a gastrostomy tube could be placed and maintained in Göttingen minipigs using a single port laparoscopic technique. As part of another study, laparoscopic gastrostomy tube placement was performed in 12 Göttingen minipigs (32 ± 2 kg) under general anesthesia. The procedure involved single port laparoscopic visualization of the stomach and placement of a locking pigtail catheter into the fundus region of the stomach. The minipigs were followed for three weeks after surgery and macroscopic and microscopic tissue reactions were evaluated at necropsy. All catheters were successfully placed and were easy to use. At necropsy it was evident that the catheter had entered the stomach in the fundus region in 11/12 of the animals. In one animal the catheter had entered the antrum region. None of the animals developed leakage or clinically detectable reactions to the gastrostomy tube. Histopathologically, only discrete changes were observed. Single port laparoscopic tube gastrostomy with a locking pigtail catheter is safe, simple and reliable and is an appropriate alternative to, for example, percutaneous endoscopic gastrostomy, when long-term enteral delivery of pharmacological or nutritional compounds is needed. The use of the gastrostomy tube was easy and, based on subjective assessment, feeding was minimally stressful to the animals.

Hyperinsulinaemic hypoglycaemia in non-anaesthetized Göttingen minipigs induces a counter-regulatory endocrine response and electrocardiographic changes

The potentially fatal cardiovascular effects of hypoglycaemia are not well understood and large animal models of the counter-regulatory responses and cardiovascular consequences of insulin-induced hypoglycaemia are needed to understand the mechanisms in humans. The aim of this study was to develop a human-like minipig model of hypoglycaemia including healthy and diabetic pigs to investigate endocrine, electrocardiographic and platelet effects. Hypoglycaemia was induced using a hyperinsulinaemic, hypoglycaemic clamp and an insulin bolus protocol. Plasma glucose, glucagon, C-peptide, insulin, epinephrine and platelet aggregation responses were measured before, during and after hypoglycaemia. Continuous electrocardiographic recordings were obtained. Hypoglycaemia at a plasma glucose concentration of 0.8–1.0 mM in the clamp induced 25-fold increase in epinephrine and sixfold and threefold increase in glucagon for healthy and diabetic pigs, respectively. The hypoglycaemic clamp induced QTc-interval prolongation and increase in cardiac arrhythmias. In the bolus approach, the non-diabetic group reached plasma glucose target of 1.5 mM and QTc-interval was prolonged after insulin injection, but before glucose nadir. The diabetic group did not reach hypoglycaemic target, but still demonstrated QTc-interval prolongation. These results demonstrate effects of hyperinsulinaemic hypoglycaemia closely resembling human physiology, indicating the minipig as a translational animal model of counter-regulatory endocrine and myocardial effects of hypoglycaemia.

Pharmacokinetic Properties of a Once-Weekly Fixed-Ratio Combination of Insulin Icodec and Semaglutide Compared with Separate Administration of Each Component in Individuals with Type 2 Diabetes Mellitus

BACKGROUND AND OBJECTIVE

IcoSema is being developed as a subcutaneous once-weekly fixed-ratio combination of the once-weekly basal insulin icodec and the once-weekly glucagon-like peptide-1 receptor agonist semaglutide. This study investigated the pharmacokinetics of icodec and semaglutide in IcoSema versus separate administration of each component in individuals with type 2 diabetes mellitus (T2DM).

METHODS

In a randomised, double-blind, three-period crossover study, 31 individuals with T2DM (18-64 years, body weight 80-120 kg, glycosylated haemoglobin 6.0-8.5%) received single subcutaneous injections of IcoSema (175 U icodec, 0.5 mg semaglutide), icodec (175 U) or semaglutide (0.5 mg) with 6-9 weeks' washout. Pharmacokinetic blood samples were drawn up to 840 h post-dose.

RESULTS

Icodec pharmacokinetics were unaffected by combining icodec with semaglutide. The 90% confidence interval (CI) of IcoSema/icodec was within 0.80-1.25 for total exposure (area under the curve from zero to last quantifiable observation; AUC0-t: ratio [90% CI] 1.06 [1.01; 1.12]) and maximum concentration (Cmax): 1.12 [1.06; 1.18]. Semaglutide AUC0-t was also unaffected by combination with icodec (IcoSema/semaglutide 1.11 [1.05; 1.17]). However, semaglutide Cmax was higher for IcoSema versus semaglutide alone (IcoSema/semaglutide 1.99 [1.84; 2.15]) and occurred earlier for IcoSema (12 versus 84 h). Results of in vitro albumin binding studies and animal pharmacokinetic studies supported that the change in semaglutide absorption pharmacokinetics in IcoSema is owing to competition for albumin binding locally at the injection site with icodec outcompeting semaglutide. IcoSema, icodec and semaglutide were well-tolerated, although more gastrointestinal related adverse events occurred with IcoSema versus icodec or semaglutide alone.

CONCLUSION

The combination of icodec and semaglutide in IcoSema leads to a higher and earlier maximum semaglutide concentration, which will guide the dose recommendations for IcoSema.

CLINICAL TRIAL

ClinicalTrials.gov identifier: NCT03789578.

Electrocardiography and heart rate variability in Göttingen Minipigs: Impact of diurnal variation, lead placement, repeatability and streptozotocin-induced diabetes

BACKGROUND

The Göttingen Minipig is widely used in preclinical research and safety pharmacology, but standardisation of porcine electrocardiography (ECG) is lacking. The aim of this study was to investigate diurnal effects, change over time and choice of lead on ECG morphology and heart rate variability (HRV) in healthy and streptozotocin (STZ) induced diabetic Göttingen Minipigs.

METHODS

Diabetes was experimentally induced using STZ in 11 Göttingen Minipigs (DIA). Seven controls (CON) were included. 24-h ECG was recorded at baseline and four months. Morphological parameters (QRS and T wave duration, P- and T-wave amplitude, PR and QT (Bazett's (QTcb) or Fridericia (QTcf) correction) intervals and ST segment), presence of cardiac arrhythmias, heart rate (HR) and HRV (time and frequency domain) were analysed.

RESULTS

Four months after induction, DIA had decreased P-wave amplitude (P < 0.0001) and T-wave duration (P = 0.017), compared to CON. QTcb was lower in DIA, but not in CON. Both groups had decreased HR (P < 0.0001) and QRS duration (lead II, P = 0.04) and length of PR-segment increased (lead I and II, P < 0.01) while selected HRV parameters also increased (all P < 0.01). Time of day influenced HR, QRS duration, PR segment, ST segment, T- and P-wave amplitude and some parameters of HRV. Inter- and intra-observer variability of morphological measurements was low (<6%).

CONCLUSION

ECG parameters were influenced by time setting, diurnal variation and lead. Some ECG and HRV changes were found in diabetic minipigs four months after STZ induction. The findings underline the need for standardisation of ECG and HRV in Göttingen Minipigs.

Development of Zalfermin, a Long-Acting Proteolytically Stabilized FGF21 Analog

Here, we describe the development of the FGF21 analog zalfermin (NNC0194-0499, 15), intended for once-weekly sc dosing. Protein engineering was needed to address inherent druggability issues of the natural FGF21 hormone. Thus, deamidation of Asp121 was solved by mutation to glutamine, and oxidation of Met168 was solved by mutation to leucine. N-terminal region degradation by dipeptidyl peptidase IV was prevented by alanine residue elongation. To prevent inactivating metabolism by fibroblast activation protein and carboxypeptidase-like activity in the C-terminal region, and to achieve t1/2 extension (53 h in cynomolgus monkeys), we introduced a C18 fatty diacid at the penultimate position 180. The fatty diacid binds albumin in a reversible manner, such that the free fraction of zalfermin potently activates the FGF-receptor complex and retains receptor selectivity compared with FGF21, providing strong efficacy on body weight loss in diet-induced obese mice. Zalfermin is currently being clinically evaluated for the treatment of metabolic dysfunction-associated steatohepatitis.

AM833, a Long Acting Amylin Analogue Induces Hypocalcemia in Young Rats via a Calcitonin Receptor Mediated Mechanism

Amylin is a peptide hormone that is co-secreted with insulin from pancreatic β-cells. It is member of the calcitonin family and activates amylin receptors (AMYRs) in the calcitonin receptor (CTR) family. During recent years, several AMYR agonists have been in clinical development for treatment of diabetes and obesity. In contrast to pramlintide, which is a short acting amylin analogue approved for use in combination with meal-time insulin in patients with diabetes, the more recent development candidates have been dual acting analogues activating both the CTR and the AMYRs. In rodents the CTR plays a significant role in calcium homeostasis, while in humans this has been associated with little long-term effect on the plasma calcium levels (Ganong, 1993; Longo et al., 2011); Rodents are usually chosen as first choice pre-clinical models for in vivo testing and introducing acute and profound hypocalcaemia can lead to general neurological and neuromuscular disturbances, which can be challenging in clinical development programs. AM833 (NNC0174-0833) is a long acting acylated dual acting amylin analogue activating both CTR and AMYRs. When combined with the long acting GLP-1 analogue semaglutide for weight management, both preclinical studies in rat models of obesity and clinical trials in humans with obesity have demonstrated significant weight loss potential. In young rats aged 7–9 weeks, single sc dose of 3–300 nmol/kg AM833 induced a reduction of total and ionized calcium of 40–50% from baseline with lowest level around 12 hours after dosing. A similar response was seen after administration of salmon calcitonin which also activates both CTR and AMYRs. Tachyphylaxis was introduced, with no effect on calcium found after sub chronic daily treatment for 2 weeks. Age played a key role in the sensitivity to calcium lowering with almost no effect found in 11 months old rats. When administering AM1213 (NNC0174-1213), a selective AMYR agonist with little activation of the CTR, no or little calcium lowering of around 10% was seen. These data indicated that the calcium lowering properties are CTR mediated. The induction of hypercalcemia was a rodent specific phenomenon as no calcium lowering outside of normal range was seen in young dogs and rabbits. Clinical data confirmed that CTR induced calcium lowering was not human relevant, but these data showed that understanding physiology and pharmacology in the animal models of investigation as well as human translational relevance is of outmost importance in the progress of an early development program. References: GaNong WF. Calcitonin. In: Review of medical physiology. 16th ed. Appleton & Lange. 1993. Longo DL et al. Calcitonin. In: Harrison’s principles of internal medicine. 18th ed. McGraw-Hill; 2011.

Laparoscopic Roux-en-Y gastric bypass in super obese Göttingen minipigs

BACKGROUND

The specific mechanisms behind weight loss and comorbidity improvements in obese patients after Roux-en-Y gastric bypass (RYGBP) are still poorly understood. The aim of this study was to establish and evaluate the feasibility of a long-term survival RYGBP model in super obese Göttingen minipigs in order to improve the translational potential relative to current animal models.

METHODS

Eleven Göttingen minipigs with diet-induced obesity underwent laparoscopic RYGBP and were followed up to 9 months after surgery. Intra- and post-operative complications, body weight (BW), food intake and necropsy data were recorded.

RESULTS

Five minipigs survived without complications to the end of the study. Four minipigs developed surgical related complications and were euthanized while two minipigs died due to central venous catheter related complications. BW and food intake is reported for the six minipigs surviving longer than 4.5 months post-surgery. Weight loss and reduced food intake was seen in all minipigs. After 2-3 months of weight loss, weight regain was evident in all but two minipigs which seemed to continue losing weight. Necropsy revealed some variation in the length of the alimentary, biliary and common limb between minipigs.

CONCLUSION

The use of obese Göttingen minipigs as a translational RYGBP model is feasible and has potential for the study of RYGBP-related changes in gut function, type-2 diabetes and appetite regulation. Still, the surgical procedure is technically highly demanding in obese Göttingen minipigs and the peri-operative animal care and follow up requires close monitoring.

Abstract 460: 64 Cu-DOTATATE for in vivo Positron Emission Tomography Imaging of Somatostatin Receptor 2 Expressing Macrophages in a Göttingen Minipig Model of Atherosclerosis

Background: Somatostatin receptor subtype 2 (SSTR 2 ) is expressed by activated macrophages which are important effector cells in atherogenesis and a major constituent of atherosclerotic plaques. SSTR 2 can be targeted non-invasively in vivo using the tracer 64 Cu-DOTATATE and positron emission tomography (PET).

Methods: Male castrated Göttingen minipigs were treated according to two diet regimes for 43 weeks: chow (lean control; n=1) or high-fat/high-cholesterol diet (HFHC, obese group; n=2). Plasma lipids: total cholesterol (TC) and triglycerides (TG) were measured and SSTR 2 expression was assessed using hybrid positron emission tomography/magnetic resonance (PET/MR) imaging of the abdominal aorta, one hour (range: 60-63 minutes) post injection with 200 MBq (range 202-214 MBq) of 64 Cu-DOTATATE. Consectutive regions of interest (ROIs) were drawn guided by MR to include vessel wall and lumen of the abdominal aorta to calculate standardized uptake values (SUVs). Target-to-background (TBR) ratios were calculated using right atrium SUVs for blood pool correction (SUV vessel /SUV right atrium = TBR) and reported as mean and maximal values (TBR mean ; TBR max ).

Results: Three minipigs (age 17 months) were included and PET/MR was completed in all animals. Mean uptake of 64 Cu-DOTATATE was lowest for the abdominal aorta in the lean control: TBR mean = 0.44 and TBR max = 0.73 (range: TBR mean = 0.29 - 0.62; TBR max = 0.49 - 1.10) and highest in the HFHC group: TBR mean = 0.66 and TBR max = 1.28 (range: TBR mean = 0.26 - 1.38; TBR max = 0.39 - 3.19). Plasma lipids: lean control: TC = 1.34 mmol/L; TG = 0.38 mmol/L; HFHC group (mean values): TC = 18.7mmol/L (range: 11.6 - 25.8mmol/L); TG = 0.6 mmol/L (range: 0.37 - 0.83mmol/L).

Conclusion: Non-invasive 64 Cu-DOTATATE PET/MR is feasible for assessment of SSTR 2 expression in a Göttingen minipig model of diet-induced atherosclerosis. Additional studies are needed including assessment of histology findings and gene expression to confirm the presence of activated macrophages in order to validate the use of 64 Cu-DOTATATE PET/MR in this model.