Immunogenicity of xenopeptide hormone therapies

A case report of severe adverse reaction of exenatide: Anaphylactic shock

BACKGROUND

Anaphylactic shock is the severe state of the allergic reaction, which is rapid in onset and fatal. This is the first study that discusses the anaphylactic shock of exenatide reexposure in the patient who has interrupted exenatide treatment.

PATIENT CONCERNS

A 47-year-old man was treated with exenatide owing to high blood glucose and obesity. Then he developed localized urticarial on the face, white lip, hands tremble, nausea, vomit, chest stuffiness, dizziness, accompanying with confusion and dyspnea. His blood glucose was 4.6 millimole per liter (mmol/L) and blood pressure was 85/50 millimeters of mercury (mm Hg).

DIAGNOSIS

Exenatide-induced anaphylactic shock was considered.

INTERVENTIONS

The emergency electrocardiogram was performed. The patient was treated with dexamethasone sodium phosphate and calcium gluconate, combined with exenatide withdrawal. He also received oral antiallergic agents and intravenous nutrition treatment.

OUTCOMES

After antishock treatment, the clinical response gradually alleviated.

LESSONS

Although exenatide is not prone to anaphylaxis, it is the synthetic peptide that can induce antibody formation. Exenatide has immunogenicity with the potential to elicit an allergic reaction upon administration. Clinicians should always pay more attention to the anaphylactic shock of exenatide, when prescribing for diabetics.

Antibacterial Peptides in Dermatology-Strategies for Evaluation of Allergic Potential

During recent decades, the market for peptide-based drugs, including antimicrobial peptides, has vastly extended and evolved. These drugs can be useful in treatment of various types of disorders, e.g., cancer, autoimmune diseases, infections, and non-healing wounds. Although peptides are less immunogenic than other biologic therapeutics, they can still induce immune responses and cause allergies. It is important to evaluate the immunogenic and allergic potential of peptides before they are forwarded to the expensive stages of clinical trials. The process of the evaluation of immunogenicity and cytotoxicity is complicated, as in vitro models and bioinformatics tools cannot fully simulate situations in the clinic. Nevertheless, several potentially promising tests for the preclinical evaluation of peptide drugs have been implemented (e.g., cytotoxicity assays, the basophil activation test, and lymphocyte activation assays). In this review, we focus on strategies for evaluation of the allergic potential of peptide-based therapeutics.

A Human Glucagon-Like Peptide-1-albumin Recombinant Protein with Prolonged Hypoglycemic Effect Provides Efficient and Beneficial Control of Glucose Metabolism in Diabetic Mice

GW002 is a recombinant protein engineered by fusing the C-terminal region of human glucagon-like peptide-1 (GLP-1) to the N-terminal region of human serum albumin (HSA) with a peptide linker. This study aims to evaluate its anti-diabetic effects both in vitro and in vivo. The GLP-1 receptor-dependent luciferase reporter plasmid was transiently transfected in NIT-1 cells to calculate the half-maximal concentration (EC₅₀) for GLP-1 receptor activation, and normal ICR mice and diabetic KKAy mice were acutely injected with GW002 (1, 3, 9 mg/kg) subcutaneously to evaluate the hypoglycemic action, while the diabetic KKAy and db/db mice were treated with GW002 once daily for 7 weeks to evaluate the effects on glucose metabolism. The results showed that GW002 activated GLP-1 receptor in NIT-1 cells with higher EC₅₀ versus exendin-4 (46.7 vs. 7.89 nM), and single subcutaneous injection of GW002 at doses of 1, 3 and 9 mg/kg efficiently restrained the glycemia variation after oral glucose loading in ICR mice for at least 4 d, as well as reducing the non-fasting blood glucose in KKAy mice for about 2 d, while repeated injections of GW002 significantly improved abnormal glycaemia, hemoglobin (Hb)A1c levels, oral glucose intolerance and β-cell function in diabetic db/db mice. These results suggested that GW002 showed prolonged hypoglycemic action by activating its cognate receptor and provided efficient control of glucose metabolism. Thus GW002 may be a potential treatment for the management of type 2 diabetes.

Immunogenicity associated with metreleptin treatment in patients with obesity or lipodystrophy

OBJECTIVE

Recombinant human leptin (metreleptin) improves glycaemia and hypertriglyceridaemia in patients with generalized lipodystrophy; antibody development with in vitro neutralizing activity has been reported. We aimed to characterize antimetreleptin antibody development, including in vitro neutralizing activity.

DESIGN

Two randomized controlled studies in patients with obesity (twice-daily metreleptin ± pramlintide for 20-52 weeks; 2006-2009); two long-term, open-label studies in patients with lipodystrophy (once-daily or twice-daily metreleptin for 2 months to 12·3 years; 2000-2014).

PATIENTS

A total of 579 metreleptin-treated patients with obesity and 134 metreleptin-treated patients with lipodystrophy (antibody/neutralizing activity data: n = 105).

MEASUREMENTS

Antimetreleptin antibodies, in vitro neutralizing activity.

RESULTS

Antimetreleptin antibodies developed in most patients (obese: 96-100%; lipodystrophy: 86-92%). Peak antibody titers (approximately 1:125 to 1:3125) generally occurred within 4-6 months and decreased with continued therapy (lipodystrophy). Antibody development did not adversely impact efficacy or safety (patients with obesity), except for inflammatory injection site reactions, but was associated with elevated leptin concentrations. Three patients with obesity developed in vitro neutralizing activity coincident with weight gain. Weight later returned to baseline in one patient despite persistent neutralizing activity. Four patients with generalized lipodystrophy developed in vitro neutralizing activity concurrent with worsened metabolic control; two with confounding comorbidities had sepsis. One patient with lipodystrophy had resolution of neutralizing activity on metreleptin.

CONCLUSIONS

Development of in vitro neutralizing activity could be associated with loss of efficacy but has not been consistently associated with adverse clinical consequences. Whether neutralization of endogenous leptin with clinical consequences occurs remains unclear.

Review of head-to-head comparisons of glucagon-like peptide-1 receptor agonists

Currently, six glucagon-like peptide-1 receptor agonists (GLP-1RAs) are approved for treating type 2 diabetes. These fall into two classes based on their receptor activation: short-acting exenatide twice daily and lixisenatide once daily; and longer-acting liraglutide once daily, exenatide once weekly, albiglutide once weekly and dulaglutide once weekly. The phase III trial of a seventh GLP-1RA, taspoglutide once weekly, was stopped because of unacceptable adverse events (AEs). Nine phase III head-to-head trials and one large phase II study have compared the efficacy and safety of these seven GLP-1RAs. All trials were associated with notable reductions in glycated haemoglobin (HbA1c) levels, although liraglutide led to greater decreases than exenatide formulations and albiglutide, and HbA1c reductions did not differ between liraglutide and dulaglutide. As the short-acting GLP-1RAs delay gastric emptying, they have greater effects on postprandial glucose levels than the longer-acting agents, whereas the longer-acting compounds reduced plasma glucose throughout the 24-h period studied. Liraglutide was associated with weight reductions similar to those with exenatide twice daily but greater than those with exenatide once weekly, albiglutide and dulaglutide. The most frequently observed AEs with GLP-1RAs were gastrointestinal disorders, particularly nausea, vomiting and diarrhoea. Nauseaoccurred less frequently, however, with exenatide once weekly and albiglutide than exenatide twice daily and liraglutide. Both exenatide formulations and albiglutide may be associated with higher incidences of injection-site reactions than liraglutide and dulaglutide. GLP-1RA use in clinical practice should be customized for individual patients, based on clinical profile and patient preference. Ongoing assessments of novel GLP-1RAs and delivery methods may further expand future treatment options.

Development of Immunocapture-LC/MS Assay for Simultaneous ADA Isotyping and Semiquantitation

Therapeutic proteins and peptides have potential to elicit immune responses resulting in anti-drug antibodies that can pose problems for both patient safety and product efficacy. During drug development immunogenicity is usually examined by risk-based approach along with specific strategies for developing “fit-for-purpose” bioanalytical approaches. Enzyme-linked immunosorbent assays and electrochemiluminescence immunoassays are the most widely used platform for ADA detection due to their high sensitivity and throughput. During the past decade, LC/MS has emerged as a promising technology for quantitation of biotherapeutics and protein biomarkers in biological matrices, mainly owing to its high specificity, selectivity, multiplexing, and wide dynamic range. In fully taking these advantages, we describe here an immunocapture-LC/MS methodology for simultaneous isotyping and semiquantitation of ADA in human plasma. Briefly, ADA and/or drug-ADA complex is captured by biotinylated drug or anti-drug Ab, immobilized on streptavidin magnetic beads, and separated from human plasma by a magnet. ADA is then released from the beads and subjected to trypsin digestion followed by LC/MS detection of specific universal peptides for each ADA isotype. The LC/MS data are analyzed using cut-point and calibration curve. The proof-of-concept of this methodology is demonstrated by detecting preexisting ADA in human plasma.

Assessment and reporting of the clinical immunogenicity of therapeutic proteins and peptides-harmonized terminology and tactical recommendations

Immunogenicity is a significant concern for biologic drugs as it can affect both safety and efficacy. To date, the descriptions of product immunogenicity have varied not only due to different degrees of understanding of product immunogenicity at the time of licensing but also due to an evolving lexicon that has generated some confusion in the field. In recent years, there has been growing consensus regarding the data needed to assess product immunogenicity. Harmonization of the strategy for the elucidation of product immunogenicity by drug developers, as well as the use of defined common terminology, can benefit medical practitioners, health regulatory agencies, and ultimately the patients. Clearly, understanding the incidence, kinetics and magnitude of anti-drug antibody (ADA), its neutralizing ability, cross-reactivity with endogenous molecules or other marketed biologic drugs, and related clinical impact may enhance clinical management of patients treated with biologic drugs. To that end, the authors present terms and definitions for describing and analyzing clinical immunogenicity data and suggest approaches to data presentation, emphasizing associations of ADA development with pharmacokinetics, efficacy, and safety that are necessary to assess the clinical relevance of immunogenicity.

Evolution of exenatide as a diabetes therapeutic

Type 2 diabetes (T2DM) is a disease of epidemic proportion associated with significant morbidity and excess mortality. Optimal glucose control reduces the risk of microvascular and possibly macrovascular complications due to diabetes. However, glycemic control is rarely optimal and several therapeutic interventions for the treatment of diabetes cause hypoglycemia and weight gain; some may exacerbate cardiovascular risk. Exenatide (synthetic exendin-4) is a glucagon- like peptide-1 receptor (GLP-1R) agonist developed as a first-in-class diabetes therapy. This review presents an overview of the evolution of exenatide as a T2DM treatment, beginning with the seminal preclinical discoveries and continuing through to clinical pharmacology investigations and phase 3 clinical trials. In patients with T2DM, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, and enhanced satiety. In controlled phase 3 clinical trials ranging from 12 to 52 weeks, 10-mcg exenatide twice daily (ExBID) reduced mean HbA1c by -0.8% to -1.7% as monotherapy or in combination with metformin (MET), sulfonylureas (SFU), and/or thiazolidinediones (TZD); with mean weight losses of -1.2 kg to -8.0 kg. In controlled phase 3 trials ranging from 24 to 30 weeks, a 2-mg once-weekly exenatide formulation (ExQW) reduced mean HbA1c by -1.3% to -1.9%, with mean weight reductions of -2.3 to -3.7 kg. Exenatide was generally well-tolerated. The most common side effects were gastrointestinal in nature, mild, and transient. Nausea was the most prevalent adverse event. The incidence of hypoglycemia was generally low. By building upon early observations exenatide was successfully developed into an effective diabetes therapy.

Clinical relevance of anti-exenatide antibodies: safety, efficacy and cross-reactivity with long-term treatment

AIMS

Antibody formation to therapeutic peptides is common. This analysis characterizes the time-course and cross-reactivity of anti-exenatide antibodies and potential effects on efficacy and safety.

METHODS

Data from intent-to-treat patients in 12 controlled (n = 2225,12-52 weeks) and 5 uncontrolled (n = 1538, up to 3 years) exenatide twice-daily (BID) trials and 4 controlled (n = 653,24-30 weeks) exenatide once weekly (QW) trials with 1 uncontrolled period (n = 128,52 weeks) were analysed.

RESULTS

Mean titres peaked early (6-22 weeks) and subsequently declined. At 30 weeks, 36.7% of exenatide BID patients were antibody-positive; 31.7% exhibited low titres (≤125) and 5.0% had higher titres (≥625). Antibody incidence declined to 16.9% (1.4% higher titre) at 3 years. Similarly, 56.8% of exenatide QW patients were antibody-positive (45.0% low/11.8% higher titre) at 24-30 weeks, declining to 45.4% positive (9.2% higher titre) at 52 weeks. Treatment-emergent anti-exenatide antibodies from a subset of patients tested did not cross-react with human GLP-1 or glucagon. Other than injection-site reactions, adverse event rates in antibody-positive and antibody-negative patients were similar. Efficacy was robust in both antibody-negative and antibody-positive patients (mean HbA1c change: -1.0 and -0.9%, respectively, exenatide BID; -1.6% and -1.3% exenatide QW). No correlation between change in HbA1c and titre was observed for exenatide BID, although mean reductions were attenuated in the small subset of patients (5%) with higher titres. A significant correlation was observed for exenatide QW with no difference between antibody-negative and low-titre patients, but an attenuated mean reduction in the subset of patients (12%) with higher titres.

CONCLUSIONS

Low-titre anti-exenatide antibodies were common with exenatide treatment (32% exenatide BID, 45% exenatide QW patients), but had no apparent effect on efficacy. Higher-titre antibodies were less common (5% exenatide BID, 12% exenatide QW) and within that titre group, increasing antibody titre was associated with reduced average efficacy that was statistically significant for exenatide QW. Other than injection-site reactions, anti-exenatide antibodies did not impact the safety of exenatide.

Exenatide: a new promising antidiabetic agent

Exenatide is a unique agent which can effectively control blood glucose levels in type 2 diabetes mellitus without producing dangerous adverse effects. In addition, it can lower body weight which is very essential for the treatment of obese type 2 diabetes mellitus patients. Since it can delay the destruction of islet beta-cells, type 2 diabetes mellitus patients are not rapidly converted to type 1 diabetes mellitus and ultimately appearance of complications of the disease is halted or delayed. Its long-acting-release formula, which would be used once per week, simultaneously retaining all the properties of twice-daily subcutaneous administration, is undergoing clinical trial. This drug is considered as an adjunct to metformin/sulfonylureas/insulin.

Impact of product-related factors on immunogenicity of biotherapeutics

All protein therapeutics have the potential to be immunogenic. Several factors, including patient characteristics, disease state, and the therapy itself, influence the generation of an immune response. Product-related factors such as the molecule design, the expression system, post-translational modifications, impurities, contaminants, formulation and excipients, container, closure, as well as degradation products are all implicated. However, a critical examination of the available data shows that clear unequivocal evidence for the impact of these latter factors on clinical immunogenicity is lacking. No report could be found that clearly deconvolutes the clinical impact of the product attributes on patient susceptibility. Aggregation carries the greatest concern as a risk factor for immunogenicity, but the impact of aggregates is likely to depend on their structure as well as on the functionality (e.g., immunostimulatory or immunomodulatory) of the therapeutic. Preclinical studies are not yet capable of assessing the clinically relevant immunogenicity potential of these product-related factors. Simply addressing these risk factors as part of product development will not eliminate immunogenicity. Minimization of immunogenicity has to begin at the molecule design stage by reducing or eliminating antigenic epitopes and building in favorable physical and chemical properties.

The effect of exenatide re-exposure on safety and efficacy

Exenatide, a synthetic peptide originally isolated from salivary secretions of Heloderma suspectum, like other subcutaneously injected peptides, can cause antibody formation. Despite that antibody formation has been observed in some patients, results from previous clinical trials have not shown safety and efficacy concerns in exenatide-naïve patients. The objective of this multicenter, open-label study was to investigate the response of anti-exenatide antibody formation and the incidence of immune-related and hypersensitivity reactions after exenatide re-exposure. Fifty-eight patients (57% male; 59+/-10 years; weight 85+/-19kg; HbA1c 8.1+/-0.9%; duration of diabetes 10+/-5 years) were enrolled. At study initiation, 98.3% of patients were taking 1 or more antidiabetes drugs, including oral medication and various types of insulin. Treatment-emergent adverse events (TEAEs) at any time during the study were observed in 40 and 47% of patients with positive and negative treatment-emergent antibodies, respectively. Immune-related AEs were observed in 6 patients (4 were antibody positive). These AEs had not been reported in their previous exposure to exenatide. Re-exposure to exenatide did not result in increased hypersensitivity reactions. Overall, 72% of patients had a baseline to endpoint reduction in HbA1c (range -0.1 to -2.8%), and 87% of antibody negative versus 62% of antibody positive patients had an HbA1c endpoint reduction. The study design and the patients' baseline characteristics, including diabetes treatment at study initiation, are confounding factors limiting clinical conclusions on exenatide's glycemic effect in this patient population. The study results indicate that anti-exenatide antibody formation did not increase the incidence of TEAEs in patients re-exposed to exenatide.

Exenatide once weekly versus twice daily for the treatment of type 2 diabetes: a randomised, open-label, non-inferiority study

BACKGROUND

Exenatide is an incretin mimetic that shares glucoregulatory properties with glucagon-like peptide 1 (GLP-1), and improves glycaemic control, with progressive bodyweight reductions, when administered twice a day in patients with type 2 diabetes. We compared the efficacy of a once-weekly formulation of exenatide to that of a twice daily dose.

METHODS

A 30-week, randomised, non-inferiority study compared a long-acting release formulation of exenatide 2 mg administered once weekly to 10 mug exenatide administered twice a day, in 295 patients with type 2 diabetes (haemoglobin A(1c) [HbA(1c)] 8.3% [SD 1.0], mean fasting plasma glucose 9 [SD 2] mmol/L, weight 102 [SD 20] kg, diabetes duration 6.7 [SD 5.0] years). The patients were naive to drug therapy, or on one or more oral antidiabetic agents. The primary endpoint was the change in HbA(1c) at 30 weeks. This study is registered with ClinicalTrials.gov, number NCT00308139.

FINDINGS

At 30 weeks, the patients given exenatide once a week had significantly greater changes in HbA(1c) than those given exenatide twice a day (-1.9 [SE 0.1%] vs -1.5 [0.1%], 95% CI -0.54% to -0.12%; p=0.0023). A significantly greater proportion of patients receiving treatment once a week versus twice a day achieved target HbA(1c) levels of 7.0% or less (77%vs 61% of evaluable patients, p=0.0039).

INTERPRETATION

Exenatide once weekly resulted in significantly greater improvements in glycaemic control than exenatide given twice a day, with no increased risk of hypoglycaemia and similar reductions in bodyweight.

Oral bioavailability of insulin contained in polysaccharide nanoparticles

The pharmacological activity of insulin-loaded dextran sulfate/chitosan nanoparticles was evaluated following oral dosage in diabetic rats. Nanoparticles were mucoadhesive and negatively charged with a mean size of 500 nm, suitable for uptake within the gastrointestinal tract. Insulin association efficiency was over 70% and was released in a pH-dependent manner under simulated gastrointestinal conditions. Orally delivered nanoparticles lowered basal serum glucose levels in diabetic rats around 35% with 50 and 100 IU/kg doses sustaining hypoglycemia over 24 h. Pharmacological availability was 5.6 and 3.4% for the 50 and 100 IU/kg doses, respectively, a significant increase over 1.6%, determined for oral insulin alone in solution. Confocal microscopic examinations of FITC-labeled insulin nanoparticles showed adhesion to rat intestinal epithelium, and internalization of insulin within the intestinal mucosa. Encapsulation of insulin into dextran sulfate/chitosan nanoparticles was a key factor in the improvement of the bioavailability of its oral delivery over insulin solution.

A risk-based bioanalytical strategy for the assessment of antibody immune responses against biological drugs

Bioanalytical assessments of anti-drug antibodies (ADAs) provide an understanding of the immunogenicity of biological drug molecules. The potential to induce ADAs after treatment with biologics is a safety issue that has become an important consideration in the development of biologics and a critical aspect of regulatory filings. US and European regulatory agencies are recommending that sponsors study immunogenicity using a risk-based approach, encouraging sponsors to formulate and implement their own risk management plans and to conduct discussions with the agencies when necessary. It follows from this that the greater the safety risks of ADAs, the more diligently one should clarify the immunogenicity of the product. Here we propose a general strategy to broadly assign immunogenicity risk levels to biological drug products, and present risk level-based 'fit-for-purpose' bioanalytical schemes for the investigations of treatment-related ADAs in clinical and nonclinical studies.

Using evolutionary information and ancestral sequences to understand the sequence-function relationship in GLP-1 agonists

Glucagon-like peptide-1 (GLP-1) is an incretin hormone with therapeutic potential for type 2 diabetes. A variety of GLP-1 sequences are known from amphibian species, and some of these have been tested here and found to be able to bind and activate the human GLP-1 receptor. While little difference was observed for the in vitro potency for the human GLP-1 receptor, larger differences were found in the enzymatic stability of these peptides. Two peptides showed increased enzymatic stability, and they group together phylogenetically, though they originate from Amphibia and Reptilia. We have used ancestral sequence reconstruction to analyze the evolution of these GLP-1 molecules, including the synthesis of new peptides. We find that the increased stability could not be observed in the resurrected peptides from the common ancestor of frogs, even though they maintain the ability to activate the human GLP-1 receptor. Another method, using residue mapping on evolutionary branches yielded peptides that had maintained potency towards the receptor and also showed increased stability. This represents a new approach using evolutionary data in protein engineering.