Effect of insulin antibodies on insulin pharmacokinetics and glucose utilization in insulin-dependent diabetic patients

Leveraging Clinical Pharmacology Data to Assess Biosimilarity and Interchangeability of Insulin Products

There is over a hundred years of clinical experience with insulin for the treatment of diabetes. The US Food and Drug Administration (FDA) approved the first insulin biosimilar interchangeable product in 2021 for improving glycemic control in adults and pediatric patients with type 1 diabetes mellitus and in adults with type 2 diabetes mellitus. Several recombinant insulin products are available in the United States, including the recently approved biosimilar insulins. The approval of the biosimilar insulin products was based on comparative analytical characterizations and comparative pharmacokinetic (PK) and pharmacodynamic (PD) data. The primary objective of this review is to discuss the scientific considerations in the demonstration of biosimilarity of a proposed insulin biosimilar to a reference product and the role of clinical pharmacology studies in the determination of biosimilarity and interchangeability. Euglycemic clamp studies are considered a "gold standard" for insulin PK and PD characterization and have been widely used to determine the time-action profiles of rapid-acting, intermediate-acting, and long-acting insulin products. Clinical pharmacology aspects of study design, including selection of appropriate dose, study population, PK, and PD end points, are presented. Finally, the role of clinical pharmacology studies in the interchangeability assessment of insulin and the regulatory pathways used for insulin and the experience with follow-on insulins and the two recently approved biosimilar insulin products is discussed.

Clinical Pharmacology of Fast-Acting Insulin Aspart Versus Insulin Aspart Measured as Free or Total Insulin Aspart and the Relation to Anti-Insulin Aspart Antibody Levels in Subjects with Type 1 Diabetes Mellitus

Background

Fast-acting insulin aspart (faster aspart) is an ultra-fast-acting formulation of insulin aspart (IAsp). This post hoc analysis investigated the pharmacokinetics of faster aspart versus IAsp, measured as free or total IAsp, and the relationship between anti-IAsp antibodies and the pharmacokinetics/pharmacodynamics of faster aspart and IAsp.

Methods

Free and total IAsp concentrations and anti-IAsp antibodies were determined in adults with type 1 diabetes mellitus receiving subcutaneous faster aspart and/or IAsp in four single-dose clinical pharmacology trials (n = 175) and a 26-week phase IIIa trial (n = 1040). Pharmacodynamics were assessed by euglycaemic clamp or meal test, respectively.

Results

The pharmacokinetic profile was left-shifted and early exposure was greater with faster aspart versus IAsp independent of free or total IAsp assay. The faster aspart-IAsp difference in the time to 50% of maximum IAsp concentration in the early part of the pharmacokinetic profile (t_{Early 50 % Cmax}) [95% confidence interval (CI)] was − 8.8 [− 10.0 to − 7.5] and − 7.6 [− 8.8 to − 6.4] min for free and total IAsp, respectively. The faster aspart/IAsp ratio for the area under the concentration–time curve (AUC) for IAsp from time zero to 30 min (AUC_{IAsp,0–30 min}) [95% CI] was 1.88 [1.74–2.04] and 1.77 [1.64–1.90] for free and total IAsp. Higher anti-IAsp antibody levels were associated with a lower ratio of free/total IAsp for the total AUC for IAsp (AUC_IAsp,0–t). Early glucose-lowering effect (AUC for the glucose infusion rate [GIR] from time zero to 60 min [AUC_{GIR,0–60 min}]) was greater by 25–44% for faster aspart versus IAsp independent of anti-IAsp antibody levels. Total glucose-lowering effect (total AUC for GIR [AUC_GIR,0–t]) in a clamp and 1-h postprandial glucose increment in a meal test appeared essentially unaffected by anti-IAsp antibodies.

Conclusions

Faster aspart provides accelerated pharmacokinetics versus IAsp regardless if based on free or total IAsp assay. Higher anti-IAsp antibodies increase total IAsp concentrations but do not influence faster aspart nor IAsp pharmacodynamics.

ClinicalTrials.gov identifiers

NCT01618188, NCT02003677, NCT01934712, NCT02568280, NCT01831765.

Electronic supplementary material

The online version of this article (10.1007/s40262-018-0718-6) contains supplementary material, which is available to authorized users.

Circulating insulin antibodies: influence of continuous subcutaneous or intraperitoneal insulin infusion, and impact on glucose control

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence, but not completely suppressed, the development of anti-insulin antibodies (IAs). Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), continuous peritoneal insulin infusion (CPII) and more recently inhaled insulin administration, appear to significantly increase circulating levels of immunoglobulin G (IgG) anti-IAs in diabetic patients. However, the increase is usually moderate and mostly transient as compared to previous observations with poorly purified animal insulin preparations. The clinical impact of these circulating anti-IAs remains unclear. Nevertheless, several studies have suggested that antibodies could retard insulin action, leading to a worsening of postprandial hyperglycaemia and/or serve as a carrier, thus leading to unexpected hypoglycaemia. CPII may be associated with more marked and sustained increase in IAs levels, possibly related to the use of an unstable insulin and the formation of immunogenic aggregates of insulin. The possible clinical consequences of these high levels of IAs remain to be evaluated because a low-glucose morning syndrome or severe insulin resistance with ketone bodies production have been reported in some cases. In conclusion, even if CSII and CPII may promote the development of circulating IAs, this increase does not lead to immunological insulin resistance, compared to that previously described with animal non-purified insulin preparations, and seems to have only marginal influence on blood glucose control or complications in most diabetic patients.

Immunological responses to exogenous insulin

Regardless of purity and origin, therapeutic insulins continue to be immunogenic in humans. However, severe immunological complications occur rarely, and less severe events affect a small minority of patients. Insulin autoantibodies (IAAs) may be detectable in insulin-naive individuals who have a high likelihood of developing type 1 diabetes or in patients who have had viral disorders, have been treated with various drugs, or have autoimmune disorders or paraneoplastic syndromes. This suggests that under certain circumstances, immune tolerance to insulin can be overcome. Factors that can lead to more or less susceptibility to humoral responses to exogenous insulin include the recipient's immune response genes, age, the presence of sufficient circulating autologous insulin, and the site of insulin delivery. Little proof exists, however, that the development of insulin antibodies (IAs) to exogenous insulin therapy affects integrated glucose control, insulin dose requirements, and incidence of hypoglycemia, or contributes to beta-cell failure or to long-term complications of diabetes. Studies in which pregnant women with diabetes were monitored for glycemic control argue against a connection between IAs and fetal risk. Although studies have shown increased levels of immune complexes in patients with diabetic microangiopathic complications, these immune complexes often do not contain insulin or IAs, and insulin administration does not contribute to their formation. The majority of studies have shown no relationship between IAs and diabetic angiopathic complications, including nephropathy, retinopathy, and neuropathy. With the advent of novel insulin formulations and delivery systems, such as insulin pumps and inhaled insulin, examination of these issues is increasingly relevant.

Effects of PEG conjugation on insulin properties

The goal of this research was to determine whether the site-specific attachment of poly(ethylene glycol) to insulin could enhance the physical and pharmacological properties of insulin without negatively affecting its biological activity or immunological properties. Electrophilically activated derivatives of low-molecular-weight monomethoxypoly(ethylene glycol) (mPEG) were chemically coupled to insulin via its amino groups at positions phenylalanine-B1 or lysine-B29, with an amide bond being formed between the polymer and protein. The site-specific attachment of mPEG to insulin did not substantially alter insulin's secondary/tertiary structure, self-association behavior, or potency in vivo. However, mPEG attachment did significantly enhance insulin's resistance to aggregation. In addition, the pegylation of insulin almost completely eliminates the resultant conjugate's immunogenicity, allergenicity, and antigenicity. Finally, the conjugates were observed to remain in the systemic circulation for longer periods of time than unmodified insulin after subcutaneous administration.

The influence of insulin antibodies on the pharmacokinetics of NPH insulin in patients with type 1 diabetes treated with human insulin

The influence of insulin binding antibodies on the pharmacokinetics of NPH insulin was studied in Type 1 diabetic patients on human insulin. Insulin-antibody binding (B(o) was measured during a screening procedure in 155 Type 1 diabetic patients. In 36 patients, B(o) was < 1.5%, and in 38 patients B(o) was > 10.0%. Of these, 6 patients, group 1 (B(o) < 1.5%) and 8 patients, group 2 (B(o) > 10.0%), respectively, subsequently participated in a pharmacokinetic study. Free insulin and the glucose infusion rate were measured using a euglycaemic clamp after subcutaneous injection of NPH insulin (0.4 U kg-1). The areas under the curve (AUC) of free insulin concentration were smaller for group 2 (p = 0.01) than for group 1 (212.2 +/- 22.0 vs 316.8 +/- 25.3 mU l-1h). The AUCs of the glucose infusion rate were also smaller for group 2 (p < 0.05) than for group 1 (2.50 +/- 0.32 vs 3.58 +/- 0.36 g kg-1). A significant negative correlation exists between the AUCs for free insulin concentration and insulin-antibody binding B(o) (r = 0.76, p = 0.001). The daily insulin dosage was higher in group 2 (p = 0.02) than in group 1 (0.66 +/- 0.03 vs 0.53 +/- 0.03 U kg-1). We conclude that insulin antibodies influence the pharmacokinetics of NPH human insulin. The demonstrable influence on the kinetics of free insulin and glucose utilization leads to a slight increase in daily total insulin requirements.

Immunogenicity of intraperitoneal insulin infusion using programmable implantable devices

Intraperitoneal insulin infusion using implantable devices in insulin-dependent diabetic (IDDM) patients is promising since it improves diabetic control and decreases frequency of hypoglycaemia. However, preliminary data show a striking increase in plasma levels of anti-insulin antibodies with this therapy. In order to more precisely evaluate the immunogenicity and its consequences, anti-insulin antibody levels in 62 IDDM patients were assessed every 3 months during a 2-year period following pump implantation. At the same time, diabetes control was evaluated with HbA1c, mean blood glucose levels, standard deviation of the daily blood glucose levels and the frequency of low blood glucose (< 3.58 mmol/l). Factors involved in antibody formation such as age, gender, HLA typing, and complement C4 alleles were also studied. After implantation, anti-insulin antibody levels increased significantly from 3.14% (range 0-26%) to 8.34% (0-49%) after 1 year and remained elevated. Patients were divided into two groups: responders able to show at least one antiinsulin antibody titre higher than 15% and non-responders whose titres were always lower than 6%. None of the factors studied was shown to statistically influence the anti-insulin antibody titres. Non-responders had significantly better metabolic results than the responders. Severe hypoglycaemic episodes decreased dramatically in both groups. Insulin requirements were comparable at time 0 and decreased initially in both groups. They remained low for the non-responders but returned to pre-implantation values for responders. Intraperitoneal insulin infusion led to a high immunogenetic response towards insulin in about half of the patients, leading to only moderately deleterious effects on metabolic control.(ABSTRACT TRUNCATED AT 250 WORDS)

Both acute and chronic near-normoglycaemia are required to improve insulin resistance in type 1 (insulin-dependent) diabetes mellitus

To determine the impact of both short- and long-term "near-normoglycaemia" on insulin resistance in Type 1 (insulin-dependent) diabetes hepatic glucose production (mg.kg-1.min-1) and peripheral glucose utilisation ("M-value", mg.kg-1.min-1) were estimated during an euglycaemic hyperinsulinaemic clamp (10 mU.kg.min) in patients with either good (HbA1c < 5.8%, groups A and B) or poor (HbA1c > 7.5%, groups C and D) long-term metabolic control (time > 12 months) and in healthy subjects (HbA1c: 5.08 +/- 0.20%; n = 8). To this end blood glucose was stabilized at 6.7 mmol/l by overnight (t = 12 h) i.v. regular insulin in groups (n = 8 each) A (HbA1c: 5.49 +/- 0.46%) and C (HbA1c: 8.83 +/- 1.20%), while groups B (HbA1c: 5.55 +/- 0.19%) and D (HbA1c: 8.51 +/- 1.09%) were kept overnight on long-acting insulin without feed-back control of blood glucose before euglycaemic clamping. Thereby, pre-equilibration of blood glucose at 6.7 mmol/l was shown to normalize basal hepatic glucose production (A: 2.27 +/- 0.48; C 2.50 +/- 0.57 mg.kg-1.min-1) despite different HbA1c values, whereas basal hepatic glucose production stayed elevated in groups B (3.09 +/- 0.38 mg.kg-1.min-1) and D (3.21 +/- 0.58 mg.kg-1.min-1) with poor actual glycaemia (B: 10.9 +/- 4.6; D: 12.1 +/- 4.6 mmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Issues in contemporary drug delivery. Part IV. Insulin therapy

Continuous insulin infusions are a valuable way of managing highly selected patients, although patients and healthcare practitioners must be aware of the limits and the increased risks involved with this type of technology. Maximum benefit from the CSII technology is achieved when the patient is part of a complete healthcare team accessible on a daily basis to respond to the changing nature of the underlying diabetes. Intranasal and pulmonary delivery of insulin, in contrast, represent a minor technology that will potentially add convenience to some diabetic management plans and possibly provide a new treatment approach for noninsulin-dependent diabetic patients.

The course and determinants of insulin action in type 1 (insulin-dependent) diabetes mellitus

The course and determinants of insulin action were investigated in 8 newly diagnosed Type 1 (insulin-dependent) diabetic patients, who were studied every 3 months for one year, and in three groups of 8 patients each with 5, 10 and 20 years diabetes, studied once. Fifteen healthy subjects matched for age, sex and body weight served as control subjects. Dose-response curves were constructed using sequential euglycaemic (5.0 mmol/l) clamps (insulin infusion rates: 0.5, 1.0, 2.0 and 5.0 mU.kg-1.min-1 in periods of 2h). After 1/2 month of insulin treatment, insulin responsiveness was normal, but sensitivity was decreased (ED50 70 +/- 7 mU/l (SEM) vs 54 +/- 4 mU/l in control subjects, p less than 0.05). After 6 months, insulin sensitivity was improved (ED50 57 +/- 4 mU/l, p less than 0.01 vs 1/2 month and not significant (NS) vs control subjects); but after 9 and 12 months, it was reduced again, similarly to 0.5 month. Insulin responsiveness remained normal at all time-points. In the three groups of patients with longstanding diabetes, impaired insulin sensitivity with normal responsiveness was noted also (ED50 73 +/- 9 mU/l, p less than 0.02 vs control subjects). At 6, 9 and 12 months, glycaemic control (HbA1) and insulin dose were inverse correlates for insulin action; in patients with longstanding disease, this was noted for HbA1 and body weight, in control subjects for body weight. In conclusion, decreased insulin sensitivity re-develops in Type 1 diabetes within the first year following an initial improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin antibodies do not influence the absorption rate of subcutaneously injected insulin

The influence of insulin antibodies on absorption rate and plasma free insulin concentrations after subcutaneous injection of insulin, was studied in two groups of insulin-treated diabetic patients, one without insulin antibodies (n = 9) and a second with high plasma concentrations of antibodies (n = 14). Except for antibody concentration there were no differences in clinical variables. During 8 h after the injection of 12 U of iodinated neutral human insulin, residual radioactivity at the injection site, plasma glucose, and free and total insulin were measured. Significant differences in absorption rate of insulin were not found between the groups. Plasma glucose (basal value 16.8 +/- 4.4 SD vs 16.1 +/- 4.2 mmol l-1) and free insulin (basal value 8.3 +/- 1.4 vs 11.4 +/- 2.3 mU l-1, maximum after 90 min 36.9 +/- 19.5 vs 30.5 +/- 18.7 mU l-1) were never significantly different between the groups, nor were areas under the curve for free insulin (191.4 +/- 69.2 vs 170.8 +/- 98.6 mU l-1 h). In the high antibody group a small increase in bound insulin was found.

The relationship of acute insulin sensitivity to the progression of vascular disease in long-term type 1 (insulin-dependent) diabetes mellitus

In 51 individuals with Type 1 (insulin-dependent) diabetes mellitus initially of more than 15 years' duration, the acute hypoglycaemic effect of intravenous insulin (0.11 IU/kg) was related to outcome over 18 years. This acute insulin sensitivity, or glucose assimilation index, was reproducible over the period of study. At 18-year follow-up, initial low glucose assimilation index (less than 0.082 mmol X l-1 X min-1 was significantly (p less than 0.01) associated with death from vascular disease. Low glucose assimilation index was similarly significantly (p less than 0.01) associated with progression of atherosclerotic disease, but not with microangiopathy alone. Hypertension (systolic blood pressure greater than 150 mmHg and/or diastolic blood pressure greater than 95 mmHg) was the only other parameter significantly (p less than 0.01) related to outcome, but this relationship was no longer significant once glucose assimilation index had been taken into account. A linear logistic analysis confirmed that acute insulin sensitivity was independently associated with outcome. Neither initial clinical control of diabetes nor glycosylated haemoglobin level in the 26 survivors was related to vascular prognosis.

Studies on overnight insulin requirements and metabolic clearance rate of insulin in normal and diabetic man: relevance to the pathogenesis of the dawn phenomenon

In order to assess whether the metabolic clearance of insulin changes overnight, 11 patients with Type 1 (insulin-dependent) diabetes and low insulin antibody titre, and 6 nondiabetic subjects were studied. In these studies insulin was always infused by a Harvard pump. Initially, the nocturnal insulin requirements were assessed in the diabetic patients by an overnight feedback insulin infusion to maintain euglycaemia. The insulin requirements decreased continuously after midnight to a nadir of 0.115 +/- 0.014 mU X kg-1 X min-1 at 04.30 hours, but after 05.00 hours the insulin requirements increased nearly 40 percent to a maximum of 0.16 +/- 0.012 mU X kg-1 X min-1 at 07.00 hours. To assess whether plasma insulin clearance changes overnight, the diabetic patients were studied on two different occasions, from 22.00-02.30 hours and from 04.00-08.30 hours. During each of these two studies insulin was infused in sequential steps of 90 min each at the rate of 0.13, 0.40 and 0.20 mU X kg-1 X min-1. Despite changes in plasma free insulin concentration, the metabolic clearance of insulin in the interval 22.00-02.30 hours (12.6 +/- 0.17 ml X kg-1 X min-1) was no different from that of the interval 04.00-08.30 hours (12.5 +/- 0.19 ml X kg-1 X min-1). The nondiabetic subjects were studied on two different occasions to assess whether the metabolic clearance of insulin changes overnight. Somatostatin (0.25 mg/h) and insulin (0.3 mU X kg-1 X min-1) were infused from 22.00-02.30 hours on one occasion, and from 04.00-08.30 hours on the other.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure and efficacy of insulin therapy in insulin dependent (type I) diabetic patients

In order to determine the degree of metabolic control (HbA1c [normal less than 5.8%], mean blood glucose [MBG], glucosuria and lipids) and the prevalence of late diabetic complications in insulin-dependent diabetic patients treated by conventional insulin therapy both patients of a diabetes center (DC: n = 130; age 37.1 +/- 1.4 years) and a rural area (RA: n = 73; age 38.4 +/- 2.4 years) were examined within their local setting. Eighty such insulin-dependent diabetic patients were also taught a technique of near normal glycemic insulin substitution (NIS), which separates basal from prandial insulin replacement and instructs the patients to immediately correct self-controlled (3.8 +/- 0.1/day) aberrant blood glucose values. None of the groups on conventional insulin therapy was able to achieve satisfactory metabolic control or to avoid late diabetic complications, but rural patients were even worse off (BG 240 +/- 10 mg/dl; HbA1c 8.7 +/- 0.2% [normal: 3/73 = 4%]) than those of the DC (MBG 191 +/- 5 mg/dl; HbA1c 7.1 +/- 0.2% [normal: 27/130 = 21%]), while the prevalence of late diabetic complications was almost identical (RA/DC: neuropathy 22%/25%; retinopathy 41%/38%; macroangiopathy 15%/13%; but proteinuria 14%/5.4%). Metabolic control was improved by NIS with twice daily injections of basal (long acting) and separately of prandial (regular) insulin (total: 4.8 +/- 0.1 injections/day; MBG 130 +/- 2 mg/dl; HbA1c 5.8 +/- 0.1% [normal: 41/80 = 51%]. We conclude (1) that conventional insulin therapy just prevents metabolic catastrophe but in more than 79% of insulin-dependent diabetic patients lacks the ability to provide good metabolic control, while (2) NIS, a more physiological form of insulin therapy, improves this deplorable situation 5- to 12.4-fold.