Single-chain Insulin Research Articles

811-P: Initiation of Once-Weekly (QW) Basal Insulin Fc (BIF) in Three Patient Populations in Phase 2 Studies Using a One-Time Loading Dose (LD) Minimizes Transient Hyperglycemia and Is Not Associated with Excess Hypoglycemia Risk vs. Degludec

BIF is a fusion protein combining a novel single chain insulin variant with a human IgG Fc domain. The safety population from 3 randomized, open-label, phase 2 treat-to-target studies included 942 people with T2D previously treated with basal insulin (T2D-Switch) or new to insulin therapy (T2D-Naïve), or with T1D on multiple daily injections (T1D). QW BIF was compared to once daily (OD) DEG for 26 or 32 wks. Given BIF's slow accumulation and extended PK profile, initiation of or transition from prior OD basal insulin to BIF was managed by “boosting” initial exposure with a one-time ~ 3-fold LD strategy to achieve therapeutic concentration more quickly. In the absence of a definitive mg to unit conversion factor, determination of the starting QW dose differed by study and was based on PK/PD modelling and individual patient characteristics. Fasting glucose and patient reported hypoglycemia <70 mg/dL were compared during the first 6 wks of treatment and showed no clinically significant differences between treatments (Table). T2D-Switch and T1D studies included CGM and data during first 6 wks of the study were reviewed; no severe hypoglycemia was reported during this time. These data suggest that the BIF LD strategy is safe and effective in reducing transient hyperglycemia, especially in T2D. Disclosure J.M.Bue-valleskey: Employee; Eli Lilly and Company. C.M.Kazda: Employee; Eli Lilly and Company. Q.Zhang: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. A.Haupt: Employee; Lilly, Stock/Shareholder; Lilly. D.Dahl: Research Support; Lilly, Novo Nordisk, Eli Lilly and Company, Boehringer Ingelheim Inc., Amgen Inc. J.P.Frias: Advisory Panel; Becton, Dickinson and Company, Pfizer Inc., Sanofi, Consultant; Akero Therapeutics, Inc., 89bio, Inc., Aimmune, Boehringer Ingelheim Inc., Eli Lilly and Company, Carmot Therapeutics, Inc., Echosens, Merck & Co., Inc., Metacrine, Inc., Novo Nordisk, Pfizer Inc., Sanofi, Employee; Ionis Pharmaceuticals, Research Support; Akero Therapeutics, Inc., 89bio, Inc., Altimmune, Axcella Health Inc., Boehringer Ingelheim Inc., Eli Lilly and Company, Intercept Pharmaceuticals, Inc., Carmot Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Madrigal Pharmaceuticals, Inc., Merck & Co., Inc., Metacrine, Inc., Novo Nordisk, Oramed Pharmaceuticals, Novartis, Pfizer Inc., Sanofi, Speaker's Bureau; Eli Lilly and Company, Sanofi. Funding Eli Lilly and Company

806-P: Once Weekly (QW) Basal Insulin Fc (BIF) and Daily Degludec (DEG) Achieve Comparable Glycemic Control in Three Patient Populations Studied during Phase 2—Clinical Insights from CGM Assessments

BIF is a fusion protein combining a novel single chain insulin variant with a human IgG Fc domain. Three randomized, open-label, treat-to-target phase 2 studies of 26 or 32 week duration assessed 912 people with T2D previously treated with basal insulin (T2D-Switch) or new to insulin therapy (T2D-Naïve), or T1D on multiple daily injections (T1D). Studies assessed QW BIF vs once daily DEG. Key results were previously disclosed and met the primary endpoint of non-inferiority in HbA1c change from baseline (non-inferiority margin=0.4%). Two studies had CGM during entire study and T2D-Naïve had blinded, intermittent CGM using 14-day sessions. Patients had baseline HbA1c of 8.1, 8.0, and 7.5% for T2D-Switch, T2D-Naïve, and T1D respectively. Figure shows average hourly mean glucose at endpoint and time in range (inset). Glucose profiles appeared comparable between treatments with 24-hour average glucose for BIF vs DEG in T2D-Naïve: 137 vs 127 mg/dL p=.042 and T1D: 175 vs 169 p=.075 (T2D-Switch not available). Average duration of hypoglycemia, <70mg/dL (min) per patient for BIF vs DEG: T2D-Switch 31 vs 35 p=NS, T2D-Naïve 51 vs 91 p<.001, and T1D 35 vs 35 p=NS. QW BIF achieved similar glycemic control vs DEG as seen in several CGM derived measures providing useful and reassuring insights into the use of QW BIF in these patient populations. Disclosure C.M.Kazda: Employee; Eli Lilly and Company. J.M.Bue-valleskey: Employee; Eli Lilly and Company. Q.Zhang: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. A.Haupt: Employee; Lilly, Stock/Shareholder; Lilly. J.P.Frias: Advisory Panel; Becton, Dickinson and Company, Pfizer Inc., Sanofi, Consultant; Akero Therapeutics, Inc., 89bio, Inc., Aimmune, Boehringer Ingelheim Inc., Eli Lilly and Company, Carmot Therapeutics, Inc., Echosens, Merck & Co., Inc., Metacrine, Inc., Novo Nordisk, Pfizer Inc., Sanofi, Employee; Ionis Pharmaceuticals, Research Support; Akero Therapeutics, Inc., 89bio, Inc., Altimmune, Axcella Health Inc., Boehringer Ingelheim Inc., Eli Lilly and Company, Intercept Pharmaceuticals, Inc., Carmot Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Madrigal Pharmaceuticals, Inc., Merck & Co., Inc., Metacrine, Inc., Novo Nordisk, Oramed Pharmaceuticals, Novartis, Pfizer Inc., Sanofi, Speaker's Bureau; Eli Lilly and Company, Sanofi. D.Dahl: Research Support; Lilly, Novo Nordisk, Eli Lilly and Company, Boehringer Ingelheim Inc., Amgen Inc. Funding Eli Lilly and Company

Safety and efficacy of once-weekly basal insulin Fc in people with type 2 diabetes previously treated with basal insulin: a multicentre, open-label, randomised, phase 2 study

The burden of daily basal insulins often causes hesitancy and delays in the initiation of insulin therapy. Basal insulin Fc (BIF, insulin efsitora alfa), designed for once-weekly administration, is a fusion protein combining a novel single-chain insulin variant with a human immunoglobulin G (IgG) Fc domain. In this study, we explored the safety and efficacy of BIF in people with type 2 diabetes who had been previously treated with basal insulin. For this phase 2, 44-site (clinical research centres and hospitals), randomised, open-label, comparator-controlled, 32-week study in the USA, Puerto Rico, and Mexico, we enrolled participants with type 2 diabetes. Eligible participants had to be adults (aged ≥18 years) and to have been treated with basal insulin and up to three oral antidiabetic medicines. Participants were randomly assigned (1:1:1) to subcutaneous administration of BIF (BIF treatment group 1 [BIF-A1] or 2 [BIF-A2]) or insulin degludec. Randomisation was stratified by country, baseline HbA1c values (<8·5% or ≥8·5%; <69·4 or ≥69·4 mmol/mol), use of sulfonylureas (yes or no), and baseline BMI (<30 or ≥30 kg/m2). The randomisation scheme was performed using an interactive web-response system, which ensured balance between treatment groups. Different fasting glucose targets for the BIF-A1 (≤7·8 mmol/L or ≤140 mg/dL; titrated every 2 weeks), BIF-A2 (≤6·7 mmol/L or ≤120 mg/dL; titrated every 4 weeks), and degludec (≤5·6 mmol/L or ≤100 mg/dL) groups were selected. Patients randomly assigned to BIF received a one-time loading dose ranging from 1·5-3 times their calculated weekly dose. The first weekly dose was administered 1 week after the loading dose. We used interstitial fasting glucose measurements from the Dexcom G6 continuous glucose monitoring system to titrate the basal insulin. The primary measure of glycaemic control was change in HbA1c from baseline to week 32 for BIF. BIF was also compared with degludec (with a non-inferiority margin of 0·40%). The efficacy analysis set consisted of data from all randomised study participants who received at least one dose of the study medication and participants were analysed according to the treatment they were assigned. The safety population was the same as the efficacy analysis set. The completed trial is registered at ClinicalTrials.gov (NCT03736785). Between Nov 15, 2018 and Feb 18, 2020, 399 participants were enrolled and randomised to BIF-A1 (n=135), BIF-A2 (n=132), or degludec (n=132); 202 (51%) were female and 197 (49%) were male. 379 were analysed for the primary outcome (BIF-A1: n=130; BIF-A2: n=125; degludec: n=124). Mean HbA1c change from baseline to week 32, the primary outcome, was -0·6% (SE 0·1%) for BIF-A1 and BIF-A2. Degludec achieved a change from baseline of -0·7% (0·1%). The pooled BIF analysis achieved non-inferiority versus degludec for the treatment difference in HbA1c (0·1% [90% CI -0·1 to 0·3]). The hypoglycaemia (≤3·9 mmol/L or ≤70 mg/dL) event rates (hypoglycaemia events per patient per year) in the BIF groups were 25% lower than those in the degludec group (treatment ratio BIF-A1 vs degludec was 0·75 [0·61-0·93]; and BIF-A2 vs degludec was 0·74 [0·58-0·94]). BIF was well tolerated; treatment-emergent adverse events were similar across groups. Weekly BIF achieved a similar efficacy compared with degludec despite higher fasting glucose targets in the BIF groups. Higher fasting glucose targets and lower glucose variability might have contributed to lower hypoglycaemia rates for BIF compared with degludec. These findings support continued development of BIF as a once-weekly insulin treatment for people with diabetes. Eli Lilly and Company.

Oral delivery of bi-autoantigens by bacterium-like particles (BLPs) against autoimmune diabetes in NOD mice

Induction of oral tolerance by vaccination with type 1 diabetes mellitus (T1DM)-associated autoantigens exhibits great potential in preventing and treating this autoimmune disease. However, antigen degradation in the gastrointestinal tract (GIT) limits the delivery efficiency of oral antigens. Previously, bacterium-like particles (BLPs) have been used to deliver a single-chain insulin (SCI-59) analog (BLPs-SCI-59) or the intracellular domain of insulinoma-associated protein 2 (IA-2ic) (BLPs-IA-2ic). Both monovalent BLPs vaccines can suppress T1DM in NOD mice by stimulating the corresponding antigen-specific oral tolerance, respectively. Here, we constructed two bivalent BLPs vaccines which simultaneously deliver SCI-59 and IA-2ic (Bivalent vaccine-mix or Bivalent vaccine-SA), and evaluated whether there is an additive beneficial effect on tolerance induction and suppression of T1DM by treatment with BLPs-delivered bi-autoantigens. Compared to the monovalent BLPs vaccines, oral administration of the Bivalent vaccine-mix could significantly reduce morbidity and mortality in T1DM. Treatment with the bivalent BLPs vaccines (especially Bivalent vaccine-mix) endowed the mice with a stronger ability to regulate blood glucose and protect the integrity and function of pancreatic islets than the monovalent BLPs vaccines treatment. This additive effect of BLPs-delivered bi-autoantigens on T1DM prevention may be related to that SCI-59- and IA-2-specific Th2-like immune responses could be induced, which was more beneficial for the correction of Th1/Th2 imbalance. In addition, more CD4+CD25+Foxp3+ regulatory T cells (Tregs) were induced by treatment with the bivalent BLPs vaccines than did the monovalent BLPs vaccines. Therefore, multiple autoantigens delivered by BLPs maybe a promising strategy to prevent T1DM by efficiently inducing antigen-specific immune tolerance.

Pharmacokinetic and pharmacodynamic properties of the novel basal insulin Fc (insulin efsitora alfa), an insulin fusion protein in development for once-weekly dosing for the treatment of patients with diabetes.

To assess the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of basal insulin Fc (BIF; LY3209590), a fusion protein combining a novel single-chain insulin variant together with human IgG2 Fc domain, following single and multiple once-weekly BIF administration. The single ascending dose, 15-day study assessed four BIF doses (5-35 mg) in healthy participants and people with type 2 diabetes (T2D). In the 6-week multiple ascending dose study, people with T2D, previously treated with basal insulin, received insulin glargine daily or a one-time loading dose of BIF followed by 5 weeks of once-weekly dosing (1-10mg). Safety, tolerability and PK and glucose PD were examined. Mean ages of people with T2D (N= 57) and healthy participants (N= 16) in the single-dose study were 58.4 and 35.8 years, respectively; mean body mass index values were 29.5 and 26.1kg/m2 . BIF had a PK half-life of approximately 17 days, which led to a sustained, dose-dependent decrease in fasting blood glucose for 5 days or longer. No severe hypoglycaemia was observed. The 6-week ascending dose study included 33 people with T2D aged 40-69 years. BIF showed a low peak-to-trough ratio of 1.14 after the last dose at week 6 (steady state). Over 6 weeks, BIF seven-point glucose profiles remained constant and were similar to insulin glargine. Rates and duration of BIF hypoglycaemic events were similar to insulin glargine. BIF was well tolerated and the PK/PD profile enabled once-weekly dosing with minimal variation in exposure in a treatment interval of 1week. The findings suggest BIF is suitable for further development as a weekly basal insulin in people with diabetes.

RF04 | PSUN233 Design of an Ultra-Stable Insulin/Glucagon Fusion Protein

Abstract Insulin replacement therapy is lifesaving for insulin-dependent diabetic patients, but it comes with an ever-present threat of hypoglycemia, which can eventually cause ischemic events, arrhythmias, neurological damage, coma, or even death. Consequently, the risk of hypoglycemia remains the most significant obstacle that prevents insulin-dependent patients from attaining adequate metabolic control. One approach to solve this issue involves the co-injection of insulin and glucagon at a fixed ratio, which has been shown to improve glycemic control with prevention of hypoglycemia. The co-administration of both hormones is based on two known physiological processes: first, insulin is a potent inhibitor of glucagon activity, especially under hyperglycemic conditions, and second, glucagon overpowers insulin and stimulates hepatic glucose production under hypoglycemic circumstances. In this work, we took this concept further into developing an insulin/glucagon fusion protein that will provide glycemic control (by the insulin portion) while preventing hypoglycemia (through the glucagon portion). Because both hormones are known to be unstable and form amyloid-like fibrils, our approach consists of using a fibrillation-resistant single-chain insulin (SCI) analog fused to a novel fibrillation-resistant glucagon analog. These molecules were independently synthesized by Solid-Phase Peptide Synthesis (SPPS) and linked together from the C-Terminus of the glucagon analog to the N-Terminus of the SCI analog by trypsin-mediated ligation. By themselves or when fused, these ultra-stable analogs didn't form fibrils after one month of agitation at 37°C in PBS (pH 7.4). By contrast, native insulin started fibrillation at 12.14 ± 3.65 hours, and native glucagon at time 0. The glucagon analog was designed to be less potent than the native molecule to allow unopposed insulin activity while in hyperglycemia but maintaining full agonism to prevent hypoglycemia. The in vitro glucagon activity was measured by cAMP production in HEK293 expressing the glucagon receptor. The glucagon analog was determined to be a full agonist with an EC50 of 125.7 nM, a ∼58-fold potency difference to the native molecule (2.175 nM). The fusion protein was tested in vitro and in vivo to determine the activities of both moieties when fused. The in vitro insulin activity of the fusion protein measured by traditional and in-cell western blot was comparable to the SCI alone. The in vitro glucagon activity of the fusion protein was also similar to the glucagon analog alone (EC50 151.2 nM), therefore validating our fusion approach. The in vivo insulin and glucagon activities are currently being tested by subcutaneous injection in diabetic (STZ) and normal rats. So far, both insulin and glucagon moieties have shown to be fully active, and hypoglycemia has not been observed in rats. Increasing doses studies are underway. We believe that this approach will allow the design of next-generation insulin treatments protected against hypoglycemia, ultra-stable, and amenable for multiplatform delivery. Presentation: Saturday, June 11, 2022 1:54 p.m. - 1:59 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Single-chain insulin analogs threaded by the insulin receptor αCT domain

Insulin is a mainstay of therapy for diabetes mellitus, yet its thermal stability complicates global transportation and storage. Cold-chain transport, coupled with optimized formulation and materials, prevents to some degree nucleation of amyloid and hence inactivation of hormonal activity. These issues hence motivate the design of analogs with increased stability, with a promising approach being single-chain insulins (SCIs), whose C domains (foreshortened relative to proinsulin) resemble those of the single-chain growth factors (IGFs). We have previously demonstrated that optimized SCIs can exhibit native-like hormonal activity with enhanced thermal stability and marked resistance to fibrillation. Here, we describe the crystal structure of an ultrastable SCI (C-domain length 6; sequence EEGPRR) bound to modules of the insulin receptor (IR) ectodomain (N-terminal α-subunit domains L1-CR and C-terminal αCT peptide; “microreceptor” [μIR]). The structure of the SCI-μIR complex, stabilized by an Fv module, was determined using diffraction data to a resolution of 2.6 Å. Remarkably, the αCT peptide (IR-A isoform) “threads” through a gap between the flexible C domain and the insulin core. To explore such threading, we undertook molecular dynamics simulations to 1) compare threaded with unthreaded binding modes and 2) evaluate effects of C-domain length on these alternate modes. The simulations (employing both conventional and enhanced sampling simulations) provide evidence that very short linkers (C-domain length of −1) would limit gap opening in the SCI and so impair threading. We envisage that analogous threading occurs in the intact SCI-IR complex—rationalizing why minimal C-domain lengths block complete activity—and might be exploited to design novel receptor-isoform-specific analogs.

215-OR: Once Weekly (QW) Basal Insulin Fc (BIF) Demonstrated Similar Glycemic Control to Once Daily (QD) Insulin Degludec (DEG) in Insulin-Naïve Patients with Type 2 Diabetes (T2D)

Basal Insulin Fc (BIF; LY3209590) , a fusion protein combining a novel single-chain insulin variant with a human IgG Fc domain, is designed for QW administration. This randomized, parallel, open-label Ph2 study assessed safety and efficacy of BIF vs. DEG in insulin-naïve patients with T2D previously treated with oral antihyperglycemic medication. BIF was injected QW, and DEG was injected QD. Both groups were titrated to fasting blood glucose (FBG) ≤100 mg/dL. The primary endpoint was HbA1c change from baseline (CFBL) to Wk 26 (non-inferiority margin=0.4%) . Patients randomized to BIF (N=129) and DEG (N=135) had a mean age of 58.4 yrs and baseline HbA1c of 8.0%. After 26 wks, BIF showed non-inferiority vs. DEG for HbA1c CFBL with a treatment difference of 0.06% (90% CI = -0.11, 0.24; p = .56) , and both groups had &amp;gt;75% time in range (70-180 mg/dL) on average at Wk 26 (Figure) . BIF and DEG significantly reduced FBG from baseline (treatment difference BIF vs. DEG = 4.7 mg/dL [90% CI = 0.1, 9.3]; p = .09) . Rate of Level 2 hypoglycemia was low and not significantly different (BIF = 0.22; DEG = 0.15 events/pt/yr; p = 0.64) . Occurrence of treatment-emergent adverse events was similar between BIF and DEG. QW BIF achieved excellent glycemic control similar to DEG with no concerning hypoglycemia or other safety findings, supporting continued development of BIF in Ph3. Disclosure J.M. Bue-Valleskey: None. C.M. Kazda: Employee; Eli Lilly and Company. Stock/Shareholder; Eli Lilly and Company. C. Ma: None. J. Chien: Employee; Eli Lilly and Company. Q. Zhang: Employee; Eli Lilly and Company. Stock/Shareholder; Eli Lilly and Company. E. Chigutsa: Employee; Eli Lilly and Company. W. Landschulz: Employee; Eli Lilly and Company. J. Swan: Employee; Eli Lilly and Company. A. Haupt: Employee; Lilly. Stock/Shareholder; Lilly. J. Frias: Advisory Panel; Altimmune, Becton, Dickinson and Company, Eli Lilly and Company, Gilead Sciences, Inc., Intercept Pharmaceuticals, Inc., Merck &amp; Co., Inc., Sanofi. Consultant; 89bio, Inc., Akero Therapeutics, Inc., Altimmune, Becton, Dickinson and Company, Carmot Therapeutics, Inc., Eli Lilly and Company, Novo Nordisk, Pfizer Inc., Sanofi. Research Support; Afimmune Limited, Akero Therapeutics, Inc., AstraZeneca, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb Company, Carmot Therapeutics, Inc., Eli Lilly and Company, Intercept Pharmaceuticals, Inc., Ionis Pharmaceuticals, Janssen Pharmaceuticals, Inc., Madrigal Pharmaceuticals, Inc., Merck &amp; Co., Inc., Novartis Pharmaceuticals Corporation, Novo Nordisk, Pfizer Inc., Poxel SA, Sanofi. Speaker's Bureau; Eli Lilly and Company, Merck &amp; Co., Inc., Novo Nordisk, Sanofi. Funding Funded by Eli Lilly and Company.

734-P: Cellular Internalization and Localization of Once-Weekly Basal Insulin Fc (BIF)

Basal Insulin Fc (BIF, LY3209590) is an insulin Fc-fusion protein in clinical testing as a once weekly treatment for diabetes mellitus. BIF is comprised of a human single-chain insulin fused to a human IgG2 Fc domain through a peptide linker. The cellular internalization characteristics of BIF compared to native insulin using U2OS cells expressing human insulin receptor (hIR) are reported in this work. Internalization and sub-cellular localization were visualized by immuno-fluorescent confocal microscopy in U2OS cells expressing human insulin receptor. Internalization of BIF was observed, and the insulin and Fc moieties remained co-localized. Co-localization studies using an antibody to the early endosomal marker Early Endosome Antigen 1 (EEA1) showed that human insulin and BIF (insulin and Fc moieties) were rapidly internalized and co-localized with EEA1. During ligand washout, the remaining insulin and Fc moieties of BIF remained largely co-localized with EEA1 and a concomitant loss of immunostaining was observed, similar to human insulin. Studies using an antibody to the lysosomal marker Lysosomal Associated Membrane Protein-1 (LAMP-1) revealed a low level of lysosomal localization for human insulin and BIF (insulin and Fc moieties), indicating a similar intracellular trafficking pattern of human insulin and BIF to the lysosomal degradative pathway. The co-localization of remaining ligand decreased over time. IR internalization and transport to early endosomes was measured using an enzyme complementation assay. The EC50 for BIF was 4.7 ± 2.1 nM (n = 3), and the EC50 for human insulin was 0.06 ± 0.01 nM (n = 3). In summary, BIF stimulated IR internalization to a similar maximum level; however, with decreased potency versus human insulin. The subcellular trafficking pattern of BIF is similar to human insulin. BIF undergoes rapid internalization and transport to early endosomes with limited transport to the lysosomes and undergoes loss of cellular immunostaining during ligand washout. Disclosure C. Volk: None. C. Zhang: Employee; Self; Eli Lilly and Company. J. S. Moyers: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. Funding Eli Lilly and Company

Preclinical Characterization of Once Weekly Basal Insulin Fc (BIF)

Weekly basal insulin injections may increase treatment adherence in subjects with diabetes and an appropriately engineered weekly basal insulin may reduce daily pharmacokinetic (PK)/pharmacodynamic (PD) fluctuations compared to currently available daily basal insulins. Therefore, a weekly insulin has the potential to not only ease the burden of insulin therapy, but also improve outcomes for subjects with diabetes in a real-world setting. Basal insulin Fc (BIF, LY3209590) is an insulin Fc-fusion protein in clinical testing as a once weekly treatment for type 1 and type 2 diabetes mellitus (T1DM, T2DM). BIF is comprised of a human single-chain insulin fused to a human IgG2 Fc domain through a peptide linker. The in vitro evaluation determined that BIF exhibited reduced insulin receptor (IR) potency with full agonism, selectivity against human insulin-like growth factor-1 receptor (hIGF-1R), and functional properties similar to native human insulin. The binding affinity of BIF for hIR isoform A, Ki = 25 nM (SEM = 4, n=10), and hIR isoform B, Ki = 26 nM (SEM = 4, n=10), was more than two orders of magnitude weaker than human insulin. BIF stimulated IR phosphorylation in cells with reduced potency, but full agonism, and showed a significantly faster hIR dephosphorylation profile than either human insulin or AspB10 insulin. BIF stimulated de novo lipogenesis in 3T3-L1 adipocytes and cell proliferation in SAOS-2 and H4IIE cells with at least a 70-fold reduction in potency compared to human insulin. BIF possessed markedly reduced binding and activation of hIGF-1R making definitive mitogenic measurements unattainable. In preclinical in vivo pharmacology studies using streptozotocin (STZ)-treated diabetic rats, a statistically significant decrease in blood glucose compared to vehicle-treated animals was seen 24 hours post-injection and persisted through 336 hours post-injection following a single subcutaneous administration (30 nmol/kg) of BIF. In STZ-treated rats, BIF reached a Tmax at 48 hours, possessed an apparent clearance rate of ~0.85 mL/hr/kg, and t1/2 of ~120 hrs. Collectively, these results demonstrate that BIF possesses selective IR agonism with a pharmacological profile similar to native insulin, however with a significantly reduced potency, and a significantly extended time action profile in preclinical animal models supporting once weekly testing in the clinic.

Buried Kex2 Sites in Glargine Precursor Aggregates Prevent Its Intracellular Processing in Pichia pastoris Muts Strains and the Effect of Methanol-Feeding Strategy and Induction Temperature on Glargine Precursor Production Parameters.

Glargine is a long-acting insulin analog with less hypoglycemia risk. Like human insulin, glargine is a globular protein composed of two polypeptide chains linked by two disulfide bonds. Pichia pastoris KM71 Muts strains were engineered to produce and secrete insulin glargine through the cleavage of two Kex2 sites. Nevertheless, the recombinant product was the single-chain insulin glargine (glargine precursor) instead of the expected double-chain glargine. Molecular model analysis of the dimeric and hexameric forms of the single-chain glargine showed buried Kex2 sites that prevent intracellular glargine precursor processing. The effect of the methanol-feeding strategy (methanol limited fed-batch vs. methanol non-limited fed-batch) and the induction temperature (28 °C vs. 24 °C) on the cell growth and production parameters in bioreactor cultures was also evaluated. Exponential growth at a constant specific growth rate was observed in all the cultures. The volumetric productivities and specific substrate consumption rates were directly proportional to the specific growth rate. The lower temperature led to increased metabolic activity of the yeast cells, which increased the specific growth rate. The methanol non-limited fed-batch culture at 24 °C showed the highest values for the process parameters. After 75 h of induction, 0.122 g/L of glargine precursor was obtained from the culture medium.

Insulin Fused to Apolipoprotein A-I Reduces Body Weight and Steatosis in DB/DB Mice.

Background: Targeting long-lasting insulins to the liver may improve metabolic alterations that are not corrected with current insulin replacement therapies. However, insulin is only able to promote lipogenesis but not to block gluconeogenesis in the insulin-resistant liver, exacerbating liver steatosis associated with diabetes. Methods: In order to overcome this limitation, we fused a single-chain insulin to apolipoprotein A-I, and we evaluated the pharmacokinetics and pharmacodynamics of this novel fusion protein in wild type mice and in db/db mice using both recombinant proteins and recombinant adenoassociated virus (AAV). Results: Here, we report that the fusion protein between single-chain insulin and apolipoprotein A-I prolonged the insulin half-life in circulation, and accumulated in the liver. We analyzed the long-term effect of these insulin fused to apolipoprotein A-I or insulin fused to albumin using AAVs in the db/db mouse model of diabetes, obesity, and liver steatosis. While AAV encoding insulin fused to albumin exacerbated liver steatosis in several mice, AAV encoding insulin fused to apolipoprotein A-I reduced liver steatosis. These results were confirmed upon daily subcutaneous administration of the recombinant insulin-apolipoprotein A-I fusion protein for six weeks. The reduced liver steatosis was associated with reduced body weight in mice treated with insulin fused to apolipoprotein A-I. Recombinant apolipoprotein A-I alone significantly reduces body weight and liver weight, indicating that the apolipoprotein A-I moiety is the main driver of these effects. Conclusion: The fusion protein of insulin and apolipoprotein A-I could be a promising insulin derivative for the treatment of diabetic patients with associated fatty liver disease.

Development of Insulin Sensors Based on Faradaic and Non-Faradaic Electrochemical Impedance Spectroscopy Detection Principle Using Single Chain Antibody (scFv)

IntroductionIn this paper, we report novel insulin sensors using insulin single-chain antibody (scFv) based on two electrochemical impedance spectroscopy (EIS) methods; faradaic EIS and non-faradaic EIS. For faradaic EIS measurement, varieties of molecular recognition elements (MREs) can be utilized, such as IgG and binding proteins, without consideration of their molecular size. However, a solubilized redox probe is necessary to aid the transfer of electrons and detection is based on the flux of electrons and the obstruction that is present on the electrode surface. Non-faradaic EIS does not require a solubilized redox probe and is based around changes within the electrical double layer. However, there are the limitation of the size for MREs, since the ideal size of MREs should be smaller than the size of electrical double layer (EDL). In this paper, thanks to the small size of scFv as MRE for EIS, we construct two different types of EIS based insulin sensors, and compare the suitability in the use for insulin monitoring, being dedicated for the management of diabetic patients.MethodsDevelopment of this sensor requires immobilization of a molecular recognition element (MRE) that binds with insulin. For this purpose, we have cultivated single-chain insulin antibody by transforming an Escherichia coli strain, harvesting and filtering the protein culture, and purifying the protein culture. Through this cultivation procedure, we obtained insulin scFv that can be immobilized on a gold surface electrode. For faradaic EIS measurement, we employed potassium ferricyanide as the solubilized redox probe to conduct insulin measurement. Binding of insulin concentrations with insulin scFv caused a change in electron flux, which thereby caused changes in charge-transfer resistance (Rct) or impedance. In non-faradaic EIS measurement, ionic liquid is typically used as the buffer to redistribute the dielectric bilayer. Thanks to the small size of insulin scFv, capacitance changes can be directly measured within EDL. Both detection principles were compared by selecting an optimized frequency which best reflects binding between insulin and the MRE.ResultsWe were able to identify an optimized frequency for both detection principles when measuring insulin, establishing a unique change in impedance. A change in Rct was noticed through faradaic EIS when measuring insulin against the insulin scFv. Additionally, at the optimized frequency the sensor had a slope of 701 Ohms/Ln(nM). With the non-Faradaic EIS detection principle, the sensor displayed changes within EDL.DiscussionWe were able to determine that faradaic and non-faradaic EIS could be used to measure changing insulin concentrations when using insulin scFv as the MRE. Differences between both detection principles existed due to the use of a solubilized redox probe for faradaic EIS versus the absence of it when conducing non-Faradaic EIS. Future work will include comparing the sensitivity and selectivity of both detection methods when measuring insulin.

Insulin and its single-chain analogue.

Insulin therapy remains the most effective method to treat diabetes mellitus (DM), and the demand for this valuable hormone has exceeded that of any other protein-based medicine as a result of the dramatic increase in the number of diabetic patients worldwide. Understanding the structure of insulin and the interaction with its receptor is important for developing proper formulations. As a result of the relatively low thermal stability of native insulin and its two-chain analogues, the application of single-chain insulin (SCI) analogues, which can be obtained relatively easily by recombinant DNA technology or chemical synthetic methods, represents a promising alternative approach. In this review, the basic knowledge of insulin (discovery, biosynthesis, and structure) and the current model of the interaction with its receptor are outlined. Furthermore, we outline the strategies for the design and production of various SCI analogues and their reported applications.

Oral delivery of single-chain insulin (SCI-59) analog by bacterium-like particles (BLPs) induces oral tolerance and prevents autoimmune diabetes in NOD mice

Oral tolerance, induced by oral administration of autoantigens, is a promising therapeutic approach to treat type 1 diabetes mellitus (T1DM). However, the degradation of antigens passing through the gastrointestinal tract (GIT) leads to low induction efficiency. Based on our previous study, a single-chain insulin (SCI-59) analog, bound to the surface of lactic acid bacteria (LAB) bacterium-like particles (BLPs), was more stable in the simulated gastric fluid, compared to free SCI-59 and insulin. Based on the analysis of diabetes progression, a significant decrease in the incidence of diabetes was observed in mice fed BLPs-SCI-59. Oral administration of BLPs-SCI-59 can enhance glucose tolerance in NOD mice and this effect may result from the protection of pancreatic islet beta cells, as compared to the free SCI-59 group and BLPs group. Oral administration of BLPs-SCI-59 can significantly reduce insulitis and preserve the ability of insulin secretion in treated mice. Oral vaccination with BLPs-SCI-59 induced SCI-59 specific T cell tolerance in treated mice, which may due to the repair of Th1/Th2 imbalance and increased CD4+CD25+FoxP3+ regulatory T cells (Tregs). These results show that oral vaccination with BLPs-SCI-59 is a promising way to prevent T1DM in NOD mice.

1086-P: Preclinical Development of an Ultralong-Acting Insulin for Once-Weekly Dosing

Basal insulin analogues have been designed to mimic endogenous insulin secretion for maintaining normoglycaemia. Current insulin therapy for type 2 diabetes (T2D) requires at least daily dosing for patients. However, such daily injections can have poor patient compliance. An insulin analogue with longer duration requiring less frequent administration could improve compliance and maintain better glycaemic control. To achieve extended insulin action pharmacology, a panel of recombinant native single chain (SC) insulin molecules, consisting of B chain to A chain-linker variants, were fused to an antibody fragment crystallizable region (Fc). Characterization of the single chain insulin-Fc (SC-Insulin-Fc) variants were conducted in insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF1R) luminescence-linked reporter assays, and with primary rodent and human hepatocyte assays for phosphorylated AKT. SC-Insulin-Fc-1 and -2 retained potency at the human IR within 6-fold of human insulin, without specificity over IGF1R binding, and induced Akt phosphorylation within a range of endogenous insulin. SC-Insulin-Fc variants lowered blood glucose levels in DIO and db/db mice by more than 50% vs. vehicle controls (p&amp;lt;0.05) for 5 days following a single dose, significantly superior to a standard insulin bolus. Continuous glucose monitoring (CGM) telemetry to profile 24 h control of blood glucose in diabetic ZDF rats was also applied. CGM telemetry revealed enhanced basal and postprandial glucose control in both light and dark cycles (p&amp;lt;0.05 vs. vehicle) up to 10 days following a single administration (90 nmol/kg). Repeat dosing of SC-Insulin-Fc variants (10/30/60 nmol/kg, Q1W) over 5 weeks resulted in dose-dependent improvements of glycaemic control (p≤0.05 vs. vehicle) with a long term readout towards decreasing %HbA1c. This dramatic shift in time spent away from hyperglycaemia toward normoglycaemia suggests once-weekly insulin as a novel viable option to treat human T2D. Disclosure V.G. Howard: Employee; Self; AstraZeneca. Stock/Shareholder; Self; AstraZeneca. C.D. Church: Employee; Self; AstraZeneca, MedImmune. S. Oldham: Employee; Self; AstraZeneca. Stock/Shareholder; Self; AstraZeneca. D.C. Hornigold: Employee; Self; AstraZeneca. Stock/Shareholder; Self; AstraZeneca. J. Trevaskis: Employee; Self; Gilead Sciences, Inc., MedImmune. Stock/Shareholder; Self; AstraZeneca. D. Baker: Stock/Shareholder; Self; AstraZeneca. C.J. Rhodes: Employee; Self; AstraZeneca, MedImmune. A. Rossi: Employee; Self; MedImmune. J. Naylor: Employee; Self; MedImmune. Stock/Shareholder; Self; AstraZeneca. J. Dhillon: Employee; Self; MedImmune. A. Buchanan: Employee; Self; MedImmune. L. Liang: None.

Display of Single-Chain Insulin-like Peptides on a Yeast Surface.

Insulin and insulin-like peptides play a pivotal role in a wide variety of cellular and physiological events, including energy storage, proliferation, aging, and differentiation. Variants of insulin and insulin-like peptides may therefore be probes for studying the insulin signaling pathway and therapeutic candidates for treating metabolic diseases. Here, we report a method for genetically displaying single-chain insulin-like peptides on the surface of Saccharomyces cerevisiae strain DY1632. Using a previously reported single-chain insulin analogue, SCI-57, as a model, we demonstrate that nearly 70% of yeast binds to insulin receptor (IR), suggesting that SCI-57 is folded correctly and maintains its IR binding property. Furthermore, the interaction between displayed SCI-57 and IR can be weakened using increasing concentrations of native insulin as a soluble competitor, suggesting that the interaction is insulin-dependent. We further applied this methodology to three other single-chain insulin analogues with various lengths and confirmed their interactions with IR. In summary, we successfully displayed a number of insulin-like peptides on a yeast surface and demonstrated insulin-dependent interactions with IR. This method may, therefore, be used for construction of libraries of insulin-like peptides to select for chemical probes or therapeutic molecules.

The Design of SCI‐57: An Ultrastable, Rapid‐acting, Single‐chain Insulin Analog

There are approximately 415 million people with Diabetes Mellitus worldwide and there exists a growing need for an ultrastable, heat resistant formulation of rapid‐acting insulin to treat the millions of people who live in developing countries where temperatures routinely exceed 45ºC. The heat resistance and stability of insulin is especially crucial due to the fact that insulin degrades ten times faster for every 10°C increase in temperature above 25°C. Several rapid‐acting insulin analogs have been created, though most do not last longer than 30 days and are reliant on the expensive cold chain delivery system of insulin analogs. This is due to chemical and physical degradation by way of deamidation, transamidation and cross‐beta assembly of linear polymers, or fibrillation. Rapid‐acting analogs must also combat the formation of the inactive hexameric formulation of insulin due to the presence of zinc and an excess of hydrogen ions. A single‐chain insulin analog has been created called SCI‐57 which consists of a glycine rich peptide (6 residues in length) that connects the A and B chains of the insulin analog. Adding a peptide tether will restrict splaying of the A and B chains, thus decreasing the risk of fibrillation even under high temperatures. To ensure that the analog is rapid‐acting and will not form storage hexamers, SCI‐57 has replaced ThrA8 with His to omit an unfavorable beta‐branched amino acid and HisB10 with Asp to create a more favorable relationship with the electrostatic dipole of the B‐chain alpha helix. Replacing HisB10 with Asp also blocks zinc binding, furthermore ensuring that the analog in its active, monomeric state. Both of these actions triple the activity of two‐chain analogs which will also benefit SCI‐57 by allowing it to bind quickly to the insulin receptor. Furthermore, SCI‐57 is much more resistant to fibrillation under high temperatures than previous analogs and maintains insulin receptor affinity as well as efficiency. The Nueva School MSOE Center for Biomolecular Modeling MAPS Team used 3‐D modeling and printing technology to examine structure‐function relationships of SCI‐57.Primary Citation:Hua, Qing‐xin, et al. “Design of an Active Ultrastable Single‐Chain Insulin Analog: SYNTHESIS, STRUCTURE, AND THERAPEUTIC IMPLICATIONS.” The Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 23 May 2008This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Solution structure of an ultra-stable single-chain insulin analog connects protein dynamics to a novel mechanism of receptor binding

Domain-minimized insulin receptors (IRs) have enabled crystallographic analysis of insulin-bound "micro-receptors." In such structures, the C-terminal segment of the insulin B chain inserts between conserved IR domains, unmasking an invariant receptor-binding surface that spans both insulin A and B chains. This "open" conformation not only rationalizes the inactivity of single-chain insulin (SCI) analogs (in which the A and B chains are directly linked), but also suggests that connecting (C) domains of sufficient length will bind the IR. Here, we report the high-resolution solution structure and dynamics of such an active SCI. The hormone's closed-to-open transition is foreshadowed by segmental flexibility in the native state as probed by heteronuclear NMR spectroscopy and multiple conformer simulations of crystallographic protomers as described in the companion article. We propose a model of the SCI's IR-bound state based on molecular-dynamics simulations of a micro-receptor complex. In this model, a loop defined by the SCI's B and C domains encircles the C-terminal segment of the IR α-subunit. This binding mode predicts a conformational transition between an ultra-stable closed state (in the free hormone) and an active open state (on receptor binding). Optimization of this switch within an ultra-stable SCI promises to circumvent insulin's complex global cold chain. The analog's biphasic activity, which serendipitously resembles current premixed formulations of soluble insulin and microcrystalline suspension, may be of particular utility in the developing world.

An ultra-stable single-chain insulin analog resists thermal inactivation and exhibits biological signaling duration equivalent to the native protein

Thermal degradation of insulin complicates its delivery and use. Previous efforts to engineer ultra-stable analogs were confounded by prolonged cellular signaling in vivo, of unclear safety and complicating mealtime therapy. We therefore sought an ultra-stable analog whose potency and duration of action on intravenous bolus injection in diabetic rats are indistinguishable from wild-type (WT) insulin. Here, we describe the structure, function, and stability of such an analog, a 57-residue single-chain insulin (SCI) with multiple acidic substitutions. Cell-based studies revealed native-like signaling properties with negligible mitogenic activity. Its crystal structure, determined as a novel zinc-free hexamer at 2.8 Å, revealed a native insulin fold with incomplete or absent electron density in the C domain; complementary NMR studies are described in the accompanying article. The stability of the analog (ΔGU 5.0(±0.1) kcal/mol at 25 °C) was greater than that of WT insulin (3.3(±0.1) kcal/mol). On gentle agitation, the SCI retained full activity for >140 days at 45 °C and >48 h at 75 °C. These findings indicate that marked resistance to thermal inactivation in vitro is compatible with native duration of activity in vivo Further, whereas WT insulin forms large and heterogeneous aggregates above the standard 0.6 mm pharmaceutical strength, perturbing the pharmacokinetic properties of concentrated formulations, dynamic light scattering, and size-exclusion chromatography revealed only limited SCI self-assembly and aggregation in the concentration range 1-7 mm Such a combination of favorable biophysical and biological properties suggests that SCIs could provide a global therapeutic platform without a cold chain.