Steven D. Kahl

pI-shifted insulin analogs with extended in vivo time action and favorable receptor selectivity

A long-acting (basal) insulin capable of delivering flat, sustained, reproducible glycemic control with once daily administration represents an improvement in the treatment paradigm for both type 1 and type 2 diabetes. Optimization of insulin pharmacodynamics is achievable through structural modification, but often at the expense of alterations in receptor affinity and selectivity. A series of isoelectric point (pI)-shifted insulin analogs based on the human insulin sequence or the GlyA21 acid stable variant were prepared by semi-synthetic methods. The pI shift was achieved through systematic addition of one or more arginine (Arg) or lysine (Lys) residues at the N terminus of the A chain, the N terminus of the B chain, the C terminus of the B chain, or through a combination of additions at two of the three sites. The analogs were evaluated for their affinity for the insulin and IGF-1 receptors, and aqueous solubility under physiological pH conditions. Notably, the presence of positively charged amino acid residues at the N terminus of the A chain was consistently associated with an enhanced insulin to IGF-1 receptor selectivity profile. Increased IGF-1 receptor affinity that results from Arg addition to the C terminus of the B chain was attenuated by cationic extension at the N terminus of the A chain. Analogs 10, 17, and 18 displayed in vitro receptor selectivity similar to that of native insulin and solubility at physiological pH that suggested the potential for extended time action. Accordingly, the in vivo pharmacokinetic and pharmacodynamic profiles of these analogs were established in a somatostatin-induced diabetic dog model. Analog 18 (A0:Arg, A21:Gly, B31:Arg, B32:Arg human insulin) exhibited a pharmacological profile comparable to that of analog 15 (insulin glargine) but with a 4.5-fold more favorable insulin:IGF-1 receptor selectivity. These results demonstrate that the selective combination of positive charge to the N terminus of the A chain and the C terminus of the B chain generates an insulin with sustained pharmacology and a near-native receptor selectivity profile.

LY2456302 is a novel, potent, orally-bioavailable small molecule kappa-selective antagonist with activity in animal models predictive of efficacy in mood and addictive disorders

Kappa opioid receptors and their endogenous neuropeptide ligand, dynorphin A, are densely localized in limbic and cortical areas comprising the brain reward system, and appear to play a key role in modulating stress and mood. Growing literature indicates that kappa receptor antagonists may be beneficial in the treatment of mood and addictive disorders. However, existing literature on kappa receptor antagonists has used extensively JDTic and nor-BNI which exhibit long-lasting pharmacokinetic properties that complicate experimental design and interpretation of results. Herein, we report for the first time the in vitro and in vivo pharmacological profile of a novel, potent kappa opioid receptor antagonist with excellent selectivity over other receptors and markedly improved drug-like properties over existing research tools. LY2456302 exhibits canonical pharmacokinetic properties that are favorable for clinical development, with rapid absorption (t(max): 1-2 h) and good oral bioavailability (F = 25%). Oral LY2456302 administration selectively and potently occupied central kappa opioid receptors in vivo (ED₅₀ = 0.33 mg/kg), without evidence of mu or delta receptor occupancy at doses up to 30 mg/kg. LY2456302 potently blocked kappa-agonist-mediated analgesia and disruption of prepulse inhibition, without affecting mu-agonist-mediated effects at doses >30-fold higher. Importantly, LY2456302 did not block kappa-agonist-induced analgesia one week after administration, indicating lack of long-lasting pharmacodynamic effects. In contrast to the nonselective opioid antagonist naltrexone, LY2456302 produced antidepressant-like effects in the mouse forced swim test and enhanced the effects of imipramine and citalopram. LY2456302 reduced ethanol self-administration in alcohol-preferring (P) rats and, unlike naltrexone, did not exhibit significant tolerance upon 4 days of repeated dosing. LY2456302 is a centrally-penetrant, potent, kappa-selective antagonist with pharmacokinetic properties favorable for clinical development and activity in animal models predictive of efficacy in mood and addictive disorders.

The Discovery, Preclinical, and Early Clinical Development of Potent and Selective GPR40 Agonists for the Treatment of Type 2 Diabetes Mellitus (LY2881835, LY2922083, and LY2922470)

The G protein-coupled receptor 40 (GPR40) also known as free fatty acid receptor 1 (FFAR1) is highly expressed in pancreatic, islet β-cells and responds to endogenous fatty acids, resulting in amplification of insulin secretion only in the presence of elevated glucose levels. Hypothesis driven structural modifications to endogenous FFAs, focused on breaking planarity and reducing lipophilicity, led to the identification of spiropiperidine and tetrahydroquinoline acid derivatives as GPR40 agonists with unique pharmacology, selectivity, and pharmacokinetic properties. Compounds 1 (LY2881835), 2 (LY2922083), and 3 (LY2922470) demonstrated potent, efficacious, and durable dose-dependent reductions in glucose levels along with significant increases in insulin and GLP-1 secretion during preclinical testing. A clinical study with 3 administered to subjects with T2DM provided proof of concept of 3 as a potential glucose-lowering therapy. This manuscript summarizes the scientific rationale, medicinal chemistry, preclinical, and early development data of this new class of GPR40 agonists.

Structure-Activity Relationships of β -MSH Derived Melanocortin-4 Receptor Peptide Agonists

The recent emergence of obesity as a major health threat in the industrialized world has intensified the search for novel and effective pharmacologic treatment. The proopiomelanocortin (POMC)-melanocortin 4 receptor (MC4R) axis has been shown to regulate food intake and energy homeostasis and is considered among the most promising antiobesity targets. Our initial efforts in this area have focused on affinity and selectivity directed optimization of the native beta-MSH(5-22) sequence and resulted in the discovery of a potent MC4R agonist: Ac-Tyr-Arg-[Cys-Glu-His-D-Phe-Arg-Trp-Cys]-NH(2) (10). Subcutaneous administration of this peptide produced an excellent in vivo efficacy in reducing food intake and increasing fat metabolism. Additionally, suppression of food intake was observed in wild type but not in MC4R deficient mice, suggesting that the effects observed in the wild type mice were mediated through MC4R signaling. Subsequent optimization efforts led to the identification of a novel series of disulfide constrained hexapeptides as exemplified by Ac-[hCys-His-D-Phe-Arg-Trp-Cys]-NH(2) (100). These cyclic hexapeptides showed a further improved potency in binding MC4R and an enhanced selectivity over MC1R. At a dose of 0.07 mg/kg analog 102 reduced food intake by 38% and increased fat utilization by 58% in rats. These cyclic peptides provide novel and enhanced reagents for the elucidation of melanocortin receptors biology and may find applications in the treatment of obesity and related metabolic disorders.

Validation of a High Throughput Scintillation Proximity Assay for 5-HydroxytryptaminelE Receptor Binding Activity

Membranes prepared from stable transfected cells expressing the human gene encoding a functional 5-hydroxytryptaminelE (5HT1E) receptor were used to investigate high-affinity [3H]serotonin ([3H]5-HT) binding with scintillation proximity assay (SPA) technology. In this nonseparation format, membranes are captured by WGA-coated SPA fluoromicrospheres for detection of receptor-bound radioligand. Total binding observed was approximately 2000 cpm compared to a nonspecific signal of 100 cpm determined in the presence of 10,uM unlabeled 5-HT. Non-proximity effects (NPE) for the radiolabel and SPA beads averaged less than 100 cpm. Saturation binding analysis yielded an equilibrium dissociation constant (Kd) of 5.38 ± 0.43 nM and a maximum binding capacity (Bmax) of 6.42 + 0.15 pmol/mg protein. Competition with unlabeled serotonergic compounds demonstrated a specificity of the assay with rank potencies (5-HT > a-Me-5-HT > 2-Me-5-HT > 5-CT) similar to those observed using traditional fitration techniques. The variability of the assay and the stability of all reagents were investigated to validate the assay for extended use throughout a typical high throughput screen operation lasting several months.

In Vivo and In Vitro Characterization of Basal Insulin Peglispro: A Novel Insulin Analog

The aim of this research was to characterize the in vivo and in vitro properties of basal insulin peglispro (BIL), a new basal insulin, wherein insulin lispro was derivatized through the covalent and site-specific attachment of a 20-kDa polyethylene-glycol (PEG; specifically, methoxy-terminated) moiety to lysine B28. Addition of the PEG moiety increased the hydrodynamic size of the insulin lispro molecule. Studies show there is a prolonged duration of action and a reduction in clearance. Given the different physical properties of BIL, it was also important to assess the metabolic and mitogenic activity of the molecule. Streptozotocin (STZ)-treated diabetic rats were used to study the pharmacokinetic and pharmacodynamic characteristics of BIL. Binding affinity and functional characterization of BIL were compared with those of several therapeutic insulins, insulin AspB10, and insulin-like growth factor 1 (IGF-1). BIL exhibited a markedly longer time to maximum concentration after subcutaneous injection, a greater area under the concentration-time curve, and a longer duration of action in the STZ-treated diabetic rat than insulin lispro. BIL exhibited reduced binding affinity and functional potency as compared with insulin lispro and demonstrated greater selectivity for the human insulin receptor (hIR) as compared with the human insulin-like growth factor 1 receptor. Furthermore, BIL showed a more rapid rate of dephosphorylation following maximal hIR stimulation, and reduced mitogenic potential in an IGF-1 receptor–dominant cellular model. PEGylation of insulin lispro with a 20-kDa PEG moiety at lysine B28 alters the absorption, clearance, distribution, and activity profile receptor, but does not alter its selectivity and full agonist receptor properties.

A selective GPR40 (FFAR1) agonist LY2881835 provides immediate and durable glucose control in rodent models of type 2 diabetes.

LY2881835 is a selective, potent, and efficacious GPR40 agonist. The objective of the studies described here was to examine the pharmacological properties of LY2881835 in preclinical models of T2D. Significant increases in insulin secretion were detected when LY2881835 was tested in primary islets from WT mice but not in islets from GPR40 KO mice. Furthermore, LY2881835 potentiated glucose stimulated insulin secretion in normal lean mice. Acute administration of LY2881835 lowered glucose during OGTTs in WT mice but not in GPR40 KO mice. These findings demonstrate that LY2881835 induces GPR40‐mediated activity ex vivo and in vivo. LY2881835 was administered orally at 10 mg/kg to diet‐induced obese (DIO) mice (an early model of T2D due to insulin resistance) for 14 days. Statistically significant reductions in glucose were seen during OGTTs performed on days 1 and 15. When a study was done for 3 weeks in Zucker fa/fa rats, a rat model of insulin resistance, normalization of blood glucose levels equivalent to those seen in lean rats was observed. A similar study was performed in streptozotocin (STZ)‐treated DIO mice to explore glucose control in a late model of T2D. In this model, pancreatic insulin content was reduced ~80% due to STZ‐treatment plus the mice were insulin resistant due to their high fat diet. Glucose AUCs were significantly reduced during OGTTs done on days 1, 7, and 14 compared to control mice. In conclusion, these results demonstrate that LY2881835 functions as a GPR40‐specific insulin secretagogue mediating immediate and durable glucose control in rodent models of early‐ and late‐stage T2D.

Combination of a Beta adrenoceptor modulator and a norepinephrine-serotonin uptake inhibitor for the treatment of obesity.

We report the novel combination of a selective beta adrenoceptor modulator and a norepinephrine-serotonin uptake inhibitor (sibutramine) with potential for the treatment of obesity. The synthesis and characterization of 6-[4-[2-[[(2S)-3-(9H-carbazol-4-yloxy)-2-hydroxypropyl]amino]-2-methylpropyl]phenoxy]pyridine-3-carboxamide (LY377604), a human β3-adrenergic receptor agonist and β1- and β2-adrenergic receptor antagonist with no sympathomimetic activity at the β1- and β2-adrenergic receptors, is reported. Some in vivo data in both rats and humans is presented.

Discovery of LY3104607: A Potent and Selective G Protein-Coupled Receptor 40 (GPR40) Agonist with Optimized Pharmacokinetic Properties to Support Once Daily Oral Treatment in Patients with Type 2 Diabetes Mellitus

As a part of our program to identify potent GPR40 agonists capable of being dosed orally once daily in humans, we incorporated fused heterocycles into our recently disclosed spiropiperidine and tetrahydroquinoline acid derivatives 1, 2, and 3 with the intention of lowering clearance and improving the maximum absorbable dose (Dabs). Hypothesis-driven structural modifications focused on moving away from the zwitterion-like structure. and mitigating the N-dealkylation and O-dealkylation issues led to triazolopyridine acid derivatives with unique pharmacology and superior pharmacokinetic properties. Compound 4 (LY3104607) demonstrated functional potency and glucose-dependent insulin secretion (GDIS) in primary islets from rats. Potent, efficacious, and durable dose-dependent reductions in glucose levels were seen during glucose tolerance test (GTT) studies. Low clearance, volume of distribution, and high oral bioavailability were observed in all species. The combination of enhanced pharmacology and pharmacokinetic properties supported further development of this compound as a potential glucose-lowering drug candidate.

Insulin-XTEN® Exhibits a Size-Dependent Alteration in Tissue Action in Rats

To optimize the action of exogenously administered insulin, we employed XTEN® technology to create insulins with variably sized XTEN amino acid polymers. Recombinant fusions of XTEN polymers linked to insulin lispro with an A21G mutation were prepared in various amino acid lengths. Insulin-XTEN molecules demonstrated 15-fold lower potency in binding and receptor phosphorylation than insulin lispro but did not differ from each other. These insulin-XTEN molecules were equally effective in lowering blood glucose at a 100nmol/kg dose in diabetic Sprague-Dawley rats. Furthermore, the larger insulin-XTEN molecules had a longer duration of glucose lowering. Insulin-XTENs were compared to insulin lispro in rat euglycemic clamp studies, using insulin doses that would elicit steady plasma insulin concentrations and equivalent increases in glucose infusion rate. Insulin-mediated suppression of endogenous glucose production was not significantly different among any of the administered insulins. However, plasma free fatty acids and soleus muscle glucose uptake were significantly decreased in an XTEN size-dependent manner when compared to insulin lispro. Additional studies demonstrated equal hepatic pAkt accumulation in rats treated with insulin lispro or any of the insulin-XTENs, but revealed a significant XTEN size-dependent reduction in skeletal muscle pAkt in rats administered insulin-XTENs compared to insulin lispro. These data suggest a possible XTEN size-dependent regulation of insulin action and that the differing sizes of the XTEN polymer may convey preferential tissue action. In conclusion, XTEN technology may permit “tuning” of the glucodynamic effects of the insulin, leading to an enhanced time extension and improved hepatic and peripheral pharmacodynamic action that could more closely mimic the action of endogenously secreted insulin into the portal circulation. Disclosure M.E. Christe: Employee; Self; Eli Lilly and Company. D. Konkol: None. J. Friedrich: None. J. Jacobs: None. E. Hawkins: Employee; Self; Eli Lilly and Company. J. Moyers: Employee; Self; Eli Lilly and Company. Stock/Shareholder; Self; Eli Lilly and Company. C. Zhang: Employee; Self; Eli Lilly and Company. S.D. Kahl: Employee; Self; Eli Lilly and Company. H.E. Baker: None. A.L. Cox: None. R.J. Hansen: Employee; Self; Eli Lilly and Company. Stock/Shareholder; Self; Eli Lilly and Company. A. Sperry: Employee; Self; Eli Lilly and Company. Stock/Shareholder; Self; Eli Lilly and Company. M. Michael: Employee; Self; Eli Lilly and Company. Stock/Shareholder; Self; Eli Lilly and Company. Employee; Spouse/Partner; Eli Lilly and Company. Stock/Shareholder; Spouse/Partner; Eli Lilly and Company. V. Schellenberger: None. D. Baldwin: None. J.M. Beals: Employee; Self; Eli Lilly and Company. A. Korytko: None.