Stephen L. Lowe

Robust Central Reduction of Amyloid-β in Humans with an Orally Available, Non-Peptidic β-Secretase Inhibitor

According to the amyloid cascade hypothesis, cerebral deposition of amyloid-β peptide (Aβ) is critical for Alzheimers disease (AD) pathogenesis. Aβ generation is initiated when β-secretase (BACE1) cleaves the amyloid precursor protein. For more than a decade, BACE1 has been a prime target for designing drugs to prevent or treat AD. However, development of such agents has turned out to be extremely challenging, with major hurdles in cell penetration, oral bioavailability/metabolic clearance, and brain access. Using a fragment-based chemistry strategy, we have generated LY2811376 [(S)-4-(2,4-difluoro-5-pyrimidin-5-yl-phenyl)-4-methyl-5,6-dihydro-4H-[1,3]thiazin-2-ylamine], the first orally available non-peptidic BACE1 inhibitor that produces profound Aβ-lowering effects in animals. The biomarker changes obtained in preclinical animal models translate into man at doses of LY2811376 that were safe and well tolerated in healthy volunteers. Prominent and long-lasting Aβ reductions in lumbar CSF were measured after oral dosing of 30 or 90 mg of LY2811376. This represents the first translation of BACE1-driven biomarker changes in CNS from preclinical animal models to man. Because of toxicology findings identified in longer-term preclinical studies, this compound is no longer progressing in clinical development. However, BACE1 remains a viable target because the adverse effects reported here were recapitulated in LY2811376-treated BACE1 KO mice and thus are unrelated to BACE1 inhibition. The magnitude and duration of central Aβ reduction obtainable with BACE1 inhibition positions this protease as a tractable small-molecule target through which to test the amyloid hypothesis in man.

Validation of a Multiplex Assay for Simultaneous Quantification of Amyloid-β Peptide Species in Human Plasma with Utility for Measurements in Studies of Alzheimer's Disease Therapeutics

The aim of this study was to validate the INNO-BIA plasma amyloid-β (Aβ) forms assay for quantification of Aβ1-40 and Aβ1-42 according to regulatory guidance for bioanalysis and demonstrate its fitness for clinical trial applications. Validation parameters were evaluated by repeated testing of human EDTA-plasma pools. In 6 separate estimates, intra-assay coefficients of variation (CV) for repeated testing of 5 plasma pools were ≤9% and relative error (RE) varied between -35% and +22%. Inter-assay CV (n = 36) ranged from 5% to 17% and RE varied from -17% to +8%. Dilutional linearity was not demonstrated for either analyte using diluent buffer, but dilution with immuno-depleted plasma by 1.67-fold gave results within 20% of target. Analyte stability was demonstrated in plasma at 2-8 °C for up to 6 h. Stability during frozen storage up to 12 months and through 3 freeze-thaw cycles at ≤ -70 °C was also demonstrated in 5 of 6 individuals but deteriorated thereafter. Neither semagacestat nor LY2811376 interfered with the assay but solanezumab at 500 mg/L reduced recovery of Aβ1-42 by 53%. Specimens from a Phase I human volunteer study of the β-secretase inhibitor LY2811376 were tested at baseline and at intervals up to 12 h after single oral doses, demonstrating a clear treatment effect. During 1,041 clinical assay runs from semagacestat studies over 10 months, the CV for plasma quality control pools at three levels were ≤15% and RE were <10%. In conclusion, the INNO-BIA plasma assay was successfully validated and qualified for use in clinical research.

Determining Pharmacological Selectivity of the Kappa Opioid Receptor Antagonist LY2456302 Using Pupillometry as a Translational Biomarker in Rat and Human

Background: Selective kappa opioid receptor antagonism is a promising experimental strategy for the treatment of depression. The kappa opioid receptor antagonist, LY2456302, exhibits ~30-fold higher affinity for kappa opioid receptors over mu opioid receptors, which is the next closest identified pharmacology. Methods: Here, we determined kappa opioid receptor pharmacological selectivity of LY2456302 by assessing mu opioid receptor antagonism using translational pupillometry in rats and humans. Results: In rats, morphine-induced mydriasis was completely blocked by the nonselective opioid receptor antagonist naloxone (3mg/kg, which produced 90% mu opioid receptor occupancy), while 100 and 300mg/kg LY2456302 (which produced 56% and 87% mu opioid receptor occupancy, respectively) only partially blocked morphine-induced mydriasis. In humans, fentanyl-induced miosis was completely blocked by 50mg naltrexone, and LY2456302 dose-dependently blocked miosis at 25 and 60mg (minimal-to-no blockade at 4–10mg). Conclusions: We demonstrate, for the first time, the use of translational pupillometry in the context of receptor occupancy to identify a clinical dose of LY2456302 achieving maximal kappa opioid receptor occupancy without evidence of significant mu receptor antagonism.

Adverse events in healthy subjects exposed to single and multiple doses of LY2140023 monohydrate: pooled results from 10 phase 1 studies.

Abstract Ten phase 1 studies of LY2140023 monohydrate (LY2140023), an mGlu2/3 receptor agonist, in healthy male and female subjects were pooled to evaluate the adverse event profile. These studies included both single-dose (5–200 mg) and multiple-dose (20–160 mg 2 times a day) treatment groups. The percentage of subjects reporting treatment-emergent adverse events (TEAEs) were assessed in placebo and LY2140023 dose groups: 5 to 20, 40, 60 to 80, and more than 80 mg (120–200 mg). The severity and duration of TEAEs were also determined. Electroencephalograms were performed in 1 study to detect if there were any prodromal signs of convulsions or seizures. Subjects who received either placebo or LY2140023 and participated in the single-dose (n = 159) and multiple-dose (n = 102) treatment groups were included in these analyses. No clear trends for increased TEAE incidence occurred with higher doses of LY2140023 in both the single-dose and multiple-dose treatment groups. The TEAEs with the highest incidence were gastrointestinal and nervous system events. No serious adverse events occurred in any of the 10 studies, and most TEAEs were mild in severity and transient in nature. There were no clinically significant changes in electroencephalograms in subjects receiving LY2140023 (n = 26). LY2140023 was generally well tolerated in healthy subjects.

A COMPARISON OF IN VIVO POTENCY IN TWO BACE INHIBITORS AS DETERMINED IN HUMANS AND DOGS

P1-365 A COMPARISON OF IN VIVO POTENCY IN TWO BACE INHIBITORS AS DETERMINED IN HUMANS AND DOGS Brian A. Willis, Patrick C. May, Scott A. Monk, Stephen L. Lowe, Stuart Friedrich, Dustin J. Mergott, Leonard Boggs, Hakop Gevorkyan, Stan Jhee, Robert A. Dean, Masako Nakano, Celedon R. Gonzales, Eli Lilly and Co., Indianapolis, Indiana, United States; Eli Lilly and Company, Indianapolis, Indiana, United States; Lilly NUS Center of Clinical Pharmacology, Singapore, Singapore; Eli Lilly and Company, Indianapolis, Indiana, United States; Eli Lilly and Co., Indianapolis, Indiana, United States; Parexel International, Glendale, California, United States; Eli Lilly Japan K.K., Kobe, Japan. Contact e-mail: p.c. may@lilly.com

The Effects on Metabolic Clearance when Administering a Potent CYP3A Autoinducer with the Prototypic CYP3A Inhibitor, Ketoconazole

Ketoconazole is recognized as the prototypical CYP3A inhibitor and is often used to determine the metabolic CYP3A liabilities of new chemical entities in preclinical and clinical studies. Ketoconazole has been commercially available for approximately 30 years and was marketed before drug-metabolizing enzymes were well characterized; consequently, little is known about its metabolic profile. Semagacestat, a γ-secretase inhibitor investigated as a potential therapy for Alzheimers disease, was determined to be a potent CYP3A autoinducer in human hepatocytes. Two human studies were conducted to assess the induction potential of semagacestat. In the first study (study 1, n = 20), semagacestat increased the mean apparent clearance (CL/F) of oral midazolam (76–324 l/h) and nifedipine (63–229 l/h) as predicted from hepatocytes. In a second (steady-state) study (study 2, n = 20), semagacestat CL/F increased from 22 after a single dose to 31 l/h. Ketoconazole decreased semagacestat CL/F by 32% after a single dose of semagacestat [geometric means ratio estimate, 0.68; 90% confidence interval (CI). 0.64, 0.73] and 46% at steady state (geometric means ratio estimate. 0.54; 90% CI, 0.51, 0.58). Ketoconazole area under the concentration-time curve over 8 h decreased 49% from first to last day of semagacestat dosing. Semagacestat significantly increases the oral clearance of CYP3A substrates, confirming its inducer designation. More importantly, when administered with a potent CYP3A inducer at steady state, ketoconazoles plasma exposure decreased, indicating that it may also be cleared by CYP3A, other inducible enzymes or transporters, or both.