Robust Pharmacodynamic Effect of LY3202626, a Central Nervous System Penetrant, Low Dose BACE1 Inhibitor, in Humans and Nonclinical Species

Background: The development of beta-site amyloid-beta precursor protein cleaving enzyme (BACE) 1 inhibitors for the treatment of Alzheimer’s disease requires optimization of inhibitor potency, selectivity, and brain penetration. Moreover, there is a need for low-dose compounds since liver toxicity was found with some BACE inhibitors. Objective: To determine whether the high in vitro potency and robust pharmacodynamic effect of the BACE inhibitor LY3202626 observed in nonclinical species translated to humans. Methods: The effect of LY3202626 versus vehicle on amyloid-β (Aβ) levels was evaluated in a series of in vitro assays, as well as in in vivo and multi-part clinical pharmacology studies. Aβ levels were measured using analytical biochemistry assays in brain, plasma, and cerebrospinal fluid (CSF) of mice, dogs and humans. Nonclinical data were analyzed using an ANOVA followed by Tukey’s post hoc test and clinical data used summary statistics. Results: LY3202626 exhibited significant human BACE1 inhibition, with an IC50 of 0.615±0.101 nM in a fluorescence resonance energy transfer assay and an EC50 of 0.275±0.176 nM for lowering Aβ 1–40 and 0.228±0.244 nM for Aβ 1–42 in PDAPP neuronal cultures. In dogs, CSF Aβ 1hboxx concentrations were significantly reduced by ∼80% at 9 hours following a 1.5 mg/kg dose. In humans, CSF Aβ 1–42 was reduced by 73.1±7.96 % following administration of 6 mg QD. LY3202626 was found to freely cross the blood-brain barrier in dogs and humans. Conclusion: LY3202626 is a potent BACE1 inhibitor with high blood-brain barrier permeability. The favorable safety and pharmacokinetic/pharmacodynamic profile of LY3202626 supports further clinical development.

Penetration Driving Force of Metformin Hydrochloride via Paracellular Pathway in Relation to its Pharmacodynamic Effect

Background: Penetration enhancement of metformin hydrochloride via its molecular dispersion in sorbitan monostearate microparticles is reported. Metformin dispersion in sorbitan monostearate as a carrier was thought to be the basic philosophy to maximize its entrapment in the matrix for maximum penetration effect.Methods: Drug dispersion in sorbitan monostearate with different theoretical drug contents (TDC) were prepared. Results: All products showed excellent micromeritics and actual drug content (ADC) increased by increasing TDC. These two features are essential for industry concerning processing and cost. The partition coefficient of the drug products showed huge improvement. This indicates the drug entrapment should be in the polar part of sorbitan monostearate as a special image. The drug entrapment process was also reflected in the drug release process due to the insolubility of the matrix in the dissolution medium. The drug permeation profiles from the different drug-sorbitan monostearate products are overlapped and its permeation parameters (permeation coefficient, total drug permeation percent & drug absorption enhancement percent) are nearly equal. The results of the permeation study by using modified non-everted sac suggested the main driving force for 11 improving the drug paracellular pathway is its dispersion in sorbitan monostearate (special image) and is independent of ADC. Pharmacodynamic of the drug products showed a significant improvement than that from the drug alone at p ˂ 0.05. ANOVA test indicated the insignificant pharmacodynamic difference between the low, middle, and high ADC of the products. There is an excellent point-to-point correlation between the drug permeation percent and the drug pharmacodynamic percent. The total amount of the drug permeation percent is equal to the mean of the total drug pharmacodynamic percent. Conclusion: The results concluded that the drug permeation driving force via the paracellular pathway is its entrapment in sorbitan monostearate as a special image and it does not depend on ADC. This entrapment mechanism improved the drug pharmacodynamic effect. The technique is simple and the products are easy to process due to having an excellent micromeritics property.

The Use, Standardization, and Interpretation of Brain Imaging Data in Clinical Trials of Neurodegenerative Disorders

Imaging biomarkers play a wide-ranging role in clinical trials for neurological disorders. This includes selecting the appropriate trial participants, establishing target engagement and mechanism-related pharmacodynamic effect, monitoring safety, and providing evidence of disease modification. In the early stages of clinical drug development, evidence of target engagement and/or downstream pharmacodynamic effect—especially with a clear relationship to dose—can provide confidence that the therapeutic candidate should be advanced to larger and more expensive trials, and can inform the selection of the dose(s) to be further tested, i.e., to “de-risk” the drug development program. In these later-phase trials, evidence that the therapeutic candidate is altering disease-related biomarkers can provide important evidence that the clinical benefit of the compound (if observed) is grounded in meaningful biological changes. The interpretation of disease-related imaging markers, and comparability across different trials and imaging tools, is greatly improved when standardized outcome measures are defined. This standardization should not impinge on scientific advances in the imaging tools per se but provides a common language in which the results generated by these tools are expressed. PET markers of pathological protein aggregates and structural imaging of brain atrophy are common disease-related elements across many neurological disorders. However, PET tracers for pathologies beyond amyloid β and tau are needed, and the interpretability of structural imaging can be enhanced by some simple considerations to guard against the possible confound of pseudo-atrophy. Learnings from much-studied conditions such as Alzheimer’s disease and multiple sclerosis will be beneficial as the field embraces rarer diseases.