Casey C. McComas

Structure-dependent Impairment of Intracellular Apolipoprotein E4 Trafficking and Its Detrimental Effects Are Rescued by Small-molecule Structure Correctors

Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer disease (AD) and likely contributes to neuropathology through various pathways. Here we report that the intracellular trafficking of apoE4 is impaired in Neuro-2a cells and primary neurons, as shown by measuring fluorescence recovery after photobleaching. In Neuro-2a cells, more apoE4 than apoE3 molecules remained immobilized in the endoplasmic reticulum (ER) and the Golgi apparatus, and the lateral motility of apoE4 was significantly lower in the Golgi apparatus (but not in the ER) than that of apoE3. Likewise, the immobile fraction was larger, and the lateral motility was lower for apoE4 than apoE3 in mouse primary hippocampal neurons. ApoE4 with the R61T mutation, which abolishes apoE4 domain interaction, was less immobilized, and its lateral motility was comparable with that of apoE3. The trafficking impairment of apoE4 was also rescued by disrupting domain interaction with the small-molecule structure correctors GIND25 and PH002. PH002 also rescued apoE4-induced impairments of neurite outgrowth in Neuro-2a cells and dendritic spine development in primary neurons. ApoE4 did not affect trafficking of amyloid precursor protein, another AD-related protein, through the secretory pathway. Thus, domain interaction renders more newly synthesized apoE4 molecules immobile and slows their trafficking along the secretory pathway. Correcting the pathological structure of apoE4 by disrupting domain interaction is a potential therapeutic approach to treat or prevent AD related to apoE4.

Development of a New Structural Class of Broadly Acting HCV Non-Nucleoside Inhibitors Leading to the Discovery of MK-8876.

Studies directed at developing a broadly acting non‐nucleoside inhibitor of HCV NS5B led to the discovery of a novel structural class of 5‐aryl benzofurans that simultaneously interact with both the palm I and palm II binding regions. An initial candidate was potent in vitro against HCV GT1a and GT1b replicons, and induced multi‐log reductions in HCV viral load when orally dosed to chronic GT1 infected chimpanzees. However, in vitro potency losses against clinically relevant GT1a variants prompted a further effort to develop compounds with sustained potency across a broader array of HCV genotypes and mutants. Ultimately, a biology and medicinal chemistry collaboration led to the discovery of the development candidate MK‐8876. MK‐8876 demonstrated a pan‐genotypic potency profile and maintained potency against clinically relevant mutants. It demonstrated moderate bioavailability in rats and dogs, but showed low plasma clearance characteristics consistent with once‐daily dosing. Herein we describe the efforts which led to the discovery of MK‐8876, which advanced into Phase 1 monotherapy studies for evaluation and characterization as a component of an all‐oral direct‐acting drug regimen for the treatment of chronic HCV infection.