Rationally Designed, Short-Acting RPE65 Inhibitors for Visual Cycle-Associated Retinopathies

J Med Chem. 2025 Aug 28;68(16):17638-17652. doi: 10.1021/acs.jmedchem.5c01353. Epub 2025 Aug 5.

Abstract

The visual cycle is a metabolic pathway essential for visual function. The bisretinoid byproducts of this pathway can induce retinal toxicity, as occurs in Stargardt disease type 1 (STGD1). Emixustat, which inhibits bisretinoid production, is a visual cycle modulator (VCM) that targets RPE65. However, it causes visual impairment due to its unfavorable duration of action. Here, we report ester-containing analogs of emixustat that are susceptible to hydrolytic clearance and function as short-acting VCMs. We show that the esterase-mediated metabolism of these compounds can be tuned while maintaining high-affinity RPE65 targeting. Compounds 6 (EYE-002) and 7 (EYE-003) containing diethyl acetate and valproate esters, respectively, allowed faster recovery of visual cycle function compared to emixustat. These molecules protected against retinal degeneration in mouse models of photic retinopathy and STGD1. These data demonstrate that shorter attenuation of the visual cycle can therapeutically intervene in retinal diseases with fewer visual side effects compared to emixustat.

MeSH terms

  • Animals
  • Drug Design*
  • Enzyme Inhibitors* / chemistry
  • Enzyme Inhibitors* / pharmacology
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Phenyl Ethers* / chemistry
  • Phenyl Ethers* / pharmacology
  • Propanolamines
  • Stargardt Disease / drug therapy
  • Structure-Activity Relationship
  • cis-trans-Isomerases* / antagonists & inhibitors
  • cis-trans-Isomerases* / metabolism

Substances

  • cis-trans-Isomerases
  • retinoid isomerohydrolase
  • emixustat
  • Phenyl Ethers
  • Enzyme Inhibitors
  • Propanolamines