Bietti crystalline dystrophy (BCD) is an autosomal recessive disorder caused by loss-of-function mutations in the CYP4V2 gene, characterized by crystal-like lipid deposits in the retina, progressive photoreceptor loss, and retinal pigment epithelium (RPE) deterioration.Currently, there are no approved treatments for BCD.VGR-R01, an investigational gene therapy, uses subretinal administration of recombinant adeno-associated virus type 8 (AAV8) vector to deliver the human CYP4V2 gene.This therapy is now undergoing phase 1/2 clin. trials (NCT05694598).The pre-clin. study results for VGR-R01 are summarized, with a focus on its pharmacol., pharmacokinetics, and toxicol.The in vitro cellular studies demonstrated that VGR-R01 induces a dose-dependent expression of the CYP4V2 protein, which significantly enhances fatty acid hydroxylase activity and reduces lipid droplet accumulations in the RPE cells.In vivo, VGR-R01 showed effectiveness in improving electroretinogram (ERG) amplitudes in 8-mo-old Cyp4v3-/- mice.VGR-R01 was well tolerated in New Zealand rabbits and non-human primates (NHPs).Furthermore, after subretinal administration, VGR-R01 was primarily distributed in the ocular tissues, especially in the retina, with minimal systemic presence, notably in the gonads.Overall, these results support the potential for clin. application of VGR-R01 in treating BCD.