Development of an ASO therapy for Angelman syndrome by targeting an evolutionarily conserved region at the start of theUBE3A-AStranscript

Abstract

Angelman syndrome is a devastating neurogenetic disorder for which there is currently no effective treatment. It is caused by mutations or epimutations affecting the expression or function of the maternally inherited allele of the ubiquitin-protein ligase E3A (UBE3A) gene. The paternal UBE3A allele is imprinted in neurons of the central nervous system (CNS) by the UBE3A antisense (UBE3A-AS) transcript, which represents the distal end of the SNHG14 transcription unit. Reactivating the expression of the paternal UBE3A allele in the CNS has long been pursued as a therapeutic option for Angelman syndrome. Here, we designed and optimized antisense oligonucleotides (ASO) targeting an evolutionarily conserved region demarcating the start of the human UBE3A-AS transcript and show that ASOs targeting this region can reverse imprinting of UBE3A in cultured Angelman syndrome neurons and throughout the CNS of a non-human primate model. Findings from this study advanced the first investigational molecular therapy for Angelman syndrome into clinical development (ClinicalTrials.gov, NCT04259281).

Generation of isogenic models of Angelman syndrome and Prader-Willi syndrome in CRISPR/Cas9-engineered human embryonic stem cells

“…While the gene�c perturba�ons contribu�ng to AS and PWS have been known for many years, the effect those anomalies have on the chromosome 15q locus and the genome as a whole remains unclear. Mouse models have provided key understandings about the facets of gene regula�ons conserved between the two species, but disease features such as the neuron-specific regula�on of UBE3A imprinted expression and protein targets of UBE3A appear to be unique to humans (Cavaillé et al, 2000;Dindot et al, 2023;Landers et al, 2004;Yamasaki et al, 2003). Available iPSC models have been powerful tools to study these disorders as well.…”

Angelman syndrome patient neuron screen identifies a potent and selective clinical ASO targeting UBE3A-ATS with long lasting effect in cynomolgus monkey

“…In addition, human specific ASOs revert functional and molecular changes in patient neurons ( 9 , 15 ). In a recent study, human/cynomolgus monkey cross reactive ASOs targeting the UBE3A-ATS revealed moderate knock-down of the UBE3A-ATS but failed to upregulate UBE3A mRNA and protein levels in non-AS neurons and NHP brains ( 30 ). It was hypothesized to be due to potential feedback regulatory mechanisms that hinder upregulation of UBE3A mRNA and protein in a non-disease context ( 30 ).…”

“…In a recent study, human/cynomolgus monkey cross reactive ASOs targeting the UBE3A-ATS revealed moderate knock-down of the UBE3A-ATS but failed to upregulate UBE3A mRNA and protein levels in non-AS neurons and NHP brains ( 30 ). It was hypothesized to be due to potential feedback regulatory mechanisms that hinder upregulation of UBE3A mRNA and protein in a non-disease context ( 30 ). Here, by generating data across three different species, specifically human derived neurons, NHPs and mice, we provide substantial evidence that potent knock-down of UBE3A-ATS enables unsilencing of paternal UBE3A expression with maximal UBE3A protein upregulation even in a “healthy context”, with no evidence for maternal allele compensation.…”

Chemically Modified Platforms for Better RNA Therapeutics

“…This structure consists of a central DNA gap region flanked by two RNA-based wings, which improves target binding capacity and reduces off-target effects. 45 Currently, three RNase H1-dependent ASO drugs are used in clinics to treat various diseases, including Fomivirsen for treating CMV retinitis in patients with AIDS, Mipomersen (Kynamro) for treating familial hypercholesterolemia (FH), and Inotersen (Tegsedi) for treating hereditary transthyretinmediated amyloidosis (hATTR).…”