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Developing antisense oligonucleotides for a TECPR2 mutation-induced, ultra-rare neurological disorder using patient-derived cellular models.

Mol Ther Nucleic Acids. 2022 Jun 22;29:189-203. doi: 10.1016/j.omtn.2022.06.015. PMID: 35860385; PMCID: PMC9287140.

Authors/Editors: Williams LA, Gerber DJ, Elder A, Tseng WC, Baru V, Delaney-Busch N, Ambrosi C, Mahimkar G, Joshi V, Shah H, Harikrishnan K, Upadhyay H, Rajendran SH, Dhandapani A, Meier J, Ryan SJ, Lewarch C, Black L, Douville J, Cinquino S, Legakis H, Nalbach K, Behrends C, Sato A, Galluzzi L, Yu TW, Brown D, Agrawal S, Margulies D, Kopin A, Dempsey GT.
Publication Date: 2022

Abstract

Mutations in the TECPR2 gene are the cause of an ultra-rare neurological disorder characterized by intellectual disability, impaired speech, motor delay, and hypotonia evolving to spasticity, central sleep apnea, and premature death (SPG49 or HSAN9; OMIM: 615031). Little is known about the biological function of TECPR2, and there are currently no available disease-modifying therapies for this disease. Here we describe implementation of an antisense oligonucleotide (ASO) exon-skipping strategy targeting TECPR2 c.1319delT (p.Leu440Argfs∗19), a pathogenic variant that results in a premature stop codon within TECPR2 exon 8. We used patient-derived fibroblasts and induced pluripotent stem cell (iPSC)-derived neurons homozygous for the p.Leu440Argfs∗19 mutation to model the disease in vitro. Both patient-derived fibroblasts and neurons showed lack of TECPR2 protein expression. We designed and screened ASOs targeting sequences across the TECPR2 exon 8 region to identify molecules that induce exon 8 skipping and thereby remove the premature stop signal. TECPR2 exon 8 skipping restored in-frame expression of a TECPR2 protein variant (TECPR2ΔEx8) containing 1,300 of 1,411 amino acids. Optimization of ASO sequences generated a lead candidate (ASO-005-02) with ∼27 nM potency in patient-derived fibroblasts. To examine potential functional rescue induced by ASO-005-02, we used iPSC-derived neurons to analyze the neuronal localization of TECPR2ΔEx8 and showed that this form of TECPR2 retains the distinct, punctate neuronal expression pattern of full-length TECPR2. Finally, ASO-005-02 had an acceptable tolerability profile in vivo following a single 20-mg intrathecal dose in cynomolgus monkeys, showing some transient non-adverse behavioral effects with no correlating histopathology. Broad distribution of ASO-005-02 and induction of TECPR2 exon 8 skipping was detected in multiple central nervous system (CNS) tissues, supporting the potential utility of this therapeutic strategy for a subset of patients suffering from this rare disease.

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