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Suárez-Herrera N, Li CHZ, Leijsten N, Karjosukarso DW, Corradi Z, Bukkems F, Duijkers L, Cremers FPM, Hoyng CB, Garanto A, Collin RWJ. Preclinical Development of Antisense Oligonucleotides to Rescue Aberrant Splicing Caused by an Ultrarare ABCA4 Variant in a Child with Early-Onset Stargardt Disease. Cells 2024; 13:601. [PMID: 38607040 PMCID: PMC11011354 DOI: 10.3390/cells13070601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/19/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024] Open
Abstract
Precision medicine is rapidly gaining recognition in the field of (ultra)rare conditions, where only a few individuals in the world are affected. Clinical trial design for a small number of patients is extremely challenging, and for this reason, the development of N-of-1 strategies is explored to accelerate customized therapy design for rare cases. A strong candidate for this approach is Stargardt disease (STGD1), an autosomal recessive macular degeneration characterized by high genetic and phenotypic heterogeneity. STGD1 is caused by pathogenic variants in ABCA4, and amongst them, several deep-intronic variants alter the pre-mRNA splicing process, generally resulting in the insertion of pseudoexons (PEs) into the final transcript. In this study, we describe a 10-year-old girl harboring the unique deep-intronic ABCA4 variant c.6817-713A>G. Clinically, she presents with typical early-onset STGD1 with a high disease symmetry between her two eyes. Molecularly, we designed antisense oligonucleotides (AONs) to block the produced PE insertion. Splicing rescue was assessed in three different in vitro models: HEK293T cells, fibroblasts, and photoreceptor precursor cells, the last two being derived from the patient. Overall, our research is intended to serve as the basis for a personalized N-of-1 AON-based treatment to stop early vision loss in this patient.
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Affiliation(s)
- Nuria Suárez-Herrera
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Catherina H. Z. Li
- Department of Ophthalmology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (C.H.Z.L.); (C.B.H.)
| | - Nico Leijsten
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Dyah W. Karjosukarso
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Femke Bukkems
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Lonneke Duijkers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Frans P. M. Cremers
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
| | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (C.H.Z.L.); (C.B.H.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
| | - Alejandro Garanto
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
- Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Rob W. J. Collin
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (N.S.-H.); (N.L.); (D.W.K.); (Z.C.); (F.B.); (L.D.); (F.P.M.C.); (A.G.)
- Dutch Center for RNA Therapeutics, 2311 EZ Leiden, The Netherlands
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Suárez-Herrera N, Riswick IB, Vázquez-Domínguez I, Duijkers L, Karjosukarso DW, Piccolo D, Bauwens M, De Baere E, Cheetham ME, Garanto A, Collin RWJ. Proof-of-concept for multiple AON delivery by a single U7snRNA vector to restore splicing defects in ABCA4. Mol Ther 2024; 32:837-851. [PMID: 38243599 PMCID: PMC10928313 DOI: 10.1016/j.ymthe.2024.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/13/2023] [Accepted: 01/12/2024] [Indexed: 01/21/2024] Open
Abstract
The high allelic heterogeneity in Stargardt disease (STGD1) complicates the design of intervention strategies. A significant proportion of pathogenic intronic ABCA4 variants alters the pre-mRNA splicing process. Antisense oligonucleotides (AONs) are an attractive yet mutation-specific therapeutic strategy to restore these splicing defects. In this study, we experimentally assessed the potential of a splicing modulation therapy to target multiple intronic ABCA4 variants. AONs were inserted into U7snRNA gene cassettes and tested in midigene-based splice assays. Five potent antisense sequences were selected to generate a multiple U7snRNA cassette construct, and this combination vector showed substantial rescue of all of the splicing defects. Therefore, the combination cassette was used for viral synthesis and assessment in patient-derived photoreceptor precursor cells (PPCs). Simultaneous delivery of several modified U7snRNAs through a single AAV, however, did not show substantial splicing correction, probably due to suboptimal transduction efficiency in PPCs and/or a heterogeneous viral population containing incomplete AAV genomes. Overall, these data demonstrate the potential of the U7snRNA system to rescue multiple splicing defects, but also suggest that AAV-associated challenges are still a limiting step, underscoring the need for further optimization before implementing this strategy as a potential treatment for STGD1.
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Affiliation(s)
- Nuria Suárez-Herrera
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands
| | - Iris B Riswick
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands
| | - Irene Vázquez-Domínguez
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands
| | - Lonneke Duijkers
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands
| | - Dyah W Karjosukarso
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands
| | | | - Miriam Bauwens
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium; Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Elfride De Baere
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium; Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | | | - Alejandro Garanto
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands; Radboud University Medical Center, Amalia Children's Hospital, Department of Pediatrics, Nijmegen 6252GA, the Netherlands
| | - Rob W J Collin
- Radboud University Medical Center, Department of Human Genetics, 6525GA Nijmegen, the Netherlands.
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Kaltak M, Blanco-Garavito R, Molday LL, Dhaenens CM, Souied EE, Platenburg G, Swildens J, Molday RS, Cremers FPM. Stargardt disease-associated in-frame ABCA4 exon 17 skipping results in significant ABCA4 function. J Transl Med 2023; 21:546. [PMID: 37587475 PMCID: PMC10428568 DOI: 10.1186/s12967-023-04406-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 08/01/2023] [Indexed: 08/18/2023] Open
Abstract
BACKGROUND ABCA4, the gene implicated in Stargardt disease (STGD1), contains 50 exons, of which 17 contain multiples of three nucleotides. The impact of in-frame exon skipping is yet to be determined. Antisense oligonucleotides (AONs) have been investigated in Usher syndrome-associated genes to induce skipping of in-frame exons carrying severe variants and mitigate their disease-linked effect. Upon the identification of a STGD1 proband carrying a novel exon 17 canonical splice site variant, the activity of ABCA4 lacking 22 amino acids encoded by exon 17 was examined, followed by design of AONs able to induce exon 17 skipping. METHODS A STGD1 proband was compound heterozygous for the splice variant c.2653+1G>A, that was predicted to result in in-frame skipping of exon 17, and a null variant [c.735T>G, p.(Tyr245*)]. Clinical characteristics of this proband were studied using multi-modal imaging and complete ophthalmological examination. The aberrant splicing of c.2653+1G>A was investigated in vitro in HEK293T cells with wild-type and mutant midigenes. The residual activity of the mutant ABCA4 protein lacking Asp864-Gly885 encoded by exon 17 was analyzed with all-trans-retinal-activated ATPase activity assay, along with its subcellular localization. To induce exon 17 skipping, the effect of 40 AONs was examined in vitro in WT WERI-Rb-1 cells and 3D human retinal organoids. RESULTS Late onset STGD1 in the proband suggests that c.2653+1G>A does not have a fully deleterious effect. The in vitro splice assay confirmed that this variant leads to ABCA4 transcripts without exon 17. ABCA4 Asp864_Gly863del was stable and retained 58% all-trans-retinal-activated ATPase activity compared to WT ABCA4. This sequence is located in an unstructured linker region between transmembrane domain 6 and nucleotide-binding domain-1 of ABCA4. AONs were designed to possibly reduce pathogenicity of severe variants harbored in exon 17. The best AON achieved 59% of exon 17 skipping in retinal organoids. CONCLUSIONS Exon 17 deletion in ABCA4 does not result in the absence of protein activity and does not cause a severe STGD1 phenotype when in trans with a null allele. By applying AONs, the effect of severe variants in exon 17 can potentially be ameliorated by exon skipping, thus generating partial ABCA4 activity in STGD1 patients.
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Affiliation(s)
- Melita Kaltak
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
- ProQR Therapeutics, Leiden, The Netherlands
| | - Rocio Blanco-Garavito
- Department of Ophthalmology, Intercommunal Hospital Center and Henri Mondor Hospital, Paris-Est Créteil University, Creteil, France
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, BC, Canada
| | - Claire-Marie Dhaenens
- University of Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience & Cognition, Lille, France
| | - Eric E Souied
- Department of Ophthalmology, Intercommunal Hospital Center and Henri Mondor Hospital, Paris-Est Créteil University, Creteil, France
| | | | | | - Robert S Molday
- Department of Biochemistry and Molecular Biology, Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, BC, Canada
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
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Zhou H, Arechavala-Gomeza V, Garanto A. Experimental Model Systems Used in the Preclinical Development of Nucleic Acid Therapeutics. Nucleic Acid Ther 2023; 33:238-247. [PMID: 37145922 PMCID: PMC10457615 DOI: 10.1089/nat.2023.0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 03/23/2023] [Indexed: 05/07/2023] Open
Abstract
Preclinical evaluation of nucleic acid therapeutics (NATs) in relevant experimental model systems is essential for NAT drug development. As part of COST Action "DARTER" (Delivery of Antisense RNA ThERapeutics), a network of researchers in the field of RNA therapeutics, we have conducted a survey on the experimental model systems routinely used by our members in preclinical NAT development. The questionnaire focused on both cellular and animal models. Our survey results suggest that skin fibroblast cultures derived from patients is the most commonly used cellular model, while induced pluripotent stem cell-derived models are also highly reported, highlighting the increasing potential of this technology. Splice-switching antisense oligonucleotide is the most frequently investigated RNA molecule, followed by small interfering RNA. Animal models are less prevalent but also widely used among groups in the network, with transgenic mouse models ranking the top. Concerning the research fields represented in our survey, the mostly studied disease area is neuromuscular disorders, followed by neurometabolic diseases and cancers. Brain, skeletal muscle, heart, and liver are the top four tissues of interest reported. We expect that this snapshot of the current preclinical models will facilitate decision making and the share of resources between academics and industry worldwide to facilitate the development of NATs.
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Affiliation(s)
- Haiyan Zhou
- Genetics and Genomic Medicine Research and Teaching Department, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
- NIHR Great Ormond Street Hospital Biomedical Research Center, London, United Kingdom
| | - Virginia Arechavala-Gomeza
- Nucleic Acid Therapeutics for Rare Disorders (NAT-RD), Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Alejandro Garanto
- Department of Pediatrics, Amalia Children's Hospital, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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