Gene therapy for Dravet syndrome: promises and impact on disease trigger and secondary modifications

Abstract

Dravet syndrome is a severe epileptic syndrome that begins during the first year of life of otherwise healthy babies. Over the years, the seizure burden changes, and pathology evolves in strong association with behavioral alterations, including cognitive delay and autistic traits. Initially, this aspect was considered a direct consequence of epilepsy severity, and DS was defined as an epileptic encephalopathy. Increasing evidence suggests that these two aspects of the disease, epilepsy and behavioral impairment, might not be so strictly connected. DS is mostly caused by heterozygous loss-of-function mutations in the SCN1A gene, which encodes for the alpha subunit of the voltage-gated sodium channel Na_v1.1, responsible for GABAergic interneuron excitability. Interneuron dysfunction is evident at symptom onset in Dravet murine models, but their activity appears to recover in the chronic phase of the disease, when a series of secondary modifications arise and likely drive the phenotype. Given that the genetic basis of the disease is clear, innovative therapies based on the restoration of sufficient expression levels of Na_v1.1 to re-establish functional neuronal activity are being developed. In this work, we review such therapeutic approaches, with a specific focus on the existing evidence of their ability to address not only epilepsy but also behavioral alterations, and to recover secondary modifications.

Keywords

Gene therapy / secondary modifications / behavioral alterations / Dravet syndrome

References

[1] Zuberi SM,Yozawitz E.ILAE classification and definition of epilepsy syndromes with onset in neonates and infants: position statement by the ILAE task force on nosology and definitions.Epilepsia2022;63:1349-97

[2] Cooper MS,Crompton DE.Mortality in Dravet syndrome.Epilepsy Res2016;128:43-7

[3] Shmuely S,Gunning WB,Thijs RD.Mortality in dravet syndrome: a review.Epilepsy Behav2016;64:69-74

[4] Wolff M,Dravet C.Severe myoclonic epilepsy of infants (Dravet syndrome): natural history and neuropsychological findings.Epilepsia2006;47 Suppl 2:45-8

[5] Nabbout R,Chipaux M.Encephalopathy in children with Dravet syndrome is not a pure consequence of epilepsy.Orphanet J Rare Dis2013;8:176 PMCID:PMC4225757

[6] Gataullina S.From genotype to phenotype in Dravet disease.Seizure2017;44:58-64

[7] Darra F,Dravet C.Dravet syndrome: early electroclinical findings and long-term outcome in adolescents and adults.Epilepsia2019;60 Suppl 3:S49-58

[8] Jansson JS,Reilly C.Intellectual functioning and behavior in Dravet syndrome: a systematic review.Epilepsy Behav2020;108:107079

[9] Brown A,Schneider AL,Anderson VA.Cognitive, behavioral, and social functioning in children and adults with Dravet syndrome.Epilepsy Behav2020;112:107319

[10] Strzelczyk A,Wilmshurst JM.Dravet syndrome: a systematic literature review of the illness burden.Epilepsia Open2023;8:1256-70 PMCID:PMC10690674

[11] Depienne C,Saint-Martin C.Spectrum of SCN1A gene mutations associated with Dravet syndrome: analysis of 333 patients.J Med Genet2009;46:183-91

[12] Claes L,Ceulemans B,Van Broeckhoven C.De novo mutations in the sodium-channel gene SCN1A cause severe myoclonic epilepsy of infancy.Am J Hum Genet2001;68:1327-32 PMCID:PMC1226119

[13] Sun H,Liu X.Analysis of SCN1A mutation and parental origin in patients with Dravet syndrome.J Hum Genet2010;55:421-7

[14] Brunklaus A,Reavey E,Zuberi SM.Genotype phenotype associations across the voltage-gated sodium channel family.J Med Genet2014;51:650-8

[15] Xu X,Wu Q.Amplicon resequencing identified parental mosaicism for approximately 10% of “de novo” SCN1A mutations in children with Dravet syndrome.Hum Mutat2015;36:861-72 PMCID:PMC5034833

[16] Brunklaus A,Brünger T.Gene variant effects across sodium channelopathies predict function and guide precision therapy.Brain2022;145:4275-86 PMCID:PMC9897196

[17] Yu FH,Westenbroek RE.Reduced sodium current in GABAergic interneurons in a mouse model of severe myoclonic epilepsy in infancy.Nat Neurosci2006;9:1142-9

[18] Ogiwara I,Morita N.Na_v1.1 localizes to axons of parvalbumin-positive inhibitory interneurons: a circuit basis for epileptic seizures in mice carrying an Scn1a gene mutation.J Neurosci2007;27:5903-14 PMCID:PMC6672241

[19] Tai C,Westenbroek RE,Catterall WA.Impaired excitability of somatostatin- and parvalbumin-expressing cortical interneurons in a mouse model of Dravet syndrome.Proc Natl Acad Sci USA2014;111:E3139-48 PMCID:PMC4121787

[20] Cheah CS,Westenbroek RE.Specific deletion of Na_v1.1 sodium channels in inhibitory interneurons causes seizures and premature death in a mouse model of Dravet syndrome.Proc Natl Acad Sci USA2012;109:14646-51 PMCID:PMC3437823

[21] Dutton SB,Papale LA.Preferential inactivation of Scn1a in parvalbumin interneurons increases seizure susceptibility.Neurobiol Dis2013;49:211-20 PMCID:PMC3740063

[22] Ogiwara I,Miyamoto H.Na_v1.1 haploinsufficiency in excitatory neurons ameliorates seizure-associated sudden death in a mouse model of Dravet syndrome.Hum Mol Genet2013;22:4784-804 PMCID:PMC3820136

[23] Rubinstein M,Tai C.Dissecting the phenotypes of Dravet syndrome by gene deletion.Brain2015;138:2219-33 PMCID:PMC5022661

[24] Stern WM,Rothwell JC.Impaired intracortical inhibition demonstrated in vivo in people with Dravet syndrome.Neurology2017;88:1659-65 PMCID:PMC5405762

[25] Du J,Brunklaus A.Differential excitatory vs inhibitory SCN expression at single cell level regulates brain sodium channel function in neurodevelopmental disorders.Eur J Paediatr Neurol2020;24:129-33

[26] Ito S,Yamada K.Mouse with Na_v1.1 haploinsufficiency, a model for Dravet syndrome, exhibits lowered sociability and learning impairment.Neurobiol Dis2013;49:29-40

[27] Almog Y,Brusel M,Anderson K.Developmental alterations in firing properties of hippocampal CA1 inhibitory and excitatory neurons in a mouse model of Dravet syndrome.Neurobiol Dis2021;148:105209

[28] Yamagata T,Tatsukawa T.Scn1a-GFP transgenic mouse revealed Na_v1.1 expression in neocortical pyramidal tract projection neurons.Elife2023;12:e87495 PMCID:PMC10205085

[29] Jones SP,Muggeo S,Kullmann DM. Developmental instability of CA1 pyramidal cells in Dravet syndrome. BioRXiv 2022. Available from: https://www.biorxiv.org/content/10.1101/2022.09.12.507264v1 [Last accessed on 1 Jul 2024]

[30] Goff KM.Vasoactive intestinal peptide-expressing interneurons are impaired in a mouse model of Dravet syndrome.Elife2019;8:e46846 PMCID:PMC6629374

[31] Goff KM,Jiang E,Goldberg EM.VIP interneuron impairment promotes in vivo circuit dysfunction and autism-related behaviors in Dravet syndrome.Cell Rep2023;42:112628 PMCID:PMC10592464

[32] Favero M,Lopez E,Goldberg EM.A transient developmental window of fast-spiking interneuron dysfunction in a mouse model of Dravet syndrome.J Neurosci2018;38:7912-27 PMCID:PMC6125809

[33] Kaneko K,Goff KM.Developmentally regulated impairment of parvalbumin interneuron synaptic transmission in an experimental model of Dravet syndrome.Cell Rep2022;38:110580 PMCID:PMC9003081

[34] Mattis J,Goff KM.Corticohippocampal circuit dysfunction in a mouse model of Dravet syndrome.Elife2022;11:e69293 PMCID:PMC8920506

[35] Engel Jr J.A proposed diagnostic scheme for people with epileptic seizures and with epilepsy: report of the ILAE task force on classification and terminology.Epilepsia2001;42:796-803

[36] Chipaux M,Sabouraud P.Unusual consequences of status epilepticus in Dravet syndrome.Seizure2010;19:190-4

[37] de Lange IM,Sonsma ACM.Influence of contraindicated medication use on cognitive outcome in Dravet syndrome and age at first afebrile seizure as a clinical predictor in SCN1A-related seizure phenotypes.Epilepsia2018;59:1154-65

[38] Feng T,Dunwoody B.Long-term predictors of developmental outcome and disease burden in SCN1A-positive Dravet syndrome.Brain Commun2024;6:fcae004 PMCID:PMC10789590

[39] Catarino CB,Liagkouras I.Dravet syndrome as epileptic encephalopathy: evidence from long-term course and neuropathology.Brain2011;134:2982-3010 PMCID:PMC3187538

[40] Brunklaus A.Dravet syndrome-from epileptic encephalopathy to channelopathy.Epilepsia2014;55:979-84

[41] Gataullina S.Is epilepsy the cause of comorbidities in Dravet syndrome?.Dev Med Child Neurol2018;60:8

[42] Ragona F.Cognitive development in children with Dravet syndrome.Epilepsia2011;52 Suppl 2:39-43

[43] Wirrell EC.Recent advances in the drug treatment of Dravet syndrome.CNS Drugs2019;33:867-81

[44] Perry MS,Sullivan J.Severe communication delays are independent of seizure burden and persist despite contemporary treatments in SCN1A+ Dravet syndrome: insights from the ENVISION natural history study.Epilepsia2024;65:322-37

[45] Sullivan J.Dravet syndrome as an example of precision medicine in epilepsy.Epilepsy Curr2023;23:4-7 PMCID:PMC10009132

[46] Perez J,Musial C.Stiripentol: efficacy and tolerability in children with epilepsy.Epilepsia1999;40:1618-26

[47] Chiron C,Tran A.Stiripentol in severe myoclonic epilepsy in infancy: a randomised placebo-controlled syndrome-dedicated trial.Lancet2000;356:1638-42

[48] Inoue Y.STP-1 Study GroupLong-term safety and efficacy of stiripentol for the treatment of Dravet syndrome: a multicenter, open-label study in Japan.Epilepsy Res2015;113:90-7

[49] Devinsky O,Miller I.Long-term cannabidiol treatment in patients with Dravet syndrome: an open-label extension trial.Epilepsia2019;60:294-302 PMCID:PMC7379690

[50] Miller I,Gunning B.Dose-ranging effect of adjunctive oral cannabidiol vs placebo on convulsive seizure frequency in Dravet syndrome: a randomized clinical trial.JAMA Neurol2020;77:613-21 PMCID:PMC7052786

[51] Lagae L,Knupp K.Fenfluramine hydrochloride for the treatment of seizures in Dravet syndrome: a randomised, double-blind, placebo-controlled trial.Lancet2019;394:2243-54

[52] Schoonjans AS.A critical evaluation of fenfluramine hydrochloride for the treatment of Dravet syndrome.Expert Rev Neurother2022;22:351-64

[53] Sullivan J,Cross JH.Fenfluramine in the treatment of Dravet syndrome: results of a third randomized, placebo-controlled clinical trial.Epilepsia2023;64:2653-66

[54] Han S,Westenbroek RE.Autistic-like behaviour in Scn1a^+/− mice and rescue by enhanced GABA-mediated neurotransmission.Nature2012;489:385-90 PMCID:PMC3448848

[55] Bender AC,Ndong C,Scott RC.Focal Scn1a knockdown induces cognitive impairment without seizures.Neurobiol Dis2013;54:297-307 PMCID:PMC3628954

[56] Bender AC,Lenck-Santini PP.Cognitive deficits associated with Na_v1.1 alterations: involvement of neuronal firing dynamics and oscillations.PLoS One2016;11:e0151538 PMCID:PMC4792481

[57] Stein RE,Li J.Hippocampal deletion of Na_V1.1 channels in mice causes thermal seizures and cognitive deficit characteristic of Dravet syndrome.Proc Natl Acad Sci USA2019;116:16571-6 PMCID:PMC6697805

[58] Jansen NA,Breukel C,van den Maagdenberg AMJM.Focal and generalized seizure activity after local hippocampal or cortical ablation of Na_V1.1 channels in mice.Epilepsia2020;61:e30-6 PMCID:PMC7216883

[59] Jansen NA,Schenke M.Impaired θ-γ coupling indicates inhibitory dysfunction and seizure risk in a Dravet syndrome mouse model.J Neurosci2021;41:524-37 PMCID:PMC7821857

[60] Di Berardino C, Mainardi M, Brusco S, Benvenuto E, Broccoli V, Colasante G. Temporal manipulation of the Scn1a gene reveals its essential role in adult brain function.Brain2024;147:1216-30 PMCID:PMC10994529

[61] Riga MS,Miquel-Rio L.Scn1a haploinsufficiency in the prefrontal cortex engages to cognitive impairment and depressive phenotype.Brain2024;awae167

[62] Salgueiro-Pereira AR,Pousinha PA.A two-hit story: seizures and genetic mutation interaction sets phenotype severity in SCN1A epilepsies.Neurobiol Dis2019;125:31-44

[63] Catterall WA.Dravet syndrome: a sodium channel interneuronopathy.Curr Opin Physiol2018;2:42-50 PMCID:PMC6091224

[64] Mistry AM,Miller AR,George AL Jr.Strain- and age-dependent hippocampal neuron sodium currents correlate with epilepsy severity in Dravet syndrome mice.Neurobiol Dis2014;65:1-11 PMCID:PMC3968814

[65] Tsai MS,Chang CY.Functional and structural deficits of the dentate gyrus network coincide with emerging spontaneous seizures in an Scn1a mutant Dravet syndrome model during development.Neurobiol Dis2015;77:35-48

[66] Valassina N,Salamone A.Scn1a gene reactivation after symptom onset rescues pathological phenotypes in a mouse model of Dravet syndrome.Nat Commun2022;13:161 PMCID:PMC8748984

[67] Rubinstein M,Yu FH,Scheuer T.Genetic background modulates impaired excitability of inhibitory neurons in a mouse model of Dravet syndrome.Neurobiol Dis2015;73:106-17 PMCID:PMC4254180

[68] De Stasi AM,Marcon I.Unaltered network activity and interneuronal firing during spontaneous cortical dynamics in vivo in a mouse model of severe myoclonic epilepsy of infancy.Cereb Cortex2016;26:1778-94 PMCID:PMC4785957

[69] Almog Y,Brusel M.Functional investigation of a neuronal microcircuit in the CA1 area of the hippocampus reveals synaptic dysfunction in Dravet syndrome mice.Front Mol Neurosci2022;15:823640 PMCID:PMC8966673

[70] Hawkins NA,Huffman AM.Gene expression profiling in a mouse model of Dravet syndrome.Exp Neurol2019;311:247-56 PMCID:PMC6287761

[71] Shi X,Guo S.RNA-seq analysis of the SCN1A-KO model based on CRISPR/Cas9 genome editing technology.Neuroscience2019;398:1-11

[72] Mantegazza M.SCN1A/Na_V1.1 channelopathies: mechanisms in expression systems, animal models, and human iPSC models.Epilepsia2019;60 Suppl 3:S25-38

[73] Miljanovic N,van Dijk RM,Rezaei A.Proteomic signature of the Dravet syndrome in the genetic Scn1a-A1783V mouse model.Neurobiol Dis2021;157:105423

[74] Isom LL.Dravet syndrome: novel approaches for the most common genetic epilepsy.Neurotherapeutics2021;18:1524-34 PMCID:PMC8608987

[75] Lubroth P,Lignani G.In vivo genome editing therapeutic approaches for neurological disorders: where are we in the translational pipeline?.Front Neurosci2021;15:632522 PMCID:PMC7930815

[76] Carpenter JC.Gene editing and modulation: the holy grail for the genetic epilepsies?.Neurotherapeutics2021;18:1515-23 PMCID:PMC8608979

[77] Chilcott E,Bertram C,Karda R.Genetic therapeutic advancements for Dravet syndrome.Epilepsy Behav2022;132:108741

[78] Higurashi N,Hirose S.Genetics and gene therapy in Dravet syndrome.Epilepsy Behav2022;131:108043

[79] Ling Q,Bradbury A.AAV-based in vivo gene therapy for neurological disorders.Nat Rev Drug Discov2023;22:789-806

[80] Colasante G,Brusco S.dCas9-based Scn1a gene activation restores inhibitory interneuron excitability and attenuates seizures in Dravet syndrome mice.Mol Ther2020;28:235-53 PMCID:PMC6952031

[81] Yamagata T,Kobayashi K.CRISPR/dCas9-based Scn1a gene activation in inhibitory neurons ameliorates epileptic and behavioral phenotypes of Dravet syndrome model mice.Neurobiol Dis2020;141:104954

[82] Sera T.Zinc-finger-based artificial transcription factors and their applications.Adv Drug Deliv Rev2009;61:513-26

[83] Tanenhaus A,Young A.Cell-selective adeno-associated virus-mediated SCN1A gene regulation therapy rescues mortality and seizure phenotypes in a dravet syndrome mouse model and is well tolerated in nonhuman primates.Hum Gene Ther2022;33:579-97 PMCID:PMC9242722

[84] Han Z,Christiansen A.Antisense oligonucleotides increase Scn1a expression and reduce seizures and SUDEP incidence in a mouse model of Dravet syndrome.Sci Transl Med2020;12:eaaz6100

[85] Carvill GL,Ramamurthy A.Aberrant inclusion of a poison exon causes Dravet syndrome and related SCN1A-associated genetic epilepsies.Am J Hum Genet2018;103:1022-9 PMCID:PMC6288405

[86] Lim KH,Jeon HY.Antisense oligonucleotide modulation of non-productive alternative splicing upregulates gene expression.Nat Commun2020;11:3501 PMCID:PMC7347940

[87] Sparber P,Pyankov D.Functional investigation of SCN1A deep-intronic variants activating poison exons inclusion.Hum Genet2023;142:1043-53

[88] Avoli M,Di Cristo G.Ligand-gated mechanisms leading to ictogenesis in focal epileptic disorders.Neurobiol Dis2023;180:106097

[89] Christiansen A,Ravipaty S,Ji S. TANGO oligonucleotides for the treatment of Dravet syndrome: safety, biodistribution and pharmacology in the non-human prima. 2019. Available from: https://www.stoketherapeutics.com/wp-content/uploads/AES2019_cyno_pharmacology_poster_2.pdf [Last accessed on 1 Jul 2024].

[90] Stoke Therapeutics. Stoke therapeutics announces positive new safety & efficacy data from patients treated with STK-001 in the phase 1/2a studies (MONARCH & ADMIRAL) and the swallowtail open-label extension (OLE) study in children and adolescents with Dravet syndrome. 2023. Available from: https://investor.stoketherapeutics.com/news-releases/news-release-details/stoke-therapeutics-announces-positive-new-safety-efficacy-data/ [Last accessed on 1 Jul 2024]

[91] Stoke Therapeutics. Stoke therapeutics announces landmark new data that support the potential for STK-001 to be the first disease-modifying medicine for the treatment of patients with Dravet syndrome. Available from: https://investor.stoketherapeutics.com/node/9156/pdf [Last accessed on 1 Jul 2024]

[92] Cross JH,Sullivan J. Monarch and admiral: phase 1/2a studies in US and UK investigating safety and drug exposure of STK-001, an antisense oligonucleotide (ASO), in children and adolescents with Dravet syndrome (DS). 2023. Available from: https://aesnet.org/abstractslisting/monarch-and-admiral-phase-1-2a-studies-in-us-and-uk-investigating-safety-and-drug-exposure-of-stk-001-an-antisense-oligonucleotide-aso-in-children-and-adolescents-with-dravet-syndrome-ds [Last accessed on 1 Jul 2024]

[93] Desurkar A,Sullivan J. Swallowtail and longwing: open-label extension (OLE) studies for children and adolescents with Dravet syndrome (DS) who previously participated in a study of antisense oligonucleotide (ASO) STK-001. 2023. Available from: https://www.stoketherapeutics.com/wp-content/uploads/SWALLOWTAIL-LONGWING_Open-Label_Extension_-Studies_Children_and_Adolescents_with_Dravet_Syndrome_who_Previously_Participated_in_Study_of_Antisense.pdf [Last accessed on 1 Jul 2024].

[94] Stoke Therapeutics. Analysis of STK-001 for the treatment of Dravet syndrome. 2024. Available from: https://investor.stoketherapeutics.com/events/event-details/analysis-stk-001-treatment-dravet-syndrome/ [Last accessed on 1 Jul 2024].

[95] Sullivan J,Knupp KG.Adaptive functioning and neurodevelopment in patients with Dravet syndrome: 12-month interim analysis of the BUTTERFLY observational study.Epilepsy Behav2024;151:109604

[96] Mora-Jimenez L,Sanchez-Carpintero R.Transfer of SCN1A to the brain of adolescent mouse model of Dravet syndrome improves epileptic, motor, and behavioral manifestations.Mol Ther Nucleic Acids2021;25:585-602 PMCID:PMC8463324

[97] Fadila S,Dopeso-Reyes IG.Viral vector-mediated expression of Na_v1.1, after seizure onset, reduces epilepsy in mice with Dravet syndrome.J Clin Invest2023;133:e159316 PMCID:PMC10266792

[98] Mich JK,Wei AD. AAV-mediated interneuron-specific gene replacement for Dravet syndrome. BioRXiv 2023. Available from: https://www.biorxiv.org/content/10.1101/2023.12.15.571820v1 [Last accessed on 1 Jul 2024]

[99] Del Rio D,Lavigne M.CAV-2 vector development and gene transfer in the central and peripheral nervous systems.Front Mol Neurosci2019;12:71 PMCID:PMC6449469

[100] Ricobaraza A,Mora-Jimenez L,Hernandez-Alcoceba R.High-capacity adenoviral vectors: expanding the scope of gene therapy.Int J Mol Sci2020;21:3643 PMCID:PMC7279171

[101] Sakkaki S,Bender AC,Lenck-Santini PP.Focal dorsal hippocampal Na_v1.1 knock down alters place cell temporal coordination and spatial behavior.Cereb Cortex2020;30:5049-66 PMCID:PMC8475810

[102] Ricobaraza A,Gonzalez-Aparicio M.Preferential expression of SCN1A in GABAergic neurons improves survival and epileptic phenotype in a mouse model of Dravet syndrome.J Mol Med2023;101:1587-601 PMCID:PMC10697872

[103] Mennechet FJD,Ouoba AR.A review of 65 years of human adenovirus seroprevalence.Expert Rev Vaccines2019;18:597-613

[104] Soudais C,Kissa K.Preferential transduction of neurons by canine adenovirus vectors and their efficient retrograde transport in vivo.FASEB J2001;15:2283-5

[105] Salinas S,Henaff D.CAR-associated vesicular transport of an adenovirus in motor neuron axons.PLoS Pathog2009;5:e1000442 PMCID:PMC2677547

[106] Stevens AJ,Shah NH,Cowburn D.Design of a split intein with exceptional protein splicing activity.J Am Chem Soc2016;138:2162-5 PMCID:PMC4894280

[107] Hensch TK.Critical period plasticity in local cortical circuits.Nat Rev Neurosci2005;6:877-88

[108] Hübener M.Neuronal plasticity: beyond the critical period.Cell2014;159:727-37

[109] Leslie JH.Activity-regulated genes as mediators of neural circuit plasticity.Prog Neurobiol2011;94:223-37 PMCID:PMC3134580

[110] Schaefer N,Blumrich EM.The malleable brain: plasticity of neural circuits and behavior - a review from students to students.J Neurochem2017;142:790-811

[111] Yuan Y,Denomme N.Antisense oligonucleotides restore excitability, GABA signalling and sodium current density in a Dravet syndrome model.Brain2024;147:1231-46 PMCID:PMC10994531