Directing Splicing of SCN8A to Treat Dravet Syndrome

指导 SCN8A 剪接治疗 Dravet 综合征

• 批准号: 8931074
• 负责人: MELANIE K TALLENT
• 金额: $ 34.52万
• 依托单位: LIFESPLICE PHARMA, LLC
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-30 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8931074
• 关键词: Adult; Adverse effects; Age; Alternative Splicing; Amino Acids; Antiepileptic Agents; Ataxia; Behavior; Binding; Boxing; Cessation of life; Child; Childhood; Computer Simulation; Data; Development; Disease; Dose; Elements; Eligibility Determination; Engineering; Epilepsy; Equilibrium; Event; Exhibits; Exons; Family; Febrile Convulsions; Flurothyl; Generalized Epilepsy; Genes; Goals; Health; Interneurons; Kinetics; Knock-out; Learning; Light; Longevity; Measures; Mediating; Messenger RNA; Molecular; Motor; Mus; Mutant Strains Mice; Mutation; Myoclonic Epilepsies; Neonatal; Oligonucleotides; Patients; Pharmaceutical Preparations; Pharmacotherapy; Phenotype; Predisposition; Process; Production; Property; Protein Isoforms; RNA; RNA Splicing; Recurrence; Resistance; Risk; SCN8A gene; Safety; Seizures; Severities; Site; Sodium; Sodium Channel; Sodium Channel Blockers; Specificity; Structure; Syndrome; Testing; Therapeutic; Thermodynamics; Time; Transcript; Tremor; base; behavioral impairment; design; drug candidate; excitatory neuron; exon skipping; in vivo; infancy; interest; loss of function mutation; mRNA Precursor; member; motor disorder; mouse model; mutant; novel; novel strategies; research study; response; tool; voltage

 DESCRIPTION (provided by applicant): Dravet Spectrum disorders resulting from SCN1A loss-of-function mutations include febrile seizures, generalized epilepsy with febrile seizure plus (GEFS+), and Dravet syndrome (severe myoclonic epilepsy of infancy or SMEI), in order of increasing severity. In the most severe cases, progressive developmental and behavioral impairments manifest along with the recurrent and varied seizure episodes that advance to include multiple seizure types by age 2. In many patients, seizures are resistant to currently available antiepileptic drugs. Thus, there is a significant and urgent need for the development of novel approaches to therapy. SCN1 channel function in inhibition is functionally opposed by the related SCN8 channel. Thus, a validated and logical strategy for rebalancing the deficit of inhibitory input caused by SCN1A loss-of-function mutation is to specifically reduce SCN8-mediated excitation. VGS channel alpha subunits undergo several alternative splicing events which regulate the inhibitory and excitatory balance of sodium currents in the CNS. SCN8A subunits are naturally alternatively spliced at two specific sites of interest which control channe function or kinetics. A novel strategy to reduce SCN8A- mediated excitation and seizures associated with SCN1A loss-of-function mutations as a treatment for DS is to direct splicing at each of these sites by developing compounds called splice modulating oligonucleotides (SMOs). SMOs are a class of synthetic RNA based compounds that sterically block or weaken interactions between elements of the splice machinery and the pre-mRNA. SMOs are ideal but under-developed drug candidates as they bind to their targets with exceptional potency, specificity, and negligible off-target effects. SMOs targeting SCN8A splicing will designed in silico and refined for potency and specificity in vivo (Aim 1) leading to an SMO drug candidate for each splice site. Each SMO candidate will be characterized by dose-response in normal mice at P10-42 days, and SMO dose-effect on flurothyl-induced seizure threshold evaluated in normal mice (Aim 2). Finally, SMOs will be evaluated as therapeutics in SNN1A R1648H mutant mice (Aim 3), for effects on longevity, motor function (ataxia, tremor) and flurothyl-induced seizure susceptibility. Safety and efficacy of SMO treatment will further be assessed for both positive and adverse effects on behavior in adult heterozygous SCN1A R1648H mice, which have a normal lifespan. The strategy of specifically reducing only the Na+ channel (SCN8A) that counterbalances SCN1A input should be more efficacious and be much less likely to cause unwanted effects than using sodium channel blockers which antagonize multiple VGS channels. The ultimate goal is to develop these SMOs as potential therapeutic for the treatment of Dravet Syndrome and related disorders in patients resistant to currently available pharmacotherapies.

 描述（由申请人提供）：由 SCN1A 功能丧失突变引起的 Dravet 谱系疾病包括热性惊厥、伴有热性惊厥的全身性癫痫 (GEFS+) 和 Dravet 综合征（婴儿期严重肌阵挛性癫痫或 SMEI），按严重程度递增的顺序排列。在最严重的病例中，会出现进行性发育和行为障碍，并伴有反复发作的各种癫痫发作，到 2 岁时，癫痫发作会发展为多种癫痫类型。在许多患者中，癫痫发作对目前可用的抗癫痫药物有耐药性。因此，迫切需要开发新的治疗方法。 SCN1 通道的抑制功能在功能上与相关的 SCN8 通道相反。因此，重新平衡 SCN1A 功能丧失突变引起的抑制输入缺陷的一个经过验证且合乎逻辑的策略是专门减少 SCN8 介导的兴奋。 VGS 通道 α 亚基经历多个选择性剪​​接事件，调节 CNS 中钠电流的抑制性和兴奋性平衡。 SCN8A 亚基自然地交替剪接在两个控制通道功能或动力学的特定感兴趣位点。作为 DS 治疗方法，减少 SCN8A 介导的与 SCN1A 功能丧失突变相关的兴奋和癫痫发作的新策略是通过开发称为剪接调节寡核苷酸 (SMO) 的化合物来直接在每个位点进行剪接。 SMO 是一类基于合成 RNA 的化合物，可在空间上阻断或削弱剪接机制元件与前 mRNA 之间的相互作用。 SMO 是理想但尚未开发的候选药物，因为它们以卓越的效力、特异性和可忽略不计的脱靶效应与靶标结合。 针对 SCN8A 剪接的 SMO 将通过计算机设计并针对体内效力和特异性进行改进（目标 1），从而为每个剪接位点提供 SMO 候选药物。每个 SMO 候选药物将通过 P10-42 天时正常小鼠的剂量反应来表征，并在正常小鼠中评估 SMO 对氟草酯诱导的癫痫阈值的剂量效应（目标 2）。最后，将评估 SMO 作为 SNN1A R1648H 突变小鼠的治疗方法（目标 3），以评估其对寿命、运动功能（共济失调、震颤）和氟洛酯诱导的癫痫易感性的影响。将进一步评估 SMO 治疗对具有正常寿命的成年杂合 SCN1A R1648H 小鼠行为的积极和不利影响的安全性和有效性。与使用拮抗多个 VGS 通道的钠通道阻滞剂相比，专门减少仅抵消 SCN1A 输入的 Na+ 通道 (SCN8A) 的策略应该更有效，并且引起不良影响的可能性要小得多。最终目标是开发这些 SMO 作为治疗 Dravet 综合征和对当前药物疗法耐药的患者相关疾病的潜在疗法。