Pachyonychia congenita clinical trial using therapeutic self-delivery siRNAs

描述（由申请人提供）：RNA干扰（RNAi）具有彻底改变显性遗传疾病治疗的潜力。小抑制rna （sirna）具有很强的效力和选择性，表现出显著的单核苷酸特异性。使用sirna的临床试验目前正在进行，用于包括皮肤在内的许多适应症。在1期资金的支持下，一项小型的1例患者的1b期临床试验进行了先天性肿甲（PC）。这种罕见的皮肤疾病是由编码角蛋白6、16和17的基因突变（包括单核苷酸变化）引起的。PC患者的主要抱怨是使人衰弱的疼痛的老茧和水泡发生在或靠近脚部的压力点。通过局部注射siRNA (TD101)，将脚底的这些特定区域作为局部siRNA治疗的目标，并取得了令人鼓舞的结果。不幸的是，与病灶注射相关的疼痛（需要口服止痛药和局部神经阻滞才能进行治疗）阻止了这种给药方式的广泛使用。这一观察结果促使人们努力确定对患者友好（即，很少或没有疼痛）的分娩方案。这项临床试验是人类首次在皮肤中使用siRNA，也是第一个针对突变基因的siRNA。在该提案的2期，我们延长了1期和1b期临床试验的进展。我们发现未修饰或稳定的sirna不容易被皮肤角质形成细胞吸收，但修饰的所谓“自我递送”（sd） sirna则容易被吸收。sd-siRNA的进一步优化将在小鼠和人类皮肤模型中进行，随后将合成用于小鼠和兔子毒理学研究的GMP材料和临床试验，其中siRNA将通过可溶解微针阵列或局部GeneCream配方递送，均由TransDerm开发和生产。GeneCream和微针阵列都是为了有效地递送sd-siRNA而设计的，几乎没有疼痛（微针的突出部分被设计成只穿透非神经支配的表皮）。虽然PC是一种罕见的疾病，但这种疾病的性质使其成为首次人体siRNA皮肤临床试验的理想原型皮肤病（定义突变，在有限的，确定的区域表达），我们完全期望吸取的经验教训将很容易推广到其他皮肤疾病。

DESCRIPTION (provided by applicant): RNA interference (RNAi) has the potential to revolutionize treatment of dominant genetic disorders. Small inhibitory RNAs (siRNAs) are highly potent and selective, demonstrating remarkable single-nucleotide specificity. Clinical trials using siRNAs are currently underway for a number of indications including skin. Facilitated by Phase 1 funding, a small one patient phase 1b clinical trial was undertaken for pachyonychia congenita (PC). This ultrarare skin disorder is caused by mutations, including single nucleotide changes, in the genes encoding keratins 6, 16, and 17. The major complaint of PC patients is the debilitating painful callusing and blistering which occurs on or near the pressure points of the feet. These defined regions on the soles of the feet were targeted for local siRNA treatment by intralesional injection of siRNA (TD101) with encouraging results. Unfortunately, the pain associated with injections into lesions (oral pain medication and regional nerve blocks were required to allow treatment), prevents widespread use of this mode of administration. This observation has led to intense efforts to identify patient-friendly (i.e., little or no pain) delivery options. This clinical trial was the first human use of siRNA in skin and also the first siRNA to target a mutated gene. In Phase 2 of this proposal, we extend the progress of Phase 1 and the Phase 1b clinical trial. We have found that unmodified or stabilized siRNAs are not taken up readily by skin keratinocytes but that modified, so-called "self-delivery" (sd) siRNAs are. Additional optimization of the sd-siRNA will be undertaken in mouse and human skin models followed by synthesis of GMP material for mouse and rabbit toxicology studies and clinical trials in which the siRNA will be delivered by dissolvable microneedle arrays or a topical GeneCream" formulation, both developed and manufactured at TransDerm. GeneCream and microneedle arrays are both designed to effectively deliver sd-siRNA with little or no pain (microneedle protrusions are designed to only penetrate to the non-innervated epidermis). Although PC is a rare disease, the nature of the disorder makes it an ideal prototype skin disorder (defined mutations with expression in limited, defined areas) for first-in-man siRNA skin clinical trials, and we fully expect the lessons learned will be readily generalized to other skin disorders. PUBLIC HEALTH RELEVANCE: Despite the discovery of the underlying mutations responsible for many inherited skin diseases, few effective treatments have emerged. The discovery that siRNAs can be developed to target specific disease-related mutations portends the advent of a new treatment paradigm. We have identified a potent and selective siRNA that targets a single nucleotide mutation in the keratin 6a gene that is responsible for the rare skin disorder pachyonychia congenita and blocks its expression. This siRNA (known to the FDA as TD101) was successfully tested in a Phase 1b clinical trial. Despite signs of efficacy, the painful nature of the administration route (intradermal injection of large volumes) required that we develop a more patient-friendly delivery system. Phase 2 of this proposal allows preclinical studies enabling a second clinical trial using microneedles loaded with a self-delivery version of TD101 siRNA. The lessons learned in applying siRNA technology for treatment of PC should be readily generalizable to a host of other dominant skin disorders and likely to other disorders resulting from mutated or overexpressed disease-causing genes.