Therapeutic siRNAs for dominant genetic skin disorders including pachyonychia congenita

Abstract

The field of science and medicine has experienced a flood of data and technology associated with the human genome project. Over 10,000 human diseases have been genetically defined, but little progress has been made with respect to the clinical application of this knowledge. A notable exception to this exists for pachyonychia congenita (PC), a rare, dominant-negative keratin disorder. The establishment of a non-profit organization, PC Project, has led to an unprecedented coalescence of patients, scientists, and physicians with a unified vision of developing novel therapeutics for PC. Utilizing the technological by-products of the human genome project, such as RNA interference (RNAi) and quantitative RT-PCR (qRT-PCR), physicians and scientists have collaborated to create a candidate siRNA therapeutic that selectively inhibits a mutant allele of KRT6A, the most commonly affected PC keratin. In vitro investigation of this siRNA demonstrates potent inhibition of the mutant allele and reversal of the cellular aggregation phenotype. In parallel, an allele-specific quantitative real-time RT-PCR assay has been developed and validated on patient callus samples in preparation for clinical trials. If clinical efficacy is ultimately demonstrated, this "first-in-skin" siRNA may herald a paradigm shift in the treatment of dominant-negative genetic disorders.

Increased interstitial pressure improves nucleic acid delivery to skin enabling a comparative analysis of constitutive promoters

“…pCMV-hMGFP/CBL, pTD151, pTD153 and pTD154 (10 mg in 50 ml PBS) were intradermally injected into mouse footpads as described above. Mice were killed at various time points (6,15,24,48,72 and 144 h for analysis of pCMV-hMGFP/CBL expression) and at 24 h (for pTD plasmids) after i.d. injection.…”

“…Although skin represents a promising target (due to large unmet clinical needs, easy access to tissue and relative ease of monitoring 1 ), only a few clinical trials have been carried out in the last decade, with the majority related to the treatment of melanoma. 2,3 A large number of genetic skin disorders, that have few if any treatment options, are amenable to gene therapy [4][5][6][7] but efforts to translate such approaches to the clinic are hampered by the difficulty of delivering nucleic acids across tissue and cellular barriers.…”

Therapeutic targeting in the silent era: advances in non-viral siRNA delivery

“…Given the ease of access to the eye and that the use of naked siRNA is effective in these cases, the most progress to date is in the treatment of eye diseases [132] . Age-related macular keratoderma with no disease specific treatment currently available [133] . In association with the Pachyonychia Congenita Project, TransDerm are performing a clinical trial into the effectiveness of TD101, an siRNA targeting mutations in N171K and more specifically the keratin K6a [133] .…”

Molecular genetics of the skin: the implications of understanding

“…[9][10][11] For other disorders caused by dominant dystrophic gene defects, knockdown of gene expression using small interfering RNAs (siRNA) offers a prospect of specific therapy. 12 In disorders due to premature termination codons, agents promoting read-through may permit restoration of gene expression. 13 Despite proof of principle for many of these approaches, practical delivery remains challenging.…”