Novel RNA Replicon Vector For Efficient Gene Delivery To The Skin

SUMMARY

A Sindbis virus-based self-amplifying RNA vector has been engineered for long-lasting, safe gene expression in skin cells, aiming to treat genetic skin disorders like recessive X-linked ichthyosis by restoring missing genes with improved durability and reduced side effects.

The Unmet Need: Gene delivery systems for high level-expression of therapeutic genes in skin cells

• Genetic skin disorders, such as recessive X-linked ichthyosis (RXLI), represent a significant clinical challenge due to their chronic nature and limited treatment options. RXLI, caused by mutations in the STS gene, leads to abnormal skin scaling and hyperkeratosis, severely impacting patient quality of life. Traditional therapies for RXLI are largely symptomatic, focusing on moisturizing and exfoliating agents that provide only temporary relief and do not address the underlying genetic defect. As a result, there is a pressing need for more effective and durable treatments that can correct the root cause of the disease. Gene therapy has emerged as a promising approach for such monogenic disorders, offering the potential to restore normal gene function directly within affected tissues, such as skin keratinocytes.

• Despite the promise of gene therapy, current approaches face significant limitations. Viral vectors, while efficient at delivering genetic material, pose risks of insertional mutagenesis and can provoke strong immune responses, potentially leading to adverse effects and reduced efficacy. Non-viral RNA-based therapeutics offer a safer alternative, but their clinical utility is hampered by the inherent instability and short half-life of RNA molecules in vivo, resulting in transient gene expression. Self-amplifying RNA (saRNA) vectors have been developed to address this by enabling intracellular RNA replication and prolonged expression; however, these systems often trigger cytopathic effects and innate immune responses that ultimately curtail their effectiveness. Thus, there remains a critical unmet need for gene delivery systems that can achieve persistent, high-level expression of therapeutic genes in skin cells without eliciting significant cytotoxicity or immune-mediated clearance.

The Proposed Solution: RNA replicon engineering for treatment of skin genetic disease

• The faculty inventor developed a Sindbis virus-derived RNA replicon vector engineered for persistent and high-level gene expression in skin keratinocytes. The vector utilizes self-amplifying RNA functions, mediated by viral nonstructural proteins, and has been optimized through directed evolution under selection pressure. Key mutations in the replicon enable robust expression of therapeutic genes, such as the STS gene for treating recessive X-linked ichthyosis (RXLI), while minimizing cytotoxicity and maintaining innate immune responses.

• Unlike conventional viral vectors, which risk insertional mutagenesis and provoke strong immune responses, this RNA replicon avoids genomic integration and is engineered to reduce cytopathic effects. The directed evolution approach, uniquely enables the identification of mutations that balance high gene expression with cell viability, a challenge for previous saRNA systems. This results in a platform capable of long-term, high-level therapeutic gene expression in skin cells, with broad potential for treating genetic skin disorders and beyond. The technology’s adaptability, safety profile, and ability to maintain efficacy in the presence of innate immune responses set it apart from existing gene therapy and RNA-based approaches.

ADVANTAGES

ADVANTAGES

• Enables persistent and high-level gene expression in primary skin keratinocytes through self-amplifying RNA technology

• Reduces cytotoxicity and innate immune response typically associated with viral RNA replication via specific mutations

• Offers a safer alternative to traditional viral vectors by minimizing risks of insertional mutagenesis and immune reactions

APPLICATIONS

• Gene delivery

• Long-term protein expression in keratinocytes

• RNA-based treatment for RXLI

• Preclinical testing in skin organoids

• Demonstrates efficacy in both preclinical mouse models and human 3-D skin organotypic cultures