Engineered RNA replicon vector platform for skin inflammatory disease therapy

Overview

RNA-based therapeutics have emerged as a powerful alternative to conventional gene therapy, highlighted by the success of COVID-19 RNA vaccines. However, a major limitation of RNA molecules is their short half-life in vivo, which restricts therapeutic efficacy. Self-amplifying RNA (saRNA) vectors address this challenge by replicating within target cells to produce sustained protein expression. This proposal introduces a novel engineered Sindbis-based RNA replicon vector optimized for durable and high-level transgene expression in skin tissue. The platform is designed to deliver anti-inflammatory cytokines and other therapeutic cargo genes for the treatment of skin inflammatory disorders, with psoriasis serving as the initial proof-of-concept indication.

Technical specifications

• Novel Sindbis replicon vector identified through a continuous directed evolution platform leveraging the intrinsic mutagenic potential of RNA replicons in primary skin keratinocytes
• Unique double mutations in the Sindbis genome that significantly enhance durability and expression potency both in vitro and in vivo, while circumventing innate immune reactions and cytopathic effects typically associated with replicon amplification
• Self-amplifying RNA design enables sustained production of therapeutic cargo proteins under a subgenomic promoter, overcoming the short half-life limitation of standard RNA therapeutics
• Lipid nanoparticle (LNP) delivery compatible with both intradermal injection and topical application for flexible skin-targeted administration
• Human skin organoid and xenograft models planned for evaluating therapeutic efficacy in human skin tissue
• Mechanistic studies using RNA-seq and host cell protein synthesis analysis to characterize innate immune responses and transcriptional changes triggered by the engineered replicon

Technology readiness level

The technology is currently at an early-to-mid preclinical stage. The engineered Sindbis replicon vector has been validated in vitro in primary skin keratinocytes with intact innate immune responses, demonstrating enhanced durability and expression potency. In vivo validation has shown promising results for transgene delivery in skin. Ongoing and planned studies include engineering the replicon to express anti-inflammatory cytokines, testing LNP-based intradermal and topical delivery in psoriasis animal models, and evaluating efficacy in human skin organoid and xenograft systems. Further optimization of vector design will be guided by mechanistic studies of host cell responses.