HTT RNAi Agent Compositions for Selective Gene Silencing
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Solution Overview
Problem
Current treatments for Huntington's disease lack an effective agent that can selectively and efficiently silence the HD gene using the cell's own RNAi machinery, with high biological activity and in vivo stability, to inhibit the expression of the Huntingtin gene effectively.
Innovation Solution
Development of RNAi agent compositions that target intron 1 retained in the truncated mutant HTT gene, using double-stranded ribonucleic acid (dsRNA) to inhibit the expression of the truncated mutant HTT transcript encoding an expanded polyglutamine repeat while sparing the full-length wild-type HTT transcript.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RNAi agents are used to silence the HD gene, then gene silencing activity is achieved, but in vivo stability is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of RNAi agents through various modifications including 2'-O-methyl, 2'-fluoro, phosphorothioate backbone modifications, and conjugation to lipophilic moieties or GalNAc. These chemical parameter changes enhance in vivo stability while preserving gene silencing activity, directly resolving the contradiction between reliability and stability.
Solution Approach 2:
The patent employs composite materials by combining RNAi agents with lipophilic moieties, cell-penetrating peptides, or GalNAc conjugates. These composite structures improve cellular uptake and in vivo stability while maintaining the core gene silencing function, thereby resolving the contradiction between gene silencing activity and in vivo stability.
2Reliability
If RNAi agents are designed to target mutant HTT transcripts, then selective silencing is achieved, but efficiency and biological activity are insufficient
Solution Approach 1:
The patent applies local quality by designing RNAi agents with specific target sequences that recognize unique regions of mutant HTT transcripts, particularly focusing on the expanded polyglutamine repeat region and intron 1. This localized targeting ensures selective silencing of mutant transcripts while preserving wild-type HTT expression, and the local chemical modifications enhance biological activity at the target site.
Solution Approach 2:
The patent uses parameter changes by optimizing the length, sequence, and chemical modifications of RNAi agents to maximize binding affinity to mutant HTT transcripts. Modifications such as 2'-O-methyl and phosphorothioate enhance both selectivity and biological activity, resolving the contradiction between selective silencing and efficiency.
3Object-affected harmful factors
If antipsychotics are used to suppress choreic movements, then symptom management is achieved, but adverse effects occur
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the harmful effect of mutant HTT protein accumulation into a beneficial therapeutic outcome through selective gene silencing. By using RNAi agents to specifically target and degrade mutant HTT transcripts, the treatment addresses the root cause of choreic movements without producing the adverse effects associated with antipsychotic medications, thereby resolving the contradiction between symptom suppression and adverse effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The RNAi agent compositions achieve targeted degradation of HTT gene transcripts, potentially providing a therapeutic approach to reduce the expression of the Huntingtin protein in Huntington's disease, offering improved efficacy and stability.
Implementation Method 1
the antisense strand comprises a region of complementarity to intron 1 retained in mutant HTT mRNA
Implementation Method 2
RNAi agent compositions which effect the RNA-induced silencing complex (RISC)-mediated cleavage of RNA transcripts of a mutant huntingin (HTT) gene
Data Source
AI summary
The disclosure relates to double stranded ribonucleic acid (dsRNAi) agents and compositions targeting a Huntingtin (HTT) gene, as well as methods of inhibiting expression of an HTT gene and methods of treating subjects having an HTT-associated disease or disorder, e.g., Huntington's disease, using such dsRNAi agents and compositions.