Position-Specific 2′-F RNAi Duplex Composition for Lower Toxicity
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Solution Overview
Problem
Existing RNAi agents face challenges with stability, toxicity, and efficacy due to the use of non-natural nucleoside analogs like 2'-F modified nucleotides, particularly in determining the optimal positions and numbers for maintaining RNAi activity while minimizing toxic side effects.
Innovation Solution
The design of RNAi agents with specific patterns of 2'-fluoro modified nucleotides in the antisense strand, such as positions 2, 5, 12, 14, and 18, or other specific configurations, to enhance stability and reduce toxicity without compromising RNAi activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If 2'-F modified nucleotides are used throughout the duplex to improve stability, then RNAi agent stability is improved, but toxic side effects increase
Solution Approach 1:
The patent applies local quality by selectively placing 2'-F modifications only at specific positions (1, 3, 4, 8, 13, 15, 16, 17, 20, 21, 22, 23, 24, 25) in the antisense strand rather than uniformly throughout the duplex. This localized modification approach maintains stability at critical positions while avoiding toxic side effects by leaving other positions unmodified or using different modifications.
Solution Approach 2:
The patent changes the parameter of modification density and distribution by limiting 2'-F modifications to specific positions and numbers (e.g., no more than 3 at positions 1-5, no more than 2 at positions 6-10, etc.). This parameter optimization resolves the contradiction by finding the sweet spot between sufficient stability and minimal toxicity.
2Stability of the object's composition
If 2'-OMe modifications are used to improve metabolic stability, then metabolic stability is improved, but RNAi activity may be interfered with
Solution Approach 1:
The patent applies local quality by using 2'-OMe modifications selectively at specific positions rather than uniformly. The combination of 2'-F and 2'-OMe at different positions creates local variations that maintain both stability and activity, with 2'-F providing stability and 2'-OMe providing metabolic resistance while preserving RNAi function.
Solution Approach 2:
The patent uses composite modifications by combining 2'-F and 2'-OMe nucleotides in specific patterns within the same antisense strand. This composite approach leverages the advantages of both modification types - 2'-F for stability and 2'-OMe for metabolic resistance - while mitigating their individual disadvantages through strategic positioning.
3Stability of the object's composition
If phosphorothioate modifications are used to improve stability, then RNAi agent stability is improved, but innate immune system activation occurs
Solution Approach 1:
The patent applies local quality by using phosphorothioate modifications selectively at specific positions (particularly at the 3' end overhang regions) rather than throughout the entire duplex. This localized approach provides stability where needed while minimizing immune activation by avoiding excessive phosphorothioate content in the gene-silencing region.
Solution Approach 2:
The patent uses partial action by incorporating phosphorothioate modifications at only certain positions and in limited numbers, rather than fully modifying all positions. This partial modification strategy achieves sufficient stability improvement while staying below the threshold that triggers innate immune activation.
Data Source
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AI summary
One aspect of the present invention relates to an RNAi (dsRNA) duplex reagent capable of inhibiting the expression of a target gene. The dsRNA duplex has a F-modified nucleotide at a specific position in an antisense strand or sense strand. Other aspects of the present invention relate to a pharmaceutical composition comprising the dsRNA reagent suitable for therapeutic use and a method for inhibiting the expression of a target gene by administering the dsRNA reagent, such as for the treatment of various disease conditions.