Morpholino Oligomers with Cationic Linkages for Antisense Activity
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Solution Overview
Problem
Existing antisense oligonucleotides face challenges with stability, membrane permeability, and sequence specificity, particularly due to electrostatic repulsion and non-specific binding, which limits their therapeutic efficacy.
Innovation Solution
Development of morpholino oligomers with a backbone of phosphorodiamidate linkages containing 20-50% cationic intersubunit linkages, including (1-piperazino) phosphinylideneoxy and (1-(4-(ω-guanidino-alkanoyl))-piperazino) phosphinylideneoxy linkages, to enhance binding affinity and specificity to target nucleic acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If negatively charged linkages (phosphorothioate) are used in oligonucleotides, then binding affinity to target nucleic acid is improved, but electrostatic repulsion and non-specific binding increase, reducing therapeutic efficacy
Solution Approach 1:
The patent changes the charge parameter of the intersubunit linkages from negative (phosphorothioate) or neutral (methylphosphonate) to positive by introducing cationic groups such as guanidinium, piperazino, and arginine-containing linkages. This parameter change reverses the electrostatic interaction with the negatively charged phosphate backbone of target nucleic acids, eliminating repulsion and enabling strong electrostatic attraction that enhances binding affinity while reducing non-specific binding to cellular components.
Solution Approach 2:
The patent creates composite linkage structures that combine morpholino ring structures with cationic intersubunit linkages containing basic side chains (guanidinium, piperazino, arginine). These composite materials integrate the nuclease resistance of morpholino backbones with the electrostatic binding advantages of cationic linkages, achieving both stability and enhanced target affinity without the drawbacks of purely anionic or neutral oligonucleotides.
2Ease of operation
If uncharged linkages (methylphosphonate) are used in oligonucleotides, then cellular uptake is improved, but binding affinity and antisense activity are reduced
Solution Approach 1:
The patent changes the charge parameter from neutral (methylphosphonate) to positive by incorporating cationic intersubunit linkages. This modification maintains the improved cellular uptake characteristics of uncharged oligonucleotides while adding electrostatic attraction to enhance binding affinity to the negatively charged phosphate backbone of target nucleic acids, thereby achieving both good cellular penetration and strong antisense activity.
3Strength
If cationic linkages are introduced to enhance binding affinity, then antisense activity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the oligonucleotide backbone into morpholino ring units connected by standardized cationic intersubunit linkages. This segmentation allows for modular synthesis where each linkage type (guanidinium, piperazino, arginine-containing) can be incorporated using established solid-phase synthesis methods, managing manufacturing complexity through systematic assembly of repeating units with defined cationic characteristics.
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 cationic linkages improve the oligomers' ability to bind specifically to DNA and RNA, increasing their antisense activity and cellular uptake, thereby enhancing their therapeutic potential by up to tenfold in cell-free and cell-based assays.
Implementation Method 1
The pendant group bears a distal nitrogen atom that can bear a positive charge at neutral or near-neutral pH... improve the oligomers' ability to bind specifically to DNA and RNA
Data Source
AI summary
Morpholino oligomers containing both uncharged and cationic intersubunit linkages are provided. The oligomers are oligonucleotide analogs containing predetermined sequences of base-pairing moieties. The presence of the cationic intersubunit linkages in the oligomers, typically at a level of about 10-50% of total linkages, provides enhanced antisense activity, in various antisense applications, relative to the corresponding uncharged oligomers. Also provided are such oligomers conjugated to peptide transporter moieties, where the transporters are preferably composed of arginine subunits, or arginine dimers, alternating with neutral amino acid subunits.