Radiolabeled Oligonucleotides via Stable Nucleoside Precursors

Solution Overview

Problem

Current methods for radiolabeling oligonucleotides face limitations such as low radiochemical yield, dilution problems, and stringent storage requirements due to the introduction of radioisotopes in the first step of synthesis, leading to lower specific activity and instability of phosphoramidite precursors.

Innovation Solution

A novel radiolabeled oligonucleotide with a specific structure and synthesis process involving a radiolabeled C1-6 alkyl group and a receptor targeting moiety, such as the GalNAc moiety, is developed, allowing for high specific activity and stability through conjugation with a radiolabeled maleimide compound, enabling effective biodistribution and pharmacokinetic studies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If radioisotopes are introduced in the first step of synthesis using phosphoramidite chemistry, then oligonucleotides can be radiolabeled, but the radiochemical yield is limited and specific activity is reduced due to dilution with natural abundance isotopes

Engineering Contradiction:

Improvespecific activityVSAvoidradiochemical yield

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The radioisotope is incorporated into the nucleoside building block before oligonucleotide assembly, ensuring that every nucleotide unit carries the radioactive label. This preliminary incorporation eliminates dilution effects and maximizes specific activity from the outset of the synthesis process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the isotopic composition parameter by using nucleosides where all hydrogen atoms are replaced with tritium (3H) or all carbon atoms are replaced with carbon-14 (14C). This complete isotopic substitution achieves maximum specific activity (e.g., 28.8 TBq/mmol for tritium-labeled nucleosides) without dilution from natural abundance isotopes

Inventive Principle:

Principle #35Parameter changes

2Reliability

If phosphoramidite precursors with radioisotopes are used, then radiolabeled oligonucleotides can be synthesized, but the precursors are reactive and prone to degradation requiring stringent storage and transportation

Engineering Contradiction:

Improvestability of radiolabeled productVSAvoidstorage and transportation requirements

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts the radioisotope from the labile phosphoramidite precursor and incorporates it into a stable nucleoside building block. This separation removes the radioactive component from the degradation-prone phosphoramidite chemistry, allowing the radiolabeled nucleosides to be stored and transported under常规 conditions without special precautions

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The radioisotope is incorporated into the nucleoside structure in advance, creating a stable, non-reactive precursor that can be stored long-term. The radioactive label is locked into the stable nucleoside framework before the actual oligonucleotide assembly, preventing degradation during storage and transportation

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If natural abundance isotopes are blended as carrier to maintain manageable synthetic scale, then synthesis can proceed at practical scales, but the specific activity of the final oligos is reduced

Engineering Contradiction:

Improvespecific activityVSAvoiddilution with carrier isotope

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The invention changes the isotopic composition parameter by using nucleosides where all hydrogen atoms are replaced with tritium (3H) or all carbon atoms are replaced with carbon-14 (14C). This complete isotopic substitution achieves maximum specific activity (e.g., 28.8 TBq/mmol for tritium-labeled nucleosides) without dilution from natural abundance isotopes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The radioisotope is incorporated into the nucleoside building block before oligonucleotide assembly, ensuring that every nucleotide unit carries the radioactive label. This preliminary incorporation eliminates dilution effects and maximizes specific activity from the outset of the synthesis process

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230087946A1Radiolabeled MOEM type oligonucleotides and process for their preparation

Publication Date: 2023.03.23 F HOFFMANN LA ROCHE INC

AI summary

The invention comprises radiolabeled MOEM type oligonucleotide of the formula (I), (I) wherein n, X1, X2, the linker (1), the linker (2), Q* and the receptor targeting moiety are as defined (I) the description. The radiolabeled oligonucleotides of the formula (I) can be used for the determination of the biodistribution and pharmacokinetics of the oligonucleotide in the tissue or body fluid.