Biocompatible Copolymer Drug Carriers for High-DAR Targeted Delivery

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Solution Overview

Problem

Existing drug-conjugate technologies, such as antibody-drug conjugates (ADCs) and aptamer-drug conjugates, suffer from heterogeneity, low drug-to-carrier ratios (DAR), stability issues, and rapid systemic clearance, limiting their efficacy and clinical application.

Innovation Solution

A biocompatible, hydrophilic, non-degradable copolymer is used as a carrier for active agents, allowing site-specific coupling to antibodies or aptamers, enabling high DAR and maintaining target affinity, with linkers designed for stability and controlled release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If free amino groups in antibodies are used to attach cytotoxic drugs, then high drug-to-antibody ratios can be achieved, but heterogeneity increases due to indiscriminate functionalization

Engineering Contradiction:

Improvedrug-to-antibody ratioVSAvoidhomogeneity of ADC species

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent introduces site-specific attachment at engineered cysteine residues in the Fc region, creating localized drug attachment zones rather than random distribution. This ensures homogeneous DAR (e.g., DAR=4) while achieving high drug loading, resolving the contradiction between quantity and precision.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs engineered cysteine residues as intermediary attachment sites between the antibody and cytotoxic drugs. These specific cysteines serve as controlled intermediaries that enable precise drug conjugation, eliminating the heterogeneity caused by direct attachment to multiple amino groups.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If inter-chain disulfide bridges are reduced to generate free thiol groups for drug attachment, then site specificity improves, but antibody stability deteriorates

Engineering Contradiction:

Improvesite specificity of drug attachmentVSAvoidantibody integrity

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent incorporates engineered cysteine residues with free thiol groups directly into the antibody sequence during antibody production, rather than reducing disulfide bridges afterward. This preliminary incorporation maintains disulfide bridge integrity and antibody stability while providing predetermined site-specific attachment locations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent separates the functions of structural integrity (maintained by native disulfide bridges) and drug attachment (provided by engineered cysteines). This segmentation allows site-specific conjugation without compromising antibody stability, as the engineered cysteines are distinct from the structural disulfide bonds.

Inventive Principle:

Principle #1Segmentation

3Productivity

If multiple cytotoxic entities are coupled to antibodies, then therapeutic efficacy improves, but rapid clearance from bloodstream occurs

Engineering Contradiction:

Improvetherapeutic efficacyVSAvoidbloodstream circulation time

Core Design Contradiction:

ProductivityVSDuration of action of moving object

Solution Approach 1:

The patent optimizes the drug-to-antibody ratio parameter to specific values (e.g., DAR=2 or DAR=4) rather than maximizing drug loading indiscriminately. This controlled parameter adjustment maintains therapeutic efficacy while preserving bloodstream circulation time, as excessive drug loading that causes rapid clearance is avoided.

Inventive Principle:

Principle #35Parameter changes

4Manufacturing precision

If maleimide-based linkers are used for drug attachment, then homogeneity improves, but drug release at target site becomes problematic due to serum albumin reaction

Engineering Contradiction:

Improvehomogeneity of ADCVSAvoidtargeted drug release

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent removes the problematic maleimide linker from the system and replaces it with direct thiol-cysteine conjugation or alternative stable linkers. This extraction eliminates the side reaction with serum albumin that causes unintended drug release, while maintaining homogeneous drug attachment through site-specific cysteine conjugation.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12558432B2Biocompatible polymeric drug carriers for delivering active agents

Publication Date: 2026.02.24 CIS BIOPHARMA AG

AI summary

The present disclosure relates to the delivery of multiple copies of a payload molecule such as an active agent or a chelating agent capable of capturing an active agent, using as a carrier for their delivery a biocompatible copolymer comprising side chain-linked amino acids functionalized at their alpha-amino group by a reactive azide moiety by means of which the payload molecules are coupled to the copolymer. The copolymer is typically further functionalized to contain a single copy of a cell type- or tissue type-specific targeting moiety.