Cleavable Polymer Drug Conjugates for Targeted Cancer Therapy
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Solution Overview
Problem
Current chemotherapy agents for cancer treatment are cytotoxic and have limited therapeutic benefit due to uncontrolled distribution throughout the body, leading to severe side effects and low drug concentration at tumor sites, with existing polymer-drug conjugates facing issues of low drug loading, aggregation, and premature drug release in the bloodstream before reaching the target tissue.
Innovation Solution
A polymer-drug conjugate with a (meth)acrylate-based backbone featuring PEG side chains and a cleavable linker, allowing for selective drug release at the tumor site, reducing toxicity and improving pharmacokinetic profiles by prolonging circulation time and enhancing drug concentration at targeted tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemotherapy agents are administered to treat cancer, then therapeutic effect is achieved, but uncontrolled distribution to healthy tissues causes severe side effects
Solution Approach 1:
The patent segments the drug delivery system into distinct functional components: a polymer backbone providing structural support, PEG side chains providing solubility and circulation time, and cleavable linkers enabling controlled drug release. This segmentation allows each component to optimize its specific function while working together to achieve targeted delivery and reduce systemic toxicity
Solution Approach 2:
The polymer-drug conjugate acts as an intermediary carrier that transports the chemotherapy agent from administration to target site. The conjugate structure includes a polymer backbone with PEG side chains that improve solubility and circulation, while cleavable linkers serve as intermediaries that remain intact during circulation but break down at the target site to release the active drug, thereby protecting healthy tissues from direct drug exposure
2Reliability
If high dose chemotherapy is administered to overcome low drug concentration at tumor site, then therapeutic benefit increases, but overall toxicity to patient increases
Solution Approach 1:
The patent extracts the drug release function from the circulation phase and relocates it to the target site phase through cleavable linkers. The drug is extracted from its active form during circulation (bound to polymer) and only released when the linker cleaves at the tumor site, ensuring high local concentration without proportional increase in systemic toxicity
Solution Approach 2:
The patent changes the chemical parameters of the drug delivery system by using cleavable linkers with specific bond strengths and hydrolysis rates. These parameter changes allow the conjugate to remain stable in blood circulation (pH 7.4) but undergo controlled degradation at the target site, thereby achieving high therapeutic benefit with reduced overall toxicity
3Reliability
If cleavable linker is used to release drug at target site, then selective drug delivery is achieved, but linker cleaves in bloodstream releasing drug prematurely
Solution Approach 1:
The patent applies local quality by designing the cleavable linker to have different stability characteristics in different physiological environments. The linker maintains stability in the bloodstream (systemic circulation) but becomes labile at the target site where specific conditions (such as lower pH, presence of specific enzymes, or redox conditions) trigger selective cleavage and drug release
Solution Approach 2:
The patent introduces dynamic behavior to the conjugate system through pH-sensitive or enzyme-sensitive cleavable linkers. The linker transitions from a stable state during circulation to a labile state at the target site in response to local environmental changes, enabling the system to adapt its drug release properties to the specific physiological context
4Reliability
If polymer-drug conjugate is designed with high molecular weight for EPR effect, then passive targeting to tumor tissue improves, but aggregation occurs reducing formulation stability
Solution Approach 1:
The patent creates a composite polymer structure combining hydrophilic PEG side chains with a polymer backbone bearing drug-conjugating groups. This composite architecture provides both the high molecular weight needed for EPR effect and passive targeting, while the PEG chains provide steric stabilization and hydrophilicity that prevent aggregation and maintain formulation stability
Data Source
Figure 1
AI summary
This invention relates to polymer drug conjugates according to formula I , methods of preparing said polymer-drug conjugates and their use for treatment of diseases such as cancer.