Amatoxin Conjugates Plasma Stability Ring Formation
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Solution Overview
Problem
Existing amatoxin conjugates for tumor therapy are not stable enough in plasma, leading to potential harmful side effects on non-target cells, and there is a need for improved stability without compromising their interaction with DNA-dependent RNA polymerase II in target cells.
Innovation Solution
The development of amatoxin conjugates with a ring formation via the two oxygen atoms bound to the γ and δ C atoms of amatoxin amino acid 3, which enhances stability while maintaining efficacy by forming a tight complex with RNA polymerase II, reducing toxicity and improving tolerability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amatoxin conjugates are used for tumor therapy, then cytotoxic activity against tumor cells is achieved, but stability in plasma is insufficient leading to harmful side effects on non-target cells
Solution Approach 1:
A plasma-stable linker is introduced as an intermediary component between the amatoxin and the antibody. This linker acts as a mediator that prevents premature release of amatoxin in plasma (reducing side effects) while allowing controlled release inside target cells (maintaining cytotoxic activity). The linker's specific chemical structure provides differential stability - resistant to plasma conditions but cleavable under intracellular conditions.
Solution Approach 2:
The chemical parameters of the linker are optimized to achieve differential stability. The linker is designed with specific bond types and structural features that confer resistance to plasma proteases and esterases while maintaining susceptibility to intracellular enzymes or pH conditions. This parameter optimization creates the desired stability profile - stable in circulation but active in the target.
2Reliability
If the stability of amatoxin conjugates in plasma is increased, then side effects on non-target cells are reduced, but interaction with DNA-dependent RNA polymerase II in target cells may be compromised
Solution Approach 1:
The plasma-stable linker serves as a temporary intermediary that maintains separation between the amatoxin and plasma components. The linker's design ensures it remains intact in plasma (maintaining stability) but is specifically cleaved inside target cells, at which point the amatoxin is released to interact with RNA polymerase II. The intermediary thus enables both stability and subsequent precise interaction.
Solution Approach 2:
The conjugate exhibits periodic behavior - stable and inert during circulation in plasma, then becomes active and releases amatoxin upon reaching the target cell. This temporal separation ensures that during the first phase (circulation), the conjugate is stable and non-reactive, while in the second phase (intracellular), the amatoxin is released to precisely interact with RNA polymerase II.
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 modified amatoxin conjugates exhibit enhanced stability in plasma, minimizing side effects on non-target cells and maintaining their cytotoxic activity against tumor cells, thereby extending the therapeutic window and ensuring safety.
Implementation Method 1
the complex between amanitin and RNA polymerase II is very tight (KD=3 nM). Dissociation of amanitin from the enzyme is a very slow process
Data Source
AI summary
The invention relates to tumor therapy. In one aspect, the present invention relates to conjugates of an amatoxin and a target-binding moiety, e.g. an antibody, connected by certain linkages, which are useful in the treatment of cancer and other disorders and diseases. In a further aspect the invention relates to pharmaceutical compositions comprising such conjugates.