Amatoxin Conjugate Stability via Tryptophan Linkage
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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 due to premature release of amatoxins, which can be toxic, especially for liver cells, and thus there is a need for more stable target-binding moiety amatoxin conjugates that minimize toxicity to non-target cells.
Innovation Solution
Attaching target-binding moieties to amatoxins via linkers at additional sites on tryptophan amino acid 4, specifically the 1'-N atom, without interfering with the interaction with DNA-dependent RNA polymerase II, using linkers such as those comprising urea moieties, to create stable conjugates that release amatoxins only after internalization in target cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amatoxins are coupled to antibodies using conventional linkers at traditional attachment sites, then the conjugates can be administered for targeted therapy, but the conjugates are not stable enough in plasma leading to premature release of amatoxins and harmful side effects
Solution Approach 1:
The invention applies local quality by selecting a specific attachment site (1'-N atom of tryptophan amino acid 4) and specific linker chemistry (urea moieties) that provide enhanced stability at that location, rather than using conventional attachment sites and linkers. This localized optimization at the attachment interface resolves the contradiction by maintaining conjugate integrity in plasma while preserving cytotoxic activity upon cellular internalization.
2Reliability
If amatoxins are directly coupled to antibodies without linkers, then the conjugates are more stable, but the cytotoxic activity is reduced and the therapeutic window is narrowed
Solution Approach 1:
The invention uses urea moiety linkers as intermediaries between the amatoxin and antibody. These linkers provide the necessary flexibility and spacing to maintain both stability and cytotoxic activity. The urea linker acts as a mediator that allows the conjugate to remain stable in circulation while enabling effective drug delivery and release upon internalization, thus resolving the contradiction between stability and efficacy.
3Ease of manufacture
If conventional attachment sites on amatoxin are used for conjugate formation, then the synthesis is straightforward, but the conjugates exhibit insufficient plasma stability and premature amatoxin release
Solution Approach 1:
The invention changes the chemical parameters of the attachment site by selecting the 1'-N atom of tryptophan amino acid 4, which has distinct chemical properties compared to conventional attachment sites. This parameter change in the attachment location, combined with using urea linker chemistry, enhances plasma stability while maintaining reasonable synthetic feasibility, thus resolving the contradiction between ease of manufacture and plasma stability.
Data Source
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AI summary
The invention relates to tumour 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. In a further aspect the invention relates to pharmaceutical compositions comprising such conjugates.