Pyrrolobenzodiazepine Dimer Sulfur Linker Cleavage
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Solution Overview
Problem
Current antibody-drug conjugates face challenges in achieving maximal efficacy with minimal toxicity due to non-selective delivery of cytotoxic agents, leading to unwanted toxicity in normal cells, and existing PBD compounds often require linker stubs that can affect reactivity after release.
Innovation Solution
A PBD dimer compound connected through the N10 position via a sulfur linker to a cell binding agent, such as an antibody, allowing for targeted delivery and release of an active PBD compound without residual linker stubs, ensuring stability extracellularly and cleavability intracellularly for enhanced cytotoxic effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linker is used to connect PBD to cell binding agent, then targeted delivery is achieved, but linker stubs remain after release affecting reactivity
Solution Approach 1:
The invention extracts and removes the linker stub from the final active compound structure. By designing a cleavable linker that releases the PBD without any residual linker portions, the harmful interference is eliminated while maintaining targeted delivery capabilities through the cell-binding agent.
Solution Approach 2:
The linker is designed with preliminary cleavage sites that are activated upon intracellular delivery. The linker stub is pre-configured to be cleaved off automatically when the conjugate reaches the target cell, ensuring clean release of the active PBD compound without requiring additional processing steps.
2Reliability
If PBD is delivered systemically, then cancer cells can be reached, but toxicity to normal cells increases
Solution Approach 1:
The cell-binding agent serves as an intermediary that mediates between the cytotoxic PBD compound and the target cancer cells. This intermediary enables selective binding to cancer cell surfaces, directing the cytotoxic agent only to the intended target while sparing normal cells from exposure.
Solution Approach 2:
The conjugate exhibits local quality through the cell-binding agent that confers cancer cell-specific targeting properties to the otherwise non-selective PBD compound. The binding agent provides localized recognition and binding能力 at the cancer cell surface, while the PBD maintains its potent cytotoxic activity only after delivery to the target.
3Ease of operation
If a carbamate protecting group is used at N10 position, then in vivo removability is achieved, but cleavage conditions may affect compound stability
Solution Approach 1:
The invention utilizes parameter changes in the enzymatic environment (pH, enzyme concentration, redox potential) between circulation and intracellular compartments to trigger selective cleavage of the carbamate protecting group. The linker is designed to be stable under circulation conditions but undergoes controlled degradation when enzymatic parameters change upon cellular internalization.
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
This approach enables targeted and efficient delivery of PBD compounds to cancer cells, minimizing toxicity to normal cells and maintaining cytotoxic efficacy by ensuring the PBD compound is released without linker residues, thus enhancing the therapeutic index.
Implementation Method 1
A PBD dimer compound connected through the N10 position via a sulfur linker to a cell binding agent, allowing for targeted delivery and release of an active PBD compound without residual linker stubs
Data Source
AI summary
A conjugate of formula (A):where Y is selected from a single bond, and a group of formulae A1 or A2:where N shows where the group binds to the N10 of the PBD moiety;RL1 and RL2 are independently selected from H and methyl, or together with the carbon atom to which they are bound form a cyclopropylene group;CBA represents a cell binding agent;Q is independently selected from O, S and NH;R11 is either H, or R or, where Q is O, SO3M, where M is a metal cation.