RAF-Degrading Bifunctional Compounds Using Cereblon Recruitment
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Solution Overview
Problem
Current treatments for diseases associated with overexpression or aggregation of Rapidly Accelerated Fibrosarcoma (RAF) proteins, such as B-Raf, are ineffective due to non-specific effects and the inability to target and modulate RAF, leading to resistance and paradoxical activation of wild-type RAF, and are unable to address RAF mutations like Class III B-Raf mutants in cancers.
Innovation Solution
Development of hetero-bifunctional compounds that recruit RAF proteins to an E3 ubiquitin ligase for targeted ubiquitination and subsequent proteasomal degradation, using a cereblon E3 ubiquitin ligase binding moiety and a RAF-targeting moiety linked by a chemical linker, to degrade RAF proteins effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current B-Raf inhibitors are used to target RAF proteins, then kinase activity is inhibited, but non-specific effects occur and resistance develops
Solution Approach 1:
The patent extracts the essential function of RAF inhibition by separating it from non-specific kinase inhibition. Instead of targeting RAF's kinase activity directly (which causes non-specific effects), the invention targets RAF for selective degradation through the proteasome pathway, removing the harmful kinase activity while avoiding non-specific effects.
Solution Approach 2:
Instead of inhibiting RAF kinase activity directly (conventional approach), the invention inverts the strategy by promoting RAF degradation through ubiquitination. This reverses the traditional inhibition paradigm and eliminates resistance mechanisms that arise from kinase inhibitors.
2Productivity
If general proteasome inhibitors are used, then protein degradation is achieved, but lack of substrate specificity limits therapeutic effectiveness
Solution Approach 1:
The patent segments the proteasome inhibition function by developing E3 ligase-specific inhibitors rather than general proteasome inhibitors. This segmentation allows targeted degradation of specific substrates (RAF proteins) while maintaining the specificity needed for therapeutic effectiveness.
Solution Approach 2:
The invention uses E3 ubiquitin ligases as intermediary proteins to mediate the degradation process. These E3 ligases serve as specific recruiters that bind to RAF substrates and facilitate their targeted degradation, providing both specificity and efficient degradation.
3Reliability
If E3 ligase ligands are developed to target specific substrates, then substrate specificity is improved, but disruption of protein-protein interactions makes development challenging
Solution Approach 1:
The patent changes the binding parameters by developing ligands that target specific E3 ligase binding sites. By optimizing the affinity and specificity of these ligands for particular E3 ligases (such as those binding to RAF substrates), the invention achieves substrate specificity while managing development complexity through focused molecular design.
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 compounds achieve selective degradation of RAF proteins, including mutants, reducing their levels and treating RAF-related diseases like cancer, cardiofaciocutaneous syndrome, and other disorders by lowering protein amounts in cells.
Implementation Method 1
The bifunctional compounds are useful as modulators of targeted ubiquitination of Rapidly Accelerated Fibrosarcoma (RAF), and mutant forms thereof, which is then degraded and/or inhibited
Implementation Method 2
E3 ubiquitin ligases (of which hundreds are known in humans) confer substrate specificity for ubiquitination, and therefore are more attractive therapeutic targets than general proteasome inhibitors
Data Source
AI summary
Bifunctional compounds, which find utility as modulators of Rapidly Accelerated Fibrosarcoma (Raf, such as c-Raf, A-Raf, and/or B-Raf), are described herein. In particular, the hetero-bifunctional compounds of the present disclosure contain on one end a moiety that binds to the cereblon E3 ubiquitin ligase and on the other end a moiety which binds Raf, such that the target protein is placed in proximity to the ubiquitin ligase to effect degradation (and inhibition) of target protein. The hetero-bifunctional compounds of the present disclosure exhibit a broad range of pharmacological activities associated with degradation/inhibition of target protein. Diseases or disorders that result from aberrant regulation of the target protein are treated or prevented with compounds and compositions of the present disclosure.