Androgen Receptor Degraders via Alternative E3 Ligase
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Solution Overview
Problem
Current treatments for metastatic castration-resistant prostate cancer (mCRPC) are limited, as existing androgen receptor (AR) antagonists become ineffective with AR gene amplification, mutation, and alternate splicing, and existing PROTAC-based AR degraders face limitations in AR degradation efficiency due to auto-ubiquitylation of the E3 ligase cIAP1.
Innovation Solution
Development of heterobifunctional small molecules, referred to as Compounds of the Disclosure, which act as AR degraders by binding to the androgen receptor and an E3 ligase system, effectively degrading the AR protein, potentially overcoming the limitations of existing AR degraders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PROTAC-based AR degraders are used to degrade androgen receptor protein, then AR degradation is achieved, but E3 ligase cIAP1 undergoes auto-ubiquitylation and degradation which limits degradation efficiency
Solution Approach 1:
The patent introduces a novel E3 ligase system as an intermediary to mediate AR degradation. Instead of using cIAP1 which undergoes harmful auto-ubiquitylation, the invention employs a different E3 ligase (such as VHL or CRBN) that can effectively ubiquitylate AR without self-degradation. This intermediary E3 ligase acts as a bridge between the PROTAC molecule and the degradation pathway, resolving the contradiction by providing a reliable degradation mechanism that doesn't compromise E3 ligase stability.
Solution Approach 2:
The patent changes the key parameter of E3 ligase identity in the PROTAC system. By switching from cIAP1 to alternative E3 ligases with different biochemical properties, the invention modifies the degradation pathway parameters to eliminate the auto-ubiquitylation problem while maintaining effective AR degradation. This parameter change allows the system to achieve both high degradation efficiency and E3 ligase stability.
2Reliability
If AR antagonists are used to inhibit androgen receptor function, then AR signaling is blocked, but effectiveness is lost with AR gene amplification, mutation, and alternate splicing
Solution Approach 1:
The patent replaces the mechanical blocking mechanism of AR antagonists with a proteolytic degradation mechanism. Instead of attempting to bind and block AR function (which fails when AR structure changes due to mutations or splicing), the PROTAC system recruits an E3 ligase to ubiquitylate and degrade the AR protein itself. This substitution of mechanism— from functional inhibition to protein destruction—overcomes resistance to AR variations because it targets the protein's presence rather than its functional conformation.
Solution Approach 2:
The patent extracts the problematic AR protein from the system through targeted degradation. Rather than trying to inhibit AR function while it remains present (which fails with AR variations), the PROTAC approach removes the AR protein entirely from the cellular environment. This extraction eliminates the target from the system, making resistance through gene amplification, mutation, or splicing irrelevant.
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
These compounds provide a therapeutic benefit by degrading the androgen receptor protein, offering a potential treatment for prostate cancer and other diseases where AR signaling is critical, potentially improving treatment outcomes for mCRPC.
Implementation Method 1
The Proteolysis Targeting Chimera (PROTAC) strategy has gained momentum with its promise in the discovery and development of completely new types of small molecule therapeutics by inducing targeted protein degradation.
Implementation Method 2
they also induce the auto-ubiquitylation and proteasomal degradation of the cIAP1 protein, the E3 ligase needed for induced degradation of AR protein
Data Source
AI summary
The present disclosure provides compounds of Formula (I): and the salts or solvates thereof, wherein A1, B1, L, and X2 are as defined in the specification. The present disclosure also relates to uses of the compounds, e.g., as androgen receptor degraders useful for the treatment of diseases (e.g., cancer).