PROTAC Molecules Degrade AR-V7 via E3 Ligase Recruitment
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Solution Overview
Problem
Current treatments for prostate cancer and other conditions related to aberrant androgen receptor (AR) regulation, such as castration-resistant prostate cancer and Kennedy's Disease, are limited by the ability to effectively target and degrade AR variants like AR-V7, which lack the ligand binding domain and remain constitutively active.
Innovation Solution
Development of bi-functional proteolysis targeting chimera (PROTAC) molecules that simultaneously bind to the androgen receptor (AR) and an E3 ubiquitin ligase, facilitating the ubiquitination and degradation of AR-V7 and AR by the proteasome, using a structure comprising an AR binding moiety linked to an E3 ubiquitin ligase binding moiety through a chemical linker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AR antagonists (enzalutamide, apalutamide) are used to inhibit AR transcriptional activity, then AR signaling is blocked in wild-type AR, but AR-V7 variants lacking the LBD remain constitutively active and resistant to treatment
Solution Approach 1:
The patent employs an intermediary approach by using a bi-functional PROTAC molecule that acts as a mediator between the AR binding moiety and the E3 ubiquitin ligase binding moiety. This intermediary structure enables the recruitment of the ubiquitin-proteasome system to target AR for degradation, bypassing the limitation of conventional antagonists that cannot affect AR-V7 variants. The PROTAC molecule serves as a bridge that connects the target protein (AR) with the degradation machinery (E3 ligase), thereby resolving the contradiction between maintaining therapeutic efficacy and achieving versatility against AR variants.
Solution Approach 2:
The invention applies parameter changes by transitioning from a reversible binding mechanism (conventional antagonists binding to LBD) to an irreversible degradation mechanism (PROTAC-mediated ubiquitination). By changing the fundamental parameter of drug action from inhibition to degradation, the therapy becomes effective against both wild-type AR and AR-V7 variants. The bi-functional structure allows the compound to bind to AR at the NTD (different from conventional LBD binding) and recruit E3 ligase, fundamentally altering the mechanism of action to overcome resistance.
2Reliability
If PROTAC molecules are designed to target AR-V7 by binding to the N-terminal domain, then degradation of AR-V7 is achieved, but the molecular complexity and synthesis difficulty increase
Solution Approach 1:
The PROTAC molecule is segmented into distinct functional modules: an AR binding moiety (comprising a bridged bicyclic heterocycloalkyl ring structure), a linker moiety, and an E3 ubiquitin ligase binding moiety. This segmentation allows each component to perform its specific function independently while contributing to the overall therapeutic effect. The modular design facilitates both the targeted degradation of AR-V7 and the manageable synthesis of the complex molecule, as each segment can be optimized and synthesized separately then assembled.
3Productivity
If bi-functional PROTAC molecules are used to degrade AR, then therapeutic potential against prostate cancer is improved, but the manufacturing and clinical translation challenges increase
Solution Approach 1:
The PROTAC molecule exhibits multi-functionality by simultaneously performing AR binding, E3 ligase recruitment, and ubiquitination induction. This universality is achieved through the bi-functional design where one moiety targets AR (specifically the NTD for AR-V7) while the other moiety targets the E3 ubiquitin ligase. The molecule thus serves multiple therapeutic functions in a single compound, improving productivity by eliminating the need for separate drugs while the modular structure aids manufacturing through standardized synthesis pathways for each functional module.
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 PROTAC molecules effectively target and degrade AR-V7 and AR, providing a potential therapeutic approach for treating prostate cancer and other AR-related conditions by modulating protein levels and inhibiting aberrant AR activity.
Implementation Method 1
facilitating the ubiquitination and degradation of AR-V7 and AR by the proteasome
Data Source
AI summary
The present invention relates to bi-functional compounds which function to recruit endogenous proteins to an E3 ubiquitin ligase for degradation, and methods for using same. More specifically, the present disclosure provides specific proteolysis targeting chimera (PROTAC) molecules which find utility as modulators of targeted ubiquitination of a variety of polypeptides and other proteins, in particular the androgen receptor of a slice variant of AR which lacks the LBD, labelled as AR-V7, which are then degraded and/or otherwise inhibited by the compounds as described herein.