Multispecific Binding Protein Degrader for Membrane Proteins
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Solution Overview
Problem
Current methods for targeting the degradation of membrane-bound and cell surface proteins are limited, particularly for proteins located on the cell surface, as existing technologies like PROTACs and LYTACs are not effective for membrane-bound proteins and require chemical conjugation or non-specific tissue targeting.
Innovation Solution
Development of multispecific binding proteins, such as bispecific or trispecific antibodies that target transmembrane E3 ubiquitin ligases like RNF43 or ZNRF3, to direct cell surface proteins to lysosomes for degradation, utilizing optimized binding affinities and formats like PROTABs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PROTACs are used to target cytosolic proteins for degradation, then cytosolic protein degradation is achieved, but membrane-bound or cell surface protein targets cannot be degraded
Solution Approach 1:
The patent uses an intermediary mechanism by recruiting endogenous E3 ubiquitin ligases (such as RNF43, ZNRF3, RNF128, RNF130, RNF133, RNF148, RNF149, RNF150, RNF167, or ZNRF4) that are naturally expressed on cell surfaces to mediate the degradation of membrane-bound proteins. These E3 ligases serve as intermediaries between the multispecific binding protein and the target membrane protein, enabling lysosomal degradation without requiring the binding protein to directly interact with cytosolic components.
Solution Approach 2:
The multisspecific binding protein is designed with multiple binding specificities: it binds to both a transmembrane E3 ubiquitin ligase and a cell surface protein target. This multi-functionality allows a single binding protein to simultaneously engage the degradation machinery (E3 ligase) and the target protein, enabling universal application across different membrane-bound protein targets while maintaining high specificity for each interaction.
2Reliability
If LYTACs are used to target membrane proteins for degradation, then membrane protein degradation is achieved, but chemical conjugation is required which needs to be controlled during manufacturing to avoid product heterogeneity
Solution Approach 1:
The system employs self-service by utilizing the cell's own endogenous E3 ubiquitin ligase machinery to perform degradation. The multispecific binding protein recruits these pre-existing cellular components, eliminating the need for external chemical conjugation steps. The E3 ligase naturally processes the target protein through ubiquitination and lysosomal degradation pathways, making the process independent of complex chemical synthesis controls.
3Reliability
If LYTACs targeting CI-M6PR are used, then membrane protein degradation is achieved, but selective degradation in specific tissues is not possible since CI-M6PR is expressed in nearly all tissues
Solution Approach 1:
The patent applies local quality by selecting E3 ubiquitin ligases that are differentially expressed in specific tissues or cell types. Different E3 ligases (e.g., RNF43 in colorectal cancer, ZNRF3 in various cancers) have distinct tissue distribution patterns, allowing the multisspecific binding protein to achieve tissue-selective degradation by choosing the appropriate E3 ligase-target combination based on the disease location and target protein expression profile.
Solution Approach 2:
The system utilizes parameter changes by varying the binding affinity and specificity parameters of the multisspecific binding protein against different E3 ligases and target proteins. By optimizing the affinity constants and binding kinetics for specific E3 ligase-target pairs, the system can enhance degradation efficiency in tissues where both components are co-expressed while minimizing off-target effects in tissues lacking the required combination.
4Reliability
If bisspecific antibodies binding E3 ligase and cell surface protein are used, then lysosomal degradation of cell surface proteins is achieved, but the general applicability and efficiency for endogenous proteins in vivo remains unknown
Solution Approach 1:
The patent applies preliminary action by pre-characterizing and optimizing the binding affinities, kinetics, and structural attributes of the multisspecific binding proteins before in vivo application. Extensive in vitro studies are conducted to establish degradation efficiency, safety margins, and dose-response relationships for endogenous protein targets. This preliminary characterization enables predictive modeling and informed decision-making for in vivo trials, accelerating the translation from bench to bedside.
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 multispecific binding proteins effectively reduce the level of target cell surface proteins on cancer cells by selectively targeting overexpressed E3 ubiquitin ligases, offering a therapeutic approach for diseases characterized by activated Wnt pathways, like colorectal cancer, with potential for in vitro and in vivo applications.
Implementation Method 1
The multispecific binding proteins use the transmembrane E3 ubiquitin ligase, for example, to target the cell surface protein of interest to lysosomes for degradation
Data Source
AI summary
The present disclosure relates to a multispecific antibody platform for targeted degradation of cell surface proteins. The disclosure relates to multispecific (e.g., bispecific or trispecific) binding molecules such as multispecific antibodies that target at least one transmembrane E3 ubiquitin ligase protein and at least one cell surface protein, for example, a cell surface protein that is intended for degradation, and methods of using the same.