Activatable Multispecific Proteins With Cleavable Target Masks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Antibody-based therapies face limitations such as toxicities due to broad target expression and rapid clearance from circulation, which reduce their therapeutic effectiveness.
Innovation Solution
Development of activatable proteins with masking moieties and cleavable moieties that inhibit target binding and half-life extension, allowing activation at the desired site to enhance therapeutic index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antibody-based therapies are administered as activatable prodrugs with masking moieties, then binding affinity and therapeutic index are improved, but the molecules require complex activation mechanisms and may have reduced stability
Solution Approach 1:
The antibody molecule is segmented into distinct functional components: masking moieties (MM) that inhibit binding, cleavable moieties (CM) that enable activation, and half-life extending moieties (EM) that prolong circulation. This segmentation allows each component to perform its specific function independently, resolving the contradiction by achieving high therapeutic index through controlled activation while maintaining manageable structural complexity through modular design
Solution Approach 2:
The masking moieties are attached to the antibody in advance to prevent premature binding and ensure stability during circulation. The cleavable moieties are pre-positioned to enable subsequent activation at the target site. This preliminary preparation allows the molecule to maintain low binding affinity initially (improving safety profile) while enabling rapid activation when needed, thus achieving high therapeutic index without excessive complexity
2Duration of action of stationary object
If half-life extending moieties are incorporated into the activatable protein, then circulation time is prolonged, but the activated protein lacks the half-life extension and is rapidly cleared
Solution Approach 1:
The molecule transitions dynamically from an inactive prodrug state with half-life extending moieties attached to an activated state where the half-life extending moieties are cleaved off. This dynamic transformation allows the parent compound to have prolonged circulation (improving delivery) while the activated form achieves rapid clearance (improving therapeutic effectiveness by limiting exposure time). The cleavable moieties serve as triggers for this dynamic transition
Solution Approach 2:
The half-life extending moieties are temporarily attached to prolong circulation and deliver the active antibody to the target site, then they are discarded through cleavage after activation. This strategy recovers the therapeutic effectiveness by ensuring the active form is generated at the right time and place, while the temporary attachment of EM moieties solves the circulation duration problem
3Object-affected harmful factors
If masking moieties are used to inhibit target binding, then off-target effects are reduced, but the molecule requires cleavable moieties for activation which adds structural complexity
Solution Approach 1:
The cleavable moieties act as intermediary elements that connect the masking moieties to the antibody framework. These intermediaries enable controlled removal of the masking moieties at the target site without requiring direct interaction between the mask and target during circulation. This intermediary approach allows simple masking during storage (reducing off-target effects) while enabling activation through a separate, controllable mechanism
Solution Approach 2:
The masking moieties are extracted or removed from the antibody structure through cleavage of the cleavable moieties at the target site. This extraction allows the antibody to transition from an inactive, low-binding state during circulation to an active state at the target. The extraction process resolves the contradiction by maintaining simplicity during storage (masking prevents off-target effects) while enabling activation when needed
Data Source
AI summary
Activatable proteins comprising a first target binding protein (TB1) that specifically binds to a first target; a second target binding protein (TB2) that specifically binds to a second target, wherein the TB2 is directly or indirectly coupled to the TB1; a first masking moiety (MM1) inhibiting the binding of the TB1 to the first target and coupled to the TB1 via a cleavable moiety, directly or indirectly, e.g., via one or more linkers or other components; a second masking moiety (MM2) inhibiting the binding of the TB2 to the second target and coupled either to the TB1 or to the TB2 via a cleavable moiety, directly or indirectly; and a half-life extending moiety (EM) coupled either to the TB1 or to the TB2 via a cleavable moiety, directly or indirectly. The activatable proteins are configured such that when the cleavable moieties are cleaved, the resulting activated protein has a shorter half life, a higher binding affinity for the first target, and a higher binding affinity for the second target as compared to the intact activatable protein.