Constrained conditionally activated binding proteins
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing monoclonal antibodies (mAbs) used in cancer treatment face challenges such as large size leading to poor bio-distribution, low potency, and long persistence in the blood pool, with issues of inhomogeneous tumor accumulation and 'on target/off tumor' effects causing side effects.
Innovation Solution
Development of Format 1, 2, and 4 proteins with constrained Fv domains and cleavable or non-cleavable linkers that are selectively activated by tumor proteases, forming active CD3-binding domains only in the tumor environment, ensuring targeted and specific tumor cell destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intact monoclonal antibodies are used, then binding specificity and affinity for tumor antigen is improved, but bio-distribution is poor and tumor penetration is limited
Solution Approach 1:
The patent divides the intact monoclonal antibody into smaller functional fragments (scFv, Fab, or other antibody-derived molecules) that maintain tumor antigen binding capability while improving tumor penetration. This segmentation allows the therapeutic molecule to be small enough to penetrate deep into tumor tissue while retaining the necessary binding specificity through preserved antigen-binding domains.
2Area of stationary object
If smaller antibody fragments are used, then tumor localization and penetration are improved, but on target/off tumor effects increase causing side effects
Solution Approach 1:
The patent employs protease-cleavable linkers that change the molecular state of the antibody fragment from an inactive, non-binding form in circulation to an active, tumor-targeting form only after cleavage by tumor-specific proteases. This parameter change ensures the smaller fragment remains inert in normal tissues (reducing off-target effects) while becoming actively tumor-specific only in the tumor microenvironment where proteases are present.
3Reliability
If intact antibodies are used, then binding affinity is improved, but persistence in blood pool is prolonged
Solution Approach 1:
The patent extracts and removes the Fc region from the intact antibody molecule, retaining only the variable regions (scFv or Fab fragments). This extraction eliminates the Fc-mediated long blood pool persistence characteristic of intact antibodies, while the retained variable regions maintain sufficient binding affinity through their antigen-specific paratopes. The fragment-based approach naturally reduces circulation time.
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 proteins achieve selective and efficient tumor targeting with reduced off-target effects, enhancing therapeutic efficacy while minimizing toxicity by activating only in the presence of tumor proteases.
Implementation Method 1
a cleavable linker (CL); g) a constrained pseudo Fv domain... wherein said first variable heavy domain and said first variable light domain are capable of binding human CD3 but said constrained Fv domain does not bind CD3
Data Source
AI summary
The invention relates to COnditional Bispecific Redirected Activation constructs, or COBRAs, that are administered in an active pro-drug format. Upon exposure to tumor proteases, the constructs are cleaved and activated, such that they can bind both tumor target antigens (TTAs) as well as CD3, thus recruiting T cells expressing CD3 to the tumor, resulting in treatment.