Bispecific Antibodies With C1q Recruitment for Targeted Cytotoxicity
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Solution Overview
Problem
Existing therapeutics that engage the complement system for targeted cell destruction are limited by the density and geometry of antibody binding to the target antigen, and the relative contribution of complement-dependent cytotoxicity versus effector cell-mediated death is unclear, hindering broad therapeutic application.
Innovation Solution
Development of bispecific antigen-binding molecules that comprise a first antigen-binding domain targeting a specific antigen and a second domain binding to a complement component, particularly C1q, to enhance complement deposition and cytotoxicity on target cells, including bacterial, viral-infected, or cancer cells, with high affinity and specificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If therapeutic antibodies engage complement via IgG1 Fc domains, then complement-dependent cytotoxicity is induced, but potency is limited by antibody binding density and geometry to the target antigen
Solution Approach 1:
The antibody is divided into separate functional modules: one domain binds the target antigen while another domain binds the complement component C1q. This segmentation allows each domain to independently perform its function, with the C1q-binding domain providing complement activation capability that does not depend on the antigen-binding domain's density or geometry on the target cell surface.
Solution Approach 2:
The bispecific antibody combines two functions in one molecule: target antigen recognition and direct complement component C1q recruitment. The C1q-binding domain provides universal complement activation capability that works independently of the specific antigen target, enabling the same antibody construct to effectively induce CDC against various targets with different antigen densities and geometries.
2Productivity
If the relative contribution of CDC versus effector cell-mediated death is unknown, then broad therapeutic application is hindered, but developing compositions for enhancing complement deposition and mediating cytotoxicity is needed
Solution Approach 1:
The bispecific antibody serves as an intermediary that directly recruits complement component C1q to the target antigen, creating a defined mechanistic pathway. By incorporating a C1q-binding domain, the antibody acts as a bridge between the target and the complement system, enabling direct visualization and measurement of complement deposition at the target site, thereby clarifying the mechanism of action and enhancing productivity.
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 bispecific molecules achieve targeted complement deposition and cytotoxicity with high efficiency, effectively killing targeted cells with EC50 of about 10 nM or less, addressing the limitations of existing therapies by enhancing cell lysis and immune response.
Implementation Method 1
C1q binds to individual Fc domains with low affinity, but antigen-induced multimerization of Fc domains results in avidity-driven enhancement of C1q binding
Implementation Method 2
The ensuing serine protease cascade results in sequential recruitment and cleavage of complement components that culminates in the insertion of the lytic membrane attack complex (MAC, C5b9) pore causing rapid loss of cell viability
Data Source
AI summary
According to certain embodiments, the present disclosure provides bispecific antigen-binding molecules comprising a first antigen-binding domain that specifically binds a target antigen and a second antigen binding domain that binds a complement component. In certain embodiments, the bispecific antigen-binding molecules of the present disclosure are capable of binding to the target antigen with an EC50 of about 10 nM or less, and/or are capable of promoting complement deposition on the target antigen with an EC50 of about 10 nM. In certain embodiments, the bispecific antigen-binding molecules of the disclosure are useful for treating diseases in which inhibition or reduction of the growth of an infectious agent or cancer cell is desired and/or therapeutically beneficial.