BCMA–CD3 Bispecific Antibody with Low-Affinity CD3 Binding
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Solution Overview
Problem
Current therapies for multiple myeloma, such as CAR-T cells and BCMA bispecific antibodies, face challenges with high treatment costs, complex preparation processes, high recurrence rates, and severe side effects like cytokine storm syndrome due to excessive T-cell activation and off-target toxicity.
Innovation Solution
Development of a novel BCMA-CD3 κλ bispecific antibody with optimized affinity and reduced Fcγ receptor binding, allowing preferential localization in BCMA+ tumor tissues and effective T-cell recruitment without excessive activation, thereby reducing cytokine storm risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high affinity CD3 antibodies are used to activate T cells, then T cell activation and tumor killing efficacy is improved, but excessive T cell activation occurs leading to cytokine storm syndrome and off-target toxicity
Solution Approach 1:
The patent changes the binding affinity parameter of the CD3 antibody from high affinity to low affinity (Kd value of about 1-100 μM). This parameter change allows the antibody to activate T cells effectively against tumor cells while avoiding excessive activation that leads to cytokine storm syndrome, thus resolving the contradiction between efficacy and safety
Solution Approach 2:
The patent creates a bispecific antibody with asymmetric structure where one arm binds to BCMA on myeloma cells and the other arm binds to CD3 on T cells. This local differentiation allows the antibody to activate T cells only at the tumor site rather than systemically, improving tumor killing efficacy while reducing off-target toxicity and cytokine storm risk
2Reliability
If high dose BCMA bispecific antibodies are administered to achieve effective tumor killing, then antitumor efficacy is improved, but side effects increase leading to cytokine storm syndrome
Solution Approach 1:
The patent changes the affinity parameter of the CD3-binding arm to low affinity (Kd of about 1-100 μM), which allows effective T cell activation and tumor killing at lower antibody doses, thereby improving antitumor efficacy while reducing side effects including cytokine storm syndrome
Solution Approach 2:
The patent introduces a low affinity CD3 antibody as an intermediary that mediates T cell activation more gently compared to high affinity CD3 antibodies. This intermediary approach activates enough T cells to kill tumors effectively while avoiding the excessive activation that causes severe side effects
3Reliability
If Fc portion of antibody binds to Fcγ receptor to enhance immune response, then immune activation is improved, but off-target toxicity increases due to Fcγ receptor aggregation
Solution Approach 1:
The patent extracts or removes the Fc portion binding function to Fcγ receptors from the antibody molecule. By using a CD3 antibody with low affinity that does not rely on Fcγ receptor binding for immune activation, the patent eliminates the source of off-target toxicity while maintaining sufficient immune activation through direct T cell engagement
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 BCMA-CD3 κλ bispecific antibody effectively inhibits tumor growth in mouse models with a reconstituted human immune system, demonstrating superior efficacy and safety compared to existing antibodies.
Implementation Method 1
a first antigen-binding portion or an antigen-binding fragment thereof bound to a BCMA antigen on the surface of a target cell... a second antigen-binding portion or antigen-binding fragment thereof bound to a CD3 antigen on the surface of a T cell
Data Source
AI summary
The present disclosure relates to the development and application of a T-cell engager therapeutic agent. A T-cell engager is a T-cell bispecific antibody, and the bispecific antibody contains a first binding domain bound to BCMA on the surface of a target cell and a second binding domain bound to CD3 on the surface of a T cell. The bispecific antibody has good tolerance, can effectively block the binding of the BCMA to a receptor APRIL, and has no adverse reaction, such as weight loss.