Non-IL-2 Blocking Anti-CD25 Antibody for Treg Depletion
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Solution Overview
Problem
Current cancer immunotherapies face limitations due to the infiltration of regulatory T cells (Tregs) in tumors, which suppress anti-tumor immune responses by altering the Teff/Treg ratio, necessitating a targeted approach to deplete Tregs without inhibiting IL-2 signaling to enhance anti-tumor immunity.
Innovation Solution
Development of a non-IL-2 blocking anti-CD25 antibody through hybridoma screening and humanization, which selectively binds to human CD25, depletes Tregs while allowing IL-2 to stimulate effector T cells, thereby correcting the tumor microenvironment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing anti-CD25 antibodies (Basiliximab, Daclizumab) are used to deplete Tregs, then Treg depletion is achieved, but IL-2 signaling is inhibited which reduces anti-tumor immunity
Solution Approach 1:
The antibody molecule is divided into distinct functional regions: the variable region (VH-VL) provides high-affinity binding to CD25 for Treg depletion, while the constant region (CH2-CH3) is engineered to avoid IL-2 receptor blockade. This segmentation allows independent optimization of Treg depletion capability while preserving IL-2 signaling pathways.
Solution Approach 2:
The antibody exhibits localized functionality: the antigen-binding site specifically targets CD25 on Tregs with high affinity, while the Fc region is designed to mediate ADCC without interfering with IL-2 binding to its natural receptor. This spatial separation of functions enables selective Treg depletion while maintaining anti-tumor immune responses.
2Reliability
If Tregs are depleted to increase Teff/Treg ratio, then anti-tumor immunity is enhanced, but existing antibodies cause off-target effects by blocking IL-2 signaling
Solution Approach 1:
The antibody serves as a selective intermediary that binds CD25 on Tregs to trigger ADCC-mediated depletion, while its engineered structure prevents interference with IL-2 binding to the complete IL-2 receptor complex on Teff cells. This intermediary action achieves Treg depletion without the off-target effects of previous antibodies.
Solution Approach 2:
The antibody's binding parameters were optimized through humanization and affinity maturation to achieve high specificity for CD25 on activated Tregs. The binding affinity (Kd) and specificity were tuned to distinguish between Treg CD25 and the IL-2 receptor complex, enabling selective depletion without blocking IL-2 signaling to effector cells.
3Reliability
If non-IL-2 blocking anti-CD25 antibody is developed, then both Treg depletion and IL-2 signaling preservation are achieved, but development complexity increases
Solution Approach 1:
The antibody development process incorporated preliminary humanization of the murine antibody framework, which pre-positioned the variable regions to bind CD25 with high affinity while using human constant regions that are incompatible with blocking IL-2 signaling. This preliminary structural preparation simplified subsequent optimization steps and ensured the desired dual functionality from the outset.
Solution Approach 2:
The successful antibody structure was copied and validated through multiple sequence variants (SEQ ID NO: 1-25 for VH, SEQ ID NO: 26-62 for VL) that maintained the core functional architecture. By copying and refining the proven design, the complex functionality was achieved through systematic optimization rather than de novo design.
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 antibody effectively increases the Teff/Treg ratio, enhancing the killing ability of effector T cells and improving anti-tumor responses by maintaining IL-2 signaling, thus offering a significant clinical benefit in cancer treatment.
Implementation Method 1
A CD25-targeted antibody with antibody-dependent cell-mediated cytotoxicity (ADCC) effect can effectively deplete Tregs in a tumor microenvironment
Implementation Method 2
IL-2 is a key cytokine for Teff responses. Therefore, antibodies targeting CD25 on the one hand can effectively deplete Tregs in the tumor microenvironment and on the other hand do not inhibit the IL-2 signaling through CD25, so that not only Treg cells can be removed mechanically, but also IL-2 can be allowed to stimulate Teff cells
Data Source
Figure 1A~1B
Figure 2A~2D
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AI summary
An anti-human-CD25 antibody molecule or an antigen-binding fragment thereof. Compared with an existing anti-CD25 antibody, the provided antibody is non-IL-2 inhibitory, and can not only eliminate Treg, but can also correct a tumor microenvironment and increase the proportion and killing ability of Teff. Further provided is the use of the antibody molecule or the antigen-binding fragment in the preparation of a drug for treating solid tumors and hematological tumors.