Modular Semisynthetic Approach to Generate T Cell-Dependent Bispecific Constructs from Recombinant IgG1 Antibodies

Area of Science:

• Immunology
• Oncology
• Biochemistry

Background:

• Bispecific antibodies redirect T cells to tumor cells for cancer treatment.
• T cell-dependent bispecific antibodies (TDBAs) are potent immunotherapeutic agents.
• Existing TDBAs can cause cytokine release syndrome due to CD3 receptor binding.

Purpose of the Study:

• To develop a novel platform for generating 2:1 T cell-dependent bispecific antibodies (TDBAs).
• To create TDBAs with bivalency for HER2 receptors and monovalency for CD3 receptors.
• To enhance tumor-killing efficacy while minimizing side effects like cytokine release syndrome.

Main Methods:

• Utilized a biogenic inverse electron-demand Diels-Alder (IEDDA) click reaction on genetically encoded tyrosine residues.
• Installed a TCO handle on the approved antibody trastuzumab.
• Performed TCO-tetrazine click chemistry with a CD3-binding Fab to create the 2:1 HER2 × CD3 TDBA.

Main Results:

• Successfully generated a novel 2:1 HER2 × CD3 TDBA construct.
• The TDBA demonstrated potent tumor-killing capability at picomolar concentrations.
• Monovalent CD3 binding is proposed to reduce cytokine release syndrome.

Conclusions:

• A versatile semisynthetic platform enables rapid generation of potent TDBA constructs.
• The developed 2:1 TDBA exhibits high efficacy in targeting HER2-expressing tumor cells.
• This approach offers a promising strategy for developing safer and more effective cancer immunotherapies.