Bispecific digoxigenin-binding antibodies for targeted payload delivery

Area of Science:

• Immunology
• Biotechnology
• Oncology

Background:

• Targeted drug delivery aims to improve therapeutic efficacy and reduce side effects.
• Bispecific antibodies offer a versatile platform for directing payloads to specific cells.
• Digoxigenin (Dig) can be used as a linker for conjugating payloads to antibodies.

Purpose of the Study:

• To generate and characterize bispecific antibodies capable of binding both tumor antigens and digoxigenin.
• To develop a system for targeted delivery of digoxigeninylated payloads to cancer cells using these bispecific antibodies.
• To assess the stability and efficacy of the bispecific antibody-payload complexes in vitro and in vivo.

Main Methods:

• Generation of bispecific antibodies by fusing a digoxigenin-binding single-chain Fv to the C-termini of IgG targeting tumor antigens (Her2, IGF1R, CD22, LeY).
• Expression and purification of bispecific antibodies in mammalian cells.
• Preparation of digoxigeninylated payloads (small molecules, proteins).
• Complexation of payloads with bispecific antibodies at a defined ratio.
• Assessment of binding specificity, stability, and targeting efficacy in vitro and in vivo.

Main Results:

• Bispecific antibodies were successfully generated, exhibiting stability and retaining binding affinity for both tumor antigens and digoxigenin.
• Digoxigeninylated payloads (Dig-Cy5, Dig-Doxorubicin, Dig-GFP) retained full functionality.
• Stable complexes of bispecific antibodies and payloads were formed with a defined 2:1 ratio.
• These complexes demonstrated effective serum stability and targeted delivery to cancer cells in vitro and in vivo.
• Separate administration of bispecific antibodies and payloads also achieved effective antibody-mediated targeting.

Conclusions:

• Novel bispecific antibodies targeting tumor antigens and digoxigenin are effective tools for targeted payload delivery.
• The developed system allows for stable complexation and targeted delivery of various digoxigeninylated payloads.
• This approach holds promise for enhanced cancer therapy by enabling precise delivery of therapeutic agents.