Antibody-epitope conjugates deliver immunogenic T-cell epitopes more efficiently when close to cell surfaces

ABSTRACT

Antibody-mediated delivery of immunogenic viral CD8⁺ T-cell epitopes to redirect virus-specific T cells toward cancer cells is a promising new therapeutic avenue to increase the immunogenicity of tumors. Multiple strategies for viral epitope delivery have been shown to be effective. So far, most of these have relied on a free C-terminus of the immunogenic epitope for extracellular delivery. Here, we demonstrate that antibody-epitope conjugates (AECs) with genetically fused epitopes to the N-terminus of the antibody can also sensitize tumors for attack by virus-specific CD8⁺ T cells. AECs carrying epitopes genetically fused at the N-terminus of the light chains of cetuximab and trastuzumab demonstrate an even more efficient delivery of the T-cell epitopes compared to AECs with the epitope fused to the C-terminus of the heavy chain. We demonstrate that this increased efficiency is not caused by the shift in location of the cleavage site from the N- to the C-terminus, but by its increased proximity to the cell surface. We hypothesize that this facilitates more efficient epitope delivery. These findings not only provide additional insights into the mechanism of action of AECs but also broaden the possibilities for genetically fused AECs as an avenue for the redirection of multiple virus-specific T cells toward tumors.

KEYWORDS:

• antibody-epitope conjugates (AECs)
• virus-specific T-cells
• immunotherapy
• redirecting T-cells
• bispecific-antibodies

Acknowledgments

The authors would like to thank Ewald van den Bremer for his expertise, input, and help with the MS analysis of the generated bispecific antibodies, and Renoud Marijnissen and Rick Hibbert for their guidance, input, and support.

Disclosure statement

BB, JS, LG, and WL are (former) employees at Genmab BV and have ownership interests (including stocks, warrants, patents, etc.).

Ethical approval

Healthy donor material from the Leiden University Medical Center Biobank for Hematological Diseases was used in this study. This research was approved by the Institutional Review Board of the Leiden University Medical Center (approval number B16.039). Materials were obtained after written informed consent in accordance with the Declaration of Helsinki.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19420862.2024.2329321

Additional information

Funding

This work was performed under a grant provided by Genmab.