Abstract

IL15 and costimulatory receptors of the tumor necrosis superfamily (TNFRSF) have shown great potential to support and drive an antitumor immune response. However, their efficacy as monotherapy is limited. Here, we present the development of a novel format for a trifunctional antibody-fusion protein that combines and focuses the activity of IL15/TNFSF-ligand in a targeting-mediated manner to the tumor site. The previously reported format consisted of a tumor-directed antibody (scFv), IL15 linked to an IL15Rα-fragment (RD), and the extracellular domain of 4-1BBL, where noncovalent trimerization of 4-1BBL into its functional unit led to a homotrimeric molecule with 3 antibody and 3 IL15-RD units. To reduce the size and complexity of the molecule, we have now designed a second format, where 4-1BBL is introduced as single-chain (sc), that is 3 consecutively linked 4-1BBL ectodomains. Thus, a monomeric trifunctional fusion protein presenting only 1 functional unit of each component was generated. Interestingly, the in vitro activity on T-cell stimulation was conserved or even enhanced for the soluble and target-bound molecule, respectively. Also, in a lung tumor mouse model, comparable antitumor effects were observed. Furthermore, corroborating the concept, OX40L and GITRL were also successfully incorporated into the novel single-chain format and the advantage of target-bound trifunctional versus corresponding combined bifunctional fusion proteins demonstrated by measuring T-cell proliferation and cytotoxic potential in vitro and antitumor effects of RD_IL15_scFv_scGITRL in a lung tumor mouse model in vivo Thus, the trifunctional antibody-fusion protein single-chain format constitutes a promising innovative platform for further therapeutic developments.

Highlights

  • Strategies interfering with the regulatory network of the immune response are intensively pursued for cancer therapy [1]

  • This involves in particular cytokines of the common-gamma chain cytokine family (e.g., IL2, IL15) and costimulatory members of the TNFR superfamily (e.g., 4-1BB, OX40, GITR; refs. 2, 3)

  • We present the further development of IL15-based trifunctional fusion proteins with costimulatory TNF-superfamily members

Read more

Summary

Introduction

Strategies interfering with the regulatory network of the immune response are intensively pursued for cancer therapy [1]. Beside the development of checkpoint inhibitors, antagonizing immune inhibition, increasing attention is being paid to the development of agonists that directly promote and drive the immune response. This involves in particular cytokines of the common-gamma chain cytokine family (e.g., IL2, IL15) and costimulatory members of the TNFR superfamily IL15 is next to IL2 one of the most promising members of the common-gamma chain cytokine family for cancer therapy [4] It induces in particular the proliferation and differentiation of CD8þ T cells and supports the survival of CD8þ memory T cells. It is involved in the generation, proliferation, and activation of natural killer (NK) cells

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call