Carcinoembryonic Antigen (CEA)-Specific 4-1BB-Costimulation Induced by CEA-Targeted 4-1BB-Agonistic Trimerbodies.

Kasper Mikkelsen,Ana Alvarez-Mendez,Francisco J. Blanco,Nekane Merino,Luis Álvarez-Vallina,Marta Compte,Seandean Lykke Harwood,Kasper Mølgaard,Simon Lykkemark

doi:10.3389/fimmu.2019.01791

Abstract

4-1BB (CD137) is an inducible costimulatory receptor that promotes expansion and survival of activated T cells; and IgG-based 4-1BB-agonistic monoclonal antibodies exhibited potent antitumor activity in clinical trials. However, the clinical development of those antibodies is restricted by major off-tumor toxicities associated with FcγR interactions. We have recently generated an EGFR-targeted 4-1BB-agonistic trimerbody that demonstrated strong antitumor activity and did not induce systemic inflammatory cytokine secretion and hepatotoxicity associated with first-generation 4-1BB agonists. Here, we generate a bispecific 4-1BB-agonistic trimerbody targeting the carcinoembryonic antigen (CEA) that is highly expressed in cancers of diverse origins. The CEA-targeted anti-4-1BB-agonistic trimerbody consists of three 4-1BB-specific single-chain fragment variable antibodies and three anti-CEA single-domain antibodies positioned around a murine collagen XVIII-derived homotrimerization domain. The trimerbody was produced as a homogenous, non-aggregating, soluble protein purifiable by standard affinity chromatographic methods. The purified trimerbody was found to be trimeric in solution, very efficient at recognizing 4-1BB and CEA, and potently costimulating T cells in vitro in the presence of CEA. Therefore, trimerbody-based tumor-targeted 4-1BB costimulation is a broadly applicable and clinically feasible approach to enhance the costimulatory environment of disseminated tumor lesions.

Highlights

In the last decade, immunostimulatory monoclonal antibodies have risen to prominence as a clinically viable approach to induce a tumor-specific immune response in cancer patients [1]
We have investigated the targeting of carcinoembryonic antigen (CEA) by a bispecific 4-1BB-agonistic trimerbody
ELISA analysis demonstrated that 1D8N18 recognized mouse 4-1BB Fc chimera (m41BB), CEA.1N17 recognized human CEA, whereas 1D8N/CCEA.1 showed specific binding to both antigens (Figure 2B)

Summary

Introduction

Immunostimulatory monoclonal antibodies (mAbs) have risen to prominence as a clinically viable approach to induce a tumor-specific immune response in cancer patients [1]. Tumor-Targeted Costimulation for Cancer Immunotherapy programmed cell death-1 (PD-1), and have been successfully used in the treatment of several types of cancers [1] Another type of cancer immunotherapy uses agonistic mAbs to achieve the same effect, but from the opposite direction [2].The agonism of T cell costimulatory receptors can enhance T cell effector functions, proliferation, and survival, which has been demonstrated using several receptors from the tumor necrosis factor (TNF) receptor superfamily (TNFRSF). One such TNFRSF member, 4-1BB (CD137, TNFRSF9) [3], forms the basis for the immunostimulatory approach used in this article. The engagement of 41BB by its ligand or agonistic mAbs provides substantial boosts to the T cell response [4], which prompted the incorporation of 4-1BB intracellular signaling domain into TCR-like chimeric antigen receptors (CARs) and greatly improved their functionality [5]

Methods

Results

Conclusion