CD3xPDL1 bi-specific T cell engager (BiTE) simultaneously activates T cells and NKT cells, kills PDL1+ tumor cells, and extends the survival of tumor-bearing humanized mice.

Lucas A Horn,Ryan Atkinson,Suzanne Ostrand-Rosenberg,Nicholas G Ciavattone,Pratima Sinha,Julia Wolf,Virginia K Clements,Munanchu Poudel,Netsanet Woldergerima

doi:10.18632/oncotarget.19865

Lucas A Horn, Ryan Atkinson + Show 7 more

Open Access

https://doi.org/10.18632/oncotarget.19865

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Abstract

Bi-specific T cell engagers (BiTEs) activate T cells through CD3 and target activated T cells to tumor-expressed antigens. BiTEs have shown therapeutic efficacy in patients with liquid tumors; however, they do not benefit all patients. Anti-tumor immunity is limited by Programmed Death 1 (PD1) pathway-mediated immune suppression, and patients who do not benefit from existing BiTES may be non-responders because their T cells are anergized via the PD1 pathway. We have designed a BiTE that activates and targets both T cells and NKT cells to PDL1+ cells. In vitro studies demonstrate that the CD3xPDL1 BiTE simultaneously binds to both CD3 and PDL1, and activates healthy donor CD4+ and CD8+ T cells and NKT cells that are specifically cytotoxic for PDL1+ tumor cells. Cancer patients’ PBMC are also activated and cytotoxic, despite the presence of myeloid-derived suppressor cells. The CD3xPDL1 BiTE significantly extends the survival time and maintains activated immune cell levels in humanized NSG mice reconstituted with human PBMC and carrying established human melanoma tumors. These studies suggest that the CD3xPDL1 BiTE may be efficacious for patients with PDL1+ solid tumors, in combination with other immunotherapies that do not specifically neutralize PD1 pathway-mediated immune suppression.

Highlights

Bi-specific T cell engagers (BiTEs) are genetically engineered recombinant proteins that have been shown to simultaneously activate cytotoxic T cells through the T cell CD3 complex and target the activated T cells to tumor cells
The CD3xPDL1/pINFUSE construct was transfected into CHO cells, and stable BiTE-producing transfectants were obtained by selection on zeocin
The studies described here demonstrate that the CD3xPDL1 BiTE binds simultaneously to T cellexpressed CD3 and tumor cell-expressed programmed death ligand 1 (PDL1)

Summary

Introduction

Bi-specific T cell engagers (BiTEs) are genetically engineered recombinant proteins that have been shown to simultaneously activate cytotoxic T cells through the T cell CD3 complex and target the activated T cells to tumor cells. They are single chain molecules that consist of the VL and VH chains of an anti-CD3 and an anti-tumor antigen antibody that are connected by short linker sequences [1]. The short bridging distance factors into the potency of the BiTE [7] and facilitates the formation of an immunological synapse that favors T cell to target cell interaction [6]. BiTEs kill target cells through a granzyme and perforin-mediated process [8], and they convert T regulatory cells to cytotoxic T cells [9]

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