Oncolytic adenovirus expressing bispecific antibody targets T-cell cytotoxicity in cancer biopsies.

Joshua D Freedman,Eleanor M Scott,Leonard W Seymour,Margaret R Duffy,Laura Spiers,Nikolaos Kanellakis,Joachim Hagel,Avinash Gupta,Rebecca Ashfield,Ioannis Psallidas,Paul Miller,Kerry D Fisher

doi:10.15252/emmm.201707567

Joshua D Freedman, Eleanor M Scott + Show 10 more

Open Access

https://doi.org/10.15252/emmm.201707567

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Abstract

Oncolytic viruses exploit the cancer cell phenotype to complete their lytic life cycle, releasing progeny virus to infect nearby cells and repeat the process. We modified the oncolytic group B adenovirus EnAdenotucirev (EnAd) to express a bispecific single‐chain antibody, secreted from infected tumour cells into the microenvironment. This bispecific T‐cell engager (BiTE) binds to EpCAM on target cells and cross‐links them to CD3 on T cells, leading to clustering and activation of both CD4 and CD8 T cells. BiTE transcription can be controlled by the virus major late promoter, limiting expression to cancer cells that are permissive for virus replication. This approach can potentiate the cytotoxicity of EnAd, and we demonstrate using primary pleural effusions and peritoneal malignant ascites that infection of cancer cells with the BiTE‐expressing EnAd leads to activation of endogenous T cells to kill endogenous tumour cells despite the immunosuppressive environment. In this way, we have armed EnAd to combine both direct oncolysis and T cell‐mediated killing, yielding a potent therapeutic that should be readily transferred into the clinic.

Highlights

Bispecific T-cell engagers (BiTEs) are fusion proteins generated from single-chain variable fragments of two different monoclonal antibodies, one normally a CD3 agonist and the other recognising a surface antigen on target cells, linked by a short flexible peptide linker (Baeuerle & Reinhardt, 2009)
Oncolytic viruses offer an intriguing new strategy to combine several therapeutic modalities within a single targeted, self-amplifying agent (Keller & Bell, 2016; Seymour & Fisher, 2016). As they replicate selectively within cancer cells and spread from cell to cell, some oncolytic viruses are thought to mediate cell death by nonapoptotic death pathways (Ingemarsdotter et al, 2010; Li et al, 2013), as part of the process allowing virus particles to escape from dying cells
We have shown that BiTE-targeted cytotoxicity is fully antigen specific, can be mediated by both CD4 and CD8 T cells (Brischwein et al, 2006) and can be incorporated into an oncolytic adenovirus and expressed only in cells that allow virus replication

Summary

Introduction

Bispecific T-cell engagers (BiTEs) are fusion proteins generated from single-chain variable fragments (scFv) of two different monoclonal antibodies, one normally a CD3 agonist and the other recognising a surface antigen on target cells, linked by a short flexible peptide linker (Baeuerle & Reinhardt, 2009). T-cell activation is a result of CD3 clustering on T cells, induced by multiple BiTE molecules simultaneously cross-linking CD3 on T cells and the target cell antigen (Offner et al, 2006; Brischwein et al, 2007), and leads to increased expression of T-cell activation markers CD69 and CD25, granzyme B, perforin, adhesion molecules and various cytokines such as IFNc and TNFa. As BiTE-mediated tumour cell killing is not MHC restricted, they provide the opportunity to target T-cell cytotoxicity to tumour cells, independent of antigen recognition and MHC class I levels on the tumour cells. Major responses have been demonstrated in various B-cell malignancies (Bargou et al, 2008; Topp et al, 2011), and BiTEs have been designed targeting different tumourassociated antigens including EpCAM, Her2/neu, EGFR, CEA, EphA2, CD33 and MCSP with some currently under clinical evaluation (Baeuerle & Reinhardt, 2009; Yuraszeck et al, 2017)

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