A gB/CD3 bispecific BiTE antibody construct for targeting Human Cytomegalovirus-infected cells

Charlotte U Brey,Jochen Pendzialek,Wolfgang Holter,Manfred Lehner,Natascha Teufert,Johannes Brozy,Markus Münz,Armin Ensser,Julia Proff,Benjamin Salzer

doi:10.1038/s41598-018-36055-2

Abstract

Bispecific T cell engager (BiTE) antibody constructs are successfully used as cancer therapeutics. We hypothesized that this treatment strategy could also be applicable for therapy of human cytomegalovirus (HCMV) infection, since HCMV-encoded proteins are abundantly expressed on the surface of infected cells. Here we show that a BiTE antibody construct directed against HCMV glycoprotein B (gB) and CD3 efficiently triggers T cells to secrete IFN-γ and TNF upon co-culture with fibroblasts infected with HCMV strain AD169, Towne or Toledo. Titration of gB expression levels in non-infected cells confirmed that already low levels of gB are sufficient for efficient triggering of T cells in presence of the BiTE antibody construct. Comparison of redirecting T cells with the bispecific antibody versus a chimeric antigen receptor (CAR) based on the same scFv showed a similar sensitivity for gB expression. Although lysis of infected target cells was absent, the BiTE antibody construct inhibited HCMV replication by triggering cytokine production. Notably, even strongly diluted supernatants of the activated T cells efficiently blocked the replication of HCMV in infected primary fibroblasts. In summary, our data prove the functionality of the first BiTE antibody construct targeting an HCMV-encoded glycoprotein for inhibiting HCMV replication in infected cells.

Highlights

The reactivation of human cytomegalovirus (HCMV) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT)[1,2]
The expression of glycoprotein B (gB) on the surface of HCMV-infected human foreskin fibroblasts (HFF) is shown in Supplemental Fig. 1a, and the phenotype of CD3/CD28-activated T cells is shown in Supplemental Fig. 1b,c
Fibroblasts infected with the HCMV strain AD169 express high levels of gB already 3 days after infection and T cells in co-culture start secreting IFN-γ and TNF upon addition of a gB specific Bispecific T cell engagers (BiTE) antibody construct

Summary

Introduction

The reactivation of human cytomegalovirus (HCMV) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT)[1,2]. Pre-emptive therapy with ganciclovir or its oral prodrug valganciclovir as first-line treatment is started as soon as virus load is detected in the blood in order to prevent progression of the asymptomatic infection This treatment has significant bone marrow toxicity and drug resistance may develop with these drugs or with foscarnet or cidofovir used in second-line treatment[7,8]. The clinical implementation of a gB targeted T cell therapy would certainly be facilitated by a strategy based on a bispecific antibody approach due to safety aspects and simplified production compared to CAR-T cells. Such a strategy was recently reported by Meng et al.[20]. We tested this construct with primary fibroblasts infected with different HCMV strains, compared it with CAR-T cells, and demonstrated that it can limit the spread of HCMV independently of cytolysis

Methods

Results

Conclusion