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

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.

Targeting SARS-CoV-2 infection through CAR-T like bispecific T cell engagers incorporating ACE2

“…Bispecific T cell engagers (Bites) are already approved for use in humans, following the accelerated approval of Blinatumomab (CD19-CD3 Bite) in March 2018 for B-cell lymphomas (Kantarjian et al, 2017). Other studies also showed that Bites could be employed against Her2 (Yu et al, 2019), BCMA (Goldstein et al, 2020), EpCAM (Ferrari et al, 2015), EGFR (Lutterbuese et al, 2010), CD20 (Hosseini et al, 2020), and PDL1 (Horn et al, 2017) expressing cancers; and diseased cells infected by CMV (Brey et al, 2018) and HIV (Sung et al, 2015). Compared to current treatments (such as neutralizing antibodies or anti-virals) ACE2-Bite approach may potentially be effective both at early stages (as neutralizer of the virus entry) and later stages of the infection when antibody immune defenses are breached, and T cells become more important in restricting the spread of the virus in vivo.…”

“…Indeed, a B cell surface protein (CD19) specific Bite called Blinatumomab (CD19-CD3 Bite) have already been approved to be used in B cell lymphoma patients in 2018 (35). Other studies also showed that Bites could be employed against Her2 (36), BCMA (37), EpCAM (38), EGFR (39), CD20 (40), and PDL1 (41) expressing cancers; and diseased cells infected by CMV (42) and HIV (43). Compared to current treatments (such as neutralizing antibodies or anti-virals) ACE2-Bite approach may potentially be effective both at early stages (as neutralizer of the virus entry) and later stages of the infection when antibody immune defenses are breached, and T cells become more important in restricting the spread of the virus in vivo.…”

Potent Bispecific Neutralizing Antibody Targeting Glycoprotein B and the gH/gL/pUL128/130/131 Complex of Human Cytomegalovirus

“…To combine the high potency of the pentamer-specific antibody and broad cell-type coverage of the gB-specific antibody, we developed a bispecific neutralizing antibody based on MAbs 3-25 and 2-18. Recently, our group and another group have reported the development of anti-CD3/anti-gB-based bispecific T-cell engagers (BiTEs) that redirect cytotoxic T cells for killing of HCMV-infected cells ( 48 , 49 ). While the anti-gB/CD3-bispecific antibodies aim to eradicate virus-infected cells, our bispecific antibody has the potential to neutralize circulating free virus and inhibit cell-to-cell viral spreading.…”

“…We previously characterized a gB AD-2-specific broadly neutralizing MAb, 3-25, and a pentamer-specific potently neutralizing MAb, 2-18 (33,35). To combine the high potency of the pentamer-specific antibody and broad cell-type coverage of the gB-specific antibody, we developed a bispecific neutralizing antibody based on engagers (BiTEs) that redirect cytotoxic T cells for killing of HCMV-infected cells (48,49). While the anti-gB/CD3-bispecific antibodies aim to eradicate virus-infected cells, our bispecific antibody has the potential to neutralize circulating free virus and inhibit cell-to-cell viral spreading.…”

CAR T Cell Immunotherapy Beyond Haematological Malignancy

“…CAR T cells targeting gB or other HCMV glycoproteins showed specific cytokine secretion and lysis of target cells in vitro , albeit with only weak efficacy ( 82 83 ). In a later study, Brey et al used bispecific antibodies targeting gB and CD3 and showed that although the T cells still had poor cytotoxic function, likely influenced by HCMV-encoded UL36 and UL37x1 which inhibit apoptosis, the cytokines secreted by the T cells halted viral replication ( 84 ). Further studies are required to assess their effectiveness in vivo .…”