Z Gastroenterol 2014; 52 - V_5_02
DOI: 10.1055/s-0033-1361008

Immunotherapeutic retargeting of effector cells towards HBV infected target cells using bispecific antibody constructs

F Bohne 1, C Meyer 1, O Quitt 1, A Dhamodaran 2, L Alvarez 2, S Caballero 2, A Guillamet 1, V Bruss 3, G Moldenhauer 2, F Momburg 2, U Protzer 1
  • 1Helmholtz Zentrum Muenchen, Institute of Virology, München, Germany
  • 2German Cancer Research Center (DKFZ), National Center for Tumor Diseases, Heidelberg, Germany
  • 3Helmholtz Zentrum Muenchen, Institute of Virology, Neuherberg, Germany

Retargeting of effector cells is a promising immune-therapeutic approach to circumvent the immunotolerant state found in malignancies and chronic viral infections. Effector cells are supplied with designed specificities allowing redirection, and can be further equipped with costimulatory signals, together reverting the immunocompromised situation.

To achieve retargeting against HBV-infected cells, we constructed tetravalent bispecific antibody constructs harboring two different binding moieties of immunoglobulins. The first binding site had been designed to target HBV-infected cells by binding the S domain of HBV envelop proteins on the plasma membrane of infected hepatocytes. The second binding motif engages immune effector cells using specificities for either T cells (CD3-T cell receptor and CD28 for costimulatory signals) or NK cells (CD16 Fc-receptor and CD56 NCAM cell adhesion molecule).

Confocal microscopy showed that all four bispecific constructs bound specifically to the surface of HBV-producing cell lines. Through the engagement of HBV-positive target and immune effector cells, the bispecific constructs induced a specific activation of effector cells, which secreted IFNγ and TNFα. Co-administration of CD3- and CD28-specific constructs had a synergistic effect and was able to induce up to 90% specific cytotoxic elimination of HBV S protein positive cells by PBMCs. Comparable results were achieved using MACS sorted NK cells and NK cell specific bispecific constructs. Importantly, bispecific antibody constructs were also able to redirect effector cells to HBV-infected HepaRG cell resulting in specific killing of infected cells. Furthermore, activation of effector cells resulted in translocation of the degranulation marker Lamp-1 to the cellular surface.

Thus, retargeting of immune effector cells towards HBV-infected cells using bispecific constructs is a promising new immune-therapeutic approach.