|
- 现金
- 62111 元
- 精华
- 26
- 帖子
- 30437
- 注册时间
- 2009-10-5
- 最后登录
- 2022-12-28
|
P0632
BISPECIFIC ANTIBODY CONSTRUCTS MEDIATE SPECIFIC
RETARGETING TOWARDS AND ELIMINATION OF HBV-POSITIVE
HEPATOCYTES AND TUMOR CELLS
F. Bohne1, J. Hasreiter1, O. Quitt1, J.-H. Bockmann1, F. Momburg2,
U. Protzer1. 1Institute of Virology, Technische Universit¨at
M¨unchen/Helmholtz Zentrum M¨unchen, Munich, 2National Center for
Tumor Diseases, German Cancer Research Center (DKFZ), Heidelberg,
Germany
E-mail: [email protected]
Background and Aims: Chronic hepatitis B is characterized by
exhausted effector cells, incapable of eradicating the virus. To
circumvent this limitation, HBV-specific retargeting of immune
effector cells using bispecific monoclonal antibody (biMab)
constructs is a promising therapeutic approach. In this study,
effector cells are supplied with biMab that redirect T cells cells
towards HBV infected cells and activate their cytotoxic potential.
Methods: We constructed tetravalent biMab harboring two single
chain fragment (scFv) binding domains. The first scFv was designed
to target the S-domain of HBV-envelope proteins (HBs) on the
plasma membrane of infected hepatocytes. The second binding
motif engages T-cells via CD3 and co-stimulates them via CD28.
The two binding moieties are connected through an IgG1-derived
Fc-domain and dimerizes through disulfide bonding in the hinge
region. This results in tetravalent homodimers comprising two scFvbinders
for the target antigen and two for effector cell recruitment.
Results: In co-culture experiments, the engagement of HBV positive
hepatocytes and immune effector cells by the biMab
induced specific elimination of target cells and activation of
effector cells. Co-administration of HBs/CD3- and HBs/CD28-
specific biMab constructs was synergistic and mediated up to 96%
specific elimination of HBs-positive target cells in co-cultures with
PBMC. Flow cytometric analysis of cytokine production showed,
that retargeted effector cells were polyfunctionally activated by
the biMab and secreted IFNg, IL-2 and TNFa simultaneously.
Importantly, biMab were also able to redirect T cells to HBVinfected
HepaRG cell resulting in specific killing. Furthermore,
soluble HBs, mimicking the high viral loads in patient serum
failed to induce effector cell activation even when added to noninfected
cells. Finally, first in vivo experiments in immunodeficient
mice transplanted with HBV-positive hepatoma cells showed that
transferred human PBMC mediated a marked decrease in tumor size
upon biMab injection indicating a functional homing in tumors.
Conclusions: Retargeting of T cells towards HBV-positive cells
using bispecific antibody constructs is a promising new
immunotherapeutic approach to treat chronic hepatitis B and
associated hepatocellular carcinoma
|
|
发表于 2015-5-25 18:00