To develop a bispecific therapeutic that could be produced and assembled stably in situ, Freitag and Kolibius et al. developed DATE – a bispecific architecture based on a fusion of a designed ankyrin repeat protein (DARPin; a stable monomeric protein scaffold) to a CD3-targeting scFv. When recombinantly produced as a therapeutic protein, a HER2/CD3-targeted DATE induced strong and selective cytotoxic T cell-mediated killing against different HER2+ cancer lines. When expressed by tumor cells in situ as the payload of a HER2-retargeted adenoviral vector, DATEs accumulated, T cells infiltrated, and tumors regressed.
Contributed by Lauren Hitchings
ABSTRACT: Bispecific T cell engagers are a promising class of therapeutic proteins for cancer therapy. Their potency and small size often come with systemic toxicity and short half-life, making intravenous administration cumbersome. These limitations can be overcome by tumor-specific in situ expression, allowing high local accumulation while reducing systemic concentrations. However, encoding T cell engagers in viral or non-viral vectors and expressing them in situ ablates all forms of quality control performed during recombinant protein production. It is therefore vital to design constructs that feature minimal domain mispairing, and increased homogeneity of the therapeutic product. Here, we report a T cell engager architecture specifically designed for vector-mediated immunotherapy. It is based on a fusion of a designed ankyrin repeat protein (DARPin) to a CD3-targeting single-chain antibody fragment, termed DATE (DARPin-fused T cell Engager). The DATE induces potent T cell-mediated killing of HER2(+) cancer cells, both as recombinantly produced therapeutic protein and as in situ expressed payload from a HER2(+)-retargeted high-capacity adenoviral vector (HC-AdV). We report remarkable tumor remission, DATE accumulation, and T cell infiltration through in situ expression mediated by a HER2(+)-retargeted HC-AdV in vivo. Our results support further investigations and developments of DATEs as payloads for vector-mediated immunotherapy.
Author Info: (1) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (2) Department of Biochemistry, University of Zurich, Winterthurerstrasse 1
Author Info: (1) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (2) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (3) Laboratory for Cancer Immunotherapy, Department of Biomedicine, University Hospital and University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland. (4) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (5) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (6) Department of Physiology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (7) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. (8) Laboratory for Cancer Immunotherapy, Department of Biomedicine, University Hospital and University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland. Division of Medical Oncology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland. (9) Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
