Related Experiment Video
Updated: Apr 1, 2026
Tracking Bispecific Antibody-Induced T Cell Trafficking Using Luciferase-Transduced Human T Cells
Published on: May 12, 2023
Enhancement of CD117-Targeted Bispecific T-cell Engagement by CD33-Targeted Bispecific T-cell Costimulation in Acute
Mara Hofstetter1,2, Laura Volta1,2, Christian Koch1,2
1Department of Medical Oncology and Hematology, University and University Hospital Zürich, Zürich, Switzerland.
Acute myeloid leukemia (AML) originates from the hematopoietic stem and progenitor cell compartment and is associated with an overall poor clinical outcome. T cell-engaging bispecific antibodies (TCE), binding to a tumor-associated antigen and to CD3, redirect T cells to target antigen-expressing cells in an MHC/TCR-independent fashion. The development of TCEs for clinical application is facing several challenges. First, it is difficult to identify a tumor-selective, non-MHC-presented tumor target, not expressed on the tissue of tumor origin, thus limiting specificity. Second, CD3-directed TCEs do not provide a second, T cell-activating signal, such as the stimulation of CD28 or 41BB, thus possibly limiting T-cell efficacy. To address both aspects, we generated a CD33xCD28 IgG4-scFv2 with CD28 agonistic activity and tested it in combination with a previously by us reported CD117xCD3 TCE in AML. Combining these two bispecific antibodies significantly improved T cell-mediated lysis of AML cell lines and primary AML samples by enhancing T-cell activation, proliferation, and cytokine release in vitro. Furthermore, the addition of CD33xCD28 IgG4-scFv2 showed faster time to cell attachment, increased lytic events, and improved specificity toward double-target-expressing cells. In summary, the data indicate that combining costimulation via a second tumor-associated antigen to CD3-TCEs enhances T-cell lytic activity and simultaneously increases specificity against double-target-expressing AML cells.
Acute myeloid leukemia (AML) originates from the hematopoietic stem and progenitor cell compartment and is associated with an overall poor clinical outcome. T cell-engaging bispecific antibodies (TCE), binding to a tumor-associated antigen and to CD3, redirect T cells to target antigen-expressing cells in an MHC/TCR-independent fashion. The development of TCEs for clinical application is facing several challenges. First, it is difficult to identify a tumor-selective, non-MHC-presented tumor target, not expressed on the tissue of tumor origin, thus limiting specificity. Second, CD3-directed TCEs do not provide a second, T cell-activating signal, such as the stimulation of CD28 or 41BB, thus possibly limiting T-cell efficacy. To address both aspects, we generated a CD33xCD28 IgG4-scFv2 with CD28 agonistic activity and tested it in combination with a previously by us reported CD117xCD3 TCE in AML. Combining these two bispecific antibodies significantly improved T cell-mediated lysis of AML cell lines and primary AML samples by enhancing T-cell activation, proliferation, and cytokine release in vitro. Furthermore, the addition of CD33xCD28 IgG4-scFv2 showed faster time to cell attachment, increased lytic events, and improved specificity toward double-target-expressing cells. In summary, the data indicate that combining costimulation via a second tumor-associated antigen to CD3-TCEs enhances T-cell lytic activity and simultaneously increases specificity against double-target-expressing AML cells.
Significance:
Current TCEs lack costimulatory signaling. The here-described CD33xCD28 IgG4-scFv2 delivers target-selective costimulation and enhances activation, proliferation, cytokine release, and cytotoxicity when used in combination with CD117xCD3 TCE in AML in vitro. Furthermore, the dual tumor-associated antigen targeting improves therapeutic specificity by preferentially eliminating CD117+CD33+ cells, possibly allowing improved bispecific antibody-mediated AML therapy.
More Related Videos
09:01Flow Cytometry to Estimate Leukemia Stem Cells in Primary Acute Myeloid Leukemia and in Patient-derived-xenografts, at Diagnosis and Follow Up
Published on: March 26, 2018
10:21Proliferation and Differentiation of Murine Myeloid Precursor 32D/G-CSF-R Cells
Published on: February 21, 2018
