Novel Bispecific Antibodies Increase γδ T-Cell Cytotoxicity against Pancreatic Cancer Cells

Abstract

The ability of human gd T cells from healthy donors to kill pancreatic ductal adenocarcinoma (PDAC) in vitro and in vivo in immunocompromised mice requires the addition of gd T-cell-stimulating antigens. In this study, we demonstrate that gd T cells isolated from patients with PDAC tumor infiltrates lyse pancreatic tumor cells after selective stimulation with phosphorylated antigens. We determined the absolute numbers of gd T-cell subsets in patient whole blood and applied a real-time cell analyzer to measure their cytotoxic effector function over prolonged time periods. Because phosphorylated antigens did not optimally enhance gd T-cell cytotoxicity, we designed bispecific antibodies that bind CD3 or Vg9 on gd T cells and Her2/neu (ERBB2) expressed by pancreatic tumor cells. Both antibodies enhanced gd T-cell cytotoxicity with the Her2/Vg9 antibody also selectively enhancing release of granzyme B and perforin. Supporting these observations, adoptive transfer of gd T cells with the Her2/Vg9 antibody reduced growth of pancreatic tumors grafted into SCID-Beige immunocompromised mice. Taken together, our results show how bispecific antibodies that selectively recruit gd T cells to tumor antigens expressed by cancer cells illustrate the tractable use of endogenous gd T cells for immunotherapy.

Resistance of cyclooxygenase-2 expressing pancreatic ductal adenocarcinoma cells against γδ T cell cytotoxicity

“…Our intention was to selectively target gd T cells to HER-2/neu-expressing tumor cells and to enhance their cytotoxicity more efficiently than selective activators of gd T cells, such as phosphorylated antigens (PAg). 18 Despite promising results in these studies, we identified PDAC cells that were nearly resistant to gd T-cell cytotoxicity.…”

“…Weak gd T cell-mediated lysis of PDAC cells could be enhanced in several but not all PDAC cells by the addition of a novel bispecific antibody [Her2£CD3] or tribody [(Her2) 2 £Vg9]. 18 The aim of our current study was to analyze the underlying mechanisms of the differential sensitivity of PDAC cells against gd T cell-mediated lysis. We analyzed 4 PDAC cell lines of distinct origins and grades of differentiation, which we previously used in our recent publications.…”

“…We analyzed 4 PDAC cell lines of distinct origins and grades of differentiation, which we previously used in our recent publications. 18,19 PancTu-I and Pt45P1 cells were initially established from primary tumors (stage G2-G3), whereas Panc89 and Colo357 cells were generated out of lymph node metastases (stage G1-G2). 20 For our analysis, we used the previously described Real Time Cell Analyzer (RTCA) system which uses impedance technology.…”

“…16, 17 We recently reported that the adoptive transfer of gd T cells in combination with application of a novel tribody [(Her2) 2 £Vg9] reduced growth of PDAC cells grafted into severe combined immunodeficiency disease (SCID)-Beige immunodeficient mice. 18 We designed a unique bispecific antibody [(Her2) 2 £Vg9] in the so-called tribody format that has one binding site for the Vg9 Tcell receptor (TCR) element on gd T cells and 2 binding sites for HER-2/neu (ERBB2) expressed by PDAC cells. Our intention was to selectively target gd T cells to HER-2/neu-expressing tumor cells and to enhance their cytotoxicity more efficiently than selective activators of gd T cells, such as phosphorylated antigens (PAg).…”

Mono- and dual-targeting triplebodies activate natural killer cells and have anti-tumor activityin vitroandin vivoagainst chronic lymphocytic leukemia

“…39 Recently, recombinant antibodies could successfully retarget g/d T cell effector functions against HER2-positive tumor cells. 40,41 Similarly, co-stimulation of NKG2D on CD8 C T cells decreased expression of anti-inflammatory cytokines IL-10, IL-9, IL-13 while induced cytotoxicity as well as expression of pro-inflammatory cytokines including IFNg and TNFa. 42,43 Taking together, we believe that ULBP2-aCD19-aCD19 not only stimulated NK cells but might have also retargeted NKT, g/d T and CD8 C T cells in mice to promote pro-inflammatory environment and deliver direct toxicity to target cells.…”