Tumor-growth inhibition with bispecific antibody fragments in a syngeneic mouse melanoma model: The role of targeted T-cell co-stimulationvia CD28

Abstract

The ability of bispecific antibodies with anti‐tumor × anti‐CD3 specificity to mediate the killing of tumor cells by activated T cells has been demonstrated in many in vitro experiments. Moreover, long‐term survival of lymphoma‐bearing mice has been observed after treatment with such reagents. The therapeutic effect of bispecific antibodies in solid‐tumor models has been less impressive, in particular if fragmented antibodies were used to avoid systemic T‐cell activation by bispecific constructs binding to Fc‐receptor‐positive cells. Here we report that bispecific anti‐tumor × anti‐CD3‐fragments markedly inhibit intraperitoneal as well as pulmonary tumor growth in mice inoculated with B16 melanoma cells, resulting in the long‐term survival of animals. Therapeutic success critically depends on the number of recruitable effector cells at the site of tumor growth. A second bispecific construct triggering the co‐stimulatory CD28‐molecule on the T‐cell surface increased tumor‐cell killing in vitro and in vivo, despite rather low avidity of this reagent to mouse T cells. Finally, long‐term‐surviving animals showed improved survival after i.v. rechallenge with tumor cells, indicating that bispecific antibodies are capable of inducing long‐lasting protective immunity. Int. J. Cancer 80:138–144, 1999. © 1999 Wiley‐Liss, Inc.

Induction of a long-lasting antitumor immunity by a trifunctional bispecific antibody

“…In contrast, the combinatorial usage of 2 bsF(abЈ) 2 fragments (CD3 ϫ EpCAM ϩ CD28 ϫ EpCAM) in the identical tumor model only led to a marginal tumor elimination and poor induction of tumor immunity. 31 This result further supports the hypothesis that the Fc portion of the bsAb is crucial for the killing capacity as well as for the induction of tumor immunity and suggests that single costimulatory signals via CD28 to the T cell are not sufficient to replace physiologic T-cell activation mediated by accessory cells.…”

Efficient Generation of Bispecific Murine Antibodies for Pre-Clinical Investigations in Syngeneic Rodent Models

“…Despite the relative late dosing compared to other B16-F10-based T-cell redirection models 12, 13, 15, 17 , therapeutic activity was observed in the same dose-range reported for other surrogate bsAbs with regular IgG architecture 4, 12 . The use of an effector function competent (active) backbone resulted in transient T-cell-mediated toxicity, consistent with the occurrence of systemic cytokine release syndrome 38 .…”

“…Immunocompetent mice are readily accessible, relatively cheap and mouse xenografts are easily established, although the number of suitable mouse cell-lines for grafting is limited 1, 44, 45 . This repertoire, however, can be greatly expanded by transfecting the tumor target of interest into the available mouse cell-lines 4, 12–15, 17 . The differences in tumorigenesis between mouse and human tumors, e.g.…”

Retargeting T Cells for HER2-Positive Tumor Killing by a Bispecific Fv-Fc Antibody

“…Specific cytotoxicity of FcabCD3 armed ATCs against HER2-expressing SKBR3 cells was evaluated using Cell Counting Kit 8 (CCK8) assay [17]. In brief, 1x10 4 SKBR3 cells were seeded in a flat-bottom 96-well plate overnight to allow cells to adhere.…”