In Vivo Fluorescence Imaging of the Activity of CEA TCB, a Novel T-Cell Bispecific Antibody, Reveals Highly Specific Tumor Targeting and Fast Induction of T-Cell-Mediated Tumor Killing.
OBJECTIVE
CEA TCB (RG7802, RO6958688) is a novel T-cell bispecific antibody, engaging CD3ε upon binding to carcinoembryonic antigen (CEA) on tumor cells. Containing an engineered Fc region, conferring an extended blood half-life while preventing side effects due to activation of innate effector cells, CEA TCB potently induces tumor lysis in mouse tumors. Here we aimed to characterize the pharmacokinetic profile, the biodistribution, and the mode of action of CEA TCB by combining in vitro and in vivo fluorescence imaging readouts.


METHODS
CEA-expressing tumor cells (LS174T) and human peripheral blood mononuclear cells (PBMC) were cocultured in vitro or cografted into immunocompromised mice. Fluorescence reflectance imaging and intravital 2-photon (2P) microscopy were employed to analyze in vivo tumor targeting while in vitro confocal and intravital time-lapse imaging were used to assess the mode of action of CEA TCB.


RESULTS
Fluorescence reflectance imaging revealed increased ratios of extravascular to vascular fluorescence signals in tumors after treatment with CEA TCB compared with control antibody, suggesting specific targeting, which was confirmed by intravital microscopy. Confocal and intravital 2P microscopy showed CEA TCB to accelerate T-cell-dependent tumor cell lysis by inducing a local increase of effector to tumor cell ratios and stable crosslinking of multiple T cells to individual tumor cells.


CONCLUSIONS
Using optical imaging, we demonstrate specific tumor targeting and characterize the mode of CEA TCB-mediated target cell lysis in a mouse tumor model, which supports further clinical evaluation of CEA TCB. Clin Cancer Res; 22(17); 4417-27. ©2016 AACRSee related commentary by Teijeira et al., p. 4277.
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland. Animal Imaging Center, Institute for Biomedical Engineering, ETH and University of Zurich, Zurich, Switzerland.
Steffi
S
Lehmann
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland. Animal Imaging Center, Institute for Biomedical Engineering, ETH and University of Zurich, Zurich, Switzerland.
Ramanil
R
Perera
Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center, Basel, Switzerland.
Hans-Peter
HP
Grimm
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Johannes
J
Sam
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Sara
S
Colombetti
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Tanja
T
Fauti
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Linda
L
Fahrni
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Teilo
T
Schaller
Roche Pharmaceutical Research and Early Development, Large Molecule Research, Roche Innovation Center Zurich, Zurich, Switzerland.
Anne
A
Freimoser-Grundschober
Roche Pharmaceutical Research and Early Development, Large Molecule Research, Roche Innovation Center Zurich, Zurich, Switzerland.
Jörg
J
Zielonka
Image and Data Analysis Unit (IDA), ScopeM, ETH Zurich, Zurich, Switzerland.
Szymon
S
Stoma
Animal Imaging Center, Institute for Biomedical Engineering, ETH and University of Zurich, Zurich, Switzerland.
Markus
M
Rudin
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Christian
C
Klein
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Pablo
P
Umana
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland.
Christian
C
Gerdes
Roche Pharmaceutical Research and Early Development, Roche Innovation Center Zurich, Zurich, Switzerland. marina.bacac@roche.com.
Marina
M
Bacac
D000818:Animals; D018033:Antibodies, Bispecific / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D000918:Antibody Specificity / Q000276:immunology; D000074322:Antineoplastic Agents, Immunological / Q000378:metabolism / Q000494:pharmacology; D015415:Biomarkers; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D002450:Cell Communication / Q000276:immunology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D057054:Molecular Imaging / Q000379:methods; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000378:metabolism / Q000628:therapy; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution
D018033:Antibodies, Bispecific; D000074322:Antineoplastic Agents, Immunological; D015415:Biomarkers; D002272:Carcinoembryonic Antigen