Tumor-specific crosslinking of GITR as costimulation for immunotherapy.
Activation of murine glucocorticoid-induced tumor necrosis factor-related receptor (mGITR) by its natural ligand (GITRL) or antiGITR agonist mAb enhances T-cell responses, inhibits regulatory T-cell (Treg)-mediated suppression and induces tumor immunity in a variety of murine tumor models. However, systemic administration of these costimulatory agents can lead to global T-cell activation and autoimmunity. To specifically manipulate the T-cell compartment in the tumor microenvironment we propose to target the tumor infiltrating T cells with a bispecific mGITRL fusion protein. For that purpose, mGITRL is linked to a single-chain antibody targeting fibroblast activation protein (FAP) as FAP expression is restricted to cancer-associated fibroblasts (CAFs) found in the stroma of epithelial cancers. AntiFAP-mGITRL fusion protein forms dimers and binds to murine GITR with 1.2 μM affinity and to murine FAP with 4.5 nM. The construct is able to costimulate CD8+ and CD4+ effector T cells resulting in increased proliferation, IFN-γ and IL-2 production. This costimulatory effect is enhanced when the fusion protein is bound to a FAP-positive cell line mimicking FAP CAFs. In suppression assays, membrane-bound antiFAP-mGITRL is 100-fold more effective in overcoming Treg-mediated suppression than unbound fusion protein. These studies suggest that targeted tumor therapy with antiFAP-mGITRL fusion protein could induce tumor rejection while minimizing autoimmune side effects.
Division of Oncology, University Hospital Zürich, Zürich, Switzerland. christoph.renner@usz.ch
Tanja
T
Burckhart
Markus
M
Thiel
Hiroyoshi
H
Nishikawa
Thomas
T
Wüest
Dafne
D
Müller
Alfred
A
Zippelius
Gerd
G
Ritter
Lloyd
L
Old
Hiroshi
H
Shiku
Christoph
C
Renner
D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D010450:Endopeptidases; D018093:Gelatinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053450:Glucocorticoid-Induced TNFR-Related Protein; D007167:Immunotherapy; D008213:Lymphocyte Activation / Q000187:drug effects; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000276:immunology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D017475:Receptors, Nerve Growth Factor / Q000276:immunology / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D000099167:Fibroblast Activation Protein Alpha
D000951:Antigens, Neoplasm; D016207:Cytokines; D010450:Endopeptidases; D018093:Gelatinases; D053450:Glucocorticoid-Induced TNFR-Related Protein; D008565:Membrane Proteins; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D057127:Single-Chain Antibodies; D000099167:Fibroblast Activation Protein Alpha; C106544:Tnfrsf18 protein, mouse