Sustained activation and tumor targeting of NKT cells using a CD1d–anti-HER2–scFv fusion protein induce antitumor effects in mice
Kathrin Stirnemann, Jackeline F. Romero, Lucia Baldi, Bruno Robert, Valérie Cesson, Gurdyal S. Besra, Maurice Zauderer, Florian Wurm, Giampietro Corradin, Jean-Pierre Mach, H. Robson MacDonald, Alena Donda
Kathrin Stirnemann, Jackeline F. Romero, Lucia Baldi, Bruno Robert, Valérie Cesson, Gurdyal S. Besra, Maurice Zauderer, Florian Wurm, Giampietro Corradin, Jean-Pierre Mach, H. Robson MacDonald, Alena Donda
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Research Article Oncology

Sustained activation and tumor targeting of NKT cells using a CD1d–anti-HER2–scFv fusion protein induce antitumor effects in mice

Abstract

Invariant NKT (iNKT) cells are potent activators of DCs, NK cells, and T cells, and their antitumor activity has been well demonstrated. A single injection of the high-affinity CD1d ligand α-galactosylceramide (αGalCer) leads to short-lived iNKT cell activation followed, however, by long-term anergy, limiting its therapeutic use. In contrast, we demonstrated here that when αGalCer was loaded on a recombinant soluble CD1d molecule (αGalCer/sCD1d), repeated injections led to sustained iNKT and NK cell activation associated with IFN-γ secretion as well as DC maturation in mice. Most importantly, when αGalCer/sCD1d was fused to a HER2-specific scFv antibody fragment, potent inhibition of experimental lung metastasis and established s.c. tumors was obtained when systemic treatment was started 2–7 days after the injection of HER2-expressing B16 melanoma cells. In contrast, administration of free αGalCer at this time had no effect. The antitumor activity of the CD1d–anti-HER2 fusion protein was associated with HER2-specific tumor localization and accumulation of iNKT, NK, and T cells at the tumor site. Targeting iNKT cells to the tumor site thus may activate a combined innate and adaptive immune response that may prove to be effective in cancer immunotherapy.

Authors

Kathrin Stirnemann, Jackeline F. Romero, Lucia Baldi, Bruno Robert, Valérie Cesson, Gurdyal S. Besra, Maurice Zauderer, Florian Wurm, Giampietro Corradin, Jean-Pierre Mach, H. Robson MacDonald, Alena Donda

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Figure 2

Binding and biological activity of recombinant CD1d molecules.

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Binding and biological activity of recombinant CD1d molecules. (A) Bindi...
(A) Binding of the sCD1d–anti-HER2 protein to HER2-expressing target cells, and recognition by FITC-labeled anti-CD1d. HER2-positive target cells (B16-HER2 and SKBR3) are recognized while HER2-negative LoVo cells are not. (B) Titration of the binding of the sCD1d–anti-HER2 scFv protein or the full anti-HER2 antibody Herceptin to B16-HER2 cells. Detection was performed using anti-CD1d–FITC and anti-human IgG FITC, respectively. (C) In vivo bioactivity of αGalCer-loaded sCD1d and sCD1d–anti-HER2, shown by the transient disappearance of liver iNKT cells secondary to the activation-induced downmodulation of the invariant T cell receptor. Liver lymphocytes were analyzed for numbers of iNKT cells 20 hours after i.p. injection of PBS (control) and 5 μg αGalCer, 20 μg unloaded or αGalCer-loaded sCD1d, 40 μg unloaded or αGalCer-loaded sCD1d–anti-HER2 fusion. Detection by FACS using PE-labeled αGalCer/CD1d-tetramer and FITC-labeled anti-CD3. Results are expressed in percent of iNKT cells from total liver lymphocytes.