A novel format for recombinant antibody-interleukin-2 fusion proteins exhibits superior tumor-targeting properties in vivo
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Tiziano Ongaro1,2, Baptiste Gouyou1, Marco Stringhini3, Riccardo Corbellari1,4, Dario Neri3 and Alessandra Villa1
1 Philochem AG, Otelfingen, Switzerland
2 University School for Advanced Studies IUSS Pavia, Pavia, Italy
3 Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, ETH Zürich, Zürich, Switzerland
4 University of Trento, CiBIO, Department of Cellular, Computational and Integrative Biology, Trento, Italy
Keywords: tumor targeting; fibronectin; immunocytokines; interleukin-2; protein engineering
Received: June 11, 2020 Accepted: August 17, 2020 Published: October 13, 2020
The targeted delivery of interleukin-2 to the tumor is gaining attention as an avenue to potentiate the action of T and NK cells at the site of disease. We have previously described the fusion of the L19 antibody, specific to the EDB domain of fibronectin, with human interleukin-2, using a non-covalent homodimeric diabody format. Here, we describe four novel formats for the L19-IL2 fusion, featuring different arrangements of antibody and IL2. A comparative quantitative biodistribution analysis in tumor-bearing mice using radioiodinated proteins revealed that the novel format (L19L19-IL2, with the antibody in single-chain diabody format) exhibited the best biodistribution results. In vitro assays on peripheral blood mononuclear cells showed a decrease activation of regulatory T cells when single IL2 domain was used. In vivo, both L19-IL2 and L19L19-IL2 inhibited tumor growth in immunocompetent mouse models of cancer. T-cell analysis revealed similar levels of CD4+ and FoxP3+ cells, with an expansion of the CD8+ T cell in mice treated with L19-IL2 and L19L19-IL2. The percentage of CD4+ regulatory T cells was markedly decreased with L19L19-IL2 combined with a mouse-specific PD-1 blocker. Collectively, these data indicate that the new L19L19-IL2 format exhibits favorable tumor-homing properties and mediates a potent anti-cancer activity in vivo.
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