ENGINEERED MULTIFUNCTIONAL TRANSFORMING GROWTH FACTOR (TGF)-b TYPE II RECEPTOR ECTODOMAIN FUSIONS FOR ONCOLOGY APPLICATIONS

Anne Engelina Gesina Lenferink^1*John Christian Zwaagstra²Jason Baardsnes²Laurence Delafosse²Marie Parat²Umar Iqbal³Etienne Lessard⁴Arsalan S Haqqani³Anna Jezierski³Afnan Abu-Thuraia⁵Sébastien Tabariès⁵Peter Siegel⁵Traian Sulea²

• ¹Medical Devices Research Centre, National Research Council of Canada (NRC), Montréal, Canada
• ²Human Health Therapeutics Research Centre, National Research Council of Canada (NRC), Montréal, Canada
• ³Human Health Therapeutics Research Centre, National Research Council Canada (NRC), Ottawa, Canada
• ⁴Human Health Therapeutics Research Centre, National Research Council of Canada, Montreal, Canada
• ⁵McGill University, Montreal, Canada

ABSTRACT The transforming growth factor-b (TGF-b) superfamily consists of a large number of evolutionarily conserved and structurally related polypeptide growth factors. TGF-b elicits a wide range of context-dependent cellular responses that play important roles in the maintenance of normal physiological processes and is implicated in various pathologies, including cancer. In healthy cells and in the early stages of cancer development, TGF-b acts as a tumor suppressor by inducing cell cycle arrest and apoptosis. However, in late-stage cancer cells, TGF-b can promote tumorigenesis, including epithelial-mesenchymal transition (EMT), metastasis and chemoresistance. The dual-function and pleiotropic nature of TGF-b makes therapeutic targeting of this molecule a significant challenge. In this report, we describe the design and development of a novel class of TGF-b-targeting therapeutics in which the TGF-b type II receptor ectodomain (TbRII-ED) can be fused to an intact antibody, such as Cetuximab, or an antibody Fc fragment, without compromising the TbRII-ED or antibody function. As such, we constructed and characterized specific TbRII-ED-Fc fusions that act as efficient TGF-b ligand traps with picomolar in vitro neutralizing potencies against TGF-b1 and TGF-b3 isoforms, but not TGF-b2. We further demonstrate that TbRII-ED-Fc is a versatile ligand-trapping module that, when combined with a specific targeting moiety, can lead to powerful anti-cancer biotherapeutics targeted to and retained at the tumor site, by efficiently neutralizing the tumor-promoting activities of TGF-b in vivo.