Description

TGF-β-neutralizing single-domain antibodies as modular cancer immunotherapeutics

Kevin A. Henry¹, Greg Hussack¹, Cathy Collins¹, John C. Zwaagstra¹, Jamshid Tanha^1,2,3, C. Roger MacKenzie^1,2

¹National Research Council Canada, Ottawa, Canada; ²School of Environmental Sciences, University of Guelph, Guelph, Canada; ³Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada

Transforming growth factor beta (TGF-β) is a pleiotrophic cytokine that accumulates in the tumour microenvironment and has immunosuppressive effects on tumour-infliltrating lymphocytes. Inhibition of TGF-β (especially targeted inhibition at tumour sites) is a promising strategy, especially in conjunction with other immunotherapies. Here, we report the isolation and functional characterization of llama V_HHs directed against human TGF-β3, including sdAbs that target the site of interaction between the cytokine and its cell-surface type II receptor. We recovered a diverse array of V_HHs that bound TGF-β with a wide range of affinities and isoform specificities. As fusions to human IgG1 Fc in multiple orientations, we show that the V_HH-Fcs potently neutralized TGF-β in in vitro cellular assays. The V_HHs identified here are currently being investigated as targeted cancer immunotherapeutics, as fusions to biomolecules targeting tumour antigens. In this application, the stability and modularity of the single IGHV domain carries important advantages over other types of therapeutics.