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Disparities between Antibody Occupancy, Orientation, and Cytotoxicity in Immunotherapy
Author(s) -
Ta Angeline N.,
Tennyson Rachel L.,
Aceveda Diane C.,
McNaughton Brian R.
Publication year - 2020
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.202000083
Subject(s) - antibody dependent cell mediated cytotoxicity , antibody , fusion protein , epitope , cytotoxicity , chemistry , immunoglobulin g , plasma protein binding , microbiology and biotechnology , immunology , biology , monoclonal antibody , biochemistry , recombinant dna , in vitro , gene
We report fusion proteins designed to bind spatially distinct epitopes on the extracellular portion of HER2, a breast cancer biomarker and established therapeutic target, and recruit IgG (either anti‐His 6 or serum IgG) to the cell surface. When the proteins were incubated with anti‐His 6 antibody and various concentrations of a single HER2‐binding protein His 6 fusion, we observed interference and a decrease in antibody recruitment at HER2‐binding protein concentrations exceeding ∼30 nM. In contrast, concomitant treatment with two or three distinct HER2‐binding protein His 6 fusions, and anti‐His 6 , results in increased antibody recruitment, even at relatively high HER2‐binding protein concentration. In some instances, increased antibody recruitment leads to increased antibody‐dependent cellular cytotoxicity (ADCC) activity. While a fusion protein consisting of a HER2‐binding nanobody and Sac7d, a protein evolved to recognize the Fc domain of IgG, binds IgG from serum, antibody recruitment does not lead to ADCC activity. Rationales for these disparities are provided. Collectively, our findings have implications for the design of efficacious targeted immunotherapeutic biologics, and ensembles thereof.