Most approved
cancer immunotherapies lack T-regulatory (Treg) or
tumor specificity.
TNF receptor 2 (
TNFR2) antibody antagonism is emerging as an attractive
immunotherapy due to its tumor microenvironment (TME) specificity. Here we show that the human
TNFR2 receptor is overexpressed on both human
tumor cells and on human
tumor-residing Tregs, but negligibly expressed on beneficial T effectors (Teffs). Further, we found widespread, if variable,
TNFR2 expression on 788 human tumor cell lines from diverse
cancer tissues. These findings provided strong rationale for developing a targeted
immunotherapy using a
TNFR2 antibody antagonist. We designed a novel, human-directed
TNFR2 antibody antagonist and tested it for function using three cell-based TME assays. The antagonist showed TME specificity by killing of TNFR2-expressing
tumor cells and Tregs, but sparing Teffs, which proliferated. However, the antagonist shuffled between five
isoforms, only one of which showed the desirable function. We designed and tested several new chimeric human versions of the antagonist, finding that the
IgG2 isotype functioned better than the
IgG1 isotype. To further improve function, we introduced targeted mutations to its amino acid sequence to stabilize the natural variability of the
IgG2 isotype's hinge. Altogether, our findings suggest that optimal
TNFR2 antagonists are of the human
IgG2 isotype, have hinge stabilization, and have wide separation of antibody arms to bind to newly synthesized
TNFR2 on rapidly growing
tumor cells. Antagonistic
antibodies with these characteristics, when bound to
TNFR2, can form a nonsignaling cell surface dimer that functions with high TME specificity.