We identified a MAGE-A4 x CD3 TCE that binds tumor-associated peptides from MAGE-A4- and MAGE-A8-pMHC but not to any other peptides tested. Binding specificity to 180+ different peptides was measured with a NFAT reporter assay using T2 cells and Jurkat NFAT reporter cells.

MAGE-A4 x CD3 TCEs show functional profiles comparable to a clinical benchmark. Functional profiles for two molecules selected for further assessment are compared to that of a clinical benchmark.

We combine our antibody discovery capabilities with our TCE platform to identify molecules with high potency and specificity for pMHC targets. We engineered 200+ bispecific molecules using 6 pMHC-binding arms and identified a potent TCE with high specificity for MAGE-A4-pMHC.

272 diverse CCR8-specific antibodies were identified from immunization and deep single-cell screening. Antibody sequence diversity was visualized using Celium™, and 272 CCR8-binding antibodies were selected for high-throughput expression based on clonal diversity.

Structure-guided humanization was used to identify candidates with optimal profiles for predicted immunogenicity and function. Homology modeling guided the assessment of residues targeted for humanized back-mutations on the light (L1-5) and heavy chains (H1-4). The impact of heavy/light chain back-mutations on function was assessed in a rational, combinatorial approach and measured in an ADCC reporter assay.

Strategic selection of diverse, developable antibodies with a range of potencies. Selected antibodies were similar to a clinical benchmark molecule in an ADCC reporter assay.

CD28-binding antibodies can enhance anti-tumor activity in combination with T-cell activating therapeutics. The anti-tumor activity of T cells, initiated via the T-cell receptor (TCR), can be enhanced through costimulatory engagement of the CD28 co-receptor. This costimulation can be leveraged therapeutically using CD28-binding antibodies to improve the efficacy of T-cell activating strategies, such as CD3 T-cell engagers (TCEs), in the tumor microenvironment.

CD28 activation in the presence or absence of FcγRIIb confirms that antibodies are conditional CD28 agonists. 92 antibodies, generated with human IgG1 Fc, were tested for CD28 FcγRIIb-dependent activation. 22 antibodies were selected for a 1-in-4, nine-point titration series.

CD28-binding antibodies do not show superagonist activity when mixed with peripheral blood mononuclear cells (PBMCs) from healthy donors. Cytokine release profiles are shown for five PBMC donors that were cultured with wet-coated antibodies.