PEGS Boston 2025

Poster sessions

Poster 1 Title: HT-SPR Evaluation of Fc Gamma Receptor Binding using Carterra LSA^XT

Abstract: Fc gamma receptors (FcγRs) are a family of proteins expressed on the surface of immune cells that can elicit activating or inhibitory responses when bound by the Fc domain of IgG antibodies. IgG Fc-containing biologics are a substantial and growing class of drugs with over 175+ antibody therapeutics already approved or undergoing regulatory review (The Antibody Society, 2023). These biologics include IgG-based mAbs, multispecific antibodies, and Fc-fusion proteins. The Fc domain can be mutated to improve, diminish, or abrogate FcγR binding. It can also be mutated to heterodimerize Fc chains for multispecific antibody construction or to extend FcRn mediated half-life, to name a few common mutational strategies. In each application, assessing the mutational impact on each FcγR interaction relative to the wild-type Fc is critical as they are all bound by a common site in the hinge region of the Fc domain and can impart different FcγR-mediated immune responses as a function of their affinity. It is also critical to assess the binding of wild-type and engineered Fc domains to relevant species FcγRs if the therapeutic is intended to be administered to the respective species for proper drug characterization and data interpretation across species. FcγR affinities are commonly measured using lower throughput, high sensitivity biosensing instruments to accurately characterize these interactions and require significant lab time, instrument usage, and protein. Pairing Carterra’s LSA^XT with ACROBiosystems’ proteins enables the development of a high-throughput assessment of FcγRs to simplify the characterization of IgG-Fc containing biologics. Herein, we detail a workflow utilizing High-Throughput SPR (HT-SPR) on the LSA^XT to characterize trastuzumab (IgG1 mAb) against 11 FcγRs with high sensitivity and reproducibility in a fraction of the time and resources.

Poster 2 Title: Full Antigen Kinetics of Fabs Directly from Crude Periplasmic Extracts on an Anti-CH1 Capture Surface

Abstract: Characterizing detailed binding kinetics of antibody fragments directly from bacterial periplasmic extracts (PPEs) has been historically challenging because purification of all primary hits is time and resource intensive. Here we have described a highly scalable, yet data rich approach to characterizing the binding kinetics of Fab candidates directly from crude PPE sources. The throughput of the can measure full kinetics (k_a, k_d, and K_D) for thousands of Fabs in a single week, while eliminating the need for purification. The assay demonstrated here using 96 unique Fabs required fewer than 9 ug of antigen and was completed in 10 hrs. Importantly, this set of 96 clones is only one-twelfth of the 1152 clone capacity that can be analyzed in a single experiment. The ability to quantitate complete kinetic profiles for responses with R_max values as low as 5 RU emphasizes that data can be obtained even for poorly expressing clones and is a key benefit of the enhanced sensitivity of the LSA^XT.