Analysis of the sequences of 819 antibodies and Fc fusion proteins in clinical trials reveals 55 different molecular formats and 80 Fc variants designed to modify effector function. We have now synthesized matched sets of antibodies to compare these variants directly. This presentation focuses particularly on approaches to reduce binding to Fc gamma receptors and so prevent unwanted inflammatory responses.

IgG3 is unique among the IgG subclasses due to its extended hinge, allotypic diversity and enhanced effector functions. It is also underrepresented as an immunotherapeutic candidate, partly due to a lack of structural information. Thom Sharp will present structural data of IgG3-mediated complement activation, which reveals an unexpected role of the extended hinge in pathogen neutralization, complement initiation, and C4b deposition.

Due to antibiotic resistance, there is now great interest in the development of antibody-based therapies against bacterial infections, for instance via antibodies that boost the host immune system. This talk aims to provide insights into the reactivity of antibodies in a functional immune response. I will demonstrate mechanisms of antibody-dependent complement activation and phagocytosis on bacteria and highlight how important pathogens evolved mechanisms to evade antibody-mediated killing.

T Cell Bispecific antibodies (TCBs) are transforming the treatment of human tumors. Whereas the role and the recruitment of T cells to tumor sites following TCB treatment has been broadly documented, the role of the other immune cells remains elusive. In this presentation, we will describe the tumor microenvironment (TME) reprogramming induced by TCB treatment and elaborate on the role that the other immune cells have in modulating the response or resistance to TCB therapy.

Human cell microarray screening enables the discovery of potential off-targets for a variety of biologics, including peptides, antibodies, scFvs, proteins, CAR T and other cell therapies. This presentation describes the generation of extensive screening libraries of expressed biosynthetic human plasma membrane and tethered secreted proteins, highlighting the role of the technology in providing specificity screening case studies relevant to safety assessment and IND submissions.

Twist Biopharma, a division of twist Bioscience, combines HT DNA synthesis technology with expertise in antibody engineering to provide end-to-end antibody discovery solutions — from gene synthesis to antibody optimization. The result is a make-test cycle that yields better antibodies against challenging targets from immunization, libraries, and machine learning. Twist Biopharma will continue to optimize and expand its discovery, library synthesis and screening capabilities in partnership with others to further utilize their make-test cycle.

A remaining challenge of anti-tumor antibody therapeutics is the on-target off-tumor toxicity induced by binding to target antigens expressed in normal tissues. To overcome this, we established a novel antibody technology, called Switch-IgTM, which enables antibody binding to antigen selectively at tumor sites but not at normal tissues. In this presentation, we will describe how we generated these conditionally active antibodies and their therapeutic application.

XPAT proteins are conditionally active T cell engagers (TCEs) designed to exploit the dysregulated protease activity in tumors. In preclinical studies across multiple tumor targets, XPAT proteins demonstrated 1) Strong masking of in vitro cytotoxicity by up to 4 logs; 2) Potent in vivo efficacy at doses similar to the efficacious doses of unmasked TCE controls; and 3) Masking increases tolerated Cmax in NHP by greater than 400-fold for HER2-XPAT. A clinical trial investigating a HER2-targeted XPAT protein has been initiated.

Several strategies have been reported to develop activatable antibodies, but most of these require sophisticated (chemo)genetic antibody engineering. Our group developed bivalent peptide-DNA locks that allow non-covalent control of antibody activity by protease activity, light or pH. In addition, I’ll present our recent development of a pH-switchable antibody-blocking protein that can be used as a generally applicable mask to allow pH-sensitive control of antibody activity.

We have generated a series of conditionally masked therapeutic antibodies that are proteolytically activated in the tumor microenvironment. Beyond masking of the antigen binding site, we also established a generic strategy of modulating effector functions of IgG1 therapeutic antibodies via Fc masking, resulting in an efficient blocking of Fc-gamma receptor binding and ADCC.

Antibody-cytokine fusions, specific to tumor-associated antigens, promise to increase the therapeutic index of the cytokine payload, as a result of a preferential localization at the tumor site. Novel strategies enable to achieve an even greater selectivity, using antibody-cytokine fusions, fulfilling the dream of “activity-on-demand” and helping spare normal tissues from undesired toxicity.

Conditional activation enables generating more efficient antibodies by minimizing on-target off-site dose-limiting effects. By reversibly masking the antibody, binding at the target site can be maximized, thereby decreasing the effective dose and minimizing potential harm in the healthy tissue. In this talk, I will present an overview of the recent progress in the field, showing the diversity of masking strategies available and highlighting the most novel and efficient approaches. In addition, we will introduce our versatile chemogenetic antibody masking method that enables activation by proteases and other stimuli.