Abstract 4524: Non-genetic generation of IgG-like immune cell-redirecting antibodies lacking effector function

Abstract

Abstract Since the early approval of catumaxomab and blinatumomab, T cell-redirecting antibodies have emerged as a promising biologics in cancer treatment. New technologies are overcoming the limitations of the 1st generation T-cell redirecting bispecifics, especially extending half-life to allow intermittent dosing, reducing immunogenicity and improving the safety profile. Today, T cell-engagers are generated as a wide variety of molecular architectures, typically IgG-type. However, nearly without exception, these bispecifics are generated by genetic fusion of a cancer-binding and an anti-CD3 antibody, which inevitably requires genetic reengineering of an existing targeting antibody and/or extensive optimization of antibody format. We have shown earlier that the native glycan of a monoclonal antibody provides a privileged site for controlled attachment of small-molecule cytotoxic drugs.1 The resulting antibody-drug conjugates (ADCs) were found to display significantly improved therapeutic index versus conventional technologies, while improving manufacturability. This proprietary technology, known as GlycoConnect™, has been adapted by various ADC developers, and entered clinical phase early 2019. Here we present the adaption of GlycoConnect™ technology for the generation of immune cell-redirecting antibodies, without requiring prior protein reengineering. Instead, a two-stage chemoenzymatic process is applied that allows the conversion of any IgG isotype into a T cell-engager by selective attachment of anti-CD3 scFv to the antibody glycan. Studies are presented to precisely control conjugation stoichiometry, providing molecular architectures with defined 2:1 or 2:2 ratio (target-binding:CD3-binding), as well as functional studies to corroborate the biological activity of these GlycoConnect™ bispecifics. Finally, early results will be presented regarding extension of the concept to bispecifics designed to redirect natural killer (NK) cells, or to engage T-cells by activation of costimulatory molecules, such as CD137 (4-1BB). 1 van Geel et al. Chemoenzymatic Conjugation of Toxic Payloads to the Globally Conserved NGlycan of Native mAbs Provides Homogeneous and Highly Efficacious Antibody−Drug Conjugates. Bioconj. Chem. 2015, 26, 2233-2242. Citation Format: Floris L. van Delft, Remon van Geel. Non-genetic generation of IgG-like immune cell-redirecting antibodies lacking effector function [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4524.