Abstract 1767: A next generation site-specific ADC targeting breast and gastric cancer

Abstract

Antibody drug conjugates are entering a renaissance period as a promising treatment option for a variety of cancers. Despite some success in the past few decades, developing effective ADCs remains a challenge due to extensive inefficiencies of industry standard conjugation technologies. Industry available methods can be limited by lack of site-specificity, inflexibility on the site of conjugation, and poor overall biophysical characteristics which can alter the efficacy, safety, and bioavailability of these therapeutics. BrickBio’s unique bioconjugation methodology enables precise (site-specific), flexible (offering numerous options for conjugation site and chemistry), efficient, and scalable generation of antibody-drug conjugates which overcome these limitations and achieve the full potential of this highly promising class of therapeutics. In this work, we incorporate an azide-containing UAAs (unnatural amino acid) into full-length antibodies targeting receptors overexpressed in breast and gastric cancer. Specifically, we have engineered variants of IgG1 antibodies to contain the aforementioned UAA, enabling site-specific attachment of cytotoxic payloads, such as auristatins, via click chemistry to generate ADCs with homogeneous DARs and at different conjugation sites. The resulting BrickADCs exhibit high therapeutic efficacy against receptor-positive cell lines, particularly lines expressing low levels of HER2, in vitro as well as in mouse xenograft models. Not only are the BrickADCs 100x more potent in demonstrated cell lines, but current research indicate that they have an improved safety profile over T-DM1. In other efforts, the BrickADC platform is leveraging a proprietary Modular Multisite Platform (MMP) to address the unmet need of eventual ADC resistance by conjugating multiple distinct payloads in a homogenous fashion. Continued preclinical work is underway for these pipeline candidates as well as investigation into other target areas. Citation Format: James Sebastian Italia, Nikos Biris, Zhi Li, Myer Hussain, John Boyce, Audrey Warner. A next generation site-specific ADC targeting breast and gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1767.