Abstract 4325: Monoclonal antibodies to transmembrane proteins.

Abstract

Abstract Transmembrane proteins, including multipass transmembrane proteins like GPCRs and ion channels, are important targets for therapeutic monoclonal antibody (mab) discovery. Therapeutic antibodies to this class of proteins are generally targeted to extracellular domains displayed on the surfaces of living cells. Challenges associated with developing antibodies to this class of targets are small numbers of extracellular amino acids, membrane-dependent protein conformation, difficulty in expression at high levels, high amino acid sequence homology of human and mouse proteins, and post-translational modifications. DNA immunization strategies with full-length constructs and high throughput flow cytometry screening of mab binding to transfected and control cells was used to generate and identify large numbers of mabs to CXCR4 and ADORA2A (GPCRs) and CD20 (a tetraspan membrane protein). Panels of mabs were generated for all 3 targets with low numbers of hybridoma fusions. For each target the mab gene sequences were shown to be unique and contain levels of somatic hypermutation comparable to existing benchmark therapeutic antibodies. Epitope mapping with mutant proteins identified diverse patterns of reactivity including known and novel specificities. Functional assays including apoptosis and receptor modulation (calcium flux and cAMP modulation) further demonstrated that the technical approach generated diverse panels of antibodies that exhibit functional activity as good or better than existing benchmark therapeutic antibodies Citation Format: Michael C. Brown, Ross Chambers, Dale V. Onisk, Tony R. Joaquim, Lewis J. Stafford, Klaus Lindpaintner, Daniel Keter, James W. Stave. Monoclonal antibodies to transmembrane proteins. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4325. doi:10.1158/1538-7445.AM2013-4325