For the GPCR and ion channel target classes, biologics offer improved selectivity, an alternative for targets with known function that have not been amenable to small molecule drugs and the potential for using antibodies for targeted delivery of therapeutics. But for the field to advance, challenges in optimizing antigen quality and presentation, discovery methodologies, protein engineering and target identification must be resolved. This two-part forum brings discovery biologists and protein engineers together to discuss next generation strategies and technologies that will allow protein therapeutics directed against membrane protein targets to advance into the clinic and beyond. Part One, Antigen Optimization and Antibody Generation, examines of state of the art approaches for producing high quality membrane protein antigens and display and immunization strategies that can be applied to discover binders with functional activity against transmembrane targets.

Final Agenda

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Tuesday, September 20

7:00 am Registration Open and Morning Coffee

8:05 Chairperson’s Opening Remarks

Lili Huang, M.D., Ph.D., Principal Research Scientist, AbbVie

8:10 KEYNOTE PRESENTATION: MEMBRANE PROTEINS AS TARGETS FOR THERAPEUTIC ANTIBODY DISCOVERY

David R. Buckler, Ph.D., Director, Therapeutic Proteins, Regeneron Pharmaceuticals

Membrane proteins constitute a challenging class of targets for antibody discovery since they must remain membrane-associated to maintain their native conformation. However, an expanding number and variety have been successfully isolated in native form for structural studies, and these advances can be leveraged for antibody discovery. Examples from the recent literature and where Regeneron’s VelocImmune antibody discovery platform has been applied to GPCR and ion channel targets will be presented.

EXPRESSION AND PRODUCTION OPTIMIZATION OF MEMBRANE PROTEIN ANTIGENS

8:50 Design of Water-Soluble Variants of Membrane Proteins

Jeffery G. Saven, Ph.D., Professor, Chemistry, University of Pennsylvania

Recent theoretical and computational methods can identify the properties of amino acid sequences consistent with targeted structures and functions. Such methods address the structural complexity of proteins and their many possible amino acid sequences. Computational redesign of membrane proteins has yielded variants that retain structure and functionally related properties.

9:20 Stabilization of Functional Membrane Proteins Using Lipid-Like Self-Assembling Peptides

Sotirios Koutsopoulos, Ph.D., Research Scientist, Center for Biomedical Engineering, Massachusetts Institute of Technology

Membrane proteins are integral proteins of the cell membrane and are directly involved in the regulation of many biological functions and in drug targeting. However, our knowledge of membrane proteins is limited due to difficulties in producing sufficient quantities of soluble, functional, and stable receptors. Designer, surfactant-like peptides may be used to extract the protein from the cell membrane and stabilize the protein outside the membrane bilayer for further studies.

9:50 Grand Opening Coffee Break in the Exhibit Hall with Poster Viewing

10:35 Strategies and Methods to Deliver Ion Channel Reagents for Antibody Discovery

Michael Mullin, Ph.D., Investigator, Protein Cellular and Structural Sciences, RD Platform Technology and Science, GlaxoSmithKline, United Kingdom

Antibody discovery relies on the generation of high quality reagents ranging from cell lines to purified proteins. Many therapeutically relevant targets are difficult to express membrane proteins and production of appropriate reagents is both challenging and time-consuming. Using inducible mammalian cell-based systems combined with membrane tagging strategies, we present a unique method to improve the expression and detection of complex membrane proteins such as ion channels for antibody discovery.

11:05 Streamlining Integral Membrane Protein Antigen Production for Biologics Discovery

Pravien Abeywickrema, Associate Principal Scientist, Screening and Protein Sciences, Merck & Co., Inc.

Integral membrane proteins represent more than 60% of current drug targets. Despite the clinical significance, therapeutic antibodies against membrane proteins have been difficult to develop. One major challenge in this field is the difficulty in producing antigens in their native form to identify conformation-specific functional antibodies. We present here strategies we developed to streamline the design, production and characterization of membrane protein antigens to enable therapeutic antibody discovery.

11:35 A Saposin-Based Nanoparticle System for Stabilization of Membrane Proteins

Jens Frauenfeld, Ph.D., CEO, Salipro Biotech AB, Sweden

We present a saposin-lipoprotein nanoparticle system, which allows for the reconstitution of membrane proteins in a lipid environment. We demonstrate the applicability of the method on purified membrane proteins as well as by the direct solubilization and nanoparticle incorporation of membrane protein complexes from the virus membrane. The Salipro system allows for high-resolution cryo-EM of membrane proteins and is applicable for the development of novel drugs, vaccines and therapeutic antibodies.

12:05 pm New Approaches for mAb Discovery against GPCRs, Ion Channels, and Transporters

Ross Chambers, Ph.D., Director, Antibody Discovery, Integral Molecular, Inc.

Integral Molecular has developed new approaches to elicit, characterize, and engineer mAbs against challenging membrane proteins using its MPS Discovery Engine®. Robust immune responses are generated against native antigens using Lipoparticles (high-concentration membrane proteins) and DNA immunization. Chickens are used because most membrane proteins are highly conserved, while both phage display and B-cell cloning are used for isolation. MAbs are engineered using high-throughput Shotgun Mutagenesis and profiled for specificity using a comprehensive membrane proteome array.

12:35 Immunization Strategies for Difficult Membrane Proteins

John Kenney, Ph.D., President, Antibody Solutions

Multi-pass transmembrane and multi-meric membrane proteins, targets for therapeutic monoclonal antibody development, are often difficult to express in a native, bio-active state with appropriate structure. We will present results using surrogate antigen strategies such as DNA, transfected cells, viral lipoparticles and nanodiscs for antibody generation and screening against such targets.

12:50 Session Break

12:55 Luncheon Presentation (Opportunity Available)

1:25 Refreshment Break in the Exhibit Hall with Poster Viewing

ANTIBODY GENERATION AND ENGINEERING STRATEGIES

2:05 Chairperson’s Remarks

Andrew Nixon, Ph.D., Independent Consultant

2:15 Generation of Synthetic Antibodies to Trap Functional Intermediates of Membrane Proteins

Tony Kossiakoff, Ph.D., Professor, Biochemistry, Molecular Biology and the Institute for Biophysical Dynamics, University of Chicago

A high throughput phage display pipeline has been established to generate Fab-based synthetic antibodies to trap conformational states of membrane proteins to facilitate probing both their static and dynamic features, as well as the transitions between states. A key component of the system is the use of lipid-filled nanodiscs to provide membrane-like environments for the proteins during phage display selections. Our results demonstrate that in many cases detergents induce conformational states that are incompatible with true membrane environments.

2:45 Generation of Functional Antibodies Against the P2X3 Ion Channel

Lili Huang, M.D., Ph.D., Principal Research Scientist, AbbVie

Targeting ion channels with antibody approaches has been challenging and largely unsuccessful due to the difficulties in generating proteins in appropriate forms for antibody generation and establishing assays for screening. We will present the discovery of functional mAbs targeting P2X3 ligand-gated ion channel as a testament of a successful antibody approach for ion channels. We will also discuss lessons learned that can be applied to other difficult multi-spanning membrane protein targets.

3:15 A Novel Approach for the Generation and Affinity Maturation of Fully Human Antibodies to Natively Expressed GPCRs

Michael Gallo, Ph.D., President, Research, Innovative Targeting Solutions Inc.

A novel mammalian display system incorporating V(D)J recombination for the generation of fully human antibodies to GPCRs is described. This in vitro system is capable of simultaneously evaluating the binding of billions of monoclonal antibodies to identify binders to a GPCR target in its native and functional confirmation expressed in the cell membrane. Application of V(D)J recombination to the affinity maturation of antibodies to GPCRs will also be presented.

3:45 Refreshment Break in the Exhibit Hall with Poster Viewing and Poster Competition Winner Announced

4:25 Inducible GPCR Cell Lines for Antibody Characterization

Eric Grazzini, Ph.D., Team Leader Rapid Protein Production, Senior Research Officer, Biologics, National Research Council of Canada, Canada

National Research Council Canada (NRC) has a strong track record in target discovery and monoclonal antibody production. Among the most interesting and well-known therapeutic targets identified, GPCRs proteins represent a challenge and an opportunity to develop and characterize mAbs. Cells expressing GPCRs of interest can be used for immunization and/or screening purposes. To this end, we have developed the proprietary cumate-inducible CHOBRI cell line for stable and modulated gene expression.
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4:55 Generation of Functional mAbs Targeting GPCRs for Fibrosis and Autoimmune Disease Indications

Kiyoshi Takayama, Ph.D., President, Research Center, NB Health Laboratory Co., Ltd., Japan

MoGRAA is a new biotherapeutic concept for a GPCR targeted drug. Using the MoGRAA discovery engine, we discovered mAbs targeting a chemokine GPCR involved in the fibrosis pathway. The mAb exerts a therapeutic effect by shutting down chemokine-induced GPCR signaling. Using the surrogate mAb for the rat target GPCR, we proved the therapeutic concept of the antibody treatment in a lung fibrosis model, with superiority over the existing drug.

5:25 Welcome Reception in the Exhibit Hall with Poster Viewing

6:25 End of Day

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Wednesday, September 21

7:30 am Registration Open and Morning Coffee

NEW TECHNOLOGIES FOR DISCOVERY OF ANTIBODIES AGAINST MEMBRANE PROTEIN TARGETS

8:00 Chairperson’s Opening Remarks

John Kenney, Ph.D., President, Antibody Solutions

8:10 Strategies to Target Cell Surface Peptide-HLA Complexes as Cancer Antigens

David M. Kranz, Ph.D., Professor, Biochemistry, University of Illinois, Urbana-Champaign

T cells, via their T-cell receptors (TCRs), evolved to target intracellular peptides as cell-surface complexes with MHC products (HLA in humans). Many cancer-associated peptides have now been identified. These peptide-HLA complexes provide a vast source for next generation targets. Strategies to target them, including engineering high-affinity TCRs or antibodies that can be formatted as soluble therapeutics or as receptors in adoptive T cell therapies, will be discussed.

8:40 New Strategies and Technologies for Ab Discovery without Purified Proteins

JT Koerber, Ph.D., Scientist, Antibody Engineering, Genentech

The generation of high quality, natively folded proteins can often limit antibody discovery efforts. Therefore, robust alternative antigen formats to recombinant antigens are highly desired. I will discuss our optimization and comparison of several different DNA immunization technologies in both mice and rats. I will also present a case study highlighting the quality of mAbs generated via DNA immunization compared to mAbs generated with recombinant protein.

9:10 Strategies to Identify High Potency Therapeutic Antibodies for Multi-TM Targets

Martin J. Scott, Ph.D., Investigator, Biopharm Molecular Discovery, GlaxoSmithKline, United Kingdom

Cellular targets such as G-protein coupled receptors (GPCRs) are typically very challenging for therapeutic antibody discovery due to their complex nature and limited antigen availability. This presentation will describe the strategies implemented by GSK to successfully identify high potency neutralizing antibodies for such targets, using both in vitro display technologies and in vivo immunization approaches.

9:40 Coffee Break in the Exhibit Hall with Poster Viewing

10:25 Generating Synthetic Nanobodies against Purified Membrane Proteins

Roger Dawson, Ph.D., Principal Scientist, Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Switzerland

Nanobodies are versatile binding proteins receiving increasing attention in drug discovery. The considerable track record of camelid nanobodies from assay development to therapeutic applications has led us to combine the benefits of this natural scaffold with the advantages of synthetic libraries and in vitro display technologies. Using the example of a purified transporter, we explain a novel workflow used to create nanobodies for structural studies.

10:55 G Protein-Coupled Receptor Antibody-Ligand Identification by Directed Evolution

John Burg, Ph.D., Head, Biochemistry, Ab Initio Biotherapeutics

G protein coupled receptors (GPCRs) are critical mediators of signaling for both endogenous ligands and therapeutics. Despite their diversity in function, GPCRs signal through a conserved mechanism where agonist binding on the extracellular receptor face stabilizes active receptor conformations to enable cytoplasmic G-protein binding and downstream signaling. Leveraging this information, we have developed selection methodologies to isolate agonist antibodies and other biologics.

11:25 Enjoy Lunch on Your Own

2:40 Refreshment Break in the Exhibit Hall with Poster Viewing

3:20 End of Conference

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