Discovery on Target. Short Course Preview Deck

Transcription

1 Discovery on Target Short Course Preview Deck Targeting of GPCRs with Monoclonal Antibodies Barbara Swanson, Ph.D. Sorrento Therapeutics, Inc. October 2014

2 GPCR Short Course Overview Introductions Brief review of GPCRs Structure, mechanism, role in diseases Methods for antibody discovery for GPCR targets In vitro assays for antibody functionality characterization Review of kinetics Agonism, antagonism, allosteric modulation Review of GPCR-targeting antibodies in the clinic and case studies Open discussion 2

3 There is no magic bullet for discovering antibodies against GPCRs. A large and diverse tool-box is needed for success against a range of GPCR targets 3

4 Why Target GPCRs with Antibodies? GPCR s are implicated in many disease conditions Opportunities for G protein-coupled receptor-targeted antibody therapeutics. Therapeutic areas in which G protein-coupled receptors (GPCRs) suitable as targets for antibody-based drugs have been identified. In total, 88/370 GPCRs have strong disease rationale and a profile suitable for targeting with an antibody. mabs 2:6, ; November/December 2010 Largest mammalian membrane receptor family with ~850 members 30-50% of small molecule drugs are targeted at GPCRs Recent success has been low Antibodies provide: Improved specificity Longer half-life Can target different epitopes More limited bio-distribution, which can limit side-effects Disadvantages: Difficult to penetrate CNS for those targets Possible immunogenicity More costly to manufacture and administer 4

5 Advantages of anti-gpcr Antibodies Multiple mechanisms of action High affinity (slow dissociation rate) Can recruit immune system functions Can carry payloads (toxins, markers) May be agonist, antagonist, or allosteric modulators Can fine-tune specificity and affinity Multiple uses Diagnostics Treatment of various types of diseases Reagents (stabilize GPCR targets) 5

6 Methods for antibody discovery Antigens to use Wide variety available Need to break tolerance? Animal immunizations Different species, ways to immunize Panning against antibody library (phage display) Libraries can be human (including B cell screening), murine or synthetic 6

7 Receptor Antigens Purified protein, cells, liposomes, magnetic nanoparticles, virus like particles, nanodiscs, peptides (free and constrained), membrane preps, post-translational modifications, different conformational states, DNA Because the receptor is an integral membrane protein, obtaining good material to use as an antigen can be challenging 7

8 Comparison of Different GPCR Antigens Antigen Pros Cons Purified protein Peptides, free or attached to carrier Pure antigen Can mutate: more stable Many are easy to make Difficult: must be properly folded and stable Most do not have 2 structure Peptides, constrained May mimic 2 ary structure May not have correct 2 structure Membrane preparations VLPs (virus-like particles) Can prepare from cell lines; GPCR should be in a proper conformation Can prepare from cell lines; GPCR should be in a proper conformation Contain other proteins; both sides of the GPCR are presented Contain other proteins In vitro synthesis Pure protein Small amounts; need to incorporate into membrane DNA Easy to make; no protein purification No control over expression 8

9 GPCR Antigen Case Studies: anti-cxcr4 mabs Liposome Cf2X4C9 cells expressing CXCR4 were used to make proteoliposomes Used an antibody that recognizes a native conformation and excludes ligand to confirm expression Performed three rounds of panning using a human scfv antibody library and the CXCR4-proteoliposomes Clones were screened for binding by cell-based ELISA Six unique clones were identified 5/6 clones showed some degree of inhibition (20-60%) of chemotaxis when expressed as scfvfc s J Immunol 2007; 179: Wikipedia 9

10 Why are Kinetics Important? GPCRs can have multiple ligands that bind at multiple sites, resulting in different types of signaling There are many possible GPCR epitopes available for an antibody Antibodies can potentially be found that are agonists or antagonists, which will affect what kind of response they generate. The desired kinetics of the antibody will depend on the desired outcome with the GPCR and cellular signaling 10

11 Anti-GPCR Antibodies in the Clinic (2012) Target Name Company Humanized Therapeutic indication Leukemia<comma> lymphoma/asthma Clinical status Phase I/II approved in Japan for relapsed or refractory T cell leukemia and lymphoma CCR4 Mogamulizumab Amgen/Kiowa Hakko Kirin Human C5aR NN-8209 G2 therapies/ Novo Nordisk Autoimmune disease Phase I CCR2 MLN1202 Takeda Inflammation Phase II-Discontinued CCR4 AT0009 Affitech Cancer Pre-clinical CCR5 PRO140 Progenics HIV Phase 2-Discontinued CCR5 HGS004 Human genome sciences HIV Phase I-Discontinued CCR5 HGS101 Human genome sciences HIV Discontinued CCR8 X Lilly Inflammation Undisclosed CCR9 MLN3126 Takeda Inflammatory bowel disease Discontinued CRTH2 Sosei/Abgenix Inflammation No Information CXCR3 AT0010 Affitech Inflammation Discovery CXCR4 MDX 1338 Medarex/BMS Leukemia Phase I CXCR4 ALX-0651 Ablynx Cancer Phase I-Discontinued CXCR4 LY Lilly Cancer Phase I-Discontinued GCG-R AMG477 Amgen Diabetes Phase I-Discontinued Abbott/Human genome Diabetes/neurologic/ GLP-1R X sciences metabolic disease No information LGR5 KM4056 Kiowa Hakko Kirin Cancer Pre-clinical VPAC-1 Thrombogenics Thrombocytopenia Pre-clinical Biochemical Pharmacology Volume 85, Issue 2, 15 January 2013, Pages David R. Webb, Tracy M. Handel, Anke Kretz-Rommel, Raymond C. Stevens 11