Ultrasound Contrast Agents for Molecular Imaging

Transcription

1 Ultrasound Contrast Agents for Molecular Imaging Design and Development Joshua Rychak, PhD Vice President for Research Targeson, Inc Adj. Assistant Professor Dept of Bioengineering University of California, San Diego Visistar and Targestar are registered trademarks of Targeson, Inc Funding and Disclosures Targeson, Inc develops and markets microparticle-based products for medical imaging and life science research Co-founder, equity, employment Research support from Siemens Ultrasound NIH: HL1496, DK83142, CA13618, EB787 No clinical data or products will be discussed Microbubble Contrast Agents Size distribution by electrozone (Coulter) sensing Confocal Microscopy Rychak et al, Microsphere Diameter (um) Targestar P-HF Intravital Microscopy Rychak et al, 7 1

2 Microbubble Contrast Agents Lipid Shell Perfluorocarbon Gas Perfusion Agent non-targeted blood pool imaging Microbubble Contrast Agents Conjugation Chemistry Targeting Ligand Tether Perfusion Agent non-targeted blood pool imaging visualization and quantification of active perfusion Molecular Imaging Agent targeted to molecular components of disease Ultrasound Molecular Imaging 1. mm B-mode Imaging plane through tumor 2

3 Ultrasound Molecular Imaging 1. mm B-mode Imaging plane through tumor VEGFR2 Molecular Imaging Blood Flow Blood Flow Ultrasound Molecular Imaging 1. mm B-mode VEGFR2 Molecular Imaging Blood Flow VEGFR2 Targeted Targeting Ligands Targeting Ligand 3

4 Targeting Ligands Antibody Peptide Targeting Ligand Protein Aptamer Molecular Target etc Targeted Cell Healthy Cells Targeting Ligands Visistar Integrin Visistar VEGFR2 Visistar Selectin Visistar VCAM-1 Cyclic peptide MW: ~1, Da Single chain VEGF MW: 29, Da glycoconjugate MW:, Da mab MW:, Da Alpha-v Integrin VEGFR2 P-selectin VCAM-1 Conjugation and Agent Synthesis Cyclic peptide MW: ~1, Da Directional conjugation (lipidation) dope microbubble with lipidated peptide 4

5 Adherent MS per FOV Adherent MS per FOV 7/1/1 Conjugation and Agent Synthesis Synthesis of Agent Panel MW Marker ligand A B C D E F Conjugation Reaction Functional Activity In Vitro Adhesion Assay microscope objective laminar flow target surface Flow Videomicroscopy Autotracked Functional Activity In Vitro Adhesion Assay: Integrin-targeted agent Endothelial Cells Recombinant α v β 3 Visistar Integrin 4 4 Visistar Control Substrate: rα Blocking mab: vβ 3 Casein rα vβ 3 anti- α vβ 3 1 Ligand: peptide control --- peptide Blocking mab: anti-αv/β3

6 Subcutaneous tumor on mouse flank Scanner in B-Mode Targeted Agent Scanner in Contrast Mode 3 2 bolus played at 4X speed MC-38 (syngeneic colon carcinoma) dwell period (4-8 min) 1 steady state Pre-contrast Baseline Time (sec) Targeted Agent Control Agent 3 bolus played at 4X speed MC-38 (syngeneic colon carcinoma) No uptake of control agent Specific Signal (~ db) steady state Pre-contrast Baseline Time (sec) Time (sec) 6

7 Early Phase agents enter tumor and surrounding tissue tumor Met-1 cells implanted in mammary fat pad surrounding tissue Late Phase (4-8 min) agents retained at target site, cleared from adjacent tissue Targeted Agent Control Agent Targeted Agent Control Agent αvβ3 Integrin CD31 DAPI Anderson et al, Invest Radiol (11) Tumor Adjacent Tissue Evaluation of multiple formulations 7

8 Evaluation in Multiple Models Human Renal Cell Cancer Human Prostate Cancer focal enhancement at base of tumor Murine Colon Cancer donut pattern of peripheral angiogenesis Human Breast Cancer diffuse enhancement focal enhancement of orthotopic tumor In Vivo Efficacy Detection of spontaneous cancer in large animal A B A prostate B Invasive carcinoma Enhancement Canine prostate (transverse) no malignancy Summary Components of Targeted Imaging Agent gas core, shell, ligand, conjugation chemistry Agent Panel ligand density, conjugation route, formulation Orthogonal Assays for Activity immunoblot, flow cytometry, ELISA, BIACORE In Vitro Activity Flow chamber /Efficacy Imaging efficacy, specificity, target organs 8