EP0991427A2 - Ameliorations apportees a des agents diagnostiques et/ou therapeutiques ou les concernant - Google Patents

Ameliorations apportees a des agents diagnostiques et/ou therapeutiques ou les concernant

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Publication number
EP0991427A2
EP0991427A2 EP97910515A EP97910515A EP0991427A2 EP 0991427 A2 EP0991427 A2 EP 0991427A2 EP 97910515 A EP97910515 A EP 97910515A EP 97910515 A EP97910515 A EP 97910515A EP 0991427 A2 EP0991427 A2 EP 0991427A2
Authority
EP
European Patent Office
Prior art keywords
agent
vector
gas
reporter
microbubbles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97910515A
Other languages
German (de)
English (en)
Inventor
Jo Klaveness
Pal Nycomed Imaging AS RONGVED
Anders Hoegset
Helge Nycomed Imaging AS TOLLESHAUG
Aslak Godal
Dagfinn Nycomed Imaging AS LOEVHAUG
Magne Nycomed Imaging AS SOLBAKKEN
Alan Nycomed Imaging AS CUTHBERTSON
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GE Healthcare AS
Original Assignee
Nycomed Imaging AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB9622365.6A external-priority patent/GB9622365D0/en
Priority claimed from GBGB9622366.4A external-priority patent/GB9622366D0/en
Priority claimed from GBGB9622367.2A external-priority patent/GB9622367D0/en
Priority claimed from GBGB9700699.3A external-priority patent/GB9700699D0/en
Priority claimed from GBGB9708265.5A external-priority patent/GB9708265D0/en
Priority claimed from GBGB9711845.9A external-priority patent/GB9711845D0/en
Priority claimed from GBGB9711842.6A external-priority patent/GB9711842D0/en
Application filed by Nycomed Imaging AS filed Critical Nycomed Imaging AS
Publication of EP0991427A2 publication Critical patent/EP0991427A2/fr
Withdrawn legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
    • A61K51/12—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by a special physical form, e.g. emulsion, microcapsules, liposomes, characterized by a special physical form, e.g. emulsions, dispersions, microcapsules
    • A61K51/1241—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by a special physical form, e.g. emulsion, microcapsules, liposomes, characterized by a special physical form, e.g. emulsions, dispersions, microcapsules particles, powders, lyophilizates, adsorbates, e.g. polymers or resins for adsorption or ion-exchange resins
    • A61K51/1255—Granulates, agglomerates, microspheres
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/54—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic compound
    • A61K47/542—Carboxylic acids, e.g. a fatty acid or an amino acid
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/54—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic compound
    • A61K47/55—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic compound the modifying agent being also a pharmacologically or therapeutically active agent, i.e. the entire conjugate being a codrug, i.e. a dimer, oligomer or polymer of pharmacologically or therapeutically active compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/54—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic compound
    • A61K47/554—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an organic compound the modifying agent being a steroid plant sterol, glycyrrhetic acid, enoxolone or bile acid
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/69—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit
    • A61K47/6921—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit the form being a particulate, a powder, an adsorbate, a bead or a sphere
    • A61K47/6925—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the conjugate being characterised by physical or galenical forms, e.g. emulsion, particle, inclusion complex, stent or kit the form being a particulate, a powder, an adsorbate, a bead or a sphere the form being a microcapsule, nanocapsule, microbubble or nanobubble
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/001—Preparation for luminescence or biological staining
    • A61K49/0013—Luminescence
    • A61K49/0017—Fluorescence in vivo
    • A61K49/0019—Fluorescence in vivo characterised by the fluorescent group, e.g. oligomeric, polymeric or dendritic molecules
    • A61K49/0021—Fluorescence in vivo characterised by the fluorescent group, e.g. oligomeric, polymeric or dendritic molecules the fluorescent group being a small organic molecule
    • A61K49/0041—Xanthene dyes, used in vivo, e.g. administered to a mice, e.g. rhodamines, rose Bengal
    • A61K49/0043—Fluorescein, used in vivo
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/001—Preparation for luminescence or biological staining
    • A61K49/0013—Luminescence
    • A61K49/0017—Fluorescence in vivo
    • A61K49/005—Fluorescence in vivo characterised by the carrier molecule carrying the fluorescent agent
    • A61K49/0054—Macromolecular compounds, i.e. oligomers, polymers, dendrimers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/001—Preparation for luminescence or biological staining
    • A61K49/0063—Preparation for luminescence or biological staining characterised by a special physical or galenical form, e.g. emulsions, microspheres
    • A61K49/0069—Preparation for luminescence or biological staining characterised by a special physical or galenical form, e.g. emulsions, microspheres the agent being in a particular physical galenical form
    • A61K49/0089—Particulate, powder, adsorbate, bead, sphere
    • A61K49/0091—Microparticle, microcapsule, microbubble, microsphere, microbead, i.e. having a size or diameter higher or equal to 1 micrometer
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K49/00—Preparations for testing in vivo
    • A61K49/22—Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations
    • A61K49/222—Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations characterised by a special physical form, e.g. emulsions, liposomes
    • A61K49/223—Microbubbles, hollow microspheres, free gas bubbles, gas microspheres
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
    • A61K51/02—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by the carrier, i.e. characterised by the agent or material covalently linked or complexing the radioactive nucleus
    • A61K51/04—Organic compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
    • A61K51/02—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by the carrier, i.e. characterised by the agent or material covalently linked or complexing the radioactive nucleus
    • A61K51/04—Organic compounds
    • A61K51/0497—Organic compounds conjugates with a carrier being an organic compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
    • A61K51/02—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by the carrier, i.e. characterised by the agent or material covalently linked or complexing the radioactive nucleus
    • A61K51/04—Organic compounds
    • A61K51/08—Peptides, e.g. proteins, carriers being peptides, polyamino acids, proteins
    • A61K51/088—Peptides, e.g. proteins, carriers being peptides, polyamino acids, proteins conjugates with carriers being peptides, polyamino acids or proteins

Definitions

  • This invention relates to diagnostic and/or therapeutically active agents, more particularly to diagnostic and/or therapeutically active agents incorporating moieties which interact with or have affinity for sites and/or structures within the body so that diagnostic imaging and/or therapy of particular locations within the body may be enhanced.
  • diagnostic agents for use in ultrasound imaging which are hereinafter referred to as targeted ultrasound contrast agents.
  • ultrasound imaging comprises a potentially valuable diagnostic tool, for example in studies of the vascular system, particularly in cardiography, and of tissue microvasculature .
  • contrast agents has been proposed to enhance the acoustic images so obtained, including suspensions of solid particles, emulsified liquid droplets, gas bubbles and encapsulated gases or liquids. It is generally accepted that low density contrast agents which are easily compressible are particularly efficient in terms of the acoustic backscatter they generate, and considerable interest has therefore been shown in the preparation of gas-containing and gas-generating systems .
  • Gas-containing contrast media are also known to be effective in magnetic resonance (MR) imaging, e.g. as susceptibility contrast agents which will act to reduce MR signal intensity.
  • Oxygen-containing contrast media also represent potentially useful paramagnetic MR contrast agents.
  • gases such as carbon dioxide may be used as negative oral contrast agents or intravascular contrast agents .
  • radioactive gases e.g. radioactive isotopes of inert gases such as xenon
  • scintigraphy for example for blood pool imaging.
  • Targeted ultrasound contrast agents may be regarded as comprising (i) a reporter moiety capable of interacting with ultrasound irradiation to generate a detectable signal; (ii) one or more vectors having affinity for particular target sites and/or structures within the body, e.g. for specific cells or areas of pathology; and (iii) one or more linkers connecting said reporter and vector (s), in the event that these are not directly joined.
  • the molecules and/or structure to which the agent is intended to bind will hereinafter be referred to as the target .
  • the target In order to obtain specific imaging of or a therapeutic effect at a selected region/structure in the body the target must be present and available in this region/structure.
  • the target may either be a defined molecular species (i.e. a target molecule) or an unknown molecule or more complex structure (i.e. a target structure) which is present in the area to be imaged and/or treated, and is able to bind specifically or selectively to a given vector molecule.
  • the vector is attached or linked to the reporter moiety in order to bind these moieties to the region/structure to be imaged and/or treated.
  • the vector may bind specifically to a chosen target, or it may bind only selectively, having affinty also for a limited number of other molecules/structures, again creating possible background problems.
  • US-A-5531980 is directed to systems in which the reporter comprises an aqueous suspension of air or gas microbubbles stabilised by one or more film-forming surfactants present at least partially in lamellar or laminar form, said surfactant (s) being bound to one or more vectors comprising "bioactive species designed for specific targeting purposes".
  • the microbubbles are not directly encapsulated by surfactant material but rather that this is incorporated in liquid- filled liposomes which stabilise the microbubbles.
  • lamellar or laminar surfactant material such as phospholipids present in such liposomes will inevitably be present in the form of one or more lipid bilayers with the lipophilic tails "back-to-back” and the hydrophilic heads both inside and outside (see e.g. Schneider, M. on “Liposomes as drug carriers: 10 years of research” in Drug targeting, Nyon, Swi tzerland, 3 -5 October 1984 , Buri, P. and Gumma, A. (Ed) , Elsevier, Amsterdam 1984) .
  • EP-A-0727225 describes targeted ultrasound contrast agents in which the reporter comprises a chemical having a sufficient vapour pressure such that a proportion of it is a gas at the body temperature of the subject.
  • This chemical is associated with a surfactant or albumin carrier which includes a protein-, peptide- or carbohydrate-based cell adhesion molecule ligand as vector.
  • the reporter moieties in such contrast agents correspond to the phase shift colloid systems described in WO-A-9416739 ; it is now recognised that administration of such phase shift colloids may lead to generation of microbubbles which grow uncontrollably, possibly to the extent where they cause potentially dangerous embolisation of, for example, the myocardial vasculature and brain (see e.g.
  • tissue-specific ultrasonic image enhancement may be achieved using acoustically reflective oligolamellar liposomes conjugated to tissue-specific ligands such as antibodies, peptides, lectins etc.
  • tissue-specific ligands such as antibodies, peptides, lectins etc.
  • the liposomes are deliberately chosen to be devoid of gas and so will not have the advantageous echogenic properties of gas -based ultrasound contrast agents.
  • the present invention is based on the finding that gas-containing and gas-generating diagnostic and/or therapeutic agents conjugated with certain non- proteinaceous, non-peptide and non-polysaccharide vectors are particularly useful targeting agents by virtue of their high degree of stability both in vi tro and in vivo .
  • Such products wherein the vectors are obtained from synthetic rather than natural sources will also avoid problems such as virus contamination and are advantageous in that the vector molecules may be clearly defined, thereby increasing product homogeneity and easy product documentation.
  • non-polysaccharide means a chain of less than 200 sugar units, preferably less than 50 units, preferably comprising two or more different sugars . Even more preferred are sugar chains comprising at least one substituent carrying amino sugar and even more preferred are branched sugar chains of a molecular weight of less than 5000.
  • One advantageous embodiment of the invention is based on the additional finding that limited adhesion to targets is a highly useful property of diagnostic and/or therapeutically active agents, which property may be achieved using vectors giving temporary retention rather than fixed adhesion to a target.
  • agents rather than being fixedly retained at specific sites, may for example effectively exhibit a form of retarded flow along the vascular endothelium by virtue of their transient interactions with endothelial cells.
  • Such agents may thus become concentrated on the walls of blood vessels, in the case of ultrasound contrast agents providing enhanced echogenicity thereof relative to the bulk of the bloodstream, which is devoid of permanent structural features.
  • the present invention is particularly suited to imaging changes occurring in normal blood vessels situated in areas of tissue necrosis.
  • a targetable diagnostic and/or therapeutic agent e.g. an ultrasound contrast agent
  • a suspension in an aqueous carrier liquid e.g. an injectable carrier liquid
  • a reporter comprising gas-containing or gas-generating material
  • said reporter being conjugated to one or more vectors, characterised in that said vectors are selected from non-polymeric synthetic or semi-synthetic vectors and oligo/polynucleotides .
  • Vectors used in accordance with the invention are preferably exogenous to the human body.
  • non-polymeric as used herein in respect of synthetic or semi-synthetic vectors is not intended to exclude oligomers.
  • Nucleotides used in accordance with the invention may, for example, contain 10-500 base units. Oligonucleotides may, for example, contain 20-50 units, whilst polynucleotides may, for example, contain 50-500 units .
  • oneor more vectors may be attached or included withinto the reporter in a manner such that the vectors are not readily exposed to the target or target receptors.
  • Increased tissue specificity may therefore be achieved by applying an additional process to expose the vectors, for example by exposing the agent after administration to external ultrasound to modify the diffusibility of the moieties containing the vectors.
  • gas any biocompatible gas may be present in the reporter of contrast agents according to the invention, the term "gas" as used herein including any substances (including mixtures) substantially or completely in gaseous (including vapour) form at the normal human body temperature of 37°C.
  • the gas may thus, for example, comprise air; nitrogen; oxygen; carbon dioxide; hydrogen; an inert gas such as helium, argon, xenon or krypton; a sulphur fluoride such as sulphur hexafluoride, disulphur decafluoride or trifluoromethylsulphur pentafluoride ; selenium hexafluoride; an optionally halogenated silane such as methylsilane or dimethylsilane; a low molecular weight hydrocarbon (e.g.
  • an alkane such as methane, ethane, a propane, a butane or a pentane, a cycloalkane such as cyclopropane, cyclobutane or cyclopentane, an alkene such as ethylene, propene, propadiene or a butene, or an alkyne such as acetylene or propyne; an ether such as dimethyl ether; a ketone; an ester; a halogenated low molecular weight hydrocarbon (e.g. containing up to 7 carbon atoms) ; or a mixture of any of the foregoing.
  • an alkane such as methane, ethane, a propane, a butane or a pentane
  • a cycloalkane such as cyclopropane, cyclobutane or cyclopentane
  • an alkene such as ethylene, propene, propadiene or a but
  • biocompatible halogenated hydrocarbon gases may, for example, be selected from bromochlorodifluoromethane , chlorodifluoromethane , dichlorodifluoromethane, bromotrifluoromethane, chlorotrifluoromethane , chloropentafluoroethane , dichlorotetrafluoroethane , chlorotrifluoroethylene , fluoroethylene, ethylfluoride, 1, 1-difluoroethane and perfluorocarbons , e.g.
  • perfluoroalkanes such as perfluoromethane, perfluoroethane, perfluoropropanes, perfluorobutanes (e.g. perfluoro-n-butane, optionally in admixture with other isomers such as perfluoro-iso- butane) , perfluoropentanes, perfluorohexanes and perfluoroheptanes ; perfluoroalkenes such as perfluoropropene, perfluorobutenes (e.g.
  • perfluorobut-2- ene and perfluorobutadiene; perfluoroalkynes such as perfluorobut-2-yne; and perfluorocycloalkanes such as perfluorocyclobutane , perfluoromethylcyclobutane , perfluorodimethylcyclobutanes , perfluorotrimethyl- cyclobutanes, perfluorocyclopentane, perfluoromethyl- cyclopentane , perfluorodimethylcyclopentanes , perfluorocyclohexane, perfluoromethylcyclohexane and perfluorocycloheptane .
  • halogenated gases include methyl chloride, fluorinated (e.g. perfluorinated) ketones such as perfluoroacetone and fluorinated (e.g. perfluorinated) ethers such as perfluorodiethyl ether.
  • perfluorinated gases for example sulphur hexafluoride and perfluorocarbons such as perfluoropropane, perfluorobutanes and perfluoropentanes, may be particularly advantageous in view of the recognised high stability in the bloodstream of microbubbles containing such gases .
  • the reporter may be in any convenient form, for example being any appropriate gas-containing or gas- generating ultrasound contrast agent formulation.
  • formulations include microbubbles of gas stabilised (e.g. at least partially encapsulated) by a coalescence-resistant surface membrane (for example gelatin, e.g. as described in W0- A-8002365) , a filmogenic protein (for example an albumin such as human serum albumin, e.g.
  • a coalescence-resistant surface membrane for example gelatin, e.g. as described in W0- A-8002365
  • a filmogenic protein for example an albumin such as human serum albumin, e.g.
  • a polymer material for example a synthetic biodegradable polymer as described in EP-A-0398935 , an elastic interfacial synthetic polymer membrane as described in EP-A-0458745, a microparticulate biodegradable polyaldehyde as described in EP-A-0441468 , a microparticulate N-dicarboxylic acid derivative of a polyamino acid - polycyclic imide as described in EP-A- 0458079, or a biodegradable polymer as described in WO- A-9317718 or O-A-9607434 ) , a non-polymeric and non- poly ⁇ nerisable wall-forming material
  • gas-containing contrast agent formulations include gas-containing solid systems, for example microparticles (especially aggregates of microparticles) having gas contained therewithin or otherwise associated therewith (for example being adsorbed on the surface thereof and/or contained within voids, cavities or pores therein, e.g. as described in EP-A-0122624, EP-A-0123235 , EP-A-0365467 , WO-A-9221382 , WO-A-9300930, WO-A-9313802 , WO-A-9313808 or WO-A- 9313809) .
  • the echogenicity of such microparticulate contrast agents may derive directly from the contained/associated gas and/or from gas (e.g. microbubbles) liberated from the solid material (e.g. upon dissolution of the microparticulate structure) .
  • Gas microbubbles and other gas-containing materials such as microparticles preferably have an initial average size not exceeding 10 ⁇ m (e.g. of 7 ⁇ m or less) in order to permit their free passage through the pulmonary system following administration, e.g. by intravenous injection.
  • phospholipid-containing compositions are employed in accordance with the invention, e.g. in the form of phospholipid-stabilised gas microbubbles
  • useful phospholipids include lecithins (i.e. phosphatidylcholines) , for example natural lecithins such as egg yolk lecithin or soya bean lecithin and synthetic or semisynthetic lecithins such as dimyristoylphosphatidylcholine , dipalmitoylphosphatidylcholine or distearoylphosphatidylcholine; phosphatidic acids; phosphatidylethanolamines ; phosphatidylserines ; phosphatidylglycerols ; phosphatidylinositols ; cardiolipins; sphingomyelins; fluorinated analogues of any of the foregoing; mixtures of any of the foregoing and mixtures with other lipids such as cholesterol
  • phospholipids predominantly (e.g. at least 75%) comprising molecules individually bearing net overall charge, e.g. negative charge, for example as in naturally occurring (e.g. soya bean or egg yolk derived) , semisynthetic (e.g. partially or fully hydrogenated) and synthetic phosphatidylserines, phosphatidylglycerols, phosphatidylinositols, phosphatidic acids and/or cardiolipins, may be particularly advantageous.
  • naturally occurring e.g. soya bean or egg yolk derived
  • semisynthetic e.g. partially or fully hydrogenated
  • synthetic phosphatidylserines e.g. partially or fully hydrogenated
  • phosphatidylglycerols phosphatidylglycerols
  • phosphatidylinositols phosphatidic acids and/or cardiolipins
  • Additional exemplary lipids which may be used to prepare gas-containing contrast agents include fatty acids, stearic acid, palmitic acid, 2-n-hexadecylstearic acid, oleic acid and other acid-containing lipid structures.
  • Such lipid structures may be coupled by amide bond formation to amino acids containing one or more amino groups; the resulting lipid-modified amino acids (e.g. dipalmitoyllysine or distearoyl-2 , 3- diaminopropionic acid) may be useful precursors for the attachment of functionalised spacer elements having coupling sites for conjugation of one or more vector molecules.
  • stabilisers include lipopeptides comprising a lipid attached to a peptide portion which is suitably functionalised for coupling to one or more vector molecules.
  • a positively charged peptide linker element e.g. comprising two or more lysine residues
  • reporter microbubbles stabilised by negatively charged phospholipid or other surfactant membranes.
  • Another embodiment of the invention invention comprises functionalised microbubbles carrying one or more reactive groups for non-specificreaction with a receptor molecules located on cell surfaces. Microbubbles comprising a thiol moiety, for example, may bind to cell surface receptors via disulphide exchange reactions.
  • microbubble flow may be controlled by altering the redox environment.
  • functionalised microbubbles with membranes comprising activated esters such as N-hydroxysuccinimide esters may be used to react with amino groups found on a multiplicity of cell surface molecules.
  • gas-containing microparticulate materials which may be useful in accordance with the invention include carbohydrates (for example hexoses such as glucose, fructose or galactose; disaccharides such as sucrose, lactose or maltose; pentoses such as arabinose, xylose or ribose; ⁇ -, ⁇ - and ⁇ -cyclodextrins ; polysaccharides such as starch, hydroxyethyl starch, amylose, amylopectin, glycogen, inulin, pulullan, dextran, carboxymethyl dextran, dextran phosphate, ketodextran, aminoethyldextran, alginates, chitin, chitosan, hyaluronic acid or heparin; and sugar alcohols, including alditols such as mannitol or sorbitol), inorganic salts (e.g.
  • X-ray contrast agents e.g. any of the commercially available carboxylic acid and non-ionic amide contrast agents typically containing at least one 2 , 4 , 6-triiodophenyl group having substituents such as carboxyl, carbamoyl , N-alkylcarbamoyl, N- hydroxyalkylcarbamoyl, acylamino, N-alkylacylamino or acylaminomethyl at the 3- and/or 5 -positions, as in metrizoic acid, diatrizoic acid, iothalamic acid, ioxaglic acid, iohexol, iopentol, iopamidol, iodixanol, iopromide, metrizamide, iodipamide, meglumine iodipamide, meglumine acetrizoate
  • the reporter may be made by any convenient process, for example by making gas-containing or gas- generating formulations.
  • Representative examples include the preparation of a suspension of gas microbubbles by contacting a surfactant with gas and mixing them in the presence of an aqueous carrier, as described in WO 9115244; or by atomising a solution or dispersion of a wall-forming material in the presence of a gas in order to obtain hollow microcapsules, as described in EP 512693A1; preparation of solid microspheres by a double emulsion process, as described in US 5648095; or a process for forming hollow microcapsules by spray-drying as described in EP 681843A2; or preparing gas-filled liposomes by shaking an aqueous solution comprising a lipid in the presence of a gas as described in US 5469854.
  • a suitable process for attachment of the desired vector to the reporter comprises a surface modification of the preformed reporter with a suitable linker employing reactive groups on the surface of both the reporter and vector. It may be particularly advantageous physically to mix the reporter material with the vector- containing substance at any step of the process. Such a process will result in incorporation or an attachment of the vector to the reporter. An optional process step may remove the excess of vector not bound to the reporter by washing the gas-containing particles following separation, by for example, floatation.
  • a preferred aspect is the use of lipopeptide structures incorporating functional groups such as thiol, maleimide biotin etc. which can be premixed if desired with other reporter molecules before formation of gas-containing agents.
  • the attachment of vector molecules may be carried out using the linker reagents listed below.
  • Linking of a reporter unit to the desired vectors may be achieved by covalent or non-covalent means, usually involving interaction with one or more functional groups located on the reporter and/or vectors.
  • functional groups located on the reporter and/or vectors.
  • chemically reactive functional groups which may be employed for this purpose include amino, hydroxyl , sulfhydryl, carboxyl, and carbonyl groups, as well as carbohydrate groups, vicinal diols, thioethers, 2-aminoalcohols, 2-aminothiols, guanidinyl, imidazolyl and phenolic groups.
  • Covalent coupling of reporter and vectors may therefore be effected using linking agents containing reactive moities capable of reaction with such functional groups.
  • N-Maleimide derivatives are also considered selective towards sulfhydryl groups, but may additionaly be useful in coupling to amino groups under certain conditions.
  • N- maleimides may be incorporated into linking systems for reporter-vector conjugation as described by Kitagawa, T. et al . in Chem . Pharm . Bull . (1981) 29, 1130 or used as polymer crosslinkers for bubble stabilisation as described by Kovacic, P. et al. in J " . Am. Chem . Soc
  • Reagents such as 2-iminothiolane, e.g. as described by Traut, R. et al . in Biochemistry (1973) 12, 3266, which introduce a thiol group through conversion of an amino group, may be considered as sulfhydryl reagents if linking occurs through the formation of disulphide bridges.
  • reagents which introduce reactive disulphide bonds into either the reporter or the vector may be useful, since linking may be brought about by disulphide exchange between the vector and reporter;
  • examples of such reagents include Ellman's reagent (DTNB) , 4 , 4 ' -dithiodipyridine, methyl- 3 -nitro-2 -pyridyl disulphide and methyl-2-pyridyl disulphide (described by Kimura, T. et al . in A ⁇ alyt. Biochem. (1982) 122, 271) .
  • Examples of reactive moieties capable of reaction with amino groups include alkylating and acylating agents.
  • N-maleimide derivatives which may react with amino groups either through a Michael type reaction or through acylation by addition to the ring carbonyl group as described by Smyth, D.G. et al . in J " . Am. Chem . Soc . (1960) 82, 4600 and Biochem . J. (1964) 91, 589; iii) aryl halides such as reactive nitrohaloaromatic compounds ; iv) alkyl halides as described by McKenzie, J.A. et al . in J. Protein Chem .
  • Representative amino-reactive acylating agents include : i) isocyanates and isothiocyanates, particularly aromatic derivatives, Which form stable urea and thiourea derivatives respectively and have been used for protein crosslinking as described by Schick, A.F. et al . in J. Biol . Chem . (1961) 236, 2477; ii) sulfonyl chlorides, which have been described by Herzig, D.J. et al .
  • Carbonyl groups such as aldehyde functions may be reacted with weak bases.
  • Weak bases include 1,2- aminothiols such as those found in N-terminal cysteine residues, which selectively form stable 5-membered thiazolidine rings with aldehyde groups, e.g. as described by Ratner, S. et al . in J “ . Am. Chem . Soc . (1937) 59, 200.
  • Other weak bases such as phenyl hydrazones may be used, e.g. as described by Heitzman, H. et al . in Proc . Na tl . Acad . Sci . USA (1974) 71, 3537.
  • Aldehydes and ketones may also be reacted with amines to form Schiff 's bases, which may advantageously be stabilised through reductive amination.
  • Alkoxylamino moieties readily react with ketones and aldehydes to produce stable alkoxamines, e.g. as described by Webb, R. et al . in Bioconjuga te Chem . (1990) 1, 96.
  • reactive moieties capable of reaction with carboxyl groups include diazo compounds such as diazoacetate esters and diazoacetamides, which react with high specificity to generate ester groups, e.g. as described by Herriot R.M. in Adv. Protein Chem . (1947) 3, 169.
  • Carboxylic acid modifying reagents such as carbodiimides, which react through O-acylurea formation followed by amide bond formation, may also usefully be employed; linking may be facilitated through addition of an amine or may result in direct vector-receptor coupling.
  • Useful water soluble carbodiimides include 1- cyclohexyl-3- (2-morpholinyl-4-ethyl) carbodiimide (CMC) and l-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC), e.g. as described by Zot, H.G. and Puett, D. in J “ . Biol . Chem. (1989) 264, 15552.
  • carboxylic acid modifying reagents include isoxazolium derivatives such as Woodwards reagent K; chloroformates such as p- nitrophenylchloroformate; carbonyldiimidazoles such as 1, 1 ' -carbonyldiimidazole; and N- carbalkoxydihydroquinolines such as N- (ethoxycarbonyl) - 2-ethoxy-l, 2-dihydroquinoline .
  • vicinal diones such as p-phenylenediglyoxal , which may be used to react with guanidinyl groups, e.g. as described by Wagner et al . in Nucleic acid Res . (1978) 5, 4065; and diazonium salts, which may undergo electrophilic substitution reactions, e.g. as described by Ishizaka, K. and Ishizaka T. in J. Immunol . (1960) 85, 163.
  • Bis-diazonium compounds are readily prepared by treatment of aryl diamines with sodium nitrite in acidic solutions. It will be appreciated that functional groups in the reporter and/or vector may if desired be converted to other functional groups prior to reaction, e.g.
  • Examples of methods useful for this purpose include conversion of amines to carboxylic acids using reagents such as dicarboxylic anhydrides; conversion of amines to thiols using reagents such as N-acetylhomocysteine thiolactone, S-acetylmercaptosuccinic anhydride, 2- iminothiolane or thiol-containing succinimidyl derivatives; conversion of thiols to carboxylic acids using reagents such as ⁇ -haloacetates; conversion of thiols to amines using reagents such as ethylenimine or 2-bromoethylamine; conversion of carboxylic acids to amines using reagents such as carbodiimides followed by diamines,- and conversion of alcohols to thiols using reagents such as tosyl chloride followed by transesterification with thioacetate and hydrolysis to the thio
  • Vector-reporter coupling may also be effected using enzymes as zero-length crosslinking agents; thus, for example, transglutaminase, peroxidase and xanthine oxidase have been used to produce crosslinked products.
  • Reverse proteolysis may also be used for crosslinking through amide bond formation.
  • Non-covalent vector-reporter coupling may, for example, be effected by electrostatic charge interactions e.g. between a polylysinyl- functionalised reporter and a polyglutamyl-functionalised vector, through chelation in the form of stable metal complexes or through high affinity binding interaction such as avidin/biotin binding.
  • a vector may be coupled to a protein known to bind phospholipids.
  • a single molecule of phospholipid may attach to a protein such as a translocase, while other proteins may attach to surfaces consisting mainly of phospholipid head groups and so may be used to attach vectors to phospholipid microspheres; one example of such a protein is ⁇ 2-glycoprotein I (Chonn, A., Semple, S.C. and
  • Phosphatidylserine-binding proteins have been described, e.g. by Igarashi, K. et al . in Journal of Biological Chemistry 270 (49) , 29075-29078.
  • Annexins are a class of phospholipid-binding proteins, many of which bind particularly avidly to phosphatidyl- serine (reviewed in Raynal, P. and H.B. Pollard.
  • a conjugate of a vector with such a phosphatidylserine-binding protein may therefore be used to attach the vector to phosphatidylserine-encapsulated microbubbles.
  • the amino acid sequence of a binding protein is known, the phospholipid-binding portion may be synthesised or isolated and used for conjugation with a vector, thus avoiding the biological activity which may be located elsewhere in the molecule.
  • microsphere-binding molecules molecules that bind specifically to the surface (or in the "membrane") of microspheres by direct screening of molecular libraries for microsphere-binding molecules.
  • libraries from combinatorial chemistry displaying small molecules on the surface of small solid microspheres (about 0.02-2 ⁇ m, preferably about 0.05-0.25 ⁇ m) could be used for such selection.
  • the selection may be made by simply mixing the gas-filled microspheres and the combinatorial library and eluting the small solid microspheres.
  • the combinatorial library could be produced on solid surfaces: the bottom of micro-titre wells. If desired, the selection may be done under "physiological conditions" (e.g.
  • binding moieties identified in this way may be coupled by chemical conjugation to a vector molecule, constituting a general tool for attaching any vector molecule to the microspheres.
  • a vector which is coupled to a peptide, lipo- oligosaccharide or lipopeptide linker which contains a element capable of mediating membrane insertion may also be useful.
  • a peptide, lipo- oligosaccharide or lipopeptide linker which contains a element capable of mediating membrane insertion
  • Non- bioactive molecules consisting of known membrane insertion anchor/signal groups may also be used as vectors for certain applications, an example being the HI hydrophobic segment from the Na,K-ATPase -subunit described by Xie, Y. and Morimoto, T. in J. Biol .
  • the anchor group may also be fatty acid(s) or cholesterol.
  • Coupling may also be effected using avidin or streptavidin, which have four high affinity binding sites for biotin. Avidin may therefore be used to conjugate vector to reporter if both vector and reporter are biotinylated. Examples are described by Bayer, E.A. and Wilchek, M. in Methods Biochem. Anal . (1980) 26, 1. This method may also be extended to include linking of reporter to reporter, a process which may encourage bubble association and consequent potentially increased echogenicity. Alternatively, avidin or streptavidin may be attached directly to the surface of reporter microparticles . Non-covalent coupling may also utilise the bifunctional nature of bispecific immunoglobulins . These molecules can specifically bind two antigens, thus linking them.
  • bispecific IgG or chemically engineered bispecific F(ab) '2 fragments may be used as linking agents.
  • Heterobifunctional bispecific antibodies have also been reported for linking two different antigens, e.g. as described by Bode, C. et al . in J “ . Biol . Chem . (1989) 264, 944 and by Staerz, U.D. et al . in Proc . Na tl . Acad . Sci . USA (1986) 83, 1453.
  • any reporter and/or vector containing two or more antigenic determinants e.g. as described by Chen, Aa et al . in Am. J “ . Pathol . (1988) 130, 216) may be crosslinked by antibody molecules and lead to formation of multi-bubble cross-linked assemblies of potentially increased echogenicity .
  • Linking agents used in accordance with the invention will in general bring about linking of vector to reporter or reporter to reporter with some degree of specificity, and may also be used to attach one or more therapeutically active agents.
  • a PEG component as a stabiliser in conjunction with a vector or vectors or directly to the reporter in the same molecule where the PEG does not serve as a spacer .
  • the reporter unit will usually remain attached to the vectors.
  • the vector which may, for instance, be derivatized with a mono- or oligosaccharide
  • the reporter is administered, coupled to a moiety which is capable of specifically binding the vector molecule (when the vector contains a sugar, the reporter may be coupled to a carbohydrate-binding molecule, such as a lectin) .
  • a carbohydrate-binding molecule such as a lectin
  • Ultrasound imaging modalities which may be used in accordance with the invention include two- and three- dimensional imaging techniques such as B-mode imaging (for example using the time-varying amplitude of the signal envelope generated from the fundamental frequency of the emitted ultrasound pulse, from sub-harmonics or higher harmonics thereof or from sum or difference frequencies derived from the emitted pulse and such harmonics, images generated from the fundamental frequency or the second harmonic thereof being preferred) , colour Doppler imaging and Doppler amplitude imaging, and combinations of the two latter with any of the modalities (techniques) above.
  • B-mode imaging for example using the time-varying amplitude of the signal envelope generated from the fundamental frequency of the emitted ultrasound pulse, from sub-harmonics or higher harmonics thereof or from sum or difference frequencies derived from the emitted pulse and such harmonics, images generated from the fundamental frequency or the second harmonic thereof being preferred
  • colour Doppler imaging and Doppler amplitude imaging and combinations of the two latter with any of the modalities (techniques) above.
  • tissue such as the heart or kidney may be collected with the aid of suitable synchronisation techniques (e.g. gating to the ECG or respiratory movement of the subject) .
  • Measurement of changes in resonance frequency or frequency absorption which accompany arrested or retarded microbubbles may also usefully be made to detect the contrast agent.
  • the present invention provides a tool for therapeutic drug delivery in combination with vector- mediated direction of the product to the desired site.
  • therapeutic or “drug” is meant an agent having a beneficial effect on a specific disease in a living human or non-human animal.
  • Therapeutic compounds used in accordance with the present invention may be encapsulated in the interior of the microbubbles/microparticles or attached to or incorporated into the structure thereof.
  • the therapeutic compound may be linked to a part of the wall or matrix, for example through covalent or ionic bonds, or may be physically mixed into the encapsulating or matrix material, particularly if the drug has similar polarity or solubility to this material, so as to prevent it from leaking out of the product before it is intended to act in the body.
  • the release of the drug may be initiated merely by wetting contact with blood following administration or as a consequence of other internal or external influences, e.g. dissolution processes catalyzed by enzymes or the use of of ultrasound.
  • the destruction of gas-containing microparticles using external ultrasound is a well known phenomenon in respect of ultrasound contrast agents, e.g. as described in WO-A-9325241; the rate of drug release may be varied depending on the type of therapeutic application, using a specific amount of ultrasound energy from the transducer.
  • the therapeutic may be covalently linked to the membrane or matrix surface using a suitable linking agent, e.g. as described herein.
  • a suitable linking agent e.g. as described herein.
  • one may initially prepare a phospholipid or lipopeptide derivative to which the drug is bonded through a biodegradable bond or linker, and then incorporate this derivative into the material used to prepare the reporter, as described above.
  • the product may initially be prepared without the therapeutic, which may then be coupled to or coated on the microbubbles or microparticles prior to use.
  • a therapeutic could be added to a suspension of microbubbles or microparticles in aqueous media and shaken in order to attach or adhere the therapeutic thereto.
  • Representative therapeutics suitable for use in the present drug delivery compositions include any known therapeutic drugs or active analogues thereof containing thiol groups which may coupled to thiol-containing microbubbles under oxidative conditions yielding disulphide groups.
  • drug/vector-modified microbubbles may be allowed to accumulate in target tissue.
  • Administration of a reducing agent such as reduced glutathione then liberates the drug molecule from the targeted microbubble in the vicinity of the target cell, increasing the local concentration of the drug and enhancing its therapeutic effect.
  • the composition may initially be prepared without the therapeutic, which may then be coupled to or coated on the microbubbles immediately prior to use; thus, for example, a therapeutic could be added to a suspension of microbubbles in aqueous media and shaken in order to attach or adhere the therapeutic to the microbubbles.
  • Other drug delivery systems include vector- modified phospholipid membranes doped with lipopeptide structures comprising a poly-L-lysine or poly-D-lysine chain in combination with a targeting vector.
  • the microbubble carrier is condensed with DNA or RNA via elecrostatic interaction with the cationic polylysine.
  • This method has the advantage that the vector or vectors used for targeted delivery are not directly attached to the polysine carrier moiety.
  • the polylysine chain is also anchored more tightly in the microbubble membrane due to the presence of the lipid chains.
  • the use of ultrasound to increase the effectiveness of delivery is also considered useful.
  • free polylysine chains are firstly modified with drug or vector molecules then condensed onto the negative surface of targeted microbubbles.
  • drugs useful in accordance with the invention include antineoplastic agents such as vincristine, vinblastine, vindesine, busulfan, chlorambucil , spiroplatin, cisplatin, carboplatin, methotrexate, adriamycin, mitomycin, bleomycin, cytosine arabinoside, arabinosyl adenine, mercaptopurine, mitotane, procarbazine, dactinomycin (antinomycin D) , daunorubicin, doxorubicin hydrochloride, taxol, plicamycin, aminoglutethimide, estramustine, flutamide, leuprolide, megestrol acetate, tamoxifen, testolactone, trilostane, amsacrine (m-AMSA) , asparaginase (L-asparaginase) , etoposide, interferon a- 2
  • RNA DNA of natural or synthetic origin, including recombinant RNA and DNA.
  • DNA encoding certain proteins may be used in the treatment of many different types of diseases. For example, tumor necrosis factor or interleukin-2 genes may be provided to treat advanced cancers; thymidine kinase genes may be provided to treat ovarian cancer or brain tumors; interleukin-2 genes may be provided to treat neuroblastoma, malignant melanoma or kidney cancer; and interleukin-4 genes may be provided to treat cancer.
  • Lipophilic derivatives of drugs linked to microbubble membranes through hydrophobic interactions may exhibit therapeutic effects as part of the microbubble or after release from the microbubble, e.g. by use of ultrasound.
  • a lipophilic group may be introduced for anchoring the drug to the membrane.
  • the lipophilic group should be introduced in a way that does not influence the in vivo potency of the molecule, or the lipophilic group may be cleaved releasing the active drug.
  • Lipophilic groups may be introduced by various chemical means depending on functional groups available in the drug molecule. Covalent coupling may be effected using functional groups in the drug molecule capable of reacting with appropriately functionalised lipophilic compounds.
  • lipophilic moieties include branched and unbranched alkyl chains, cyclic compounds, aromatic residues and fused aromatic and non-aromatic cyclic systems. In some instances the lipophilic moiety will consist of a suitably functionalised steroid, like cholesterol and related compounds .
  • functional groups particularly suitable for derivatisation include nucleophilic groups like amino, hydroxy and sulfhydryl groups.
  • Suitable processes for lipophilic derivatisation of any drug containing a sulfhydryl group, like captopril may include direct alkylation, e.g. reaction with an alkyl halide under basic conditions and thiol ester formation by reaction with an activated carboxylic acid.
  • a preferred embodiment comprises attachment of cholesterol to a therapeutic compound by forming a degradable ester bond.
  • a preferred application of the present invention relates to angiogenesis , which is the formation of new blood vessels by branching from existing vessels.
  • the primary stimulus for this process may be inadequate supply of nutrients and oxygen (hypoxia) to cells in a tissue.
  • the cells may respond by secreting angiogenetic factors, of which there are many; one example is vascular endothelial growth factor.
  • Tumors must initiate angiogenesis when they reach millimeter size in order to keep up their rate of growth.
  • angiogenesis is accompanied by characteristic changes in the endothelial cells and their environment, this process is a promising target for therapeutic intervention.
  • angiogenesis mav be detected by the majority of the imaging modalities in use in medicine. Contrast-enhanced ultrasound may possess additional advantages, the contrast medium being microspheres which are restricted to the interior of blood vessels. Even if the target antigens are found on many cell types, the microspheres will attach exclusively to endothelial cells.
  • prodrugs may also be used in agents according to the invention.
  • drugs may be derivatised to alter their physicochemical properties and to adapt them for inclusion into the reporter; such derivatised drugs may be regarded as prodrugs and are usually inactive until cleavage of the derivatising group regenerates the active form of the drug.
  • Another alternative is to incorporate the prodrug, the prodrug-activating enzyme and the vector in the same microbubble in a system where the prodrug will only be activated after some external stimulus.
  • a stimulus may, for example, be a tumour-specific protease as described above, or bursting of the bubbles by external ultrasound after the desired targeting has been achieved.
  • Therapeutics may easily be delivered in accordance with the invention to diseased or necrotic areas including the heart and vasculature in general , and to the liver, spleen and kidneys and other regions such as the lymph system, body cavities or gastrointestinal system.
  • Products according to the present invention may be used for targeted therapeutic delivery either in vivo or in vi tro.
  • the products may be useful in in vi tro systems such as kits for diagnosis of different diseases or characterisation of different components in blood or tissue samples.
  • Similar techniques to those used to attach certain blood components or cells to polymer particles (e .g . monodisperse magnetic particles) in vi tro to separate them from a sample may be used in the present invention, using the low density of the reporter units in agents of the present invention to effect separation of the gas-containing material by floatation and repeated washing.
  • So-called zero-length linking agents which induce direct covalent joining of two reactive chemical groups without introducing additional linking material (e.g. as in amide bond formation induced using carbodiimides or enzymatically) may, if desired, be used in accordance with the invention, as may agents such as biotin/avidin systems which induce non-covalent reporter-vector linking and agents which induce hydrophobic or electrostatic interactions.
  • the linking agent will comprise two or more reactive moieties, e.g. as described above, connected by a spacer element.
  • a spacer element permits bifunctional linkers to react with specific functional groups within a molecule or between two different molecules, resulting in a bond between these two components and introducing extrinsic linker-derived material into the reporter- vector conjugate.
  • the reactive moieties in a linking agent may be the same (homobifunctional agents) or different (heterobifunctional agents or, where several dissimilar reactive moieties are present, heteromultifunctional agents) , providing a diversity of potential reagents that may bring about covalent bonding between any chemical species, either intramolecularly or intermolecularly .
  • extrinsic material introduced by the linking agent may have a critical bearing on the targeting ability and general stability of the ultimate product.
  • it may be desirable to introduce labile linkages e.g. by using spacers which are biodegradable or chemically sensitive or which incorporate enzymatic cleavage sites.
  • the spacer may include polymeric components, e.g. to act as surfactants and enhance bubble stability.
  • the spacer may also contain reactive moieties, e.g. as described above to enhance surface crosslinking, or it may contain a tracer element such as a fluorescent probe, spin label or radioactive material .
  • Contrast agents according to the present invention are therefore useful in all imaging modalities since contrast elements such as X-ray contrast agents, light imaging probes, spin labels or radioactive units may readily be incorporated in or attached to the reporter units .
  • Spacer elements may typically consist of aliphatic chains which effectively separate the reactive moieties of the linker by distances of between 5 and 30 A. They may also comprise macromolecular structures such as poly (ethylene glycols). Such polymeric structures, hereinafter referred to as PEGs, are simple, neutral polyethers which have been given much attention in biotechnical and biomedical applications (see e.g. Milton Harris, J.
  • PEGs are soluble in most solvents, including water, and are highly hydrated in aqueous environments, with two or three water molecules bound to each ethylene glycol segment; this has the effect of preventing adsorption either of other polymers or of proteins onto PEG-modified surfaces.
  • PEGs are known to be nontoxic and not to harm active proteins or cells, whilst covalently linked PEGs are known to be non- immunogenic and non-antigenic .
  • PEGs may readily be modified and bound to other molecules with only little effect on their chemistry. Their advantageous solubility and biological properties are apparent from the many possible uses of PEGs and copolymers thereof, including block copolymers such as PEG-polyurethanes and PEG-polypropylenes .
  • Appropriate molecular weights for PEG spacers used in accordance with the invention may, for example, be between 120 Daltons and 20 kDaltons.
  • the major mechanism for uptake of particles by the cells of the reticuloendothelial system (RES) is opsonisation by plasma proteins in blood; these mark foreign particles which are then taken up by the RES.
  • the biological properties of PEG spacer elements used in accordance with the invention may serve to increase contrast agent circulation time in a similar manner to that observed for PEGylated liposomes (see e.g. Klibanov, A.L. et al . in FEBS Let ters (1990) 268, 235- 237 and Blume, G. and Cevc, G. in Biochim . Biophys . Acta (1990) 1029, 91-97) .
  • Increased coupling efficiency to areas of interest may also be achieved using antibodies bound to the terminii of PEG spacers (see e.g. Maruyama, K. et al . in Biochim. Biophys . Acta (1995) 1234, 74-80 and Hansen, C.B. et al . in Biochim . Biophys . Acta (1995) 1239, 133-144) .
  • a PEG component as a stabiliser in conjunction with a vector or vectors or directly to the reporter in the same molecule where the PEG does not serve as a spacer.
  • Other representative spacer elements include structural-type polysaccharides such as polygalacturonic acid, glycosaminoglycans, heparinoids, cellulose and marine polysaccharides such as alginates, chitosans and carrageenans ; storage-type polysaccharides such as starch, glycogen, dextran and aminodextrans ; polyamino acids and methyl and ethyl esters thereof, as in homo- and co-polymers of lysine, glutamic acid and aspartic acid; and polypeptides and oligosaccharides, which may or may not contain enzyme cleavage sites.
  • structural-type polysaccharides such as polygalacturonic acid, glycosaminoglycans, heparinoids, cellulose and marine polysaccharides such as alginates, chitosans and carrageenans ; storage-type polysaccharides such as starch, glycogen, dextran and aminodextrans ; polyamin
  • spacer elements may contain cleavable groups such as vicinal glycol, azo, sulfone, ester, thioester or disulphide groups.
  • X and Z are selected from -0-, -S-, and -NR- (where R is hydrogen or an organic group) ; each Y is a carbonyl, thiocarbonyl, sulphonyl, phosphoryl or similar acid-forming group: m and n are each zero or 1; and R 1 and R 2 are each hydrogen, an organic group or a group -X.Y. (Z) m -, or together form a divalent organic group] may also be useful; as discussed in, for example, WO-A- 9217436 such groups are readily biodegraded in the presence of esterases, e.g. in vivo, but are stable in the absence of such enzymes. They may therefore advantageously be linked to therapeutic agents to permit slow release thereof.
  • Poly [N- (2 -hydroxyethyl) methacrylamides] are potentially useful spacer materials by virtue of their low degree of interaction with cells and tissues (see e.g. Volfova, I., Rihova, B. and V.R. and Vetvicka, P. in J “ . Bioact . Comp . Polymers (1992) 7, 175-190) .
  • Work on a similar polymer consisting mainly of the closely related 2 -hydroxypropyl derivative showed that it was endocytosed by the mononuclear phagocyte system only to a rather low extent (see Goddard, P., Williamson, I., Bron, J., Hutchkinson, L.E., Nicholls, J. and Petrak, K. in J " . Bioct . Compat . Polym . (1991) 6, 4-24.).
  • polymeric spacer materials include: i) copolymers of methyl methacrylate with methacrylic acid; these may be erodible (see Lee, P.I. in Pharm. Res . (1993) 10, 980) and the carboxylate substituents may cause a higher degree of swelling than with neutral polymers ; ii) block copolymers of polymethacrylates with biodegradable polyesters (see e.g. San Roman, J. and
  • cyanoacrylates i.e. polymers of esters of 2- cyanoacrylic acid - these are biodegradable and have been used in the form of nanoparticles for selective drug delivery (see Forestier, F., Gerrier, P., Chaumard, C, Quero, A.M., Couvreur, P. and Labarre, C. in J " . Anti icrob . Chemoter. (1992) 30, 173-179); iv) polyvinyl alcohols, which are water-soluble and generally regarded as biocompatible (see e.g. Langer, R. in J. Control .
  • polyesters consisting of alternating units of ethylene glycol and terephthalic acid, e.g. Dacron R , which are non-degradable but highly biocompatible; ix) block copolymers comprising biodegradable segments of aliphatic hydroxyacid polymers (see e.g. Younes, H. , Nataf, P.R., Cohn, D., Appelbaum, Y.J., Pizov, G. and Uretzky, G. in Bio ater. Artif . Cells Artif . Organs (1988) 16, 705-719) , for instance in conjunction with polyurethanes (see Kobayashi, H., Hyon, S.H.
  • polyurethanes which are known to be well- tolerated in implants, and which may be combined with flexible "soft” segments, e.g. comprising poly(tetra methylene glycol) , poly (propylene glycol) or poly (ethylene glycol)) and aromatic "hard” segments, e.g. comprising 4 , 4 ' -methylenebis (phenylene isocyanate) (see e.g. Ratner, B.D., Johnston, A.B. and Lenk, T.J. in J. Biomed . Mater. Res : Applied Biomaterials (1987) 21,
  • polyanhydrides such as copolymers of sebacic acid (octanedioic acid) with bis (4 -carboxy-phenoxy) propane, which have been shown in rabbit studies (see Brem, H., Kader, A., Epstein, J.I., Tamargo, R.J., Domb, A., Langer, R. and Leong, K.W. in Sel . Cancer Ther. (1989) 5, 55-65) and rat studies (see Tamargo, R.J., Epstein, J.I., Reinhard, C.S., Chasin, M. and Brem, H. in J. Biomed . Ma ter. Res .
  • Vectors which may be usefully employed in targetable agents according to the invention include the following, where appropriate in the form of non- bioactive analogues:
  • Non-peptide agonists/antagonists or binders of receptors for cell adhesion molecules, cytokines, growth factors and peptide hormones may include non-bioactive vectors which will be neither agonists nor antagonist but which may nonetheless exhibit valuable targeting ability.
  • Oligonucleotides and modified oligonucleotides which bind DNA or RNA through Watson-Crick or other types of base-pairing DNA is usually only present in extracelluar space as a consequence of cell damage, so that such oligonucleotides, which will usually be non- bioactive, may be useful in, for example, targeting of necrotic regions, which are associated with many different pathological conditions.
  • Oligonucleotides may also be designed to bind to specific DNA- or RNA-binding proteins, for example transcription factors which are very often highly overexpressed or activated in tumour cells or in activated immune or endothelial cells.
  • Combinatorial libraries may be used to select oligonucleotides which bind specifically to any possible target molecules (from the examples of proteins to caffeine) and which therefore may be employed as vectors for targeting.
  • DNA-binding drugs may behave similarly to oligonuclotides, but may exhibit biological acitvity and/or toxic effects if taken up by cells.
  • Protease substrates/inhibitors are involved in many pathological conditions and the substrates/inhibitors of such proteases are often non- peptidic. Some low molecular weight protease substrates and inhibitors are known to be non-bioactive.
  • Non-peptide vector molecules e.g aptamers (nucleic acid molecules) may be generated from combinatorial libraries without necessarily knowing the exact molecular target, by functionally selecting (in vitro, ex vivo or in vivo) for molecules binding to the region/structure, to be imaged.
  • the target structure can be sugars, lipids, peptides, proteins or nucleic acids.
  • Vectors comprising non-peptide agonists/antagonists or non-bioactive binders of receptors for cytokines/growth factors/peptide hormones/cell adhesion molecules
  • Modified oligonucleotide vectors e.g. modified to increase stability in vivo
  • Receptors comprising DNA-binding drugs
  • Receptors comprising protease substrates
  • Receptors comprising protease inhibitors
  • Example 1 Gas -filled microbubbles encapsulated with phosphatidylserine. phosphatidylcholine and biotin- amidocaproate-PEG 3 ⁇ nn-Ala-cholesterol
  • Ala-cholesterol is added to a solution of Boc-NH-PEG 340 o- SC (t-butyl carbamate poly (ethylene glycol) - succinimidyl carbonate) (Shearwater) in chloroform, followed by triethylamine .
  • the suspension is stirred at 41 °C for 10 minutes.
  • the crude product is purified by chromatography .
  • Boc-NH-PEG 34oo -Ala-cholesterol is stirred in 4 M hydrochloric acid in dioxane for 2.5 hours at ambient temperature .
  • the solvent is removed by rotary evaporation and the residue is taken up in chloroform and washed with water.
  • the organic phase is rotary evaporated to dryness .
  • the crude product may be purified by chromatography.
  • Biotinamidocaproate-PEG 3400 -Ala- cholesterol dissolved in water is added the washed microbubbles, which are placed on a roller table for several hours. The washing procedure is repeated following incorporation of the biotinamidocaproate- PEG 3400 -Ala-cholesterol into the microbubble membranes.
  • Example 2 Gas-containing microparticles comprising phosphatidylserine. phosphatidylcholine. biotin- amidocaproate-PEG ⁇ nn-Ala-Cholesterol and drug-cholesterol
  • Cholesterol (4mmol) a drug having an acid group (see Example 4 (b) for a list of cholesterol-derivatised drugs) and dimethylaminopyridine (4 mmol) are dissolved in dimethylformamide/tetrahydrofuran (20 ml + 5 ml) and dicyclohexylcarbodiimide is added. The reaction mixture is stirred at ambient temperature overnight. Dicyclohexylurea is filtered off and the solvent is rotary evaporated. The title compound is purified by chromatography .
  • Biotin may be attached to microbubbles in many different ways, e.g. in a similar way to that described by Corley, P. and Loughrey, H.C. in (1994) Biochim . Biophys . Acta 1195, 149-156.
  • the resulting bubbles are analysed by flow cytometry, e.g. by employing fluorescent streptavidin to detect attachment of biotin to the bubbles.
  • radioactive or enzyme-labelled streptavidin/avidin is used to analyse biotin attachment.
  • Example 4 Gas-filled microbubbles encapsulated with 1.2-distearoyl-sn-Glycero-3- fPhospo-L-Serinel and biotin-DPPE
  • Example 5 Gas-filled microbubbles encapsulated with phosphatidylserine and biotinylated vector non- covalently bound to streptavidin-Succ-PEG-DSPE
  • NH 2 -PEG 3400 -DSPE (prepared as in Preparation 1) is carboxylated using succinic anhydride, e.g. by a similar method to that described by Nayar, R. and Schroit, A.J. in Biochemistry (1985) 24, 5967-71.
  • Streptavidin is covalently bound to Succ-PEG 3400 -DSPE in the membrane by standard coupling methods using a water- soluble carbodiimide.
  • the sample is placed on a roller table during the reaction. After centrifugation the infranatant is exchanged with water and the washing is repeated.
  • the functionality of the attached streptavidin is analysed by binding, e.g. to fluorescently labeled biotin, biotinylated antibodies (detected with a fluorescently labeled secondary antibody) or biotinylated and fluorescence- or radioactively-labeled oligonucleotides. Analysis is performed by fluorescence microscopy or scintillation counting.
  • Example 6 Gas-filled microbubbles encapsulated with phosphatidylserine and biotinlated oligonucleotide non- covalently bound to streptavidin-Succ-PEG-DSPE
  • NH 2 -PEG 3400 DSPE (prepared as in Preparation 1) is carboxylated using succinic anhydride, e.g. by a similar method to that described by Nayar, R. and Schroit, A.J. in Biochemistry (1985) 24, 5967-71.
  • Streptavidin is covalently bound to succ-PEG 3400 -DSPE in the microbubbles by standard coupling methods using a water soluble carbodiimide.
  • the sample is placed on a roller table during the reaction. After centrifugation the infranatant is exchanged with water and the washing is repeated.
  • the functionality of the attached streptavidin is analysed by binding, e.g. to fluorescently labeled biotin, biotinylated antibodies (detected with a fluorescently labeled secondary antibody) or biotinylated and fluorescence- or radioactively-labeled oligonucleotides. Analysis is performed by fluorescence microscopy or scintillation counting.
  • Microbubbles from (c) above are incubated in a solution containing a biotinylated oligonucleotide.
  • the oligonucleotide-coated bubbles are washed as described above. Binding of the oligonucleotide to the bubbles is detected e.g. by using fluorescent-labeled oligonucleotides for attachment to the bubbles, or by hybridising the attached oligonucleotide to a labeled (fluorescence or radioactivity) complementary oligonucleotide.
  • the functionality of the oligonucleotide-carrying microbubbles is analysed, e.g.
  • an oligonucleotide complementary to ribosomal DNA (of which there are many copies per haploid genome) and an oligonucleotide complementary to an oncogene (e.g. ras of which there is one copy per haploid genome) are used.
  • Example 7 Gas- filled microbubbles encapsulated with phosphatidylserine and folate-PEG-Succ-DSPE
  • Folate-PEG-Succ-DSPE is synthesised as described by Lee, R.J. and Low, P.S. in (1995) Biochimica . Biophysica . Acta 1233, 134-144.
  • microbubbles are prepared as described in Preparation 1(e) or (f) .
  • Analysis of folate attachment may for example be done by microscopic study of the binding of the folate- containing microbubbles to cells expressing different levels of folate receptors.
  • Example 8 Gas-containing microparticles comprising polymer from ethylidene bis (16-hydroxyhexadecanoate) and adipoyl chloride and biotin-amidocaproate-Ala covalently attached to the polymer
  • the polymer is prepared from ethylidene bis (16- hydroxyhexadecanoate) and adipoyl chloride as described in WO-A- 9607434, and a polymer fraction with molecular weight 10000 is purified using gel permeation chromatography (GPC) .
  • GPC gel permeation chromatography
  • 10 g of the material (corresponding to 1 mmol OH groups) , Z-alanine (5 mmol) and dimethylaminopyridine (4 mmol) are dissolved in dry dimethylformamide/tetrahydrofuran and dicyclohexylcarbodiimide is then added.
  • the reaction mixture is stirred at ambient temperature overnight.
  • Dicyclohexylurea is filtered off and the solvent is removed using rotary evaporation.
  • the product is purified by chromatography, fractions containing the ti tle compound are combined and the solvent is removed using rotary evaporation.
  • the structure of the product
  • Z-Ala-polymer (0.1 mmol) is stirred in toluene/tetrahydrofuran and glacial acetic acid (15% of the total volume) and hydrogenated in the presence of 5 % palladium on charcoal for 2 hours. The reaction mixture is filtered and concentrated in vacuo .
  • Example 9 Gas-filled microbubbles encapsulated with phosphatidylserine. phosphatidylcholine and 3 ⁇ - TN- (N' . N' -dimethylaminoethane) carbamoyll cholesterol
  • Monolayer-encapsulated microbubbles containing perfluorobutane are made from a mixture of 10 % phosphatidylserine, 50-80 % phosphatidylcholine (PC) and 10-40 % 3S- [N- (N' ,N l -dimethylaminoethane) - carbamoyl] cholesterol (DC-chol) (Farhood, H., Gao, X, Barsoum, J. and Huang, L., Anal. Biochem. 225, 89-93 (1995) ) .
  • Example 10 Functionalisation of of gas-filled albumin microspheres (GAM) wi h biotin
  • GAM gas-filled albumin microspheres
  • Two 10 ml aliquots were centrifuged (170 x g, 5 minutes) to promote flotation of the microspheres and 8 ml of the underlying infranatant was removed by careful suction and replaced by an equal volume of air-saturated phosphate buffered saline, the preparations being rotated for 15-20 minutes to resuspend the microspheres. This procedure was repeated twice, whereafter only negligible amounts of free non-microsphere-associated albumin were assumed to remain.
  • streptavidin conjugated to horseradish peroxidase was added to both suspensions and the tubes were rotated for 1 hour to allow for reaction.
  • the microspheres were then washed three times, resuspended in 100 mM citrate-phosphate buffer (pH 5) containing 0.1 mg/ml phenylenediamine dihydrochloride and 0.01% hydrogen peroxide, and rotated for 10 minutes. Development of a yellow-green colour was indicative of the presence of enzyme. The following results were obtained:
  • Example 11 Gas-filled microbubbles encapsulated with distearoylphosphatidylserine comprising a captopril- containing molecule for diagnostic therapeutic applications
  • the structure shown above was synthesised by the manual bubbler method starting with Fmoc protected Rink Amide MBHA resin (Novabiochem) on a 0.125 mmol scale. All amino acids were purchased from Novabiochem and palmitic acid from Fluka. Coupling was carried out using standard TBTU/HOBt/DIEA protocol. Bromoacetic acid was coupled through the side-chain of Lys as a symmetrical anhydride using DIC preactivation. Captopril (Sigma) dissolved in DMF was introduced on the solid phase using DBU as base.
  • a solution of 1.4% propylene glycol/2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) and product from a) (0.5 mg) in a vial .
  • the mixture was sonicated for 5 min and then warmed to 80 °C for 5 min (vial was shaken during warming) .
  • the vial was cooled and the head space was flushed with perfluorobutane gas.
  • the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from a) in the final wash solution.
  • Example 12 Gas-filled microbubbles encapsulated with phosphatidyl-serine comprising a vector with affinity for adrenergic receptors for diagnostic and therapeutic applications
  • the human endothelial cell line ECV 304 derived from a normal umbilical cord (ATCC CRL-1998) was cultured in
  • the cells were subcultured with a split ratio of 1:5 to
  • Microbubbles from c) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump.
  • the flow rate could be adjusted to simulate any physiologically relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly.
  • a camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 13 Gas-filled microbubbles encapsulated with phosphatidylserine comprising a lipophilic derivative of atenolol with affinity for adrenergic receptors for diagnostic and/or therapeutic applications
  • the reaction mixture was poured onto water (25 ml) containing sodium carbonate (2.5 g) and sodium chloride (4.0 g) .
  • Precipitated material was filtered off, washed with water, and taken up in chloroform.
  • the chloroform phase was washed with 5% sodium carbonate and water and dried (Na2S04) .
  • the solution was filtered and concentrated to give 150 mg of yellow-white crude material.
  • the product was purified by column chromatography (silica, chloroform/methanol 95:5) to give 118 mg (80%) of white material.
  • the structure was verified by X H (500 MHz) and 13 C (125 Mhz) .
  • the product was further characterised by MALDI mass spectrometry, giving a M+Na peak at 614 as expected.
  • Example 14 Gas-filled microbubbles encapsulated with phosphatidyl-serine and a compound containing folic acid for diagnostic applications
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) and product from a) (0.5 mg) in a vial.
  • Dilute ammonia (to pH 8) and DMSO (40 ⁇ l) were added and the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) .
  • the solution was filtered and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • the human endothelial cell line ECV 304 were grown as described in Example 12. Cover-glasses, 22mm in diameter, were sterilised and placed on the bottom of 12 well culture plates (Costar) before cells in 0.5 ml complete medium with serum was added on top. When the cells reached confluence, the coverslips were placed in a custom-made flow-chamber .
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove, thus forming a flow channel.
  • Microbubbles from b) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump. The flow rate could be adjusted to simulate any physiologically relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly. A camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 15 Gas-filled microbubbles of distearoyl- phosphatidyl-serine containing a cholesteryl ester of chlorambucil for diagnostic and/or therapeutic applications
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 4.5- mg) and product from a) (0.5 mg) in a vial .
  • the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from a) in the final wash solution.
  • Example 16 Gas-filled microbubbles encapsulated with phosphatidyl-serine comprising a lipopeptide containing atenolol and a cholesterol derivative of chlorambucil for diagnostic and therapeutic applications
  • This example is directed towards providing microbubbles comprising a non-peptidic vector for targeting, plus a therapeutic moiety.
  • a lipopeptide functionalised with atenolol was synthetized as in Example 12 and a cholesterol ester of chlorambucil was synthetized as in Example 15.
  • a solution of 1.4% propylene glycol/2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 5.0 mg) , atenolol-functionalised lipopeptide (0.5 mg) and chlorambucil cholesteryl ester (0.5 mg) in a vial.
  • the mixture was sonicated for 5 min and then warmed to 80 °C for 5 min (vial was shaken during warming) .
  • the solution was filtered and cooled.
  • the head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • the human endothelial cell line ECV 304 were grown as described in Example 12. Cover-glasses, 22mm in diameter, were sterilised and placed on the bottom of 12 well culture plates (Costar) before cells in 0,5 ml complete medium with serum was added on top.
  • the coverslips were placed in a custom-made flow-chamber .
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove thus forming a flow channel .
  • Microbubbles from a) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump. The flow rate could be adjusted to simulate any physiologically relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly. A camera mounted on the microscope was connected to a colour video printer and a monitor.
  • microbubbles gradually accumulated on the cells at a rate which depended on the flow rate.
  • the cells started to detach from the coverslip while the microbubbles were still bound to the cells.
  • Control bubbles not carrying the vector did not adhere to the endothelial cells and disappeared from the cells under minimal flow conditions.
  • Example 17 Gas-filled microbubbles encapsulated with phosphatidyl-serine comprising a cholesterol derivative of atenolol for diagnostic and therapeutic applications
  • Precipitated material was extracted into chloroform. The organic phase was washed with water and dried (MgS0 4 ) . After filtration and concentration crude material (132 mg)was purified by column chromatography (silica, chloroform/methanol/acetic acid, 95:4:1). Pooled fractions were concentrated, taken up in glacial acetic acid and lyophilised. Yield 83 mg (69%) , yellow-white solid. Structure was confirmed by 1H NMR analysis
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of Distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) and product from d) (0.5 mg) in a vial .
  • the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from b) in the final wash solution.
  • the human endothelial cell line ECV 304 was cultured as in Example 12. Cover-glasses, 22mm in diameter were sterilised and placed on the bottom of 12 -well culture plates (Costar) before cells in 0,5 ml complete medium with serum was added on top.
  • the coverslips were placed in a custom-made flow-chamber.
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove thus forming a flow channel.
  • Ultrasound micro bubbles from d) above were passed from a reservoir held at 37 C to the flow chamber and back to the reservoir through a peristaltic pump. The flow rate could be adjusted to simulate any physiological relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly. A camera mounted on the microscope was connected to a colour video printer and a monitor. A gradual accumulation of the microbubbles on the cells took place which depended on the flow rate.
  • the cells started to detach from the coverslip; however, the microbubbles were still bound to the cells. Control bubbles not carrying the vector did not adhere to the endothelial cells and disappeared from the cells under minimal flow conditions .
  • Example 18 Gas-filled microbubbles of phosphatidyl- serine comprising a lipopeptide containing atenolol and a lipophilic derivative of captopril for diagnostic and therapeutic applications
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) , product from a) (0.5 mg) and b) (0.5 mg) in a vial.
  • the mixture was sonicated for 5 min and then heated- at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from a) or b) in the final wash solution.
  • the human endothelial cell line ECV 304 was cultured as in Example 12. Cover-glasses, 22mm in diameter were sterilised and placed on the bottom of 12 -well culture plates (Costar) before cells in 0,5 ml complete medium with serum was added on top .
  • the coverslips were placed in a custom-made flow-chamber.
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove thus forming a flow channel.
  • Ultrasound micro bubbles from c) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump.
  • the flow rate could be adjusted to simulate any physiological relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly.
  • a camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 19 Gas-filled microbubbles encapsulated with Distearoyl-phosphatidyl-serine comprising a lipopeptide containing chlorambucil for diagnostic and therapeutic applications
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) and product from a) (0.5 mg) in a vial .
  • the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from a) in the final wash solution.
  • the human endothelial cell line ECV 304 was cultured as in Example 12. Cover-glasses, 22mm in diameter were sterilised and placed on the bottom of 12-well culture plates (Costar) before cells in 0,5 ml complete medium with serum was added on top.
  • the coverslips were placed in a custom-made flow-chamber .
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove thus forming a flow channel.
  • Ultrasound micro bubbles from b) above were passed from a reservoir held at 37 C to the flow chamber and back to the reservoir through a peristaltic pump.
  • the flow rate could be adjusted to simulate any physiological relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly.
  • a camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 20 Gas-filled microbubbles encapsulated with phosphatidylserine comprising biotinamide-PEG- ⁇ -Ala- Cholesterol and a cholesteryl ester of chlorambucil for diagnostic and therapeutic applications
  • a solution of 1.4% propylene glycol / 2.4% glycerol (1.0 ml) was added to a mixture of DSPS (Avanti, 5 mg) and product from b) (0.5 mg) and c) (0.5 mg) in a vial.
  • the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from b) and c) in the final wash solution.
  • Example 21 Preparation of thiol-functionalised gas- filled microbubbles for ultrasound imaging.
  • This example is directed to the preparation of microbubbles having a reactive group on the surface for non-specific attachment, principally utilising disulphide exchange reactions to effect binding to a multiplicity of cellular targets.
  • the lipid structure shown above was synthesised on a ABI 433A automatic peptide synthesiser starting with Fmoc- Cys (Trt ) -Wang resin (Novabiochem) on a 0.25 mmol scale using 1 mmol amino acid cartridges . All amino acids and palmitic acid were preactivated using HBTU coupling chemistry.
  • DSPS vanti, 5.0 mg
  • thiol containing lipid structure from example 15 a 1.0 mg
  • the mixture was warmed to 80°C for 5 minutes (vials shaken during warming) and- filtered while still hot through a 40 micron filter.
  • the samples were cooled to room temperature and the head space flushed with perfluorobutane gas.
  • the vials were shaken in a cap mixer for 45 s and the microbubbles placed on roller table overnight. Bubbles were washed several times with deionised water and analysed for thiol group incorporation using Ellman' s reagent.
  • Example 22 Preparation of microbubbles coated with poly-L-lysine complexed to fluorescein labeled DNA fragments from plasmid pBR322
  • This example is directed to the preparation of microbubbles for gene therapy/anti-sense applications. It is envisaged that specific targeting may be achieved by further doping of microbubble membranes with vector modified lipid structures as described in example 1.
  • Distearoyl-phosphatidyl-serine (Avanti, 4.5 mg) was weighed into a clean vial. 1.0 mL of a solution of 1.4% propylene glycol/ 2.4% glycerol was added and the mixture sonicated for 2 min, then warmed to 80°C for 5 minutes. Immediately following warming, the solution was filtered through a 4 micron filter. The sample was cooled to room temperature and the head space flushed with perfluorobutane gas. The vial was shaken in a cap mixer for 45 s. Bubbles were then washed once with deionised water and the infranatant discarded. The microbubbles were then resuspended in 0.5 mL water.
  • Example 23 Gas-filled microbubbles of phosohatidyl - serine comprising a lipopeptide containing atenolol for cell targeting and a lipophilic thiol ester of captopril for therapeutic use.
  • the human endothelial cell line ECV 304 were grown as described in Example 12. Cover-glasses, 22mm in diameter, were sterilised and placed on the bottom of 12 well culture plates (Costar) before cells in 0.5 ml complete medium with serum was added on top.
  • the coverslips were placed in a custom-made flow-chamber.
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove, thus forming a flow channel.
  • Microbubbles from b) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump. The flow rate could be adjusted to simulate any physiologically relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly. A camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 24 Gas- filled microbubbles encapsulated with phosphatidyl-serine comprising a lipopeptide containing a derivative of bestatin for diagnostic and therapeutic applications
  • the structure shown above was synthesised by the manual bubbler method starting with Fmoc protected Rink Amide MBHA resin (Novabiochem) on a 0.125 mmol scale, using amino acids from Novabiochem and palmitic acid from Fluka. Coupling was carried out using standard TBTU/HOBt/DIEA protocols.
  • a solution of 1.4% propylene glycol/2.4% glycerol (1.0 ml) was added to a mixture of Distearoyl-phosphatidyl- serine (Avanti, 4.5 mg) and product from a) (0.5 rag) in a vial .
  • the mixture was sonicated for 5 min and then heated at 80 °C for 5 min (vial was shaken during warming) and cooled. Head space was flushed with perfluorobutane gas and the vial was shaken in a cap mixer for 45s followed by extensive washing with deionised water.
  • MALDI mass spectrometry showed no detectable level of compound from a) in the final wash solution.
  • the human endothelial cell line ECV 304 were grown as described in Example 12. Cover-glasses, 22mm in diameter, were sterilised and placed on the bottom of 12 well culture plates (Costar) before cells in 0.5 ml complete medium with serum was added on top.
  • the coverslips were placed in a custom-made flow-chamber .
  • the chamber has a groove carved into a built-in glass plate.
  • the cover slip with cells was placed on this plate with the cells facing the groove, thus forming a flow channel.
  • Microbubbles from b) above were passed from a reservoir held at 37°C to the flow chamber and back to the reservoir through a peristaltic pump.
  • the flow rate could be adjusted to simulate any physiologically relevant shear rate.
  • the flow chamber was placed under a microscope so that the interaction between the microspheres and the cells could be viewed directly.
  • a camera mounted on the microscope was connected to a colour video printer and a monitor.
  • Example 25 Gas-filled microbubbles of distearoyl- phosphatidylserine comprising a lipopeptide containing a vector with affinity for endothelin receptors for targeted ultrasound imaging
  • the aqueous solution was acidified with dilute hydrochloric acid and organic material was extracted into ethyl acetate.
  • the organic phase was washed with dilute hydrochloric acid, water and brine, treated with active charcoal and dried (MgS0 4 ) .
  • the solution was filtered and concentrated to give 280 mg (76%) of white solid.
  • the structure was verified by H (300 MHz) and 13 C (75 MHz) NMR spectroscopy. Further characterisation was carried out using MALDI mass spectrometry (ACH matrix) , giving a M+Na peak at m/z 390 and a M+K peak at m/z 406 as expected.
  • MALDI mass spectrometry ACH matrix
  • the structure shown above was synthesised on a manual nitrogen bubbler apparatus starting with Fmoc-protected Rink Amide BMHA resin on a 0.125 mmol scale, using appropriate amino acids , palmitic acid and the compound from (a) . Coupling was carried out using standard TBTU/HOBt/DIEA protocols. Simultaneous removal of the peptide from the resin and deprotection of side-chain protecting groups was carried out in TFA containing 5% EDT and 5% water for 2 hours. Crude material was precipitated from ether.

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Abstract

L'invention a pour objet des agents diagnostiques et/ou thérapeutiquement actifs pouvant être ciblés, par exemple des agents de contraste utilisés en échographie, qui comprennent une suspension dans un liquide porteur aqueux d'un rapporteur contenant un matériau contenant ou produisant du gaz, ledit porteur étant conjugué à un ou plusieurs vecteurs non protéiniques, non peptidiques et non polysaccharides.
EP97910515A 1996-10-28 1997-10-28 Ameliorations apportees a des agents diagnostiques et/ou therapeutiques ou les concernant Withdrawn EP0991427A2 (fr)

Applications Claiming Priority (18)

Application Number Priority Date Filing Date Title
GB9622367 1996-10-28
GB9622366 1996-10-28
GBGB9622365.6A GB9622365D0 (en) 1996-10-28 1996-10-28 Improvements in or relating to diagnostic/therapeutic agents
GBGB9622366.4A GB9622366D0 (en) 1996-10-28 1996-10-28 Improvements in or relating to diagnostic/therapeutic agents
GBGB9622367.2A GB9622367D0 (en) 1996-10-28 1996-10-28 Improvements in or relating to diagnostic/therapeutic agents
GB9622365 1996-10-28
GBGB9700699.3A GB9700699D0 (en) 1997-01-15 1997-01-15 Improvements in or relating to diagnostic/therapeutic agents
GB9700699 1997-01-15
GBGB9708265.5A GB9708265D0 (en) 1997-04-24 1997-04-24 Contrast agents
GB9708265 1997-04-24
US4926597P 1997-06-06 1997-06-06
US4926797P 1997-06-06 1997-06-06
US4926497P 1997-06-06 1997-06-06
GB9711845 1997-06-06
GBGB9711845.9A GB9711845D0 (en) 1997-06-06 1997-06-06 Improvements in or relating to diagnostic/therapeutic agents
GBGB9711842.6A GB9711842D0 (en) 1997-06-06 1997-06-06 Improvements in or relating to diagnostic/therapeutic agents
GB9711842 1997-06-06
PCT/GB1997/002955 WO1998018495A2 (fr) 1996-10-28 1997-10-28 Ameliorations apportees a des agents diagnostiques et/ou therapeutiques ou les concernant

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EP0991427A2 true EP0991427A2 (fr) 2000-04-12

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US5846517A (en) * 1996-09-11 1998-12-08 Imarx Pharmaceutical Corp. Methods for diagnostic imaging using a renal contrast agent and a vasodilator
US20010003580A1 (en) 1998-01-14 2001-06-14 Poh K. Hui Preparation of a lipid blend and a phospholipid suspension containing the lipid blend
GB9808599D0 (en) * 1998-04-22 1998-06-24 Nycomed Imaging As Improvements in or realting to contrast agents
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GB9809084D0 (en) * 1998-04-28 1998-06-24 Nycomed Imaging As Improvements in or relating to diagnostic/therapeutic agents
CA2727746A1 (fr) * 1998-12-18 2000-06-22 Bristol-Myers Squibb Pharma Company Medicaments antagonistes du recepteur de la vitronectine de quinolone
US6984373B2 (en) 2000-12-23 2006-01-10 Dyax Corp. Fibrin binding moieties useful as imaging agents
FI117488B (fi) 2001-05-16 2006-10-31 Myorigo Sarl Informaation selaus näytöllä
US7794693B2 (en) 2002-03-01 2010-09-14 Bracco International B.V. Targeting vector-phospholipid conjugates
US7261876B2 (en) 2002-03-01 2007-08-28 Bracco International Bv Multivalent constructs for therapeutic and diagnostic applications
US8623822B2 (en) 2002-03-01 2014-01-07 Bracco Suisse Sa KDR and VEGF/KDR binding peptides and their use in diagnosis and therapy
ES2506142T3 (es) 2002-03-01 2014-10-13 Dyax Corp. Péptidos de unión a KDR y a VEGF/KDR y su uso en diagnóstico
EP1587944A4 (fr) 2002-03-01 2007-03-21 Dyax Corp Peptides de liaison kdr et vegf/kdr et leur utilisation a des fins diagnostiques et therapeutiques
US7226577B2 (en) 2003-01-13 2007-06-05 Bracco Imaging, S. P. A. Gastrin releasing peptide compounds
DK2284180T3 (en) 2003-03-03 2015-12-21 Dyax Corp Uses of peptides that specifically bind to the HGF receptor (cMET)
CA2826960A1 (fr) 2005-12-09 2007-06-14 Bracco Suisse Sa Conjugues vecteur de ciblage-phospholipides
EP2147684A1 (fr) 2008-07-22 2010-01-27 Bracco Imaging S.p.A Agents de diagnostics sélectifs contre les métalloprotéases
WO2015038968A1 (fr) 2013-09-13 2015-03-19 The General Hospital Corporation Sondes de liaison à la fibrine activables
EP3240579B1 (fr) 2014-12-31 2022-07-27 Lantheus Medical Imaging, Inc. Compositions de microsphères de gaz encapsulées dans des lipides et procédés associés
TWI832081B (zh) 2016-05-04 2024-02-11 美商藍瑟斯醫學影像公司 用於形成充氣微球體及成像個體之方法、震盪裝置及電腦可讀軟體
US9789210B1 (en) 2016-07-06 2017-10-17 Lantheus Medical Imaging, Inc. Methods for making ultrasound contrast agents

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US5780010A (en) * 1995-06-08 1998-07-14 Barnes-Jewish Hospital Method of MRI using avidin-biotin conjugated emulsions as a site specific binding system
ATE248511T1 (de) * 1996-03-12 2003-09-15 Univ Nebraska Zusammensetzung zur zielortspezifischen verabreichung eines medikamentes und verfahren zur anwendung
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WO1998018495A2 (fr) 1998-05-07

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