CONTRAST MEDIA

Abstract: The invention relates to the use of particulate contrast media in the in vivo imaging of lung draining lymph nodes, e.g. to stage lung cancer patients.

Description: CONTRAST MEDTA This invention relates to contrast agents for imaging of the lung draining lymph nodes, and to methods of in vivo imaging of lung draining lymph nodes . Lung cancer is responsible for a major proportion of cancer diagnoses, representing some 200000 new cases per year in the USA alone. Suspected and confirmed cases are staged by CT (X-ray) scanning of lymph nodes with the physician looking at the size of the nodes . Big nodes are assumed to contain metastatic disease while smaller nodes are assumed to be disease free. This however is by no means always the case. Large lymph nodes may simply be inflamed and not cancerous while small nodes can be infiltrated with metastatic cells. Accordingly, the patients' treatment and prognosis is often decided upon relatively inaccurate information. Besides CT-scanning, the only other conventional diagnostic check is mediastinoscopy, a surgical procedure which involves removal of the mediastinal lymph nodes and histopathologic assessment of disease state. This surgical procedure is usually only done efficiently at large tertiary cancer centres . There is thus a need for alternative, more effective means for assessing the status of the lung draining lymph nodes and so providing better staging of the extent of disease in lung cancer patients. We have now found that after administration of insoluble particulate contrast agents into the lungs it is possible to visualize adequately the lung draining lymph nodes in in vivo diagnostic imaging procedures in order to stage lung cancer. Thus viewed from one aspect the invention provides a method of in vivo imaging of lung draining lymph nodes, said method comprising administering into the lung of an air breathing animal (e.g. a human or other mammal, or a reptile or bird), e.g. by direct instillation into the airways of the deep lung or at or near sites of particular interest, a diagnostically effective amount of a physiologically tolerable, substantially water-insoluble, particulate contrast agent, and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal, e.g. by using an X-ray, MR, nuclear or ultrasound diagnostic imaging modality. Viewed from a further aspect the invention provides the use of a physiologically tolerable, substantially water-insoluble, particulate contrast agent for the manufacture of a diagnostic contrast agent composition for use in a method of diagnosis involving administration of said composition into the lungs of an air-breathing animal and, after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes, generating an image of at least part of the lungs of said animal. Viewed from a further aspect the invention provides a contrast agent composition for use in a method of diagnosis involving administration of said composition into the lungs of an air-breathing animal and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal, said composition comprising a physiologically tolerable, substantially water- insoluble, particulate contrast agent together with at least one physiologically tolerable carrier or excipient, e.g. a gas or gas-precursor or a liquid. Viewed from a yet further aspect the invention provides a contrast agent composition package comprising an aerosol or powder dispenser containing a physiologically tolerable substantially water-insoluble, particulate contrast agent optionally together with at least one physiologically tolerable carrier or excipient, e.g. a gas or gas-precursor or a liquid such as water. The particulate contrast agent used according to the invention may be particles of any substantially water-insoluble, physiologically tolerable material capable of enhancing contrast in the diagnostic imaging modality of choice. The particles may be liquid droplets or flexible vesicles but more preferably will be solid particles. By substantially water-insoluble is meant that the particles do not dissolve in the lung fluids to any significant extent, e.g. particles of up to 1% which by weight dissolves in water at 37°C in 10 days. The particle size should desirably be as uniform as possible, e.g. 90% or more by number should desirably be within 10% of the numerical mean particle size, ie . substantially monodisperse . The mean particle size will desirably be in the range 1 to lOOOOnm, preferably 5nm to lμm, especially preferably 8 to 400nm. Such particles can be prepared by precipitation or emulsification techniques or by milling. Where the diagnostic imaging modality is X-ray (e.g. CT-scanning) , the particles will desirably be of an iodine or heavy metal (i.e. atomic number 37 or greater) containing material, e.g. a bismuth, tungsten or barium compound such as barium sulphate or a solid or liquid iodinated compound (e.g. triiodophenyl compound) as discussed in US-A-5330739, US-A-5318768 , US-A- 5310537, US-A-5308607, US-A-5312616 , US-A-5316755 , US-A- 5260049, US-A-5326553, US-A-5310538 , US-A-5260478 , US-A- 5318767 and US-A-5264610. For use in MR imaging, the contrast agent is preferably an inorganic ferromagnetic, ferrimagnetic, superparamagnetic or paramagnetic material optionally provided with a coating or matrix material, e.g. a polymeric coating such as a silane or polystyrene. Nanometer sized iron oxide particles, i.e. SPIO's or USPIO's, namely particles of the type present in Nycomed' s ABDOSCAN product or Advanced Magnetic 's Biomag M4200 product or as described in PCT/GB97/00067 may thus be used. Alternatively, particles of gadolinium oxalate or another relatively insoluble paramagnetic compound may be used. Furthermore, paramagnetic metal compound loaded molecular sieve particles (e.g. particles of the type used in Gadolite) may be used. Similarly, insoluble particles of gadolinium loaded polychelants, e.g. loaded dendrimeric macrocyclic chelant carrying compounds (see for example WO93/06868) , may be used. For ultrasound imaging any echogenic material may be used as a contrast agent and these may, for example, be particles of greater or lesser density than the body fluid in the lymph nodes, e.g. inorganic particulates (e.g. barium sulphate) or gas filled synthetic polymer capsules. Suitable gases are described in PCT/GB97/00459 and WO-96/40285 (Unger) . Preferred as gases are air, perfluorobutane and perfluoropentane . The capsule material may be any biotolerable polymer or cross-linked membrane forming material, see for example W093/17718 and EP-A-458745. For other imaging modalities, appropriate contrast enhancing substances may be used. Preferably the contrast agent is an X-ray contrast agent and in particular an insoluble, solid (at 37°C) iodinated compound. The contrast agent will generally be administered as a dry powder dust or as a liquid aerosol and conventional liquid suspension media, e.g. water for injections, saline, phosphate buffered saline, and mixed aqueous/non-aqueous solvent systems (eg. aqueous alkanolic solutions) may be used. If desired the compositions administered may contain further components, such as stabilizers (e.g. polyalkylene oxides, such as pluronics) , surfactants, dispersants, pH and osmolality adjusting agents, antioxidants and the like. Thus the composition administered may be entirely composed of contrast agent or may for example contain as little as 0.001% w/w contrast agent. The actual content clearly will depend on the imaging modality used. However, generally the composition will contain 1 to 99% w/w contrast agent, more preferably 10-70%, for CT and X-ray imaging procedures. The contrast agent, or the composition containing the contrast agent, may be filled into inhaler devices of the type conventionally used for administration of dry powders or aerosols into the lungs. Preferably these devices will be metered inhalers so that a predetermined amount of contrast agent is delivered per activation. The required contrast agent dosage may then be delivered by multiple activations of the device. Devices of the kind disclosed in W096/19253, WO96/04948, WO92/10229 and WO92/09323 are preferred. Alternatively, and more preferably, the contrast agent may be instilled directly into the lungs via a tube inserted through the mouth or nose . Direct instillation via bronchoscopy into the deep lung or to the region of a lesion of interest is preferred. Again the contrast agent will preferably be delivered as a dry powder or an aerosol spray, or as a liquid suspension. The total dosage of contrast agent required will clearly depend on the subject under study and the imaging modality used. Generally however contrast agent dosages will be 0.1 to 500 mg/kg bodyweight, preferably 0.1 to 200 mg/kg, or 10 5 to 10 20 particles/kg bodyweight, preferably 10 7 to 10 15 particles/kg. For X-ray imaging the dosage will preferably be in the range 20 to 400 mg/kg, more preferably 60 to 200 mg/kg; for MR imaging with paramagnetic particulates 0.1 to 10 mmol paramagnetic metal/kg; for MR imaging with superparamagnetic particles 1 to 100 mg/kg; for ultrasound imaging with inorganic particulates 0.1 to 100 mg/kg, more preferbly 1 to 20 mg/kg; and for ultrasound imaging with gas or gas precursor containing particles (e.g. vesicles, micelles, liposomes, microballoons, etc.) 0.1 to 100 mg/kg, more preferably 1 to 20 mg/kg. Image generation will suitably be effected after contrast agent transport to the lung draining lymph nodes has occurred, e.g. 120 mins to 60 days, preferably 2 to 40 days, especially preferably 6 to 20 days after contrast agent administration. For most insoluble particulates image generation may be effected after even longer delays, e.g. up to 60 days. It is preferred that the delay before image generation is sufficient to allow substantial particle clearance from the lungs e.g. via the mucociliary pathway; in humans a delay of at least about 4 days is preferred. The image generation may be by conventional techniques, e.g. X-ray CT, B-mode ultrasound, spin-echo MRI, etc. For gas-containing contrast agents, e.g. with envelopes similar to that in Schering AG's Cavisome product, increased ultrasound intensity may be used to burst particles contained in the lymph nodes and the ultrasound signal from the bursts may be imaged using the "popcorn" technique. If desired, the contrast agent may be delivered together with a therapeutic agent (e.g. a cytotoxic or gene therapy agent) where lung cancer has already been diagnosed. In this way the delivery of the therapeutic agent and the progress of therapy may be monitored using the technique of the invention. If this is to be done the therapeutic agent, e.g. cisplatin, may be in dissolved or more preferably particulate form and if particulate it and the contrast may be in the same or different particles. Thus for example a therapeutic agent may be encapsulated within a contrast agent which is in vesicle form, it may be coated onto or in the pores of a contrast agent in solid form, or it may be bound to the surface of a contrast agent particle . The dosage of therapeutic agent required will be dependent on the particular agent chosen and may for example be the same or less than the conventional dosage for the selected agent . Such combined imaging and therapy, and the compositions for use therein, form further aspects of the present invention. Thus viewed from a further aspect the invention provides a method of imaging and treatment of lung cancer, said method comprising administering into the lungs of an affected animal a particulate composition comprising therapeutically and diagnostically effective amounts of a therapeutic agent and a physiologically tolerable, substantially water-insoluble, particulate contrast agent and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal, e.g. by using an X- ray, MR, nuclear or ultrasound diagnostic imaging modality. The use of direct instillation to administer particulate therapeutic agents into the lung, e.g. to the region of a lesion of interest within the lung or to the deep lung, is also a further aspect of the invention. Thus viewed from another aspect the invention provides a method of treatment of the human or non-human animal body comprising direct instillation of a particulate therapeutic agent into the lung of said animal e.g. to the region of a lesion of interest within the lung or to the deep lung. Such therapy will be advantageous since, unlike subcutaneous injection where most of the dose remains for a time at the injection site, direct instillation in the lung will be followed by rapid dispersion within the lung due to the presence of the lung surfactant itself and movement out of the lung via the bronchociliary pathway . The resolution of the image generated using the method of the invention will be dependent upon imaging modality and dose. CT-X-ray enables both morphology and filling defects in the lymph nodes to be imaged in vivo at or below millimetre dimensions. MRI will allow excellent contrast at particle dosage levels below those required for CT. This will also be true of radiopharmaceuticals (containing longer lived isotopes such as indium or iodine isotopes, rather than technecium) used in nuclear medicine imaging techniques, e.g. gamma imaging. The publications referred to herein are hereby incorporated by reference. The invention will now be described further with reference to the following non-limiting examples, and to the accompanying drawings in which: Figure 1 is a schematic diagram of the lungs in the dog; and Figures 2 and 3 are X-ray CT images of the dog lung at 9 and 16 days post contrast administration. Example 1 CT Suspension Nanoparticulate NC 70146* 75mgI/mL Pluronic F68 3.5% w/v Water for injections .ad 100% w/w * An insoluble iodinated compound prepared as described in Example 3 of US-A-5525328 , particle size 132 ± 40 nm Example 2 CT Suspension Nanoparticulate NC 70146* 75mgI/mL Pluronic F108 3.0% w/v Water for injections a 100% w/w * An insoluble iodinated compound prepared as described in Example 3 of US-A-5525328 , particle size 127 ± 45 nm Example 3 Three beagle dogs were instilled with the suspension of Example 1. The instillations were carried out via bronchoscope as follows: 1.5ml in the lower left lobe, 3 x 1.5ml in the right lower lobe, 1.5ml vehicle only in the small, central lower lobe, and 1.5ml of saline in the upper left lobe. (See Figure 1). The instillations were video taped via the bronchoscope with no adverse events associated with the instillation. Immediately after instillation, the anaesthetized dogs were imaged by conventional X-ray to view the placement of the test agent . The dogs were then returned to their cages . Thereafter, the dogs were imaged by Computed Tomography (CT) . The imagings were carried out at days 2, 9 and 16 post instillation using standard clinical settings for small child, thoracic scan (120 kV, pitch = 1) on a Picker spiral CT scanner. The dogs were again imaged by conventional X-ray and sacrificed on day 17 for morphologic and histopathologic evaluation of the lung tissues . Images of days 9 and 16 appear as Figures 2 and 3 hereto. The results of these studies were: 1. A complete absence of adverse events during the instillations and the in life phase of the study. 2. Clear visualization of the test article at the instillation site via conventional X-ray at instillation. CT confirmation at day 2. Only lung windowed images demonstrated test article at the instillation site by day 9. Clearance from the instillation site was complete before the final imaging on day 16. 3. Increasing CT opacification of the tracheo- bronchial lymph nodes with time; minimal enhancement at day 2, moderate enhancement at day 9, excellent enhancement at day 16 post instillation. 4. No evidence of residual test article at the instillation site by either conventional X-ray at day 17 or CT scans at day 16. 5. Minimal observations at sacrifice of small, residual amounts of nanoparticle test agent on the surface of the lung near the original instillation sites. No macroscopic observations of tissue damage, inflammation, or necrosis/fibrosis were noted at necropsy. Example 4 Three beagle dogs were instilled with the suspension of Example 2. The instillations were carried out via bronchoscope as follows: 1.5ml in the lower left lobe, 3 x 1.5ml in the lower right lobe, 1.5ml vehicle only in the small, central lower lobe, and 1.5ml of saline in the upper left lobe. (See Figure 1). The instillations were video taped via the bronchoscope with no adverse events associated with the instillation. Immediately after instillation, the anaesthetized dogs were imaged by conventional X-ray to view the placement of the test agent . The dogs were then returned to their cages . Thereafter, the dogs were imaged by Computed Tomography (CT) . The imagings were carried out at days 6, 13 and 34 post instillation using standard clinical settings for a small child, thoracic scan (100 kV, pitch = 1) on a Picker spiral CT scanner. The dogs were again imaged by conventional X-ray and sacrificed on day 35 for morphologic and histopathologic evaluation of the lung tissues . Results in this study are: 1. Excellent imaging at both day 6 and 13 post instillation. 2. A complete absence of any adverse events during or after instillation. 3. No observation of residual test article at the instillation site by day 13.

Claims: CLAIMS : 1. A method of in vivo imaging of lung draining lymph nodes, said method comprising administering into the lung of an air breathing animal a diagnostically effective amount of a physiologically tolerable, substantially water-insoluble, particulate contrast agent, and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal . 2. A method as claimed in claim 1 wherein said contrast agent is administered by direct instillation into the airways of the deep lung or at or near sites of particular interest. 3. A method as claimed in claim 1 wherein said image is generated by an x-ray, MR, nuclear or ultrasound imaging modality. 4. A method as claimed in claim 1 wherein said contrast agent is an iodinated organic compound. 5. The use of a physiologically tolerable, substantially water-insoluble, particulate contrast agent for the manufacture of a diagnostic contrast agent composition for use in a method of diagnosis involving administration of said composition into the lungs of an air-breathing animal and, after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes, generating an image of at least part of the lungs of said animal. 6. Use as claimed in claim 5 wherein said contrast agent is an iodinated organic compound. 7. A contrast agent composition for use in a method of diagnosis involving administration of said composition into the lungs of an air-breathing animal and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal, said composition comprising a physiologically tolerable, substantially water- insoluble, particulate contrast agent together with at least one physiologically tolerable carrier or excipient . 8. A contrast agent composition package comprising an aerosol or powder dispenser containing a physiologically tolerable substantially water-insoluble, particulate contrast agent optionally together with at least one physiologically tolerable carrier or excipient . 9. A method of imaging and treatment of lung cancer, said method comprising administering into the lungs of an affected animal a particulate composition comprising therapeutically and diagnostically effective amounts of a therapeutic agent and a physiologically tolerable, substantially water-insoluble, particulate contrast agent and after a period of time sufficient for uptake of particles of said contrast agent by lung draining lymph nodes generating an image of at least part of the lungs of said animal . 10. A pharmaceutical composition comprising an anticancer agent and a physiologically tolerable, substantially water-insoluble, particulate contrast agent . 11. A method of treatment of the human or non- human animal body comprising direct instillation of a particulate therapeutic agent into the lung of said animal . 12. A method as claimed in claim 11 wherein said agent is instilled to the region of a lesion of interest within the lung or to the deep lung.

Inventors: BACON EDWARD RICHARD, COCKBAIN JULIAN, HAYLEY PATRICK JOSEPH, MCINTIRE GREGORY LYNN, TONER JOHN LUKE, BACON, EDWARD, RICHARD, COCKBAIN, JULIAN, HAYLEY, PATRICK, JOSEPH, MCINTIRE, GREGORY, LYNN, TONER, JOHN, LUKE
Applicants: BACON EDWARD RICHARD, COCKBAIN JULIAN, HAYLEY PATRICK JOSEPH, MCINTIRE GREGORY LYNN, NYCOMED IMAGING AS, TONER JOHN LUKE, BACON, EDWARD, RICHARD, COCKBAIN, JULIAN, HAYLEY, PATRICK, JOSEPH, MCINTIRE, GREGORY, LYNN, TONER, JOHN, LUKE
Application year: 1998
Main classification: A61K49
IPC codes: A61K49