Classifications

• • 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
  • A61K51/041—Heterocyclic compounds
  • A61K51/044—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine, rifamycins
  • A61K51/0459—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine, rifamycins having six-membered rings with two nitrogen atoms as the only ring hetero atoms, e.g. piperazine
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P43/00—Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
  • A61P9/12—Antihypertensives
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D473/00—Heterocyclic compounds containing purine ring systems
  • C07D473/02—Heterocyclic compounds containing purine ring systems with oxygen, sulphur, or nitrogen atoms directly attached in positions 2 and 6
  • C07D473/04—Heterocyclic compounds containing purine ring systems with oxygen, sulphur, or nitrogen atoms directly attached in positions 2 and 6 two oxygen atoms
  • C07D473/06—Heterocyclic compounds containing purine ring systems with oxygen, sulphur, or nitrogen atoms directly attached in positions 2 and 6 two oxygen atoms with radicals containing only hydrogen and carbon atoms, attached in position 1 or 3
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
  • G01T1/16—Measuring radiation intensity
  • G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
  • G01T1/164—Scintigraphy
  • G01T1/1641—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
  • G01T1/1642—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras using a scintillation crystal and position sensing photodetector arrays, e.g. ANGER cameras
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
  • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
  • G01T1/2914—Measurement of spatial distribution of radiation
  • G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)

Definitions

• the present invention relates to tracers for use in diagnostic techniques
• compositions of particular interest are radiolabeled compositions which selectively bind to PDE1, which is associated with conditions of interest in various tissues and organs.
• PDE1C is enriched in arterial smooth muscle cells
• Positron emitter-labeled compositions targeting PDE1C would enable PET diagnostic imaging of tissue at risk of functional degradation characteristic of PAH and provide a basis for novel therapies for Central Nervous System (CNS) and Cardiovascular (CV) disorders.
• CNS Central Nervous System
• CV Cardiovascular
• Gamma radiation-based imaging techniques employ tracer compounds that are introduced into the body to be imaged.
• the tracer compounds contain a
• radionuclide which directly or indirectly releases photons whose locations of origin within the body are then calculated from intercept data gathered by gamma radiation detectors.
• Two commonly employed gamma radiation-based imaging techniques are Positron Emission Tomography (referred to as PET) and Single Photon Emission Computed Tomography (referred to as SPECT).
• PET Positron Emission Tomography
• SPECT Single Photon Emission Computed Tomography
• the radionuclide indirectly releases a pair of oppositely directed photons.
• the PET radionuclide emits a positron, which upon contact with an electron in its immediate vicinity triggers anti-matter annihilation of both particles which event emits the pair of photons.
• the radionuclide is a direct gamma emitter.
• isotopes useful in gamma radiation-based imaging include Carbon-11 (referred to as n C or Cll), Fluorine-18 (referred to as 18 F or F18), Technetium-99m (referred to as 99m Tc or Tc99m), Indium-Ill (referred to as m In or Inlll) and Iodine-123
• the tracer compound comprises a ligand which provides an affinity of the tracer to a selected target associated with one or more tissues, organs or conditions of interest.
• PDEl is a family of three sub-types PDE1-A, B, and C.
• PDE1B is primarily located in the brain.
• PDE1A is expressed in brain and sperm.
• PDE1C is enriched in arterial smooth muscle cells, myocardium and atherosclerotic lesions as well as other tissues.
• the inhibitors used in the literature are known to be very unselective.
• PDEl is capable of hydrolysis of both cAMP and cGMP is another positive aspect that would indicate beneficial effects on both smooth muscle cell proliferation and on pulmonary vascular hypertension.
• PDEl-specific drug candidates have been developed including several series of agents with nanomolar potencies and remarkable specificities.
• radiolabeled inhibitors of phosphodiesterase! are provided.
• PDE1 inhibitors are radiolabeled in the last step of synthesis using chemical methods that are appropriate for the radiochemistry laboratory.
• a further aspect of the invention provides PET ligands of excellent radiochemical product yield, chemical purity, and specific activity.
• An additional aspect provides PET ligands useful as diagnostic tools to facilitate the identification and development of novel clinical agents for PAH disease.
• biomarkers such as novel PET ligands, that will report on the target occupancy of the inhibitors and that will allow a proper estimation of drug action.
• Another aspect of the invention is to provide new agents for diagnosis and therapy of Pulmonary Arterial Hypertension, Central Nervous System (CNS) and
• CV Cardiovascular
• Figure 1 is an illustration of the preparation of a PET ligand.
• Figure 2 is an illustration of the results of an HPLC separation.
• phophodiesterase 1 (PDEl), and these PDEl inhibitors and methods of preparation thereof are thoroughly described in co-pending United States Patent Applications, including Serial No. 11/916,761 filed on December 6, 2007, published as US-2008- 0188492-A1 on August 7, 2008; Serial No. 12/303,618 filed on December 5, 2008; PCT/US08/13410, filed on December 6, 2008, based upon Provisional Application Serial No. 61/012,045 filed on December 6, 2007; PCT/US08/13411, filed on December 6, 2008, based upon U.S. Provisional Application Serial No. 61/012,040 filed on December 6, 2007; U.S. Provisional Application Serial No. 61/120,438 filed on December 6, 2008; U.S.
• each of (i), (ii), (iii) and (iv) are substituted at the 1- or 2- position with C2-9 alkyl, C3-9 cycloalkyl, heteroarylalkyl, or substituted arylalkyl.
• PDEl inhibitors can be modified by replacing an atom in the structure with a radionuclide while maintaining affinity and selectivity of the molecule for PDEl.
• the agents are evaluated for inhibition of PDEl in high-throughput PDEl enzyme assays and further evaluated against 11 families of PDE enzymes to identify low nanomolar potency versus PDEl and greater than 10-fold selectivity to other PDE enzyme families.
• Another aspect is methods of producing particular selective and potent PDEl inhibitors, including radiolabeling, for example in the last step of synthesis, using chemical methods that are appropriate for the PET radiochemistry laboratory.
• radionuclides are Carbon-11 (referred to as n C or Cll),
• the agents are evaluated for inhibition of PDEl in high-throughput PDEl enzyme assays and further evaluated against the 11 families of PDE enzymes to identify low nanomolar potency versus PDEl and greater than 10-fold selectivity to other PDE enzyme families.
• Another aspect is methods of producing multiple series of selective and potent PDEl inhibitors, including radiolabeling in the last step of synthesis - using chemical methods that are appropriate for the PET radiochemistry laboratory.
• a rapid semi-preparative HPLC separation of precursor and product to support the PET radiolabeling is also provided. Such a rapid separation is ideal for a short-lived radioligand such as 11C.
• the method implied under this application involves dosing suitable animal species such as rat and baboon and measurement of whole body distribution.
• the method will entail performing preliminary occupancy studies with unlabeled PDEl inhibitors.
• animal or human subjects are dosed with the agent and distribution evaluated over time in appropriate organs. Signal to noise ratio is established and the distribution corresponds to the known distribution of PDEl in the pulmonary vasculature.
• Radiotracers meeting the radiochemistry criteria are evaluated for displacement in the lung by cold specific and potent PDE1 inhibitors.
• the candidate radiotracers are rank ordered with respect to brain uptake, kinetics, displacement by specific cold inhibitors and a lack of displacement by a non-specific cold inhibitor.
• Such a ligand will be beneficial in furthering development of novel therapeutic agents and by offering novel PET ligands.
• Another aspect is a method to evaluate the effect of pharmacological doses of a related PDE1 inhibitor for effect on sheep and rat models of pulmonary arterial hypertension (PAH).
• triphenylphosphine (42 mg, 0.16 mmol) is added, followed by 7-isobutyl-5-methyl- 3-(phenylamino)-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (50 mg, 0.16 mmol).
• the mixture is cooled to -78 °C, and then DIAD (95%, 50 ⁇ ,) is added slowly. After the reaction is complete, the mixture is purified on a basic alumina column to give 76 mg of product (yield: 81%).
• MS (ESI) m/z 587.3 [M+H] + .
• LiAlH 4 is suspended in 2 mL of anhydrous THF at 0 °C, and then tert-butyl 2-(4- (methoxycarbonyl)phenyl)pyrrolidine-l-carboxylate (238 mg, 0.78 mmol) in anhydrous THF (5 mL) is added dropwise over 5 min. The mixture is stirred at 0°C for lh, and then carefully quenched with 1 mL of water. The mixture is diluted with THF and filtered through a layer of celite. The collected filtrate is evaporated to dryness to give 232 mg of product, which is used for the next reaction without further purification.
• Example 5 Preparation of n C-labeled PET ligand, 7-Isobutyl-5-methyl-2-(4-(l- [ n C]methylpyrrolidin-2-yl)benzyl)-3-(phenylamino)-2H-pyrazolo[3,4- d]pyrimidine-4,6(5H,7H)-dione.
• the procedure of Example 4 is repeated, except that in place of the final step (el), the following step (e2) is followed.
• Example 4 The procedure of Example 4 is repeated, except that in place of the final step (el), the following step (e3) is followed. (e3) 7-Isobutyl-5-methyl-2-(4-(l-methylpyrrolidin-2-yl)benzyl]-3-(phenylamino)- 2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione.

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• 2010
  • 2010-10-07 EP EP10822355.3A patent/EP2485771A4/en not_active Withdrawn
  • 2010-10-07 US US13/500,941 patent/US8858911B2/en active Active
  • 2010-10-07 JP JP2012533137A patent/JP2013507360A/ja not_active Withdrawn
  • 2010-10-07 WO PCT/US2010/002707 patent/WO2011043816A1/en not_active Ceased
• 2014
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