Patents by Inventor Xuan Zhao

Xuan Zhao has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8497357
    Abstract: A heterobifunctional poly(ethylene glycol) is provided having a hydrolytically degradable linkage, a first terminus comprising an acrylate group, and a second terminus comprising a target such as a protein or pharmaceutical agent or a reactive moiety capable of coupling to a target. Hydrogels can be prepared. The hydrogels can be used as a carrier for a protein or a pharmaceutical agent that can be readily released in a controlled fashion.
    Type: Grant
    Filed: April 13, 2012
    Date of Patent: July 30, 2013
    Assignee: Nektar Therapeutics
    Inventors: J. Milton Harris, Xuan Zhao
  • Patent number: 8440816
    Abstract: The present invention is directed to branched reactive water-soluble polymers comprising at least two polymer arms, such as poly(ethylene glycol), attached to a central aliphatic hydrocarbon core molecule through ether linkages. The branched polymers bear at least one functional group for reacting with a biologically active agent to form a biologically active conjugate. The functional group of the branched polymer can be directly attached to the aliphatic hydrocarbon core or via an intervening linkage, such as a heteroatom, -alkylene-, —O-alkylene-O—, -alkylene-O-alkylene-, -aryl-O—, —O-aryl-, (—O-alkylene-)m, or (-alkylene-O—)m linkage, wherein m is 1-10.
    Type: Grant
    Filed: August 24, 2012
    Date of Patent: May 14, 2013
    Assignee: Nektar Therapeutics
    Inventors: Michael David Bentley, Xuan Zhao, Xiaoming Shen, William Dudley Battle, III
  • Patent number: 8394365
    Abstract: Provided herein are water-soluble prodrugs, compositions comprising such prodrugs, and related methods of making and administering the same. The prodrugs of the invention comprise a water-soluble polymer having three or more arms, at least three of which are typically covalently attached to an active agent, e.g., a small molecule. The conjugates of the invention provide an optimal balance of polymer size and structure for achieving improved drug loading, since the conjugates of the invention possess three or more active agents releasably attached to a multi-armed water-soluble polymer. The prodrugs of the invention are therapeutically effective, and exhibit improved properties in-vivo when compared to unmodified parent drug.
    Type: Grant
    Filed: November 30, 2007
    Date of Patent: March 12, 2013
    Assignee: Nektar Therapeutics
    Inventors: Xuan Zhao, Michael David Bentley, Zhongxu Ren, Tacey X. Viegas
  • Patent number: 8338545
    Abstract: The invention provides methods for making copolymers and multi-arm block copolymers useful as drug delivery vehicles. The multi-arm block copolymers comprise a central core molecule, such as a residue of a polyol, and at least three copolymer arms covalently attached to the central core molecule, each copolymer arm comprising an inner hydrophobic polymer segment covalently attached to the central core molecule and an outer hydrophilic polymer segment covalently attached to the hydrophobic polymer segment, wherein the central core molecule and the hydrophobic polymer segment define a hydrophobic core region. The solubility of hydrophobic biologically active agents can be improved by entrapment within the hydrophobic core region of the block copolymer. The invention further includes pharmaceutical compositions including such block copolymers, pharmaceutical compositions, and methods of using the block copolymers as drug delivery vehicles.
    Type: Grant
    Filed: November 2, 2011
    Date of Patent: December 25, 2012
    Assignee: Nektar Therapeutics
    Inventor: Xuan Zhao
  • Publication number: 20120322134
    Abstract: The present invention is directed to branched reactive water-soluble polymers comprising at least two polymer arms, such as poly(ethylene glycol), attached to a central aliphatic hydrocarbon core molecule through ether linkages. The branched polymers bear at least one functional group for reacting with a biologically active agent to form a biologically active conjugate. The functional group of the branched polymer can be directly attached to the aliphatic hydrocarbon core or via an intervening linkage, such as a heteroatom, -alkylene-, —O-alkylene-O—, -alkylene-O-alkylene-, -aryl-O—, —O-aryl-, (—O-alkylene-)m, or (-alkylene-O—)m linkage, wherein m is 1-10.
    Type: Application
    Filed: August 24, 2012
    Publication date: December 20, 2012
    Applicant: Nektar Therapeutics
    Inventors: Michael David Bentley, Xuan Zhao, Xiaoming Shen, William Dudley Battle, III
  • Patent number: 8323632
    Abstract: The invention provides a multi-arm block copolymer for use in delivering a variety of bioactive agents. The copolymer of the invention contains a central core from which extend multiple (3 or more) copolymer arms. Each copolymer arm possesses an inner polypeptide segment and an outer hydrophilic polymer segment. Thus, the overall structure of the copolymer comprises an inner core region that includes the central core and the inner polypeptide segment, while the outer core region is hydrophilic in nature. The multi-arm copolymer of the invention is particularly useful for delivery of biologically active agents that can be entrapped within the inner core region.
    Type: Grant
    Filed: June 2, 2011
    Date of Patent: December 4, 2012
    Assignee: Nektar Therapeutics
    Inventors: Xuan Zhao, Zhongxu Ren, Kazunori Emoto
  • Patent number: 8318145
    Abstract: Provided herein are water-soluble prodrugs. The prodrugs of the invention comprise a water-soluble polymer having three or more arms, at least three of which are covalently attached to an active agent, e.g., a small molecule. The conjugates of the invention provide an optimal balance of polymer size and structure for achieving improved drug loading, since the conjugates of the invention possess three or more active agents releasably attached to a multi-armed water soluble polymer. The prodrugs of the invention are therapeutically effective, and exhibit improved properties in-vivo when compared to unmodified parent drug.
    Type: Grant
    Filed: March 19, 2010
    Date of Patent: November 27, 2012
    Assignee: Nektar Therapeutics
    Inventors: Xuan Zhao, Michael D. Bentley, Zhongxu Ren, Tacey X. Viegas
  • Publication number: 20120282671
    Abstract: A multi-arm polyethylene glycol (I) having different kinds of reactive groups and the uses thereof are disclosed, which is formed by polymerizing ethylene oxide with oligo-pentaerythritol as an initiator, wherein, PEG is same or different and is —(CH2CH2O)m-, the average value of m is an integer of 2-250; I is an integer of 1 or more. The method for producing the multi-arm polyethylene glycol having different kinds of reactive groups, the multi-arm polyethylene glycol active derivatives comprising linking groups X attached to PEG and terminal reactive groups F attached to X, the gels formed by the multi-arm polyethylene glycol active derivatives, the drug conjugates formed by the multi-arm polyethylene glycol active derivatives and drug molecules, and the uses thereof in preparing drugs are also disclosed.
    Type: Application
    Filed: December 23, 2010
    Publication date: November 8, 2012
    Applicant: JENKEM TECHNOLOGY CO. LTD., TIANJIN BRANCH
    Inventors: Xuan Zhao, Meina Lin
  • Patent number: 8283434
    Abstract: Methods for preparing a poly(ether carbonates) of the formula HO—[(CH2CH2—O)n—CO2]m—(CH2CH2—O)n—H are provided. The method comprises polymerizing an activated oligomer of the formula of H—O—(CH2CH2—O)n—CO2—Z, where Z is reactive leaving group.
    Type: Grant
    Filed: January 5, 2012
    Date of Patent: October 9, 2012
    Assignee: Nektar Therapeutics
    Inventors: J. Milton Harris, Michael David Bentley, Xuan Zhao, Xiaoming Shen
  • Patent number: 8273833
    Abstract: The present invention is directed to branched reactive water-soluble polymers comprising at least two polymer arms, such as poly(ethylene glycol), attached to a central aliphatic hydrocarbon core molecule through ether linkages. The branched polymers bear at least one functional group for reacting with a biologically active agent to form a biologically active conjugate. The functional group of the branched polymer can be directly attached to the aliphatic hydrocarbon core or via an intervening linkage, such as a heteroatom, -alkylene-, —O-alkylene-O—, -alkylene-O-alkylene-, -aryl-O—, —O-aryl-, (—O-alkylene-)m, or (-alkylene-O—)m linkage, wherein m is 1-10.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: September 25, 2012
    Assignee: Nektar Therapeutics
    Inventors: Michael David Bentley, Xuan Zhao, Xiaoming Shen, William Dudley Battle, III
  • Patent number: 8263062
    Abstract: Provided herein are water-soluble prodrugs. The prodrugs of the invention comprise a water-soluble polymer having three or more arms, at least three of which are covalently attached to an active agent, e.g., a small molecule. The conjugates of the invention provide an optimal balance of polymer size and structure for achieving improved drug loading, since the conjugates of the invention possess three or more active agents releasably attached to a multi-armed water soluble polymer. The prodrugs of the invention are therapeutically effective, and exhibit improved properties in-vivo when compared to unmodified parent drug.
    Type: Grant
    Filed: February 22, 2010
    Date of Patent: September 11, 2012
    Assignee: Nektar Therapeutics
    Inventors: Xuan Zhao, Michael D. Bentley, Zhongxu Ren, Tacey X. Viegas
  • Publication number: 20120195846
    Abstract: A heterobifunctional poly(ethylene glycol) is provided having a hydrolytically degradable linkage, a first terminus comprising an acrylate group, and a second terminus comprising a target such as a protein or pharmaceutical agent or a reactive moiety capable of coupling to a target. Hydrogels can be prepared. The hydrogels can be used as a carrier for a protein or a pharmaceutical agent that can be readily released in a controlled fashion.
    Type: Application
    Filed: April 13, 2012
    Publication date: August 2, 2012
    Applicant: Nektar Therapeutics AL, Corporation
    Inventors: J. Milton Harris, Xuan Zhao
  • Patent number: 8183338
    Abstract: The invention provides a sterically hindered polymers and conjugates formed therefrom that comprise a water-soluble and non-peptidic polymer backbone having at least one terminus covalently bonded to an alkanoic acid or alkanoic acid derivative prior to conjugation, wherein the carbon adjacent to the carbonyl group of the acid or acid derivative group has an alkyl or aryl group pendent thereto. The steric effects of the alkyl or aryl group allow greater control of the hydrolytic stability of polymer derivatives. The polymer backbone may be poly(ethylene glycol).
    Type: Grant
    Filed: May 3, 2011
    Date of Patent: May 22, 2012
    Assignee: Nektar Therapeutics
    Inventors: Michael D. Bentley, Xuan Zhao, Xiaoming Shen, Lihong Guo
  • Publication number: 20120108785
    Abstract: Methods for preparing a poly(ether carbonates) of the formula HO—[(CH2CH2—O)n—CO2]m—(CH2CH2—O)n—H are provided. The method comprises polymerizing an activated oligomer of the formula of H—O—(CH2CH2—O)n—CO2-Z, where Z is reactive leaving group.
    Type: Application
    Filed: January 5, 2012
    Publication date: May 3, 2012
    Applicant: Nektar Therapeutics
    Inventors: J. Milton Harris, Michael David Bentley, Xuan Zhao, Xiaoming Shen
  • Publication number: 20120046422
    Abstract: The invention provides methods for making copolymers and multi-arm block copolymers useful as drug delivery vehicles. The multi-arm block copolymers comprise a central core molecule, such as a residue of a polyol, and at least three copolymer arms covalently attached to the central core molecule, each copolymer arm comprising an inner hydrophobic polymer segment covalently attached to the central core molecule and an outer hydrophilic polymer segment covalently attached to the hydrophobic polymer segment, wherein the central core molecule and the hydrophobic polymer segment define a hydrophobic core region. The solubility of hydrophobic biologically active agents can be improved by entrapment within the hydrophobic core region of the block copolymer. The invention further includes pharmaceutical compositions including such block copolymers, pharmaceutical compositions, and methods of using the block copolymers as drug delivery vehicles.
    Type: Application
    Filed: November 2, 2011
    Publication date: February 23, 2012
    Applicant: Nektar Therapeutics
    Inventor: Xuan Zhao
  • Patent number: 8119756
    Abstract: Methods for delivering a biologically active agent into the body of a mammal are provided, the method comprising administering a carbamate-containing conjugate to the mammal.
    Type: Grant
    Filed: February 14, 2011
    Date of Patent: February 21, 2012
    Assignee: Nektar Therapeutics
    Inventors: J. Milton Harris, Michael D. Bentley, Xuan Zhao, Xiaoming Shen
  • Patent number: 8071692
    Abstract: The invention provides methods for making copolymers and multi-arm block copolymers useful as drug delivery vehicles. The multi-arm block copolymers comprise a central core molecule, such as a residue of a polyol, and at least three copolymer arms covalently attached to the central core molecule, each copolymer arm comprising an inner hydrophobic polymer segment covalently attached to the central core molecule and an outer hydrophilic polymer segment covalently attached to the hydrophobic polymer segment, wherein the central core molecule and the hydrophobic polymer segment define a hydrophobic core region. The solubility of hydrophobic biologically active agents can be improved by entrapment within the hydrophobic core region of the block copolymer. The invention further includes pharmaceutical compositions including such block copolymers, pharmaceutical compositions, and methods of using the block copolymers as drug delivery vehicles.
    Type: Grant
    Filed: August 7, 2009
    Date of Patent: December 6, 2011
    Assignee: Nektar Therapeutics
    Inventor: Xuan Zhao
  • Publication number: 20110286956
    Abstract: A novel multi-arm polyethylene glycol (PEG) (I) and preparation method thereof. Active derivatives (II) based on the multi-arm PEG. Gels formed of the active derivatives. Drug conjugates formed of the active derivatives and drug molecules and uses thereof in medical preparation. The multi-arm PEG is formed by polymerizing ethylene oxide with pentaerythritol oligomers as initiator, wherein PEG is the same or different and is a —(CH2CH2O)m-, the average value of m is an integer of 3-1000, l is an integer more than or equal to 2. An 8-arm PEG is preferred, wherein l is equal to 3. The active derivatives (II) comprise link groups X attached to PEG and active end groups F attached to X.
    Type: Application
    Filed: September 28, 2009
    Publication date: November 24, 2011
    Applicant: BEIJING JENKEM TECHNOLOGY CO. LTD.
    Inventors: Xuan Zhao, Yuhe Zhao
  • Patent number: 8034825
    Abstract: The invention provides small molecule drugs that are chemically modified by covalent attachment of a water-soluble oligomer obtained from a monodisperse or bimodal water-soluble oligomer composition. A conjugate of the invention, when administered by any of a number of administration routes, exhibits a reduced biological membrane crossing rate as compared to the biological membrane crossing rate of the small molecule drug not attached to the water-soluble oligomer.
    Type: Grant
    Filed: June 24, 2010
    Date of Patent: October 11, 2011
    Assignee: Nektar Therapeutics
    Inventors: Michael D. Bentley, Tacey X. Viegas, Richard R. Goodin, Lin Cheng, Xuan Zhao
  • Publication number: 20110237747
    Abstract: The invention provides a multi-arm block copolymer for use in delivering a variety of bioactive agents. The copolymer of the invention contains a central core from which extend multiple (3 or more) copolymer arms. Each copolymer arm possesses an inner polypeptide segment and an outer hydrophilic polymer segment. Thus, the overall structure of the copolymer comprises an inner core region that includes the central core and the inner polypeptide segment, while the outer core region is hydrophilic in nature. The multi-arm copolymer of the invention is particularly useful for delivery of biologically active agents that can be entrapped within the inner core region.
    Type: Application
    Filed: June 2, 2011
    Publication date: September 29, 2011
    Applicant: Nektar Therapeutics
    Inventors: Xuan Zhao, Zhongxu Ren, Kazunori Emoto