Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: A method for conjugation of PEG to a protein in an aqueous solution at a pH less than or equal to about 7.0 or neutral pH comprising combining an activated PEG reagent and a protein in the presence of an activating agent at a pH of less than about 7.0 or neutral pH. In one embodiment, the method produces mixed populations of moderately PEGylated proteins, including 1:1, 2:1, and 3:1 PEGylated proteins.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: Reagents for use in preparing a therapeutic liposome composition sensitized to a target cell are described. The reagents include a liposomal composition composed of pre-formed liposomes having an entrapped therapeutic agent and a plurality of targeting conjugates composed of a lipid, a hydrophilic polymer and a targeting ligand. The therapeutic, target-cell sensitized liposome composition is formed by incubating the liposomal composition with a selected conjugate.

Abstract: A liposomal composition and a method of using the same for achieving intracellular delivery of a liposome-entrapped agent is described. The liposomes are composed of a pH sensitive lipid and include a targeting ligand to direct the liposomes to a target cell. The liposomes also include a stabilizing component, such a polymer-derivatized lipid, where the polymer is attached to the lipid by a releasable linkage. Administration of the liposomes results in cellular internalization and destabilization of the liposome for intracellular delivery of the entrapped agent.

Abstract: Reagents for use in preparing a therapeutic liposome composition sensitized to a target cell are described. The reagents include a liposomal composition composed of pre-formed liposomes having an entrapped therapeutic agent and a plurality of targeting conjugates composed of a lipid, a hydrophilic polymer and a targeting ligand. The therapeutic, target-cell sensitized liposome composition is formed by incubating the liposomal composition with a selected conjugate.

Abstract: A liposome composition for delivery of a nucleic acid in vivo or ex vivo is described. The liposomes in the composition are comprised of (i) a lipid that is neutral in charge at physiologic pH and positively charged at pH values less than physiologic pH and (ii) a lipid joined to a hydrophilic polymer by a dithiobenzyl linkage. The liposomes are associated with a nucleic acid for delivery to a cell.

Abstract: A liposomal composition and a method of using the same for achieving intracellular delivery of a liposome-entrapped agent is described. The liposomes are composed of a pH sensitive lipid and include a targeting ligand to direct the liposomes to a target cell. The liposomes also include a stabilizing component, such a polymer-derivatized lipid, where the polymer is attached to the lipid by a releasable linkage. Administration of the liposomes results in cellular internalization and destabilization of the liposome for intracellular delivery of the entrapped agent.

Abstract: A liposome composition comprised of liposomes having the peptide boronic acid proteasome inhibitor compound bortezomib entrapped in the liposomes is described. The boronic acid compound is entrapped in the liposomes in the form of a boronate ester, subsequent to interaction with a liposome-entrapped polyol. In one embodiment, the liposomes have an outer coating of hydrophilic polymer chains and are used to treat a solid tumor in a subject.

Abstract: A liposome composition comprised of liposomes having a peptide boronic acid proteasome inhibitor compound entrapped in the liposomes is described. The boronic acid compound is entrapped in the liposomes in the form of a boronate ester, subsequent to interaction with a liposome-entrapped polyol. In one embodiment, the liposomes have an outer coating of hydrophilic polymer chains and are used to treat a malignancy in a subject.

Abstract: Conjugates of formula I, below, are useful in biomedicinal applications such as delivery of drugs or labeling moieties or as components of liposomes or micelles. In formula I, A is a hydrophilic polymer, each of L and L? is independently a linker group, B is a lipid moiety; and Z is a diagnostic ligand, a biologically relevant ligand, or a reactive linking moiety, which is generally linked to the phosphorus atom of the conjugate via a nitrogen, oxygen or sulfur atom in Z.

Abstract: Microparticle and nanoparticles comprised of a polymer and of a lipid-polymer conjugate (lipopolymer) are described. The particles can include a therapeutic or diagnostic agent and/or a ligand attached to the lipopolymer. Compositions comprising the particles and methods of treatment using the particles are also described.

Abstract: A composition for administration of a therapeutic compound to a multi-drug resistant cell in a person suffering from a drug-resistant cancer is described. The composition is composed of a carrier molecule and a folate targeting ligand, which is covalently attached to the carrier, and the therapeutic compound. In one preferred embodiment, the carrier is a liposome having a surface coating of hydrophilic polymer chains where a folate ligand is attached to the free distal end of at least a portion of the hydrophilic polymer chains, and the therapeutic agent is entrapped in the liposomes. The composition is effective to achieve accumulation of the therapeutic compound in the cell in an amount sufficient to be cytotoxic. Also described are methods for administering a therapeutic compound to a person suffering from a multi-drug resistant condition.

Abstract: A conjugate formed in vivo and comprised of endogenous albumin and an amine-containing compound, such as a protein or a drug, is described. The conjugate is formed by in vivo cleavage of a polymer-dithiobenzyl-therapeutic agent conjugate to form an albumin-dithiobenzyl-therapeutic agent conjugate. The dithiol moiety of the albumin-therapeutic agent conjugate is cleaved in vivo to yield the free therapeutic agent in native form.

Abstract: Conjugates of a hydrophobic moiety, such as a lipid, linked through a cleavable dithiobenzyl linkage to a therapeutic agent are described. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of the therapeutic agent in its original form. The linkage is stable under nonreducing conditions. The conjugate can be incorporated into liposomes for administration in vivo and release of the therapeutic agent in response to endogeneous in vivo reducing conditions or in response to administration of an exogeneous reducing agent.

Abstract: Polymer-biomolecule conjugates are prepared, generally in a site-specific or -selective manner, by a four-component condensation reaction. The method may be used to prepare conjugates having two polymer molecules attached at a single site on a biomolecule. The conjugates are typically water soluble and have beneficial pharmacological properties, such as reduced immunogenicity and increased circulation time.

Abstract: A lipid represented by the formula: wherein each of R1 and R2 is an alkyl or alkenyl chain having between about 8 to about 24 carbon atoms; n=0–20; L is selected from the group consisting of (i) —X—(C?O)—Y—, (ii) —X—(C?O)—, and (iii) —X—CH2—, wherein X and Y are independently selected from oxygen, NH, and a direct bond; and Z is a weakly basic moiety that has a pK of less than about 7.4 and greater than about 4.0 is described.

Abstract: Conjugates of a hydrophobic moiety, such as a lipid, linked through a cleavable dithiobenzyl linkage to a therapeutic agent are described. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of the therapeutic agent in its original form. The linkage is stable under nonreducing conditions. The conjugate can be incorporated into liposomes for administration in vivo and release of the therapeutic agent in response to endogeneous in vivo reducing conditions or in response to administration of an exogeneous reducing agent.

Abstract: Conjugates comprising a lipid or a hydrophilic polymer, such as polyethyleneglycol, linked to a ligand derived from an amine- or hydroxyl-containing compound, such as a drug or protein, are stable under conditions of storage, and are cleavable under mild thiolytic conditions to regenerate the amine- or hydroxyl-containing compound in its native form, without the formation of undesirable side products.

Abstract: A lipid represented by the formula: wherein each of R1 and R2 is an alkyl or alkenyl chain having between about 8 to about 24 carbon atoms; n=0-20; L is selected from the group consisting of (i) —X—(C?O)—Y—, (ii) —X—(C?O)—, and (iii) —X—CH2—, wherein X and Y are independently selected from oxygen, NH and a direct bond; and Z is a weakly basic moiety that has a pK of less than about 7.4 and greater than about 4.0 is described.