title: Enhanced circulating half-life and antitumor activity of a site-specific pegylated interferon-alpha protein therapeutic.
abstract: Recombinant interferon alpha-2 (IFN-alpha2) has proven useful for treating a variety of human cancers and viral diseases. IFN-alpha2 has a short circulating half-life in vivo, which necessitates daily or thrice weekly administration to patients. It is possible to extend the circulating half-life of IFN-alpha2 by random modification of lysine residues in the protein with polyethylene glycol (PEG); however, such preparations have heterogeneous structures and low specific activities, and may not provide optimal therapeutic benefits to patients. A long-acting, site-specific, monoPEGylated IFN-alpha2 protein has now been created by targeted attachment of a 20 kDa or a 40 kDa maleimide-PEG to a cysteine analogue of IFN-alpha2, M111C. In vitro bioactivities of the purified 20 kDa and 40 kDa PEG-M111C proteins were within 2- to 3-fold of those of wild type IFN-alpha2 and 7- to 10-fold better than that of a 40 kDa PEG IFN-alpha2 protein created using nontargeted, amine-PEGylation methodology. The 20 kDa and 40 kDa PEG-M111C proteins demonstrated 26- to 38-fold longer half-lives, respectively, than IFN-alpha2 following subcutaneous administration to rats. The 20 kDa PEG M111C protein inhibited growth of human NIH:OVCAR-3 cells transplanted into nude mice by >90%, as measured by tumor size, tumor weight, and number of animals with detectable tumors at necropsy, and was significantly more effective than a comparable dose of IFN-alpha2. These data extend our previous findings that bioactivity of IFN-alpha2 can be largely preserved by targeted attachment of PEG moieties to nonessential sites in the protein and provide evidence that site-specific PEGylated IFN-alpha2 proteins possess enhanced tumoricidal properties in vivo.
authors.affiliation: Bolder BioTechnology, Inc., 2945 Wilderness Place, Boulder, Colorado 80301, USA.
authors.forename: Stacie J
authors.initials: SJ
authors.lastname: Bell
authors.forename: Christine M
authors.initials: CM
authors.lastname: Fam
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Chlipala
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Carlson
authors.forename: Ji I
authors.initials: JI
authors.lastname: Lee
authors.forename: Mary S
authors.initials: MS
authors.lastname: Rosendahl
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Doherty
authors.forename: George N
authors.initials: GN
authors.lastname: Cox
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000097:blood* / Q000493:pharmacokinetics / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003545:Cysteine; D006207:Half-Life; D006801:Humans; D016898:Interferon-alpha / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D011092:Polyethylene Glycols / Q000737:chemistry*; D011994:Recombinant Proteins / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D012680:Sensitivity and Specificity; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D016898:Interferon-alpha; D011994:Recombinant Proteins; D011092:Polyethylene Glycols; D003545:Cysteine