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Binding characteristics and tumor targeting of a covalently linked divalent CC49 single‐chain antibody
Author(s) -
Beresford Guy W.,
Pavlinkova Gabriela,
Booth Barbara J.M.,
Batra Surinder K.,
Colcher David
Publication year - 1999
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/(sici)1097-0215(19990611)81:6<911::aid-ijc12>3.0.co;2-o
Subject(s) - biodistribution , monoclonal antibody , chemistry , microbiology and biotechnology , recombinant dna , divalent , linker , size exclusion chromatography , antibody , escherichia coli , pharmacokinetics , biochemistry , biology , in vitro , immunology , enzyme , organic chemistry , pharmacology , gene , computer science , operating system
Multivalency is a recognized means of increasing the functional affinity of single‐chain Fvs (scFvs) for optimizing tumor uptake. A unique divalent single‐chain Fv protein [sc(Fv) 2 ], based on the variable regions of the monoclonal antibody (MAb) CC49, has been generated that differs from other dimeric single‐chain constructs in that a linker sequence (L) is encoded between the repeated V L and V H domains (V L ‐L‐V H ‐L‐V L ‐L‐V H ). This construct was expressed in soluble form in Escherichia coli and purified by ion‐exchange and gel‐filtration chromatography. Purity and immunoreactivity were determined by SDS‐PAGE, HPLC and competitive RIA. sc(Fv) 2 exhibited a relative K A (3.34 × 10 7 M −1 ) similar to that of the native IgG (1.14 × 10 8 M −1 ) as determined by BIAcore analysis. Pharmacokinetic studies showed rapid blood clearance for sc(Fv) 2 , with a T 1/2 less than 40 min. Whole‐body clearance analysis also revealed rapid clearance, suggesting no significant retention in the extravascular space or normal tissues. Biodistribution studies of radiolabeled sc(Fv) 2 showed tumor uptake greater than 6% ID/g after 30 min, which remained at this level for 6 hr. High tumor uptake and retention of sc(Fv) 2 coupled with rapid blood and whole‐body clearance makes this dimeric scFv of MAb CC49 a strong candidate for imaging and therapeutic applications. Int. J. Cancer 81:911–917, 1999. © 1999 Wiley‐Liss, Inc.