Abstract:
:Recombinant immunotoxins, consisting of single-chain variable fragments (scFv) genetically fused to polypeptide toxins, represent potentially effective candidates for cancer therapeutics. We evaluated the affinity of various anti-Her2/neu scFv fused to recombinant gelonin (rGel) and its effect on antitumor efficacy and off-target toxicity. A series of rGel-based immunotoxins were created from the human anti-Her2/neu scFv C6.5 and various affinity mutants (designated ML3-9, MH3-B1, and B1D3) with affinities ranging from 10(-8) to 10(-11) mol/L. Against Her2/neu-overexpressing tumor cells, immunotoxins with increasing affinity displayed improved internalization and enhanced autophagic cytotoxicity. Targeting indices were highest for the highest affinity B1D3/rGel construct. However, the addition of free Her2/neu extracellular domain (ECD) significantly reduced the cytotoxicity of B1D3/rGel because of immune complex formation. In contrast, ECD addition had little impact on the lower affinity constructs in vitro. In vivo studies against established BT474 M1 xenografts showed growth suppression by all immunotoxins. Surprisingly, therapy with the B1D3-rGel induced significant liver toxicity because of immune complex formation with shed Her2/neu antigen in circulation. The MH3-B1/rGel construct with intermediate affinity showed effective tumor growth inhibition without inducing hepatotoxicity or complex formation. These findings show that while high-affinity constructs can be potent antitumor agents, they may also be associated with mistargeting through the facile formation of complexes with soluble antigen leading to significant off-target toxicity. Constructs composed of intermediate-affinity antibodies are also potent agents that are more resistant to immune complex formation. Therefore, affinity is an exceptionally important consideration when evaluating the design and efficacy of targeted therapeutics.
journal_name
Mol Cancer Therjournal_title
Molecular cancer therapeuticsauthors
Cao Y,Marks JD,Huang Q,Rudnick SI,Xiong C,Hittelman WN,Wen X,Marks JW,Cheung LH,Boland K,Li C,Adams GP,Rosenblum MGdoi
10.1158/1535-7163.MCT-11-0519subject
Has Abstractpub_date
2012-01-01 00:00:00pages
143-53issue
1eissn
1535-7163issn
1538-8514pii
1535-7163.MCT-11-0519journal_volume
11pub_type
杂志文章abstract::DNA cytosine methylation plays a considerable role in normal development, gene regulation, and carcinogenesis. Hypermethylation of the promoters of some tumor suppressor genes and the associated silencing of these genes often occur in certain cancer types. The reversal of this process by DNA methylation inhibitors is ...
journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章,评审
doi:
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-10-0157
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-08-0959
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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pub_type: 杂志文章
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更新日期:2016-10-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0210
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-10-0763
更新日期:2011-04-01 00:00:00
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0046
更新日期:2005-08-01 00:00:00
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-06-0388
更新日期:2007-02-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0363
更新日期:2006-09-01 00:00:00
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pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-20-0378
更新日期:2020-12-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-05-0313
更新日期:2006-11-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-07-0079
更新日期:2007-10-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
doi:10.1158/1535-7163.MCT-10-0370
更新日期:2010-09-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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更新日期:2016-10-01 00:00:00
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journal_title:Molecular cancer therapeutics
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pub_type: 杂志文章
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更新日期:2012-11-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
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更新日期:2002-09-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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更新日期:2005-01-01 00:00:00
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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journal_title:Molecular cancer therapeutics
pub_type: 杂志文章
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