title: Antitumor activity of a humanized, bivalent immunotoxin targeting fn14-positive solid tumors.
abstract: The TNF-like weak inducer of apoptosis (TWEAK; TNFSF12) receptor Fn14 (TNFRSF12A) is expressed at low levels in normal tissues but frequently highly expressed in a wide range of tumor types such as lung, melanoma, and breast, and therefore it is a potentially unique therapeutic target for these diverse tumor types. We have generated a recombinant protein containing a humanized, dimeric single-chain anti-fibroblast growth factor-inducible 14-kDa protein (Fn14) antibody fused to recombinant gelonin toxin as a potential therapeutic agent (designated hSGZ). The hSGZ immunotoxin is a highly potent and selective agent that kills Fn14-positive (Fn14(+)) tumor cells in vitro. Treatment of cells expressing the MDR protein MDR1 (ABCB1B) showed no cross-resistance to hSGZ. Induced overexpression of Fn14 levels in MCF7 cells through HER2 (ERBB2) signaling translated to an improved therapeutic index of hSGZ treatment. In combination with trastuzumab, hSGZ showed an additive or synergistic cytotoxic effect on HER2(+)/Fn14(+) breast cancer cell lines. Also, hSGZ treatment inhibited Erb3/Akt signaling in HER2-overexpressing breast cancer cells. Pharmacokinetic studies in mice revealed that hSGZ exhibited a biexponential clearance from plasma with a rapid initial clearance (t1/2α = 1.26 hours) followed by a seven-fold longer plasma half-life (t1/2β = 7.29 hours). At 24, 48, and 72 hours after injection, uptake of the hSGZ into tumors was 5.1, 4.8, and 4.7%ID/g, with a tumor-to-muscle ratio of 5.6, 6.2, and 9.0, respectively. Therapeutic efficacy studies showed significant tumor inhibition effects using an MDA-MB-231/Luc breast cancer xenograft model. Our findings show that hSGZ is an effective anticancer agent and a potential candidate for clinical studies.
authors.affiliation: Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.forename: Walter N
authors.initials: WN
authors.lastname: Hittelman
authors.forename: Hideo
authors.initials: H
authors.lastname: Yagita
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Cheung
authors.forename: Stuart S
authors.initials: SS
authors.lastname: Martin
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Winkles
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenblum
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D018033:Antibodies, Bispecific / Q000493:pharmacokinetics / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D005260:Female; D006207:Half-Life; D006801:Humans; D000922:Immunotoxins / Q000493:pharmacokinetics / Q000494:pharmacology*; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000493:pharmacokinetics / Q000494:pharmacology; D054789:Ribosome Inactivating Proteins, Type 1 / Q000493:pharmacokinetics / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D000074050:TWEAK Receptor; D000068878:Trastuzumab; D023041:Xenograft Model Antitumor Assays
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018033:Antibodies, Bispecific; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000922:Immunotoxins; D051057:Proto-Oncogene Proteins c-akt; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D000074050:TWEAK Receptor; D000068878:Trastuzumab; C000613297:TNFRSF12A protein, human; C000613299:Tnfrsf12a protein, mouse; C025674:GEL protein, Gelonium multiflorum; C581292:ERBB3 protein, human