title: A cleavable molecular adapter reduces side effects and concomitantly enhances efficacy in tumor treatment by targeted toxins in mice.
abstract: Two of the main problems associated with administration of receptor-targeted toxins in tumor therapy are severe systemic side effects and low transfer of the toxins into the cytosol after binding to the tumor cell surface. To improve chimeric toxins in this respect we have developed a molecular adapter that links the toxic moiety and ligand. The adapter is designed to improve cytosolic uptake, retain the toxin inside the cytosol and detoxify the drug after cell death. The plant toxin saporin linked either directly or via the adapter to epidermal growth factor (EGF) served to evaluate efficacy to inhibit tumor growth and reduce side effects in vivo. The lethal dose for BALB/c mice was three times less for the adapter-containing toxin (SA2E) than for the adapter-free construct (SE). Furthermore, SE only reduced the average weight of induced tumors by 33% whereas SA2E-treated mice exhibited 71% reduction with an almost complete suppression in 60% of the cases. Additionally, severe side effects like hyperalgesia, alopecia and death were drastically reduced in SA2E-treated animals. Tumors without target receptor were only slightly affected by SA2E and the reduction in side effects less pronounced indicating specific depletion from the blood by target receptor expressing cells.
authors.affiliation: Zentralinstitut für Laboratoriumsmedizin und Pathobiochemie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany. hendrik.fuchs@charite.de
authors.forename: Hendrik
authors.initials: H
authors.lastname: Fuchs
authors.forename: Christopher
authors.initials: C
authors.lastname: Bachran
authors.forename: Tongyu
authors.initials: T
authors.lastname: Li
authors.forename: Iring
authors.initials: I
authors.lastname: Heisler
authors.forename: Horst
authors.initials: H
authors.lastname: Dürkop
authors.forename: Mark
authors.initials: M
authors.lastname: Sutherland
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D001219:Aspartate Aminotransferases / Q000378:metabolism; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D016503:Drug Delivery Systems; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics; D000922:Immunotoxins / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000188:drug therapy*; D010957:Plasmids / Q000235:genetics; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D000922:Immunotoxins; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D066246:ErbB Receptors