title: A novel fully human antitumor immunoRNase resistant to the RNase inhibitor.
abstract: The ErbB2 tyrosine kinase receptor is an attractive target for immunotherapy, as it is overexpressed in many carcinomas. ImmunoRNases, made up of a human anti-ErbB2 scFv (single chain antibody fragment) and human RNases, have been engineered to overcome the limits of immunotoxins, made up of mouse antibodies and plant or bacterial toxins, such as immunogenicity and non-specific toxicity. Here we describe the construction and characterization of a second-generation anti-ErbB2 immunoRNase, called ERB-HP-DDADD-RNase, obtained by fusing Erbicin, a human ErbB2-directed scFv, with an inhibitor-resistant variant of human pancreatic RNase (HP-DDADD-RNase). This novel immunoRNase retains both the enzymatic activity of human pancreatic RNase and the specific binding of the parental scFv to ErbB2-positive cells, showing an affinity comparable with that of the previously reported parental immunoRNase (ERB-HP-RNase). Moreover, the novel immunoRNase is endowed with an effective and selective in vitro antiproliferative action for ErbB2-positive tumor cells, which is more potent than that of the parental immunoRNase on tumor cells expressing low levels of ErbB2, due to its resistance to the RNase inhibitor. Thus, the novel immunoRNase could represent a valuable tool for ErbB2-positive cancer therapy.
authors.affiliation: Dipartimento di Biologia Strutturale e Funzionale,  Università Federico II, Napoli,  Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Riccio
authors.forename: Chiara
authors.initials: C
authors.lastname: D'Avino
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Raines
authors.forename: Claudia
authors.initials: C
authors.lastname: De Lorenzo
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000201:enzymology / Q000276:immunology / Q000628:therapy*; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003001:Cloning, Molecular / Q000379:methods; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D006801:Humans; D007167:Immunotherapy; D051379:Mice; D008875:Middle Aged; D015202:Protein Engineering; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D012259:Ribonuclease, Pancreatic / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D018076:DNA, Complementary; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D012259:Ribonuclease, Pancreatic; D057127:Single-Chain Antibodies