title: A single-chain fragment against prostate specific membrane antigen as a tool to build theranostic reagents for prostate cancer.
abstract: Prostate carcinoma is the most common non-cutaneous cancer in developed countries and represents the second leading cause of death. Early stage androgen dependent prostate carcinoma responds well to conventional therapies, but relatively few treatment options exist for patients with hormone-refractory prostate cancer. One of the most suitable targets for antibody-mediated approaches is prostate specific membrane antigen (PSMA) which is a well known tumour associated antigen. PSMA is a type II integral cell-surface membrane protein that is not secreted, and its expression density and enzymatic activity are increased progressively in prostate cancer compared to normal prostate epithelium, thereby making PSMA an ideal target for monoclonal antibody imaging and therapy. To obtain a small protein that can better penetrate tissue, we have engineered a single-chain variable fragment (scFv) starting from the variable heavy and light domains of the murine anti-PSMA monoclonal antibody D2B. scFvD2B was analysed in vitro for activity, stability, internalisation ability and in vivo for targeting specificity. Maintenance of function and immunoreactivity as well as extremely high radiolabelling efficiency and radiochemical purity were demonstrated by in vitro assays and under different experimental conditions. Despite its monovalent binding, scFvD2B retained a good strength of binding and was able to internalise around 40% of bound antigen. In vivo we showed its ability to specifically target only PSMA expressing prostate cancer xenografts. Due to these advantageous properties, scFvD2B has the potential to become a good theranostic reagent for early detection and therapy of prostate cancers.
authors: Molecular Therapies Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: B
authors: B
authors: Frigerio
authors: Department of Pathology and Diagnostics, Section of Immunology, University of Verona, Verona, Italy.
authors: G
authors: G
authors: Fracasso
authors: Molecular Therapies Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: E
authors: E
authors: Luison
authors: Medical Oncology, Azienda Ospedaliera Universitaria Integrata (AOUI), Verona, Italy.
authors: S
authors: S
authors: Cingarlini
authors: Molecular Therapies Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: M
authors: M
authors: Mortarino
authors: Department of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: A
authors: A
authors: Coliva
authors: Department of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: E
authors: E
authors: Seregni
authors: Department of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: E
authors: E
authors: Bombardieri
authors: Istituto Oncologico Veneto IRCCS, Padova, Italy.
authors: G
authors: G
authors: Zuccolotto
authors: Istituto Oncologico Veneto IRCCS, Padova, Italy; Department of Surgery, Oncology and Gastroenterology, University of Padova, Padova, Italy.
authors: A
authors: A
authors: Rosato
authors: Department of Pathology and Diagnostics, Section of Immunology, University of Verona, Verona, Italy.
authors: M
authors: M
authors: Colombatti
authors: Molecular Therapies Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy.
authors: S
authors: S
authors: Canevari
authors: Molecular Therapies Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy. Electronic address: mariangela.figini@istitutotumori.mi.it.
authors: M
authors: M
authors: Figini
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology*; D014408:Biomarkers, Tumor / Q000276:immunology; D004268:DNA-Binding Proteins; D055088:Early Detection of Cancer; D004795:Enzyme Stability; D004797:Enzyme-Linked Immunosorbent Assay; D043425:Glutamate Carboxypeptidase II / Q000276:immunology*; D064593:Heterografts; D006801:Humans; D007074:Immunoglobulin G; D007150:Immunohistochemistry; D007202:Indicators and Reagents; D008297:Male; D051379:Mice; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D011485:Protein Binding; D011863:Radioimmunoassay; D057127:Single-Chain Antibodies / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D057127:Single-Chain Antibodies; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II