Selection of human antitumor single-chain Fv antibodies from the B-cell repertoire of patients immunized against autologous neuroblastoma

Background We used phage display technology to clone human recombinant anti tumor antibodies from the antibody repertoire of neuroblastoma patients imm unized with cytokine-gene transduced tumor cells. Procedure. Lymphocytes ob tained from neuroblastoma patients either at diagnosis or after immunizatio n with an autologous interleukin-2 gene transduced tumor vaccine were used to construct two human single-chain Fv (scFV) phage libraries. Tumor-reacti ve phage were characterized using ELISA, flow cytometry, and sequencing ana lysis. Results. The initial screening after panning on neuroblastoma cells yielded a substantially higher proportion of selectivity tumor-binding phag e clones derived from the immunized patients library (12.9%) than from the unvaccinated patients library (0.8%). The antibodies stained the cells from several additional pediatric malignancies, including Ewing sarcoma and rha bdomyosarcoma, in the absence of binding to any normal tissue cultures or e pithelial tumor cell lines. The pattern of reactivity was different from th at of antibodies recognizing other widely distributed neuroblastoma-associa ted antigens, suggesting recognition of a novel shared tumor antigen. Concl usion. The human recombinant scFV antibodies reported here appear to repres ent a tumor-specific B-cell response induced by autologous tumor immunizati on and are potentially useful targeting moieties for the treatment of selec ted childhood tumors. (C) 2000 Wiley-Liss, Inc.