title: Tumor cell purging by ex vivo expansion of hemopoietic stem cells from breast cancer patients combined with targeting ErbB receptors.
abstract: Tumor cell contamination might induce relapse after autologous transplantation in breast cancer patients. We used an ex vivo purging strategy to decrease the number of contaminating breast tumor cells in leukaphereses without altering the engraftment potential of the hemopoietic progenitor cells. This method is based on immunoselection of CD34+ cells derived from mobilized peripheral blood of patients with metastatic breast cancer and expansion in the presence of flt3 ligand, stem cell factor, interleukin 6, and thrombopoietin. Tumor contamination before and after culture was monitored by mammaglobin messenger RNA amplification by quantitative polymerase chain reaction. We analyzed both adherent and suspended cells obtained after 2 weeks of culture. Hemopoietic progenitors were increased among suspended cells. In this fraction, tumor cell contamination was decreased, whereas it increased within the adherent cell fraction. Experimental models using CD34+ cells from healthy donors spiked with breast cancer cells were also constructed to investigate whether treatment with anti-ErbB-receptor drugs could further reduce the tumor load without affecting the clonogenic potential of hemopoietic cells. For this purpose, we successfully assayed trastuzumab, a monoclonal antibody against ErbB-2, and gefitinib, an epidermal growth factor receptor tyrosine kinase receptor inhibitor. These results suggest that positively selected CD34+ cells from cancer patients contain tumor cells and that ex vivo expansion can reduce the tumor load of the suspended fraction. Target-based agents against ErbB-2, epidermal growth factor receptor, or both--such as trastuzumab or gefitinib--might increase the efficiency of purging.
authors.affiliation: Division of Medical Oncology, University of Turin Medical School, Institute for Cancer Research and Treatment, Turin, Italy. francesco.leone@ircc.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Leone
authors.forename: Giuliana
authors.initials: G
authors.lastname: Cavalloni
authors.forename: Monica
authors.initials: M
authors.lastname: Gunetti
authors.forename: Ymera
authors.initials: Y
authors.lastname: Pignochino
authors.forename: Wanda
authors.initials: W
authors.lastname: Piacibello
authors.forename: Massimo
authors.initials: M
authors.lastname: Aglietta
mesh_terms: D000328:Adult; D018952:Antigens, CD34; D001943:Breast Neoplasms / Q000473:pathology* / Q000628:therapy*; D018929:Cell Culture Techniques / Q000379:methods; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D018189:Immunomagnetic Separation; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000473:pathology; D018739:Oncogene Proteins v-erbB / Q000037:antagonists & inhibitors* / Q000276:immunology; D036102:Peripheral Blood Stem Cell Transplantation / Q000379:methods*; D014182:Transplantation, Autologous; D047368:Tumor Burden
chemical_list: D018952:Antigens, CD34; D018739:Oncogene Proteins v-erbB