title: Anti-EGFR antibody cetuximab enhances the cytolytic activity of natural killer cells toward osteosarcoma.
abstract: OBJECTIVE
  Osteosarcoma and Ewing's sarcoma are the most common bone tumors in children and adolescents. Despite intensive chemotherapy, patients with advanced disease have a poor prognosis, illustrating the need for alternative therapies. Sarcoma cells are susceptible to the cytolytic activity of resting natural killer (NK) cells which can be improved by interleukin (IL)-15 stimulation. In this study, we explored whether the cytolytic function of resting NK cells can be augmented and specifically directed toward sarcoma cells by antibody-dependent cellular cytotoxicity (ADCC).
  
  
  METHODS
  Epidermal growth factor receptor (EGFR) expression was examined on osteosarcoma and Ewing's sarcoma cell lines by flow cytometry and in osteosarcoma biopsy and resection specimens by immunohistochemistry. Cetuximab-mediated ADCC by NK cells from osteosarcoma patients and healthy controls was measured with 4-hour (51)Cr release assays.
  
  
  RESULTS
  EGFR surface expression was shown on chemotherapy-sensitive and chemotherapy-resistant osteosarcoma cells (12/12), most primary osteosarcoma cultures (4/5), and few Ewing's sarcoma cell lines (2/7). In the presence of cetuximab, the cytolytic activity of resting NK cells against all EGFR-expressing sarcoma cells was substantially increased and comparable with that of IL-15-activated NK cells. Surface EGFR expression on primary osteosarcoma cultures correlated with EGFR expression in the original tumor. The cytolytic activity of osteosarcoma patient-derived NK cells against autologous tumor cells was as efficient as that of NK cells from healthy donors.
  
  
  CONCLUSIONS
  Our data show that the cytolytic potential of resting NK cells can be potentiated and directed toward osteosarcoma cells with cetuximab. Therefore, cetuximab-mediated immunotherapy may be considered a novel treatment modality in the management of advanced osteosarcoma.
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Jens H W
authors.initials: JH
authors.lastname: Pahl
authors.forename: S Eriaty N
authors.initials: SE
authors.lastname: Ruslan
authors.forename: Emilie P
authors.initials: EP
authors.lastname: Buddingh
authors.forename: Susy J
authors.initials: SJ
authors.lastname: Santos
authors.forename: Karoly
authors.initials: K
authors.lastname: Szuhai
authors.forename: Massimo
authors.initials: M
authors.lastname: Serra
authors.forename: Hans
authors.initials: H
authors.lastname: Gelderblom
authors.forename: Pancras C W
authors.initials: PC
authors.lastname: Hogendoorn
authors.forename: R Maarten
authors.initials: RM
authors.lastname: Egeler
authors.forename: Marco W
authors.initials: MW
authors.lastname: Schilham
authors.forename: Arjan C
authors.initials: AC
authors.lastname: Lankester
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity; D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D000068818:Cetuximab; D002648:Child; D018920:Coculture Techniques; D004354:Drug Screening Assays, Antitumor; D066246:ErbB Receptors / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D012512:Sarcoma, Ewing / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000099192:CD69 Antigens
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000970:Antineoplastic Agents; D000068818:Cetuximab; D066246:ErbB Receptors; D037181:Lectins, C-Type; D000099192:CD69 Antigens; C512478:EGFR protein, human