title: Trastuzumab administration can effectively target chemotherapy-resistant cytokeratin-19 messenger RNA-positive tumor cells in the peripheral blood and bone marrow of patients with breast cancer.
abstract: OBJECTIVE
  The detection of disseminated occult breast cancer cells in peripheral blood and bone marrow is associated with poor prognosis. Since a high proportion of these cells express the HER-2 receptor, we evaluated the effectiveness of the anti-HER-2 antibody trastuzumab (Herceptin) administration to eliminate them.
  
  
  METHODS
  Thirty patients with prior chemotherapy exposure were recruited to the study on the basis of having detectable cytokeratin-19 (CK-19) mRNA transcripts by nested reverse transcription (RT)-PCR in the peripheral blood and/or bone marrow. There were 13 patients with stage I, II, or III breast cancer and 17 with stage IV disease. They were treated in two cohorts with either 4 to 8 weekly infusions of trastuzumab at 2 mg/kg (4 mg/kg loading dose; 20 patients) or 2 to 3 infusions every 3 weeks at 6 mg/kg (8 mg/kg loading dose; 10 patients). All of the patients' samples were also analyzed for HER-2 by nested RT-PCR, but detectable HER-2 messenger RNA (mRNA) was not required for inclusion in the study. After trastuzumab infusions, patients were closely monitored by nested RT-PCR and real-time RT-PCR for the detection of CK-19 mRNA-positive cells.
  
  
  RESULTS
  Before trastuzumab infusions, CK-19 mRNA-positive cells were detected in the peripheral blood (n = 10), bone marrow (n = 14), or both (n = 6). In 25 of 30 patients (83%), HER-2 mRNA expression was detected by nested RT-PCR in the pretrastuzumab CK-19-positive sample. After trastuzumab infusions, overall, 28 of 30 (93%) patients became CK-19 mRNA negative by nested RT-PCR and 20 of 30 (67%) by real-time RT-PCR. After a median follow-up of 6 months (range 2 to 22+), the median duration of CK-19 mRNA negativity by nested RT-PCR was 9, 12, and 6 months for stage I/II, III, and IV disease, respectively.
  
  
  CONCLUSIONS
  Therapy-resistant CK-19 mRNA-positive cells in the peripheral blood and bone marrow can be effectively targeted by trastuzumab administration. Further studies are needed to evaluate the prognostic significance of the disappearance of these cells.
authors.affiliation: Department of Medical Oncology, University General Hospital of Heraklion, Crete, Greece.
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Bozionellou
authors.forename: Dimitris
authors.initials: D
authors.lastname: Mavroudis
authors.forename: Maria
authors.initials: M
authors.lastname: Perraki
authors.forename: Savvas
authors.initials: S
authors.lastname: Papadopoulos
authors.forename: Stella
authors.initials: S
authors.lastname: Apostolaki
authors.forename: Efstathios
authors.initials: E
authors.lastname: Stathopoulos
authors.forename: Aliki
authors.initials: A
authors.lastname: Stathopoulou
authors.forename: Evi
authors.initials: E
authors.lastname: Lianidou
authors.forename: Vassilis
authors.initials: V
authors.lastname: Georgoulias
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001853:Bone Marrow / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007633:Keratins / Q000235:genetics*; D008875:Middle Aged; D009360:Neoplastic Cells, Circulating / Q000187:drug effects* / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D012334:RNA, Neoplasm / Q000097:blood; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D007633:Keratins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab