Rare expression of epithelial cell adhesion molecule on residual micrometastatic breast cancer cells after adjuvant chemotherapy.
OBJECTIVE
Over the past 5 years, several clinical studies on a total of approximately 2500 patients have shown that the immunocytochemical detection of occult metastatic tumor cells in bone marrow (BM) at primary surgery provides important prognostic information in breast cancer (e.g., Ref 13 ). Here, we evaluated whether these cells can survive first-line chemotherapy and express epithelial cell adhesion molecule (Ep-CAM), recently suggested as promising target for immunotherapeutic interventions in breast cancer.


METHODS
A total of 62 patients with node-negative and -positive breast cancer but without distant metastases (Tumor-Node-Metastasis stage M(0)) was treated with two or more courses of various forms of adjuvant chemotherapy (e.g., cyclophosphamide-methotrexate-5-fluorouracil, anthracyclines). After chemotherapy, BM was aspirated from the upper iliac crest and analyzed for the presence of tumor cells. A first cohort of 34 BM aspirates was enriched for tumor cells by Ficoll density gradient centrifugation, and 2-4 x 10(6) mononuclear cells were analyzed per patient. The tumor cells were detected by anticytokeratin monoclonal antibody (Mab) A45-B/B3 and double labeled with Mab 3B10 against an Ep-CAM-epitope. The subsequent 27 BM aspirates were specifically enriched for Ep-CAM(+) cells using magnetic beads coupled to Mab 3B10, and tumor cells were identified by Fab fragments of Mab A45-B/B3 directly conjugated with alkaline phosphatase.


RESULTS
After chemotherapy, 10 of 35 (28.6%) Ficoll-enriched BM samples contained cytokeratin-positive tumor cells. In total, 26 cytokeratin-positive cells were detected, but none of these cells coexpressed Ep-CAM. Even within the second cohort of 27 Ep-CAM-enriched BM samples, only 2 specimens (7.4%) harbored cytokeratin-positive cells costaining with the Ep-CAM antibody.


CONCLUSIONS
Our results indicate that disseminated breast cancer cells in BM can survive first-line adjuvant chemotherapy. Ep-CAM expression is, however, restricted to a subset of these cells, which may limit the broad applicability of Ep-CAM as target for second-line adjuvant therapy in breast cancer.
Thurm
Holger
H
Institute for Tumor Biology, University Hospital Hamburg-Eppendorf, D-20246 Hamburg, Germany.
Ebel
Sebastian
S
Kentenich
Christina
C
Hemsen
Alice
A
Riethdorf
Sabine
S
Coith
Cornelia
C
Wallwiener
Diethelm
D
Braun
Stephan
S
Oberhoff
Carsten
C
Jänicke
Fritz
F
Pantel
Klaus
K
D000328:Adult; D000368:Aged; D018943:Anthracyclines / Q000627:therapeutic use; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D001854:Bone Marrow Cells / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D002499:Centrifugation, Density Gradient; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D003520:Cyclophosphamide / Q000627:therapeutic use; D000071858:Epithelial Cell Adhesion Molecule; D000939:Epitopes; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D007150:Immunohistochemistry; D007167:Immunotherapy; D008727:Methotrexate / Q000627:therapeutic use; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000378:metabolism; D011379:Prognosis
D018943:Anthracyclines; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D000939:Epitopes; D003520:Cyclophosphamide; D005472:Fluorouracil; D008727:Methotrexate