Kinetics of serum HER-2/neu changes in patients with HER-2-positive primary breast cancer after initiation of primary chemotherapy.
BACKGROUND
The purpose of the study was to determine the utility of quantitation of the extracellular domain (ECD) of the HER-2/neu receptor in the serum for predicting response to treatment in patients with primary breast cancer receiving neoadjuvant therapy.


METHODS
HER-2/neu ECD was measured in sera obtained from 39 patients with HER-2-amplified stage II-III primary breast cancer undergoing neoadjuvant chemotherapy. Patients were randomly assigned to either 4 cycles of paclitaxel followed by 4 cycles of fluorouracil, epirubicin, and cyclophosphamide (FEC) (n = 10) or to the same chemotherapy with simultaneous weekly trastuzumab for 24 weeks (n = 29). Changes in HER-2 ECD were monitored with the Bayer HER-2/neu assay over 6 months and correlated with pathological response to treatment.


RESULTS
Before initiation of chemotherapy, 28.2% of patients had elevated concentration of the HER-2 ECD (>15 ng/mL). The median baseline serum HER-2 ECD concentration was 13.6 ng/mL (mean +/- SD, 20.3 +/- 35.5 ng/mL). A decrease in the median HER-2 ECD levels from baseline to Week 3 and from baseline to Week 6 of chemotherapy was seen regardless of treatment regimen. No significant difference in baseline HER-2 ECD levels was observed between the groups who achieved pathological complete response (pCR) and the group with residual disease (P = .41). However, a 9% drop from Week 3 to Week 6 after initial chemotherapy was predictive of pCR (P = .04).


CONCLUSIONS
A decrease in serum HER-2 ECD levels early during treatment was associated with pathological response in patients receiving primary chemotherapy, particularly trastuzumab-based regimens. Serum HER-2 ECD levels may serve to monitor neoadjuvant therapy in HER-2-positive primary breast cancer.
Mazouni
Chafika
C
Department of Breast Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77230-1439, USA.
Hall
Angeline
A
Broglio
Kristine
K
Fritsche
Herbert
H
Andre
Fabrice
F
Esteva
Francisco J
FJ
Hortobagyi
Gabriel N
GN
Buzdar
Aman U
AU
Pusztai
Lajos
L
Cristofanilli
Massimo
M
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000097:blood; D001943:Breast Neoplasms / Q000097:blood / Q000188:drug therapy*; D018270:Carcinoma, Ductal, Breast / Q000097:blood / Q000188:drug therapy; D018275:Carcinoma, Lobular / Q000097:blood / Q000188:drug therapy; D003520:Cyclophosphamide / Q000008:administration & dosage; D015251:Epirubicin / Q000008:administration & dosage; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011379:Prognosis; D011446:Prospective Studies; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood*; D000068878:Trastuzumab
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; D003520:Cyclophosphamide; D015251:Epirubicin; D005472:Fluorouracil; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab