Amplification and overexpression of topoisomerase IIalpha predict response to anthracycline-based therapy in locally advanced breast cancer.
OBJECTIVE
The putative association between erbB-2 overexpression and favorable response to anthracyline-based therapy in breast cancer is controversial, and the mechanism unclear. We sought to determine whether coamplification and overexpression of the topoisomerase IIalpha gene, near erbB-2 on chromosome 17, and a known anthracycline target, may underlie the association.


METHODS
Thirty-five patients who had locally advanced breast cancer (LABC) and who had received neoadjuvant, anthracycline-based therapy were studied. Copy number of topoisomerase IIalpha and erbB-2 was determined by fluorescence in situ hybridization, and expression by immunohistochemistry.


RESULTS
Of 8 patients with erbB-2 amplification, 5 had a complete response (CR) or minimal residual disease (MRD), 3 had a partial response (PR), and none had stable (StD) or progressive disease (PD) at the time of mastectomy, versus 3 CR or MRD, 16 PR, and 8 StD or PD for patients without amplification (P = 0.008). In contrast, erbB-2 overexpression was not significantly associated with response (P = 0.114). Of 6 patients with topoisomerase IIalpha amplification, 4 had CR or MRD, 2 PR, and none StD or PD, versus 4 CR or MRD, 17 PR, and 8 StD or PD for patients without amplification (P = 0.034). All of the tumors with topoisomerase IIalpha amplification also had erbB-2 amplification, but not vice versa. Overexpression of topoisomerase IIalpha (9 patients) was also associated with favorable response (P = 0.021).


CONCLUSIONS
Coamplification of erbB-2 and topoisomerase IIalpha is significantly associated with favorable local response to anthracycline-based therapy in LABC. The expression data favor a plausible mechanism based on topoisomerase IIalpha biology.
Coon
John S
JS
Rush Medical College, Chicago, Illinois 60612, USA. jcoon@rush.edu
Marcus
Elizabeth
E
Gupta-Burt
Shalina
S
Seelig
Steven
S
Jacobson
Kris
K
Chen
Shande
S
Renta
Vivian
V
Fronda
Geraldo
G
Preisler
Harvey D
HD
D000328:Adult; D000368:Aged; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D000951:Antigens, Neoplasm; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins; D005260:Female; D005784:Gene Amplification; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D000951:Antigens, Neoplasm; D004250:DNA Topoisomerases, Type II; D004268:DNA-Binding Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases