NY-BR-1 Protein Expression in Metastatic Breast Carcinoma
Ana L Cota, Yun Wu, Liu Haiping, Muralitharan Sharimini, Savitri Krishnamurthy. University of Texas MD Anderson Cancer Center, Houston, TX; Thermo Fisher Scientific, Fremont, CA
Background: NY-BR-1 is a mammary differentiation antigen that is expressed in normal and neoplastic breast tissues. In addition to its role as a breast immunomarker for identifying the origin of primary and metastatic tumors, it is a potential target for cancer immunotherapy. The stability of NY-BR-1 expression in metastatic breast cancer and influence of chemotherapy on its expression are not known. Our primary objective was to evaluate the expression of NY-BR-1 in metastatic breast carcinomas from chemotherapy-naïve (CN) and chemotherapy-treated (CT) patients.
Design: We studied 150 axillary lymph nodes containing metastatic breast carcinoma obtained from 67 (45%) CN patients and 83 (55%) CT patients. Immunostaining was performed on formalin-fixed, paraffin-embedded tissue sections using a primary antibody (Thermo Fisher Scientific, CA) against NY-BR-1 with antigen retrieval (EDTA buffer). Cytoplasmic staining in tumor cells was scored semiquantitatively for proportion (0-100% of cells) and intensity (1-3) using the H score method (0-300). An H score of more than 10 was regarded as positive. The influences of chemotherapy and primary tumor positivity for ER/PR and HER2 on NY-BR-1 protein expression were determined using the chi-square test.
Results: Immunopositivity for NY-BR-1 was observed in 83% (125) of the specimens, with a mean and median H score of 147 and 160. NY-BR-1 was noted in 97% (65/67) of CN specimens but only in 72% (60/183) of CT specimens; the difference was statistically significant (p=0.0001). The mean and median H scores were 498 and 200 in the CN group and 105 and 80 in the CT group. NY-BR-1 was noted in 98% (54/55) of metastases from ER/PR positive tumors in the CN group and 75% (48/64) of metastases from ER/PR positive tumors in the CT group. Expression of NY-BR-1 in metastases correlated significantly with ER/PR positivity of the primary breast carcinoma only in the CN group (P=0.03). There was no association between expression of NY-BR-1 in metastases and HER2 positivity of the primary tumor.
Conclusions: 1) NY-BR-1 was positive in 83% of metastatic breast carcinomas 2) Immunopositivity for NY-BR-1 was significantly higher in CN than in CT specimens of metastatic breast carcinoma. 3) Expression of NY-BR-1 correlated with positive ER/PR status only in CN patients. 4) Our findings suggest that NY-BR-1 may be useful as a marker of breast origin for metastatic tumors and as a target for immunotherapy in patients with metastatic breast carcinoma.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 22, Wednesday Afternoon