Abstract P2-01-15: Noninvasive assessment of axillary lymph node metastases in breast cancer using EpCAM antibody

Abstract

Abstract Background:Axillary lymph node metastasis is one of the most important prognostic determinants for patients with breast cancer. It’s a big progress from axillary lymph node dissection (ALND) to sentinel lymph node biopsy (SLNB), however, SLNB also has some limitations, including the detection failure rate, false negative rate, tracer allergies et al. Since about 70% of early breast cancer patients have negative SLNs, surgery maybe overtreatment for these patients and noninvasive assessment of axillary staging seems to be a better choice. It’s not easy to detect and mapping metastasis lymph nodes in vivo non-invasively because we don’t have specific cancer markers, but what we know is that most breast cancer cells come from epithelial origin and should have epithelial markers, and this kind of markers should not show up in lymph system. EpCam is a surface epithelial marker and expressed in 80-100% breast cancer patients. The aim of this study was to evaluate the value of EpCAM antibody in detecting breast cancer lymph node metastases non-invasively.Methods:VX2 rabbit model which is an epithelial tumor model with lymph node metastasis was used in this experiment. Anti-EpCAM was labeled with a near infra-red (NIR) fluorescence imaging agent Cy7 and selected as metastasis tracer. New Zealand white rabbits were assigned to study group and control group at random. Twelve rabbits in the study group received VX2 tumor injection to bilateral mammary glands and 12 rabbits in the control group were tumor free. Twenty four cases of axillary lymph nodes metastasis were investigated in each group because of bilateral experiments. Anti-EpCAM/Cy7 was subcutaneously injected around the tumors in study group or in mammary gland in control group at a dosage of 0.1ml (10umol/L). After 30 hours of screening by a NIR fluorescence detection machine, all the axillary lymph nodes in both groups were removed for pathological examination and the fluorescence status of each node was recorded. Result:The fluorescence signal could be detected 2 hours after injection in 24 cases in the control group and 23 cases in the study group. Thirty hours later, fluorescence disappeared in all cases in the control group and all the lymph nodes resected were pathological negative. While in study group, fluorescence signal could be detected continuously in 14 cases and 13 were proven to be pathological metastasis. The case failed to have fluorescence image from the beginning finally proved to be vascular invasion and cancerous node formation. The sensitivity, specificity rate of anti-EpCAM/Cy7 to detect axillary lymph node metastasis was 92.8% (13/14) and 90.0% (9/10). Conclusion:The NIR dye labeled EpCAM antibody (anti-EpCAM/Cy7) has a high accuracy in evaluating the axillary lymph node status of breast cancer in the animal experiment. Our tiny preclinical experiment showed the value of using EpCAM antibody as a new method for noninvasive lymph node evaluation for breast cancer and potentially extended in a lot of other epithelial originated cancers. Citation Format: Shu Wang, Jiajia Guo, Liulu Zhang, Houpu Yang. Noninvasive assessment of axillary lymph node metastases in breast cancer using EpCAM antibody [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-01-15.