Intraoperative Assessment of Breast Cancer Margins ex vivo using Aqueous Quantum Dot-Functionalized Molecular Probes

Abstract

Breast cancer is increasingly diagnosed at an early stage, allowing the diseased breast to be removed only partially or breast conserving surgery (BCS). Current BCS procedures have no rapid methods during surgery to assess if the surgical margin is clear of cancer, often resulting in re-excision. The current breast cancer re-excision rate is estimated to be 15% to as high as 60%. It would be desirable if there is a rapid and reliable breast cancer margin assessment tool in the operating room to help assess if the surgical margin is clean to minimize unnecessary re-excisions. In this research, we seek to develop an intraoperative, molecular probe-based breast cancer surgical margin assessment tool using aqueous quantum dots (AQDs) coupled with cancer specific biomarkers. Quantum dots (QDs) are photoluminescent semiconductor nanoparticles that do not photobleach and are brighter than organic fluorescent dyes. Aqueous quantum dots (AQDs) such as CdSe and near infrared (NIR) CdPbS developed in Shihs lab emit light longer than 600 nm. We have examined conjugating AQDs with antibodies to cancer specific biomarkers such as Tn antigen, a cancer-associated glycan antigen for epithelial cancers. We showed that AQDs could achieve ~80% antibody conjugation efficiency, i.e., 100 times less antibodies than required by commercial, making such AQD molecular probe surgical margin evaluation economically feasible. By conjugating AQDs with anti-Tn-antigen antibody, the AQDs molecular probe exhibited 94% sensitivity and 92% specificity in identifying breast cancer against normal breast tissues as well as benign breast tumors in 480 tissue blocks from 126 patients. Furthermore, mice model and clinical human studies indicated that AQDs imaging did not interfere with the following pathological staining. More interestingly, we showed that it it possible to directly conjugate one antibody to multiple AQDs, further reduces the required amount of antibodies needed, a feat that could not be accomplished by commercial QDs. To date, using a home-built imaging system consisted of 4 LEDs and a NIR CCD camera we have successfully imaged several human breast surgical margins with high sensitivity in less than 30 min.%%%%Ph.D., Biomedical Engineering – Drexel University, 2013