Abstract
EpCAM is expressed at low levels in a variety of normal human epithelial tissues, but is overexpressed in 70–90% of carcinomas. From a clinico-pathological point of view, this has both prognostic and therapeutic significance. EpCAM was first suggested as a therapeutic target for the treatment of epithelial cancers in the 1990s. However, following several immunotherapy trials, the results have been mixed. It has been suggested that this is due, at least in part, to an unknown level of EpCAM expression in the tumors being targeted. Thus, selection of patients who would benefit from EpCAM immunotherapy by determining EpCAM status in the tumor biopsies is currently undergoing vigorous evaluation. However, current EpCAM antibodies are not robust enough to be able to detect EpCAM expression in all pathological tissues. Here we report a newly developed EpCAM RNA aptamer, also known as a chemical antibody, which is not only specific but also more sensitive than current antibodies for the detection of EpCAM in formalin-fixed paraffin-embedded primary breast cancers. This new aptamer, together with our previously described aptamer, showed no non-specific staining or cross-reactivity with tissues that do not express EpCAM. They were able to reliably detect target proteins in breast cancer xenograft where an anti-EpCAM antibody (323/A3) showed limited or no reactivity. Our results demonstrated a more robust detection of EpCAM using RNA aptamers over antibodies in clinical samples with chromogenic staining. This shows the potential of aptamers in the future of histopathological diagnosis and as a tool to guide targeted immunotherapy.
Highlights
Surgical pathology has become the ‘gold standard’ for the diagnosis of tumors [1]
Antibodies have become an integral part of the pathology laboratory in the last 40 years [3]
In addition to being an integral part of the diagnostic arsenal, IHC is being used to identify or differentiate those patients who are likely to benefit from certain directed or targeted therapies [5,6]. Such is the case in HER2 positive breast cancer patients who benefit from treatment with trastuzumab [7]
Summary
Surgical pathology has become the ‘gold standard’ for the diagnosis of tumors [1]. Antibodies have become an integral part of the pathology laboratory in the last 40 years [3]. In addition to being an integral part of the diagnostic arsenal, IHC is being used to identify or differentiate those patients who are likely to benefit from certain directed or targeted therapies [5,6]. Such is the case in HER2 positive breast cancer patients who benefit from treatment with trastuzumab [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
