Abstract
Abstract Background Innate and acquired chemoresistance to anticancer therapies are a well-known phenomenon in Esophageal Squamous Cell Carcinomas (ESCC). There are presently no viable approaches for real-time monitoring of resistance in ESCC. We used a novel method for chemo-interrogation (CI) by harvesting sufficient number of Circulating-Tumor Associated Cells (C-TACs) which are defined as apoptosis-resistant cells of tumorigenic origin and are positive for Epithelial Cell Adhesion Molecule (EpCAM) and pan-cytokeratins (pan-CK) irrespective of CD45 status. Methods Peripheral blood was collected from 80 patients with confirmed diagnosis of ESCC, among whom 52 were recently diagnosed therapy-naive, while 28 were pretreated patients. Peripheral blood mononuclear cells (PBMCs) were harvested by centrifugation and treated with commercially available stabilizing agents, by a proprietary protocol, to stabilize apoptosis resistant C-TACs. Surviving C-TACs were confirmed by immunostaining for EpCAM, pan-CK and CD45. Harvested C-TACs were treated in vitro with a panel of conventional cytotoxic anticancer agents and fraction of surviving cells were estimated to determine resistance profiles. Results Among the 52 cases of recently diagnosed therapy naive ESCC, innate chemoresistance was observed towards platinum agents in 40.8% samples (unique patient-drug combinations), taxanes in 34.6% samples, topoisomerase inhibitors in 42.9% samples and antimetabolites in 34.6% samples. Among the 28 cases of previously treated ESCC, resistance towards previously administered systemic agents was observed in 87% of all samples, which included resistance towards platinum agents in 87.5% samples, taxanes in 82.1% samples, topoisomerase inhibitors in 100% samples and antimetabolites in 85.7% samples, respectively. Conclusions We show for the first time that sufficient C-TACs can be harvested for meaningful CI in newly diagnosed treatment naive ESCC as well as refractory ESCCs. Post-treatment chemoresistance being an order of magnitude higher than the untreated cohort, indicates that C-TACs in ESCC are resistance-educated by previous treatments and can guide treatment strategy in ESCC. Legal entity responsible for the study The authors. Funding Datar Cancer Genetics Limited. Disclosure D. Patil: Full / Part-time employment: Datar Cancer Genetics Limited. D. Akolkar: Full / Part-time employment: Datar Cancer Genetics Limited. V. Datta: Full / Part-time employment: Datar Cancer Genetics Limited. S. Schuster: Full / Part-time employment: Datar Cancer Genetics Limited. C. Sims: Full / Part-time employment: Datar Cancer Genetics Limited. R. Patil: Full / Part-time employment: Datar Cancer Genetics Limited. A. Srinivasan: Full / Part-time employment: Datar Cancer Genetics Limited. S. Khan: Full / Part-time employment: Datar Cancer Genetics Limited. S. Patil: Full / Part-time employment: Datar Cancer Genetics Limited. V. Mhase: Full / Part-time employment: Datar Cancer Genetics Limited. S. Apurwa: Full / Part-time employment: Datar Cancer Genetics Limited. R. Datar: Shareholder / Stockholder / Stock options, Licensing / Royalties, Officer / Board of Directors: Datar Cancer Genetics Limited. All other authors have declared no conflicts of interest.
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