B152
The isolation and enumeration of circulating tumour cells from patients with advanced oesophageal or gastric cancer
David Watkins1, Ian Chau1, Andrea Turner1, Arjan Tibbe2, Bjorn Lunter2, David Cunningham1
1Royal Marsden Hospital, London and Sutton, UK, 2Veridex, New Jersey, USA
Background
Circulating tumour cells (CTC) have been shown to be a prognostic marker in advanced prostate, breast and colorectal cancer and CTC can provide a non-invasive source of tumour tissue for biomarker analysis. Utilising the CellSearch immunomagnetic CTC detection platform we undertook a pilot study to assess the prevalence of CTC in patients with advanced oesophageal or gastric cancer (OG) adenocarcinoma.
Method
Eligible patients had histologically confirmed advanced OG adenocarcinoma and had either received no prior therapy or had progressed following prior chemotherapy treatment. Blood samples for CTC analysis were obtained prior to the initiation of a new line of chemotherapy and during the course of treatment. Initial analysis was planned after enrolment of 25 patients.
Results
Due to the withdrawal of commercial support for this study recruitment has been prematurely discontinued with 22 eligible patients enrolled and 66 CTC samples analysed. 10 of 66 samples were not suitable for CTC enumeration. Baseline CTC results were obtained in 18 of 22 pts (all 18 pts were chemonaive). Primary sites of disease were gastric (n=7), OGJ (n=9) and oesophageal (n=2). At baseline, 10 pts had <5 CTC and 8 pts had ≥5 CTC (median 20, range 5-1007). Baseline disease characteristics in patients with pre-treatment CTC of <5 vs ≥5 were median CEA 2 (1-29) vs 30 (1-5473) and presence of liver metastases in 5 of 10 vs 3 of 8 respectively. Patients with pre-treatment CTC levels of ≥5 demonstrated a reduction in CTC levels following the 1st cycle of chemotherapy (median 21, range 4-996) which was associated with a radiological response in 2/8 cases
Conclusion
Pre-treatment circulating tumour cells of ≥5 were detected in 8 of 22 pts (36%). These data support the further evaluation of CTC using the CellSearch platform in patients with oesophagogastric cancer.
