Prospective multicentric trial evaluating prognostic and predictive value of circulating tumor cells in first-line chemotherapy metastatic breast patients.

Abstract

10544 Background: Detection of five or more circulating tumor cells (CTCs) per 7.5 ml in peripheral blood has been reported as an independent prognostic factor in metastatic breast cancer (MBC). A decrease in CTC during treatment could be associated with a better outcome (Cristofanilli, NEJM 2004). We conducted a multicentric prospective study to validate this marker in a large series of patients receiving specifically first line chemotherapy for MBC. Methods: CTC were measured in 7.5 ml of whole blood at baseline, before cycle 2, at clinical and/or radiological evaluation (C3-C4) and at tumor progression. Analysis was performed using the CellSearch System, combining EpCAM immunomagnetic selection (IMS) followed by anti-cytokeratin (A45B/B3) staining for CTC. Double labeling for HER2 was performed in a subgroup of patients. Results: From 06/07 to 9/09, 271 patients with measurable or evaluable disease were included in five French Cancer Centers. 261 were evaluable for CTC levels at baseline, before first cycle of chemotherapy. At baseline, median number of CTC was 2 (range 0-16 885). After one cycle of chemotherapy, median CTC number was 1 (range: 0-202). Incidence of CTC during treatment is shown in the Table. CTC HER2 status was assessed in 117 patients at baseline and was positive in 62% of the cases in at least one cell. Correlation with other clinical and biological parameters as serum marker (CA15.3) is ongoing. 18 months median follow-up will be reached in April 2010. Conclusions: We observed a clear decrease of CTC level after only one cycle of chemotherapy. These findings support the role of CTC enumeration as an adjunct to standard methods of monitoring disease status in MBC. However, about one-third of the patients with MBC had undetectable CTC level during first line treatment and even at tumor progression, suggesting a need for more sensitive methods of detection. Baseline C2 C3-C4 Progression ≥ 1 CTC 169 (65%) 77 (37%) 59 (28%) 20 (46%) ≥ 5 CTC 113 (43%) 38 (18%) 25 (12%) 13 (30%) Number of patients 261 209 210 43 Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Veridex Veridex