Value of circulating epithelial tumor cells and circulating endothelial cells (CTCs/CECs) in patients with HER2-negative recurrent or metastatic breast cancer treated with bevacizumab (B) in combination with paclitaxel (P) and gemcitabine (G) as first-line therapy (AVALUZ trial).

Abstract

e21088 Background: CTCs in peripheral blood are an ideal source for the detection of tumor dissemination. Their prognosis significance has been demonstrated in metastasic breast carcinoma (Cristofanilli, NEJM 2004). Beacizumab in combination with CT, improves progression free survival (PFS) of first line treatments, may modify CTC and CEC levels. Aims of this study are the evaluation of the prevalence and kinetics of CTCs and CECs before and after treatment with B in pts with MBC Methods: Pts received B 10mg/kg/q2w combined with P 150mg/m2 and G 2000mg/m2 d1,15/q28d therapy until disease progression, unacceptable toxicity or withdrawal. CTC/CEC were measured in 7.5ml of blood at baseline and after the 1st cycle of treatment. Enumeration was performed by CellSearch System, Veridex Results: Data were available for 37 pts. Median of f-up was 16.2 m. The media of CTCs was 41 cells (min0-max845) in the 1st determination and 5 cells (min0-max99) in 2nd determination. Baseline CTCs>2 was associated with statistic lower PFS 10.8 m (95%CI:7.66-16.91) compared to those with CTCs<2, PFS 17.7m (95%CI:17.60-NA),p=0.046. Baseline CTCs>10 vs CTCs<10 was associated with statistic lower OS (14%vs45% of deaths), p=0.035. 92% (N=22) of pts that had stable disease/partial response, decreased or maintained CTCs value. CTC level was not correlated with CEC level, p=0.74. Media value of baseline CECs was 130 (min4-max1407) and 60.3 (min0-max349) in 2nd determination. Baseline CECs>200 was associated with lower PFS 8.2m (95%CI:0.6-10.8) compared to those with <200, PFS 16.9m (95%CI:8.78-NA),p=0.003. No difference was observed in OS. 74% of pts (N=14) that had stable disease/partial response, decreased or maintained CECs value. Baseline CTCs >5 was associated with a median PFS of 15.2 m (95%CI:7.6-16.9) Conclusions: Our study suggests significant correlations between levels of baseline CTCs and CECs and poor prognosis. Addiction of B to 1st-line CT was related with high reduction of CECs and CTCs count.