Circulating tumor cells and brain metastasis outcome in patients with HER2-positive breast cancer: the LANDSCAPE trial.

BACKGROUND Decrease of circulating tumor cells (CTC) during treatment is an independent prognostic factor in metastatic breast cancer (MBC). We specifically evaluated the impact of CTC on brain metastasis outcome. METHODS HER2-positive MBC with brain metastasis not previously treated with whole-brain radiotherapy received first-line combination of lapatinib and capecitabine in a phase II study. CTC were detected at baseline and day 21 (CellSearch). RESULTS Median follow-up of the 44 analyzed patients was 21.2 months. The central nervous system objective response (CNS-OR) rate was 66%. At baseline, 20 of 41 assessable patients for CTC (49%) had ≥1 CTC (range 1-301, median 3) and 9 (22%) had ≥5 CTC. At day 21, 7 of 38 patients (18%) had ≥1 CTC (P = 0.006, versus baseline), and CTC had disappeared in 11 patients. CNS-OR rate was significantly higher in patients with no CTC at day 21 [25 of 31 (80%) versus 2 of 7 (29%), P = 0.01]. The 1-year overall survival rate was 83.9% in patients with no CTC at day 21 versus 42.9% in patients with ≥1 CTC (P = 0.02). CONCLUSIONS This is the first report showing a correlation between CNS metastasis response, outcome and early CTC clearance under targeted treatment of HER2+ MBC. CLINICAL TRIALS NUMBER NCT00967031.