Clinical Validity of Repeated Circulating Tumor Cell Enumeration as an Early Treatment Monitoring Tool for Metastatic Breast Cancer in the PREDICT Global Pooled Analysis

Purpose: The aim of PREDICT was to confirm clinical validity whereas 2,009 (45.3%) patients had at least one CTC at both time and the potential for clinical utility of serial circulating tumor cell points (pos/pos). The median OS for the neg/neg, neg/pos, pos/ (CTC) enumeration in patients with metastatic breast cancer, neg, and pos/pos group was 45.6, 26.1, 32.3, and 17.3 months, focusing on its prognostic value in different breast cancer sub- respectively (P < 0.0001, global log-rank test). CTC responders types and clinical settings. (pos/neg) showed a lower risk of death compared with CTC Experimental Design: In total, 4,436 individual patient-level nonresponders (pos/pos; HR, 0.48; 95% confidence interval, 0.44–data with CTC results from both baseline and one follow-up (Cell- 0.53). Similar results were obtained in subgroup analyses Search; Menarini Silicon Biosystems) were analyzed to evaluate the according to hormone receptor and HER2 subtype, treatment association between CTC detection and overall survival (OS) in the type, and with a ≥5 CTC cutoff for CTC positivity. full patient cohort and separately for tumor and treatment types. Conclusions: Follow-up CTC assessments strongly predict OS Results: Using the cutoff ≥1 CTC for CTC positivity, 913 independently from tumor subtype and treatment. New ran-(20.6%) patients had 0 CTCs at both time points (neg/neg) and domized trials to define the clinical utility of CTC monitoring for 325 (7.3%) and 1,189 (26.8%) patients converted from CTC risk stratification and as an early response marker in metastatic negative to CTC positive (neg/pos) or vice versa (pos/neg), breast cancer are urgently needed.