As reported in the Journal of Clinical Oncology by François-Clément Bidard, MD, PhD, and colleagues, the French phase III STIC CTC trial showed a nonsignificant overall survival benefit with a circulating tumor cell (CTC) count–driven approach to therapy vs physician’s choice in the first-line treatment of hormone receptor–positive, HER2-negative advanced breast cancer. The primary analysis of the trial showed that CTC-driven therapy was noninferior to investigator’s choice in 2-year progression-free survival in this setting.
François-Clément Bidard, MD, PhD
Study Details
In the multicenter open-label trial, 755 patients were randomly assigned between February 2012 and July 2016 to the CTC group (n = 378) or the standard group (n = 377). In the CTC group, patients received chemotherapy if their CTC count was ≥ 5 CTCs/7.5 ml (CTC-high) or endocrine therapy if their CTC count was lower (CTC-low). In the standard group, patients received chemotherapy for clinically high-risk disease (Clin-high) or endocrine therapy for clinically low-risk disease (Clin-low) at physician’s discretion.
Key Findings
Median follow-up was 4.7 years. Median overall survival was 51.3 months (95% confidence interval [CI] = 46.8–55.1 months) in the CTC group vs 45.5 months (95% CI = 40.9–51.1 months) in the standard group (hazard ratio [HR] = 0.85, 95% CI = 0.69–1.03, P = .11).
With additional follow-up, median progression-free survival was 15.7 months (95% CI = 12.8–17.4 months) in the CTC group vs 13.8 months (95% CI = 12.1–15.9 months) in the standard group (HR = 0.94, 95% CI = 0.81–1.09).
Patients with discordant Clin-low/CTC-high features had better outcomes with chemotherapy in the CTC group vs endocrine therapy in the standard group. Among these patients, median overall survival was 51.8 months (95% CI = 43.3 months to not reached) in the CTC group vs 35.4 months (95% CI = 30.4–45.4 months) in the standard group (HR = 0.53, 95% CI = 0.36–0.78, P = .001).
The investigators concluded: “[T]he STIC trial established the overall safety of using the CTC count as a standalone biomarker, and despite a lack of significant survival benefit in the general population, it showed that patients with a high CTC count and a low clinical risk estimate may derive a significant overall survival benefit from chemotherapy.”
Dr. Bidard, MD, PhD, of Institut Curie, Saint-Cloud, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by Institut Curie, the French National Cancer Institute, Menarini Silicon Biosystems, and others. For full disclosures of the study authors, visit ascopubs.org.
