Intermittent versus continuous first-line treatment for HER2-negative metastatic breast cancer: the Stop & Go study of the Dutch Breast Cancer Research Group (BOOG).

Purpose: We determined if intermittent first-line treatment with paclitaxel plus bevacizumab was not inferior to continuous treatment in patients with HER2-negative, advanced breast cancer.
Methods: Patients were randomized to 2 × 4 cycles or continuous 8 cycles of paclitaxel plus bevacizumab, followed by bevacizumab maintenance treatment until disease progression or unacceptable toxicity. The primary endpoint was overall progression-free survival (PFS). A proportional-hazards regression model was used to estimate the HR. The upper limit of the two-sided 95% CI for the HR was compared with the non-inferiority margin of 1.34.
Results: A total of 420 patients were included with well-balanced characteristics. In the intention-to-treat analysis, median overall PFS was 7.4 months (95% CI 6.4-10.0) for intermittent and 9.7 months (95% CI 8.9-10.3) for continuous treatment, with a stratified HR of 1.17 (95% CI 0.88-1.57). Median OS was 17.5 months (95% CI 15.4-21.7) versus 20.9 months (95% CI 17.8-24.0) for intermittent versus continuous treatment, with a HR of 1.38 (95% CI 1.00-1.91). Safety results and actually delivered treatments revealed longer durations of treatment in the continuous arm, without significant unexpected findings.
Conclusion: Intermittent first-line treatment cannot be recommended in patients with HER2-negative advanced breast cancer.
Clinical Trial Registration: EudraCT 2010-021519-18; BOOG 2010-02.