Everolimus plus aromatase inhibitors as maintenance therapy after first-line chemotherapy: Final results of the phase III randomised MAIN-A (MAINtenance Afinitor) trial

Despite endocrine therapy being the mainstay of treatment for hormone receptor positive (HR+)/HER2− metastatic breast cancer, patients at risk of visceral crisis or doubt for endocrine sensitivity are still offered first-line chemotherapy. Maintenance hormonal therapy is generally offered at the discontinuation of chemotherapy. The MAINtenance Afinitor study is a randomised, phase III trial comparing maintenance everolimus combined with aromatase inhibitors (AIs) versus AI monotherapy in patients with disease control after first-line chemotherapy. Patients with stable disease, partial response or complete response after first-line chemotherapy were randomised to everolimus plus AIs (exemestane or letrozole or anastrozole) or to AIs alone. Primary aim was progression-free survival (PFS). Secondary aims included response rate, safety and overall survival (OS). In total, 110 patients were randomised to everolimus + AIs (n = 52) or to AIs (n = 58). Median PFS was 11.0 months (95% confidence interval [CI] 8.1–13.8) in the everolimus + AI arm and 7.2 months (95% CI 4.7–10.9) in the AI monotherapy arm (hazard ratio [HR] 0.71, 95% CI 0.47–1.06). Objective response rate was 22.4% in everolimus + AI arm and 19.2% in AI monotherapy arm. A higher proportion of disease progression as best response was reported in the AI monotherapy arm (28.8% versus 14.3%). Median OS was 35.7 months (95% CI 26.0–47.8) in the combination arm versus 33.5 (95% CI 26.4–42.7) in the AI alone arm (HR 1.0, 95% CI 0.61–1.62). EVE + AIs did not significantly impact on the outcome of metastatic breast cancer patients deemed suitable for first-line chemotherapy. Also taking into account treatment tolerability, maintenance endocrine therapy remains the standard. EudraCT: 2013-004153-24. •Maintenance everolimus plus AIs did not show significant PFS prolongation over AIs.•A higher number of disease progression as best response was observed in the AI arm.•Taking into account tolerability, maintenance endocrine therapy remains the standard.