Study of Amcenestrant (SAR439859) Versus Tamoxifen for Patients With Hormone Receptor-positive (HR+) Early Breast Cancer, Who Have Discontinued Adjuvant Aromatase Inhibitor Therapy Due to Treatment-related Toxicity

This was a phase III, randomized, double blind, multicenter, 2-arm study evaluating the efficacy and safety of amcenestrant compared with tamoxifen in participants with hormone receptor-positive early breast cancer who discontinued adjuvant aromatase inhibitor (AI) therapy due to treatment related toxicity. The primary objective was to demonstrate the superiority of amcenestrant versus tamoxifen on invasive breast cancer-free survival. The treatment duration per participant was to be 5 years, followed with a subsequent 5-years follow-up period. For the treatment period, visits were scheduled at the start of treatment, then at 4 weeks and 12 weeks after treatment start, and then every 12 weeks for the first 2 years and every 24 weeks for year 3 to 5. For the follow-up period, visits were scheduled 30 days after last treatment and then every 12 months. Three periods were planned: * A screening period of up to 28 days, * A treatment period of up to 5 years, * A follow-up period of up to 5 years.