# Amcenestrant (SAR439859) Plus Palbociclib as First Line Therapy for Patients With ER (+) HER2(-) Advanced Breast Cancer

> **NCT04478266** · PHASE3 · TERMINATED · sponsor: **Sanofi** · enrollment: 1068 (actual)

## Conditions studied

- Breast Cancer

## Interventions

- **DRUG:** Amcenestrant-matching placebo
- **DRUG:** SAR439859
- **DRUG:** Palbociclib
- **DRUG:** Letrozole
- **DRUG:** Goserelin
- **DRUG:** Letrozole-matching placebo

## Key facts

- **NCT ID:** NCT04478266
- **Lead sponsor:** Sanofi
- **Sponsor class:** INDUSTRY
- **Phase:** PHASE3
- **Study type:** INTERVENTIONAL
- **Status:** TERMINATED
- **Start date:** 2020-10-14
- **Primary completion:** 2022-06-28
- **Final completion:** 2023-05-26
- **Target enrollment:** 1068 (ACTUAL)
- **Why stopped:** The study was terminated based on the review by an independent data monitoring committee of the prespecified interim analysis of the Phase 3 AMEERA-5 efficacy data. No new safety signals were observed.
- **Last updated:** 2025-09-11


## Primary source

ClinicalTrials.gov registry: https://clinicaltrials.gov/study/NCT04478266

## Citation

> US National Library of Medicine, ClinicalTrials.gov registration NCT04478266, "Amcenestrant (SAR439859) Plus Palbociclib as First Line Therapy for Patients With ER (+) HER2(-) Advanced Breast Cancer". Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/clinical/NCT04478266. Licensed CC0.

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