New breast cancer drug test halted after just 3 patients

NCT ID NCT05128773

Terminated Disease control Sponsor: Sanofi Source: ClinicalTrials.gov ↗

First seen Jun 26, 2026 · Last updated Jun 26, 2026

Summary

This study aimed to see if a new drug called amcenestrant could help prevent breast cancer from coming back in people with hormone receptor-positive early breast cancer who had side effects from standard aromatase inhibitor therapy. It was designed to compare amcenestrant against tamoxifen over 5 years of treatment. However, the trial was stopped early after enrolling only 3 participants, so no conclusions can be drawn.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: amcenestrant
What this could lead to: If it worked, amcenestrant could offer a better-tolerated alternative to tamoxifen for preventing breast cancer recurrence in patients who cannot take aromatase inhibitors.
What could go wrong: The trial was terminated early with only 3 participants enrolled, so no meaningful results are available. It is unknown if amcenestrant is effective or safe compared to tamoxifen.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

breast cancer breast neoplasm hormone receptor-positive breast cancer

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

BREAST CANCER

Contacts and locations

Locations

Investigational Site Number :1521622

Santiago, Reg Metropolitana de Santiago, Chile
Investigational Site Number :1561599

Haikou, 570311, China

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