New drug acolbifene takes on tamoxifen in breast cancer prevention trial

NCT ID NCT05941520

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study tests whether acolbifene or a low dose of tamoxifen can reduce breast cancer risk in premenopausal women at high risk. Both drugs block estrogen from reaching breast cells. Researchers will measure changes in breast tissue, blood, and mammograms over six months in 80 women.

What this could mean

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

Active substance

acolbifene and tamoxifen

What this could lead to

If successful, this could point toward a new prevention option for breast cancer in high-risk premenopausal women, potentially with fewer side effects than standard tamoxifen.

What could go wrong

This is a small Phase 2 trial with only 80 participants, so results may not apply to all women. The study measures biological markers, not actual cancer rates, so it's unclear if these changes lead to fewer cancers.

Disclaimer Read more

This is a summary of the original study . Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.

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Conditions

The condition(s) this trial relates to.

atypical lobular breast hyperplasia breast carcinoma breast carcinoma in situ breast neoplasm ductal breast carcinoma in situ lobular breast carcinoma in situ breast cancer prevention target

As listed by the trial registrant

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

Contacts and locations

Locations

  • City of Hope Comprehensive Cancer Center

    RECRUITING

    Duarte, California, 91010, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

    Contact

  • Northwestern University

    RECRUITING

    Chicago, Illinois, 60611, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

    Contact

  • Ohio State University Comprehensive Cancer Center

    RECRUITING

    Columbus, Ohio, 43210, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

    Contact

  • University of Kansas Cancer Center

    RECRUITING

    Kansas City, Kansas, 66160, United States

    Contact Phone: •••-•••-•••• Email: •••••@•••••

    Contact