New drug cocktail aims to tame Hard-to-Treat breast cancer

NCT ID NCT03332797

First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 2 times

Summary

This early-stage trial is testing a new drug called GDC-9545 (giredestrant), alone or combined with other medications, in people with advanced ER-positive breast cancer that has spread. The main goals are to check safety, find the best dose, and see if it shrinks tumors. About 181 participants will receive the drug daily until their disease gets worse or side effects become too much.

What this could mean

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

Active substance
GDC-9545 (giredestrant) with or without palbociclib and/or an LHRH agonist
What this could lead to
If successful, this could lead to a new treatment option for advanced ER-positive breast cancer that may help control the disease longer.
What could go wrong
This is a very early (Phase 1) trial, so the drug may not work as hoped or could have unexpected side effects. Results are preliminary and may not apply to all patients.

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.

As listed by the trial registrant

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

Contacts and locations

Locations

  • Asan Medical Center

    Seoul, 05505, South Korea

  • Barts Health NHS Trust

    London, E1 2ES, United Kingdom

  • Beth Israel Deaconess Medical Center

    Boston, Massachusetts, 02215, United States

  • Centro Oncologioco MD Anderson Internacional

    Madrid, 28033, Spain

  • Dana Farber Cancer Institute

    Boston, Massachusetts, 02215, United States

  • Hospital Clinico Universitario de Valencia

    Valencia, 46010, Spain

  • Hospital General Universitario Gregorio Maranon

    Madrid, 28007, Spain

  • Hospital Quiron Barcelona

    Barcelona, 08023, Spain

  • Hospital Universitari Vall d'Hebron

    Barcelona, 08035, Spain

  • Hospital Universitario HM Sanchinarro

    Madrid, 28050, Spain

  • Hospital Universitario Ramón y Cajal

    Madrid, 28034, Spain

  • ICO L'Hospitalet

    L'Hospitalet de Llobregat, Barcelona, 08908, Spain

  • Massachusetts General Hospital.

    Boston, Massachusetts, 02115, United States

  • Memorial Sloan Kettering Cancer Center

    New York, New York, 10065, United States

  • National Cancer Center

    Gyeonggi-do, 410-769, South Korea

  • Peter Maccallum Cancer Centre

    Melbourne, Victoria, 3000, Australia

  • Samsung Medical Center

    Seoul, 06351, South Korea

  • Seoul National University Hospital

    Seoul, 03080, South Korea

  • Severance Hospital, Yonsei University Health System

    Seoul, 03722, South Korea

  • St Vincent's Hospital Sydney

    Darlinghurst, New South Wales, 2010, Australia

  • The Royal Marsden Hospital

    Suttton, SM2 5PT, United Kingdom

  • University of Colorado

    Aurora, Colorado, 80045, United States

  • Vanderbilt University Medical Center

    Nashville, Tennessee, 37204, United States

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