for females ages 18 years and up (full criteria)
study started
estimated completion



This is a randomized, multicenter, open-label, two-arm, Phase II study to evaluate the efficacy, safety, and pharmacokinetics of giredestrant versus anastrozole (in the window-of-opportunity phase) and giredestrant plus palbociclib compared with anastrozole plus palbociclib (in the neoadjuvant phase) in postmenopausal women with untreated, estrogen receptor (ER)-positive, human epidermal growth factor receptor-2 (HER2)-negative, early breast cancer. The study consists of a screening period of up to 28 days, a window-of-opportunity phase for 14 days, followed by a neoadjuvant treatment phase for 16 weeks (four 28-day cycles), surgery, and an end of study visit (28 days after the final dose of study treatment).

Official Title

A Randomized, Multicenter, Open-Label, Two-Arm, Phase II, Neoadjuvant Study Evaluating the Efficacy, Safety, and Pharmacokinetics of GDC-9545 Plus Palbociclib Compared With Anastrozole Plus Palbociclib for Postmenopausal Women With Estrogen Receptor-Positive and HER2-Negative Untreated Early Breast Cancer


Early Breast Cancer Breast Neoplasms Palbociclib Anastrozole Giredestrant Surgery Giredestrant + Palbociclib Anastrozole + Palbociclib


You can join if…

Open to females ages 18 years and up

  • Postmenopausal women age ≥18 years
  • Histologically confirmed operable or inoperable invasive breast carcinoma
  • Candidate for neoadjuvant treatment and considered appropriate for endocrine therapy
  • Willingness to undergo breast surgery after neoadjuvant treatment and to provide three mandatory tumor samples
  • Documented estrogen receptor (ER)-positive tumor in accordance to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines (Allison et al.2020), assessed locally and defined as ≥1% of tumor cells stained positive on the basis of the most recent tumor biopsy
  • Documented progesterone receptor status (positive or negative) as per local assessment
  • Documented human epidermal growth factor receptor-2 (HER2)-negative tumor in accordance to 2018 ASCO/CAP guidelines (Wolff et al. 2018), assessed locally on the most recent tumor biopsy
  • Ki67 score ≥5% analyzed centrally or locally
  • Eastern Cooperative Oncology Group Performance Status 0-1
  • Adequate organ function

You CAN'T join if...

  • Stage IV (metastatic) breast cancer
  • Inflammatory breast cancer (cT4d)
  • Bilateral invasive breast cancer
  • History of invasive breast cancer, ductal carcinoma in situ or lobular carcinoma in situ and other malignancy within 5 years prior to screening
  • Previous systemic or local treatment for the primary breast cancer currently under investigation
  • History of any prior treatment with aromatase inhibitors (AIs), tamoxifen, selective estrogen receptor down regulator, or cyclin-dependent kinase 4 and 6 inhibitors
  • Major surgery within 4 weeks prior to randomization
  • Known clinically significant history of liver disease consistent with Child-Pugh Class B or C, including hepatitis
  • Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the patient inappropriate for entry into this study
  • History of allergy to anastrozole, or palbociclib or any of its excipients
  • Known issues with swallowing oral medication
  • History of documented hemorrhagic diathesis, coagulopathy, or thromboembolism
  • Active cardiac disease or history of cardiac dysfunction
  • Current treatment with medications that are well known to prolong the QT interval
  • Active inflammatory bowel disease or chronic diarrhea, short bowel syndrome, or major upper gastrointestinal surgery including gastric resection
  • Treatment with strong CYP3A4 inhibitors or inducers within 14 days or 5 drug elimination half-lives prior to randomization
  • Known HIV infection
  • Serious infection requiring oral or IV antibiotics, or other clinically significant infection within 14 days prior to screening
  • Any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes the patient's safe participation in and completion of the study


  • UCLA - Beverly Hills accepting new patients
    Beverly Hills California 90212 United States
  • UCLA - Burbank accepting new patients
    Burbank California 91505 United States
  • UCLA Hematology/Oncology-Encino accepting new patients
    Encino California 91436 United States
  • UCLA Hematology Oncology - Irvine accepting new patients
    Irvine California 92604 United States
  • UCLA - Laguna Hills accepting new patients
    Laguna Hills California 92653 United States
  • UCLA - Pasadena accepting new patients
    Pasadena California 91105 United States
  • UCLA Hemetology Oncology; Porter Ranch accepting new patients
    Porter Ranch California 91326 United States
  • UCLA Hematology Oncology-Santa Monica accepting new patients
    Santa Monica California 90404 United States
  • UCLA Hem/Onc - Torrance accepting new patients
    Torrance California 90505 United States
  • UCLA Hematology/Oncology-Santa Clarita accepting new patients
    Valencia California 91355 United States
  • UCLA; UCLA Hematology Oncology Ventura accepting new patients
    Ventura California 93003 United States
  • UCLA Hematology Oncology - Westlake accepting new patients
    Westlake Village California 91361 United States


accepting new patients
Start Date
Completion Date
Hoffmann-La Roche
Phase 2
Study Type
Last Updated