for people ages 18 years and up (full criteria)
study started
estimated completion
Principal Investigator
by Sara Hurvitz (ucla)Leland Duer Powell (ucla)



This study will evaluate the effect of adding abemaciclib to fulvestrant for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer that progressed or recurred after previous treatment with a type of drug known as a CDK4/6 inhibitor and endocrine therapy. Participation could last up to 5 years, depending on how you and your tumor respond.

Official Title

postMONARCH: A Randomized, Double Blind, Placebo-Controlled, Phase 3 Study to Compare the Efficacy of Abemaciclib Plus Fulvestrant to Placebo Plus Fulvestrant in Participants With HR+, HER2-, Advanced or Metastatic Breast Cancer Following Progression on a CDK4 & 6 Inhibitor and Endocrine Therapy


Breast Neoplasm, Neoplasm Metastasis, Neoplasms, Breast Neoplasms, Fulvestrant, Abemaciclib, Abemaciclib plus Fulvestrant


You can join if…

Open to people ages 18 years and up

  • Have a diagnosis of HR+, HER2- locally advanced or metastatic breast cancer
  • Have radiologic evidence of disease progression or recurrence either
    • On treatment with a CDK4/6 inhibitor with aromatase inhibitor (AI) as initial therapy for advanced disease, or
    • On/after treatment with a CDK4/6 inhibitor plus endocrine therapy (ET) administered as adjuvant therapy for early stage breast cancer
  • Must be deemed appropriate for treatment with ET
  • If female, have a postmenopausal status by natural or surgical means or by ovarian function suppression
  • Have Response Evaluable Criteria in Solid Tumors (RECIST) evaluable disease (measurable disease and/or nonmeasurable disease)
  • Have a performance status of 0 or 1 on the Eastern Cooperative Oncology Group scale (Oken et al. 1982)
  • Have adequate renal, hematologic, and hepatic organ function
  • Must be able to swallow capsules/tablets

You CAN'T join if...

  • Have visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis
  • Have symptomatic or untreated central nervous system metastasis
  • Have received any systemic therapy between disease recurrence/progression and study screening
  • Have received more than 1 line of therapy for advanced or metastatic disease.
  • Have received prior chemotherapy for metastatic breast cancer (MBC)
  • Have received prior treatment with fulvestrant, any investigational estrogen receptor (ER)-directed therapy (including selective ER degraders [SERDs] and non-SERDs), any phosphatidylinositol 3-kinase (PI3K)-, mammalian target of rapamycin (mTOR)-, or protein kinase B (AKT)-inhibitor


  • UCLA Hematology/Oncology - Parkside accepting new patients
    Santa Monica California 90404 United States
  • Olive View-UCLA Medical Center accepting new patients
    Sylmar California 91342 United States
  • TRIO-US (Translational Research in Oncology-US) accepting new patients
    Los Angeles California 90024 United States
  • USC/Norris Comprehensive Cancer Center accepting new patients
    Los Angeles California 90033 United States
  • Cancer and Blood Specialty Clinic accepting new patients
    Los Alamitos California 90720 United States
  • Torrance Memorial Physician Network / Cancer Care accepting new patients
    Torrance California 90505 United States
  • Providence Medical Foundation accepting new patients
    Fullerton California 92835 United States
  • PIH Health Hematology & Oncology accepting new patients
    Whittier California 90602 United States

Lead Scientists at University of California Health


accepting new patients
Start Date
Completion Date
Eli Lilly and Company
Abemaciclib (LY2835219) Plus Fulvestrant Compared to Placebo Plus Fulvestrant in Previously Treated Breast Cancer (postMONARCH)
Phase 3 research study
Study Type
Expecting 350 study participants
Last Updated