for people ages 18 years and up (full criteria)
at Sacramento, California and other locations
study started
estimated completion
Principal Investigator
by Helen Chew



The main purpose of this study is to measure how well abemaciclib works in participants with early breast cancer who are taking hormone therapy after surgery. Participants must have breast cancer that is hormone receptor positive (HR+) and human epidermal receptor 2 positive (HER2+). Your participation could last up to 10 years depending on how you and your tumor respond.

Official Title

eMonarcHER: A Randomized, Double Blind, Placebo-Controlled Phase 3 Study of Abemaciclib Plus Standard Adjuvant Endocrine Therapy in Participants With High-Risk, Node-Positive, HR+, HER2+ Early Breast Cancer Who Have Completed Adjuvant HER2-Targeted Therapy


Breast Neoplasms Abemaciclib Abemaciclib Plus (+) Endocrine Therapy (ET)


You can join if…

Open to people ages 18 years and up

  • Have confirmed HR+, HER2+ in initial diagnostic tissue, early invasive breast cancer without evidence of disease recurrence or distant metastases
  • Have undergone definitive surgery of the primary breast tumor(s)
  • Have tumor tissue from breast (preferred) or lymph node
  • Have received a minimum of four cycles of chemotherapy in either the neoadjuvant or adjuvant setting per standard of care therapy
  • Have completed approximately nine months to one year of standard HER2-targeted therapy without evidence of disease recurrence (neoadjuvant/adjuvant combined duration)
  • Have received one of the following eligible HER2-targeted adjuvant regimens AND be randomized within 12 weeks of completing the regimen:
  • For participants treated with neoadjuvant therapy (chemotherapy administered with

HER2-targeted therapy): Single agent adjuvant ado-trastuzumab emtansine or

  • For participants not treated with neoadjuvant therapy: Adjuvant pertuzumab with trastuzumab
  • Have high risk disease, defined by one of the following:
  • For participants treated with neoadjuvant therapy (as defined above): Pathologically detected axillary nodal disease in the surgical specimen
  • For participants not treated with neoadjuvant therapy: Axillary node positive disease meeting one of the following criteria:
  • Pathological tumor involvement in greater than or equal to (≥) four ipsilateral axillary lymph nodes OR
  • Pathological tumor involvement in one to three ipsilateral axillary lymph node(s) and at least 1 of the following criteria:
  • Histological Grade 3
  • Primary invasive tumor size ≥5 centimeters determined pathologically

You CAN'T join if...

  • Have breast cancer with any of the following features:
  • Disease recurrence or distant metastatic disease (including contralateral axillary lymph nodes)
  • Lymph node-negative status
  • Pathological complete response from any prior systemic treatments for early breast cancer
  • Inflammatory breast cancer
  • Have other medical conditions including:
  • Previous breast cancer (Exceptions: Ipsilateral ductal carcinoma in situ [DCIS] treated by locoregional therapy alone ≥5 years ago; contralateral DCIS treated by locoregional therapy at any time)
  • Other cancer being treated and/or not in complete remission within the last 5 years (Exceptions: Appropriately treated non-melanomatous skin cancer or carcinoma in situ of cervix, bladder, or colon)
  • Females who are pregnant or lactating
  • History of venous thromboembolism
  • Other serious medical conditions
  • Have previously received treatment with:
  • Any cyclin-dependent kinase (CDK)4 and CDK6 inhibitor
  • Prior adjuvant treatment with immunotherapy, tucatinib, neratinib, investigational HER2 directed therapy, or trastuzumab deruxtecan for treatment of breast cancer
  • Endocrine therapy (ET) (i.e., tamoxifen, raloxifene or aromatase inhibitor) for breast cancer prevention (without diagnosis of breast cancer)
  • Additional chemotherapy, anti-cancer ET, or HER2-targeted therapy beyond standard of care therapy for their breast cancer at study enrollment


  • University of California, Davis - Health Systems not yet accepting patients
    Sacramento California 95817 United States
  • Kaiser Foundation Research Institute not yet accepting patients
    Vallejo California 94589 United States

Lead Scientist at UC Davis

  • Helen Chew
    Professor, Hematology and Oncology. Authored (or co-authored) 53 research publications.


accepting new patients
Start Date
Completion Date
Eli Lilly and Company
Sign up for this study
Phase 3
Study Type
Last Updated