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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

Not Enrolling

Trial ID:NCT05169567

View complete trial on

Protocol #:22-170

877-DF-TRIAL (877-338-7425)

Condition(s):Breast Neoplasm, Neoplasm Metastasis


Principal Investigator:Jeselsohn, Rinath, Malka

Site Research Nurse(s):Abraham, Elizabeth,
Beeler, Maureen,
Brule, Maurice, N.
Campbell, Margaret,
Finn, Kristen,
Fleming, Norah, Michelle
Freeman, Stefani, Danielle
Ginter, Lindsey,
Hixon, Nicole, R.
Padden, Sarah,
Patel, Nikita,
Roche, Kathleen, A.
Rutter, Morgan,
Weitz, MaryAnn,

Trial Description:
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.

Eligibility Requirements:
- 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
Exclusion Criteria:
- 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

Protocol #: 22-170

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