A Study of Abemaciclib (LY2835219) Plus Tamoxifen or Abemaciclib Alone in Women With Metastatic Breast Cancer (Next MONARCH 1)

January 19, 2026 updated by: Eli Lilly and Company

A Randomized, Open-Label, Phase 2 Study of Abemaciclib Plus Tamoxifen or Abemaciclib Alone, in Women With Previously Treated Hormone Receptor-Positive, HER2-Negative, Metastatic Breast Cancer

The main purpose of this study is to evaluate the safety and efficacy of abemaciclib plus tamoxifen or abemaciclib alone in women with previously treated hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-), metastatic breast cancer.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
234

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Expanded Access

Expanded Access

A way for patients with serious diseases or conditions who cannot participate in a clinical trial to gain access to a medical product that has not been approved by the U.S. Food and Drug Administration (FDA). Also called compassionate use. There are different expanded access types.
Approved

Approved

  • Available: Expanded access is currently available for this investigational treatment, and patients who are not participants in the clinical study may be able to gain access to the drug, biologic, or medical device being studied.
  • No longer available: Expanded access was available for this intervention previously but is not currently available and will not be available in the future.
  • Temporarily not available: Expanded access is not currently available for this intervention but is expected to be available in the future.
  • Approved for marketing: The intervention has been approved by the U.S. Food and Drug Administration for use by the public.
 for sale to the public. See expanded access record.

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Argentina
      • Salta, Argentina, 4400
        • Sanatorio Parque
    • Buenos Aires
      • CABA, Buenos Aires, Argentina, C1125ABD
        • CENIT Centro de Neurociencias, Investigacion y Tratamiento
    • Jujuy Province
      • San Salvador de Jujuy, Jujuy Province, Argentina, Y4600APW
        • Fundación ARS Médica
    • Río Negro Province
      • Viedma, Río Negro Province, Argentina, R8500ACE
        • Clinica Viedma
    • Santa Fe Province
      • Rosario, Santa Fe Province, Argentina, S2000KZE
        • Instituto de Oncologia de Rosario
    • Tucumán Province
      • San Miguel de Tucumán, Tucumán Province, Argentina, 4000
        • Centro Para la Atención Integral del Paciente Oncologico (CAIPO)
  • Austria
      • Vienna, Austria, 1090
        • AKH
    • Styria
      • Graz, Styria, Austria, 8036
        • Medizinische Universitaet Graz
    • Tyrol
      • Innsbruck, Tyrol, Austria, 6020
        • Universitatsklinik Innsbruck
  • Belgium
      • Charleroi, Belgium, 6000
        • Grand Hopital de Charleroi-Site Notre-Dame
      • Liège, Belgium, 4000
        • Centre Hospitalier Universitaire Sart Tilman
    • Oost-Vlaanderen
      • Ghent, Oost-Vlaanderen, Belgium, 9000
        • Universitair Ziekenhuis Gent
      • Sint-Niklaas, Oost-Vlaanderen, Belgium, 9100
        • Vitaz
  • Brazil
      • São Paulo, Brazil, 01317-000
        • Clínica de Pesquisas e Centro de Estudos em Oncologia Ginecológica e Mamária Ltda
      • São Paulo, Brazil, 01246000
        • ICESP - Instituto do Cancer do Estado de Sao Paulo
    • Rio Grande do Sul
      • Porto Alegre, Rio Grande do Sul, Brazil, 90610-000
        • Hospital São Lucas - PUCRS - ONCOLOGY
    • São Paulo
      • Barretos, São Paulo, Brazil, 14784400
        • Fundacao Pio XII - Hospital de Cancer de Barretos
  • Czechia
      • Prague, Czechia, 100 34
        • Fakultni nemocnice Kralovske Vinohrady
      • Prague, Czechia, 150 06
        • Fakultni nemocnice v Motole
      • Prague, Czechia, 128 08
        • Fakultni poliklinika VFN
      • Praha 4 - Krc, Czechia, 140 59
        • Thomayerova nemocnice
    • Czech Republic
      • Brno, Czech Republic, Czechia, 656 53
        • Masarykuv Onkologicky Ustav
  • France
    • Hauts-de-France
      • Lille, Hauts-de-France, France, 59020
        • Centre Oscar Lambret
    • Provence-Alpes-Côte d'Azur Region
      • Marseille, Provence-Alpes-Côte d'Azur Region, France, 13273
        • Institut Paoli-Calmettes
  • Germany
      • Hamburg, Germany, 22087
        • Kath. Marienkrankenhaus gGmbH
    • Baden-Wurttemberg
      • Ulm, Baden-Wurttemberg, Germany, 89081
        • Universitätsklinikum Ulm
  • Italy
      • Bologna, Italy, 40139
        • Ospedale Bellaria - Azienda USL di Bologna
      • Napoli, Italy, 80131
        • Azienda Ospedaliera Universitaria Federico II
    • Rome
      • Roma, Rome, Italy, 00161
        • Polic.Umberto I -Univ. La Sapienza
    • Verona
      • Negrar, Verona, Italy, 37024
        • Ospedale Sacro Cuore Don G. Calabria
  • Mexico
      • Mexico City, Mexico, 03310
        • Grupo Medico Camino Sc
      • Oaxaca City, Mexico, 68000
        • Oaxaca Site Management Organization
    • Sinaloa
      • Culiacán, Sinaloa, Mexico, 80020
        • Neurociencias Estudios Clinicos
    • Toluca
      • San Bernardino, Toluca, Mexico, 50080
        • Centro Hemato Oncologico Privado
  • Russia
      • Kazan', Russia, 420029
        • Republic Oncology Dispensary of MoH of Republic Tatarstan
      • Saint Petersburg, Russia, 197758
        • St-Petersburg scientifical practical center of specialized medical care
      • Saint Petersburg, Russia, 198255
        • Saint-Petersburg City Clinical Oncology Dispensary
  • Spain
      • Barcelona, Spain, 08036
        • Hospital Clinic I Provincial
      • Madrid, Spain, 28040
        • Hospital Clinico San Carlos
      • Madrid, Spain, 28041
        • Hospital Universitario 12 de Octubre
      • Madrid, Spain, 28007
        • Hospital General Universitario Gregorio Marañón
      • Valencia, Spain, 46010
        • Hospital Clínico Universitario de Valencia
    • Barcelona [Barcelona]
      • Barcelona, Barcelona [Barcelona], Spain, 08035
        • Hospital Universitari Vall d'Hebron
    • Madrid, Comunidad de
      • Madrid, Madrid, Comunidad de, Spain, 28034
        • Hospital Universitario Ramon y Cajal
  • Taiwan
      • New Taipei City, Taiwan, 235
        • Taipei Medical University Shuang Ho Hospital
      • Taichung, Taiwan, 40447
        • China Medical University Hospital
      • Taipei, Taiwan, 11217
        • Taipei Veterans General Hospital
      • Taipei, Taiwan, 10449
        • Mackay Memorial Hospital
      • Taoyuan, Taiwan, 33305
        • Chang Gung Memorial Hospital - Linkou
  • Turkey (Türkiye)
      • Adana, Turkey (Türkiye), 1250
        • Baskent University Dr. Turgut Noyan Research and Training Center
      • Ankara, Turkey (Türkiye), 06100
        • Hacettepe University Faculty of Medicine
      • Istanbul, Turkey (Türkiye), 34214
        • Medipol Mega University Hospital
      • Istanbul, Turkey (Türkiye), 34668
        • Marmara University Medical Faculty
    • Melikgazi
      • Kayseri, Melikgazi, Turkey (Türkiye), 38039
        • Erciyes University Faculty of Medicine
  • United States
    • Arizona
      • Tucson, Arizona, United States, 85724
        • The University of Arizona Cancer Center
    • New Hampshire
      • Lebanon, New Hampshire, United States, 03766
        • Dartmouth Hitchcock Medical Center
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Tennessee Oncology PLLC
    • Texas
      • Fort Worth, Texas, United States, 76104
        • The Center for Cancer and Blood Disorders
    • Wisconsin
      • Madison, Wisconsin, United States, 53705
        • University of Wisconsin Clinical Research Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Have a diagnosis of HR+, HER2- breast cancer.
  • Relapsed or progressed following endocrine therapy.
  • Have received prior treatment with at least 2 chemotherapy regimens, of which at least 1 but no more than 2 have been administered in the metastatic setting.
  • Have the presence of measureable disease as defined by the Response Evaluation Criteria in Solid Tumors (RECIST 1.1).
  • Have a performance status ≤1 on the Eastern Cooperative Oncology Group (ECOG) scale.
  • Have discontinued previous therapies for cancer (including specifically, aromatase inhibitors, anti-estrogens, chemotherapy, radiotherapy, and immunotherapy) for at least 21 days for myelosuppressive agents or 14 days for nonmyelosuppressive agents prior to receiving study drug, and recovered from the acute effects of therapy (until the toxicity resolves to either baseline or at least Grade 1) except for residual alopecia or peripheral neuropathy.
  • Have adequate organ function.
  • Have negative serum pregnancy test within 7 days prior to the first dose of study treatment and agree to use highly effective precautions to prevent pregnancy during the study and for 3 weeks following last dose of study treatment.
  • Are able to swallow oral medication.

Exclusion Criteria:

  • Have clinical evidence or history of central nervous system metastasis.
  • Have a personal history of any of the following conditions: syncope of either unexplained or cardiovascular etiology, ventricular tachycardia, ventricular fibrillation, or sudden cardiac arrest.
  • Have active bacterial or fungal infection (that is, requiring intravenous antibiotics at the time of initiating study treatment) and/or detectable viral infection.
  • Have received treatment with a prior cyclin-dependent kinase (CDK4) and CDK 6 inhibitor.
  • Have a preexisting chronic condition resulting in persistent diarrhea.
  • Have a history of any other cancer (except nonmelanoma skin cancer or carcinoma in-situ of the cervix or breast), unless in complete remission with no therapy for a minimum of 3 years.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Abemaciclib + Tamoxifen
Abemaciclib given orally every 12 hours (Q12H) in combination with tamoxifen given orally every day. Participants may continue to receive treatment until discontinuation criteria are met.
Drug: Abemaciclib
Administered orally
Other Names:
  • LY2835219
Drug: Tamoxifen
Administered orally
Experimental: Abemaciclib
Abemaciclib given orally Q12H. Participants may continue to receive treatment until discontinuation criteria are met.
Drug: Abemaciclib
Administered orally
Other Names:
  • LY2835219
Experimental: Abemaciclib + Prophylactic Loperamide
Abemaciclib given orally Q12H in combination with prophylactic loperamide given orally. Participants may continue to receive treatment until discontinuation criteria are met.
Drug: Abemaciclib
Administered orally
Other Names:
  • LY2835219
Drug: Prophylactic Loperamide
Administered orally

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Progression Free Survival (PFS)
Time Frame: Baseline to Objective Disease Progression or Death from Any Cause (Up to 21 Months)
Progression-free survival time was measured from the date of randomization to the date of investigator-determined objective progression as defined by RECIST v1.1, or death from any cause, whichever occurred first. Progressive disease (PD) is defined as at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum on study and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions. Participants who have neither progressed nor died were censored at the day of their last radiographic tumor assessment (if available) or date of randomization if no post baseline radiographic assessment is available.
Baseline to Objective Disease Progression or Death from Any Cause (Up to 21 Months)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Objective Response Rate (ORR): Percentage of Participants With a Complete Response (CR) or Partial Response (PR)
Time Frame: Baseline to Objective Disease Progression (Up to 21 Months)
Objective response rate was defined as the percentage of participants with CR or PR according to RECIST v1.1. CR was defined as the disappearance of all target and non-target lesions and no appearance of new lesions. PR was defined as at least a 30% decrease in the sum of the LD (longest diameter) of target lesions (taking as reference the baseline sum LD), no progression of non-target lesions, and no appearance of new lesions.
Baseline to Objective Disease Progression (Up to 21 Months)
Duration of Response (DoR)
Time Frame: Date of CR or PR to Date of Objective Disease Progression or Death Due to Any Cause (Up to 21 Months)
DoR is defined as the time from the date of first evidence of a CR or PR to the date of objective progression or death from any cause, whichever is earlier as defined by Recist v1.1. CR was defined as the disappearance of all target and non-target lesions and no appearance of new lesions. PR was defined as at least a 30% decrease in the sum of the LD of target lesions (taking as reference the baseline sum LD), no progression of non-target lesions, and no appearance of new lesions.
Date of CR or PR to Date of Objective Disease Progression or Death Due to Any Cause (Up to 21 Months)
Overall Survival (OS)
Time Frame: Baseline to Death from Any Cause (Approximately 36 Months)
Baseline to Death from Any Cause (Approximately 36 Months)
Pharmacokinetics (PK): Mean Single Dose Concentration of Abemaciclib and Its Metabolites
Time Frame: Cycle (C) 1 Day (D) 1 post dose
Mean single dose concentrations of Abemaciclib and its metabolites (M2 & M20) are reported.
Cycle (C) 1 Day (D) 1 post dose
Pharmacokinetics (PK): Steady State Concentration of Abemaciclib and Its Metabolites
Time Frame: Cycle 1 Day 15, Cycle 2 Day 1, Cycle 2 Day 15, Cycle 3 Day 1 post dose

Mean steady state concentrations of Abemaciclib and its metabolites (M2 & M20) are reported.

C=Cycle D= Day
Cycle 1 Day 15, Cycle 2 Day 1, Cycle 2 Day 15, Cycle 3 Day 1 post dose
PK: Mean Single Dose Concentration of Tamoxifen and Endoxifen
Time Frame: Cycle 1 Day 1 post dose
Mean single dose concentrations of Tamoxifen and its metabolite (Endoxifen) were reported.
Cycle 1 Day 1 post dose
PK: Multiple Dose Concentration of Tamoxifen and Endoxifen
Time Frame: Cycle 1 Day 15, Cycle 2 Day 1, Cycle 2 Day 15, Cycle 3 Day 1 post dose
Mean multiple dose concentrations of Tamoxifen and its metabolite (Endoxifen) were reported.
Cycle 1 Day 15, Cycle 2 Day 1, Cycle 2 Day 15, Cycle 3 Day 1 post dose
Change From Baseline in Symptom Burden on the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30)
Time Frame: Baseline, 21 Months

The EORTC QLQ-C30 self-reported general cancer instrument consists of 30 items covered by 1 of 3 dimensions:

  1. Global health status/quality of life (2 items) with scores ranging from 1 (Very Poor) to 7 (Excellent).
  2. Functional scales (15 total items addressing either physical, role, emotional, cognitive, or social functioning), each item scores ranging from 1 (not at all) to 4 (very much)
  3. Symptom scales (13 total items addressing either fatigue, nausea/vomiting, pain, dyspnea, insomnia, appetite loss, constipation, diarrhea, or financial impact), each item scores ranging from 1 (not at all) to 4 (very much).

Raw scores are linearly converted to a 0-100 scale with higher scores reflecting higher levels of function/QOL or higher levels of symptom burden.
Baseline, 21 Months
Change From Baseline in Pain and Symptom Burden Assessment on the Modified Brief Pain Inventory-Short Form (mBPI-sf)
Time Frame: Baseline, 21 Months
mBPI-sf is an 11-item instrument used as a multiple-item measure of cancer pain intensity. In addition to pain intensity (4 items), the mBPI-sf is designed for participants to record the presence of pain in general, pain relief, and pain interference with function (general activity, mood, ability to walk, ability to perform normal work, relations with others, sleep, enjoyment of life). Responses for the mBPI-sf items are captured through the use of 11-point numeric rating scales anchored at 0 (no pain or does not interfere) and 10 (pain as bad as you can imagine or completely interferes). The mBPI-sf recall period is 24 hours and typical completion time for this instrument is less than 5 minutes.
Baseline, 21 Months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Eli Lilly and Company

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Call 1-877-CTLILLY (1-877-285-4559) or 1-317-615-4559 Mon - Fri 9 AM - 5 PM Eastern time (UTC/GMT - 5 hours, EST), Eli Lilly and Company

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 14, 2016

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 15, 2018

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 19, 2016

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 19, 2016

First Posted (Estimated)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 21, 2016

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 6, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 19, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 16339
  • I3Y-MC-JPCG (Other Identifier: Eli Lilly and Company)
  • 2016-000288-18 (EudraCT Number)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

IPD Sharing Time Frame

Data are available 6 months after the primary publication and approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

IPD Sharing Access Criteria

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • CSR

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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