NCT05169567 · CITED IN SOURCE DOCUMENTS

Abemaciclib (LY2835219) Plus Fulvestrant Compared to Placebo Plus Fulvestrant in Previously Treated Breast Cancer

An NCI or FDA source cites this study. A citation does not establish that it applies to an individual diagnosis.

Phase: PHASE3
Status at capture: ACTIVE NOT RECRUITING
Registry last update: 2026-01-16

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.

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What did the study report?

Outcomes, safety and baseline populations are separate source sections. Quality-of-life measures appear under their original outcome titles.

flow

Participant flow

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baseline

Baseline characteristics

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outcome · POSTED

Progression-Free Survival (PFS)

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outcome · POSTED

Progression Free Survival (PFS) Determined by Blinded Independent Central Review (BICR)

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outcome · POSTED

Objective Response Rate (ORR): Percentage of Participants Who Achieved a Best Overall Response (BOR) of Complete Response (CR) or Partial Response (PR)

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adverse events

Adverse events

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more info

Limitations, agreements, and source contact

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Who could take part

eligibility Criteria: Inclusion Criteria: * 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
healthy Volunteers: false
minimum Age: 18 Years
sex: ALL
std Ages: ADULT
OLDER_ADULT

Treatment arms and interventions

arm Groups

description
Abemaciclib 150 milligram (mg) administered orally twice daily (BID) on Days 1 to 28 of a 28-day cycle in combination with fulvestrant 500 mg administered intramuscularly (IM) on Days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and beyond. Participants received treatment until discontinuation criteria were met.
intervention Names
Drug: Abemaciclib
Drug: Fulvestrant
label
Arm A: Abemaciclib plus Fulvestrant
type
EXPERIMENTAL
description
Placebo administered orally BID on Days 1 to 28 of a 28-day cycle in combination with fulvestrant 500 mg administered IM on Days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and beyond. Participants received treatment until discontinuation criteria were met.
intervention Names
Drug: Fulvestrant
Drug: Placebo
label
Arm B: Placebo plus Fulvestrant
type
ACTIVE_COMPARATOR

interventions

arm Group Labels
Arm A: Abemaciclib plus Fulvestrant
description
Administered orally.
name
Abemaciclib
type
DRUG
arm Group Labels
Arm A: Abemaciclib plus Fulvestrant
Arm B: Placebo plus Fulvestrant
description
Administered IM.
name
Fulvestrant
type
DRUG
arm Group Labels
Arm B: Placebo plus Fulvestrant
description
Administered orally.
name
Placebo
type
DRUG

Study design

allocation

RANDOMIZED

intervention Model

PARALLEL

masking Info

masking: DOUBLE
who Masked: PARTICIPANT
INVESTIGATOR

primary Purpose

TREATMENT

Enrollment

count: 368
type: ACTUAL

Registered outcome plans (not posted results)

primary Outcomes

description
PFS defined as the time from the date of randomization to the first evidence of disease progression as defined by response evaluation criteria in solid tumors (RECIST) v1.1 or death from any cause. Progressive Disease (PD) was 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. If a participant does not have a complete baseline disease assessment, then the PFS time was censored at the date of randomization, regardless of whether or not objectively determined disease progression or death has been observed for the participant. If a participant was not known to have died or have objective progression as of the data inclusion cutoff date for the analysis, the PFS time was censored at the last adequate tumor assessment date.
measure
Progression-Free Survival (PFS)
time Frame
Randomization to the date of first documented progression of disease or death from any cause (Up to 21 Months)

secondary Outcomes

description
PFS is defined as the time from the date of randomization to the earliest date of disease progression determined by blinded independent central review (BICR) or death from any cause, whichever occurs first.
measure
Progression Free Survival (PFS) Determined by Blinded Independent Central Review (BICR)
time Frame
Randomization to the date of first documented progression of disease or death from any cause (Up to 22 Months)
description
ORR is the best overall tumor response of CR or PR as classified by the investigator according to the Response Evaluation Criteria In Solid Tumors (RECIST v1.1). CR is a disappearance of all target and non-target lesions and normalization of tumor marker level. PR is an at least 30% decrease in the sum of the diameters of target lesions (taking as reference the baseline sum diameter) without progression of non-target lesions or appearance of new lesions.
measure
Objective Response Rate (ORR): Percentage of Participants Who Achieved a Best Overall Response (BOR) of Complete Response (CR) or Partial Response (PR)
time Frame
Randomization until measured progressive disease (Up to 22 Months)

Full study description

brief Summary: 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.

Source references

references

citation
Zapatero-Solana E, Ding Y, Pulliam N, de Dios A, Ortiz-Ruiz MJ, Lallena MJ. Models of Early Resistance to CDK4/6 Inhibitors Unveil Potential Therapeutic Treatment Sequencing. Int J Mol Sci. 2025 Mar 14;26(6):2643. doi: 10.3390/ijms26062643.
pmid
40141282
type
DERIVED
citation
Kalinsky K, Bianchini G, Hamilton E, Graff SL, Park KH, Jeselsohn R, Demirci U, Martin M, Layman RM, Hurvitz SA, Sammons S, Kaufman PA, Munoz M, Lai JI, Knoderer H, Sandoval C, Chawla AR, Nguyen B, Zhou Y, Ravenberg E, Litchfield LM, Smyth L, Wander SA. Abemaciclib Plus Fulvestrant in Advanced Breast Cancer After Progression on CDK4/6 Inhibition: Results From the Phase III postMONARCH Trial. J Clin Oncol. 2025 Mar 20;43(9):1101-1112. doi: 10.1200/JCO-24-02086. Epub 2024 Dec 18.
pmid
39693591
type
DERIVED