Fulvestrant and Abemaciclib for ER-Positive, HER2-Negative Metastatic Breast Cancer
This study is for people with ER-positive (estrogen receptor-positive), HER2-negative (human epidermal growth factor receptor 2-negative) metastatic breast cancer that has grown despite previous treatment with a CDK4/6 inhibitor and an aromatase inhibitor. Researchers want to see if taking a break from the CDK4/6 inhibitor, abemaciclib, for one month before restarting it with fulvestrant will make the treatment more effective. You would first receive fulvestrant for one month, followed by both abemaciclib and fulvestrant. The study will measure how long you stay on this treatment before it needs to be stopped for any reason. About 28 people are planned to join this study, but its current status is unclear.
- Study design
- This is a single-arm study, meaning all participants receive the same treatment plan. It involves a planned enrollment of 28 participants.
- What's involved
- You would receive fulvestrant for one month, followed by abemaciclib and fulvestrant every 28 days.
- Compensation
- Not stated in the trial record.
- Follow-up
- The primary endpoint measures time to treatment failure, which is the time from the start of therapy to discontinuation for any cause.
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NCT05305924
Fulvestrant+Abemaciclib With Run-In of Fulvestrant in Er-Positive, Her2-Negative Metastatic Breast Cancer
Recruiting
PHASE2Ages 18+InterventionalTreatmentThe Methodist Hospital Research InstituteInvestigator-initiated
~28 participants
Updated 2026-01-28 on ClinicalTrials.gov
What's tested:Fulvestrant Run-In
At a glance
Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Time to treatment failure (TTF) for fulvestrant plus abemaciclib with a 1-month run-in of fulvestrant
Measured over TTF will be defined as time from start of therapy to discontinuation for any cause.
Conditions
Where it's being run
1 sites across 1 statesTexas1
Study leadership
- Polly Niravath, MD · PRINCIPAL_INVESTIGATOR · The Methodist Hospital Research Institute
Who to contact
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Do you actually qualify for this trial?
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Eligibility criteria
Inclusion
IHC 1+ or 0
In situ hybridization negative based on:
Single-probe average HER2 copy number \<4.0 signals/cell
Dual-probe HER2/CEP17 ratio \<2.0 with an average HER2 copy number \<4.0 signals/cell. 4. Measurable disease according to the RECIST 1.1 or bone-only disease. 5. Postmenopausal status or receiving ovarian ablation with a gonadotropin-releasing hormone (GnRH) agonist. Postmenopausal status is defined by any one of the following criteria:
Prior bilateral oophorectomy
Age ≥55 years
Age \<55 years and amenorrheic for at least 12 months (spontaneous cessation of menses for 12 consecutive months or more in the absence of chemotherapy, tamoxifen, toremifene, or ovarian suppression) and follicle-stimulating hormone and estradiol levels in the postmenopausal range without an alternative cause If the patient does not meet criteria for postmenopausal status but is receiving ovarian ablation therapy with a GnRH agonist, the patient is eligible for this trial, provided that the GnRH agonist is started at least 2 weeks prior to the first dose of trial treatment. 6. Eastern Cooperative Oncology Group performance status of 0 or 1. 7. Life expectancy ≥6 months. 8. Patients who received chemotherapy must have recovered (Common Terminology Criteria for Adverse Events \[CTCAE\] Grade ≤1) from the acute effects of chemotherapy except for residual alopecia or Grade 2 peripheral neuropathy prior to randomization. A washout period of at least 21 days is required between last chemotherapy dose and randomization (provided the patient did not receive radiotherapy). Patients who received radiotherapy must have completed and fully recovered from the acute effects of radiotherapy. A washout period of at least 21 days is required between end of radiotherapy and randomization. 9. Adequate organ function:
Absolute neutrophil count ≥1500/µL (without granulocyte colony stimulating factor support within 2 weeks of laboratory test used to determine eligibility)
Platelets ≥100,000/µL (without transfusion within 2 weeks of laboratory test used to determine eligibility)
Hemoglobin ≥9 g/dL (without blood transfusion)
White blood cell count \>2,500/µL and \<15,000/µL
Lymphocyte count ≥500/µL
Serum bilirubin ≤1.5x upper limit of normal (ULN; patients with known Gilbert's disease who have serum bilirubin level ≤3 x ULN may be enrolled)
Serum transaminases (aspartate transaminase \[AST\] or alanine transaminase \[ALT\]) activity ≤3.0 x ULN with normal alkaline phosphatase (\[ALP\]; patients with liver metastases ≤5 x ULN) OR AST and ALT ≤1.5 x ULN with ALP \>2.5 x ULN
International normalized ratio and activated partial thromboplastin time ≤1.5 x ULN
Serum creatinine at or below the institutional normal value. 10. Able to swallow oral medication. 11. Patients who are made postmenopausal through use of GNRH agonists must be willing to use an adequate method of contraception for the course of the trial through 1 year after the last dose of trial treatment. 12. Patients who are made postmenopausal through use of GNRH agonists should have a negative serum pregnancy (β-human chorionic gonadotropin) within 7 days prior to trial treatment administration. 13. Willing and able to provide written informed consent/assent for the trial.
Exclusion
Any corticosteroid use for brain metastases must have been discontinued without the subsequent appearance of symptoms for ≥2 weeks before trial treatment administration.
Treatment for brain metastases may have included whole brain radiotherapy, radiosurgery, or a combination as was deemed appropriate by the treating physician.
Patients who meet the above criteria and are clinically stable on anticonvulsant medication are eligible only if their anticonvulsant does not alter hepatic CYP activity in a way that might interfere with the metabolism of abemaciclib. 16. Have received any live vaccination within 28 days of trial treatment administration. 17. History within the last 12 months of any of the following conditions: syncope of cardiovascular etiology, ventricular tachycardia, ventricular fibrillation, or sudden cardiac arrest. 18. Pregnant or breastfeeding.
What this trial measures
- Time to treatment failure (TTF) for fulvestrant plus abemaciclib with a 1-month run-in of fulvestrantTTF will be defined as time from start of therapy to discontinuation for any cause.
Time to treatment failure (TTF) for fulvestrant plus abemaciclib with a 1-month run-in of fulvestrant in patients with ER-positive, HER2-negative metastatic breast cancer that has progressed on a CDK4/6 inhibitor in combination with an AI, as assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1.