NCT05696626 · Sermonix Pharmaceuticals Inc.
Evaluation of Lasofoxifene Combined With Abemaciclib Compared With Fulvestrant Combined With Abemaciclib in Locally Advanced or Metastatic ER+/HER2- Breast Cancer With an ESR1 Mutation
(ELAINEIII)
What this study is about
The goal of this clinical trial is to assess the effectiveness, safety and how well patients handle the treatment of the combination of lasofoxifene and abemaciclib compared to fulvestrant and abemaciclib for the treatment of pre- and postmenopausal women and men who have previously received ribociclib or palbociclib-based treatment and have locally advanced or metastatic estrogen receptor positive (ER+)/human epidermal growth factor 2 negative (HER2-) breast cancer with an estrogen receptor 1 (ESR1) mutation. The main quest
View original scientific description
The goal of this clinical trial is to assess the efficacy, safety and tolerability of the combination of lasofoxifene and abemaciclib compared to fulvestrant and abemaciclib for the treatment of pre- and postmenopausal women and men who have previously received ribociclib or palbociclib-based treatment and have locally advanced or metastatic estrogen receptor positive (ER+)/human epidermal growth factor 2 negative (HER2-) breast cancer with an estrogen receptor 1 (ESR1) mutation.
Interventions
DRUG
Lasofoxifene in combination with abemaciclib
5 mg/d of oral lasofoxifene plus oral abemaciclib 150 mg twice a day
DRUG
Fulvestrant in combination with abemaciclib
Fulvestrant 500 mg intramuscular (IM) on Days 1, 15, and 29 and then once monthly thereafter plus oral abemaciclib 150 mg twice a day
Primary outcome measures
Progression free survival (PFS)
Time frame: Within approximately 3 years
PFS is defined as the time from the date of randomization \[Visit 0 (Day 1)\] to the earliest date of first documented progression per RECIST 1.1 as determined by BICR or death due to any cause.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Pre- or postmenopausal women or men. 2. Locally advanced and/or metastatic ER+ breast cancer with radiological or clinical evidence of progression on an AI in combination with either palbociclib or ribociclib as their first hormonal treatment for metastatic disease. 3. Histological or cytological confirmation of ER+/HER2 - disease 4. No evidence of progression for at least 6 months on an AI/CDKi combination for advanced breast cancer. 5. At least 1 or more ESR1 point mutations in the ESR1 ligand binding domain as assessed in cell- free ctDNA obtained from a blood or breast cancer tissue. 6. Locally advanced or metastatic breast cancer with either measurable (according to RECIST 1.1) or non-measurable lesions. 7. Subjects may have received 1 cytotoxic chemotherapy regimen in the metastatic disease setting prior to study entry, but must have recovered from chemotherapy acute toxicity excluding alopecia and Grade 2 peripheral neuropathy. 8. Eastern Cooperative Onco
Where
- Scottsdale, Arizona
- Tucson, Arizona
- Santa Rosa, California
- Jacksonville, Florida
- Miami, Florida
- Plantation, Florida
- Atlanta, Georgia
- Louisville, Kentucky
- Baltimore, Maryland
- Boston, Massachusetts
- Grand Rapids, Michigan
- Minneapolis, Minnesota
And 16 more locations — see the full list below.
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 22, 2026 · Source of record for eligibility and locations