Breast CancerPhase 2NCT07766018
A Phase 2 Bridging Study of Elacestrant Monotherapy in Advanced or Metastatic Breast Cancer
A Phase 2 study testing Elacestrant in people with Breast Cancer, run by Stemline Therapeutics, Inc. at 26 sites in Japan.
Trial summary
This is a multicenter, open-label, Phase 2 bridging study to evaluate the efficacy and safety of elacestrant in Japanese post-menopausal women and men with estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer with estrogen receptor 1 gene… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Breast Cancer
- What is being tested?
- Elacestrant
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 70 participants
- Where
- 26 sitesJapan
- Study dates
- 18 Aug 2026to Oct 2028
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Must have a histologically or cytologically proven diagnosis of adenocarcinoma of the breast with evidence of either locally advanced disease not amenable to resection or radiation therapy with curative intent or metastatic disease not amenable to curative therapy
- Female participants must be post-menopausal (as defined by the protocol)
- Must have ER+ and HER2- tumor status confirmed per local laboratory testing
- Participants must be ESR1-mutant positive determined via testing with the Guardant360 Companion Diagnostic panel test prior to enrollment
- Must have disease progression during or within 28 days of completion of prior treatment with a CDK4/6 inhibitor in combination with either fulvestrant or an aromatase inhibitor (this counts as a line of prior endocrine therapy) for metastatic breast cancer
Who cannot join
- Prior treatment with: elacestrant or investigational or approved selective estrogen receptor degrader or ER antagonist; antibody-drug conjugate therapy for advanced/metastatic breast cancer; anti-cancer or investigational drug treatment
- Radiation therapy within 14 days (28 days for brain lesions) before the first dose of study drug
- Intact uterus with a history of endometrial intraepithelial neoplasia (atypical endometrial hyperplasia or higher-grade lesion)
- Diagnosis of any other malignancy within 5 years before enrollment, except for adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or second primary breast cancer
- Note: Other protocol-defined inclusion/exclusion criteria may apply.
Trial locations and contacts
26 sites in 1 country. Contact the study team or a site near you to ask about taking part.
26 sites in 1 country
Japan26 sites, 26 recruiting
- Recruiting
Chiba Cancer Center
Chiba
Rikiya Nakamura
- Recruiting
Kyushu University Hospital
Fukuoka
Makoto Kubo
- Recruiting
National Hospital Organization - Kyushu Medical Center
Fukuoka
Nobutaka Iwakuma
- Recruiting
Kansai Medical University Hospital
Hirakata
Masahiro Takada
- Recruiting
Hiroshima University Hospital
Hiroshima
Hideo Shigematsu
- Recruiting
Saitama Cancer Center
Ina
Shigenori Nagai
- Recruiting
Tokai University Hospital
Isehara
Naoki Niikura
- Recruiting
Social medical corporation Hakuaikai - Sagara Hospital
Kagoshima
Yasuaki Sagara
- Recruiting
The Cancer Institute Hospital of JFCR (Japanese Foundation For Cancer Research)
Kōtō City
Meiko Nishimura
- Recruiting
Kumamoto Shinto General Hospital
Kumamoto
Tomofumi Osako
- Recruiting
Kumamoto University Hospital
Kumamoto
Yutaka Yamamoto
- Recruiting
Nagoya City University Hospital
Nagoya
Tatsuya Toyama
- Recruiting
National Hospital Organization - Nagoya Medical Center
Nagoya
Masataka Sawaki
- Recruiting
National Hospital Organization - Osaka National Hospital
Osaka
Hiroyuki Yasojima
- Recruiting
Kindai University Hospital
Sakaishi
Satomi Watanabe
- Recruiting
Hokkaido University Hospital
Sapporo
Masato Takahashi
- Recruiting
National Hospital Organization - Hokkaido Cancer Center
Sapporo
Kenichi Watanabe
- Recruiting
Jichi Medical University Hospital
Shimotsuke
Michiko Harao
- Recruiting
Shizuoka General Hospital
Shizuoka
Michiko Tsuneizumi
- Recruiting
Osaka University Hospital
Suita
Tetsuhiro Yoshinami
- Recruiting
Juntendo University Hospital
Tokyo
Junichiro Watanabe
- Recruiting
Saint Luke's International Hospital
Tokyo
Jun Hashimoto
- Recruiting
Tokyo Medical University Hospital
Tokyo
Yoichi Koyama
- Recruiting
Mie University Hospital
Tsu
Kosuke Kawaguchi
- Recruiting
University of Tsukuba Hospital
Tsukuba
Hiroko Bando
- Recruiting
Kanagawa Cancer Center
Yokohama
Toshinari Yamashita
About this study
Official title: A Phase 2 Open-Label, Single-Arm, Multicenter Trial to Evaluate the Efficacy and Safety of Elacestrant Monotherapy for the Treatment of Japanese Participants With ER+/HER2- Advanced or Metastatic Breast Cancer With ESR1-mutation Following CDK4/6 Inhibitor Therapy
This is a multicenter, open-label, Phase 2 bridging study to evaluate the efficacy and safety of elacestrant in Japanese post-menopausal women and men with estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer with estrogen receptor 1 gene mutation (ESR1-mut) whose disease has relapsed or progressed on at least 1 and no more than 2 prior lines of endocrine therapy for metastatic breast cancer, which must have included cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy in combination with fulvestrant or an aromatase inhibitor.
- Conditions
- Breast Cancer
- Being tested
- Elacestrant
- Keywords
- Elacestrant, Bridging Study, Japan, ESR1-mutation, Breast Cancer, CDK4/6i
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ElacestrantDrug
Administered as an oral tablet
| Study group | Role | What they receive |
|---|---|---|
| Elacestrant | Experimental | Participants will receive elacestrant once daily. Receives: Drug: Elacestrant |
What is being measured
The primary outcome is the main question the study is designed to answer.
Progression-free Survival as Assessed by the Imaging Review Committee
Measured: Up to approximately 27 months
Secondary outcomes (4)
Number of Participants with Adverse Events
Measured: Up to approximately 27 months
Plasma Concentration of Elacestrant
Measured: Up to approximately 27 months
Progression-free Survival as Assessed by the Investigator
Measured: Up to approximately 27 months
Overall Survival
Measured: Up to approximately 27 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Aug 2026
- Study start18 Aug 2026
- Primary completionOct 2028 (estimated)
- Study completionOct 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by Stemline Therapeutics, Inc.The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 70 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Stemline Therapeutics, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, Study director, Stemline Therapeutics, Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07766018
- Sponsor's protocol ID
- STML-ELA-0326
- Other IDs
- 2026-0020
- Status last verified
- Nov 2026
- First submitted
- 10 Aug 2026
- Last updated
- 5 Nov 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Open-Label, Single-Arm, Multicenter Trial to Evaluate the Efficacy and Safety of Elacestrant Monotherapy for the Treatment of Japanese Participants With ER+/HER2- Advanced or Metastatic Breast Cancer With ESR1-mutation Following CDK4/6 Inhibitor Therapy
- ClinicalTrials.gov ID
- NCT07766018
- Acronym / sponsor ID
- STML-ELA-0326
- Conditions
- Breast Cancer
- Keywords
- Elacestrant, Bridging Study, Japan, ESR1-mutation, Breast Cancer, CDK4/6i
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 70 participants (estimated)
- Lead sponsor
- Stemline Therapeutics, Inc.Industry (pharma, biotech, devices)
- Study start
- 18 Aug 2026 (actual)
- Primary completion
- Oct 2028 (estimated)
- Study completion
- Oct 2028 (estimated)
- First posted
- 14 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a multicenter, open-label, Phase 2 bridging study to evaluate the efficacy and safety of elacestrant in Japanese post-menopausal women and men with estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer with estrogen receptor 1 gene mutation (ESR1-mut) whose disease has relapsed or progressed on at least 1 and no more than 2 prior lines of endocrine therapy for metastatic breast cancer, which must have included cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy in combination with fulvestrant or an aromatase inhibitor.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Elacestrant | Experimental | Drug: ElacestrantParticipants will receive elacestrant once daily. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Must have a histologically or cytologically proven diagnosis of adenocarcinoma of the breast with evidence of either locally advanced disease not amenable to resection or radiation therapy with curative intent or metastatic disease not amenable to curative therapy
- Female participants must be post-menopausal (as defined by the protocol)
- Must have ER+ and HER2- tumor status confirmed per local laboratory testing
- Participants must be ESR1-mutant positive determined via testing with the Guardant360 Companion Diagnostic panel test prior to enrollment
- Must have disease progression during or within 28 days of completion of prior treatment with a CDK4/6 inhibitor in combination with either fulvestrant or an aromatase inhibitor (this counts as a line of prior endocrine therapy) for metastatic breast cancer
Key exclusion criteria (5 listed)
- Prior treatment with: elacestrant or investigational or approved selective estrogen receptor degrader or ER antagonist; antibody-drug conjugate therapy for advanced/metastatic breast cancer; anti-cancer or investigational drug treatment
- Radiation therapy within 14 days (28 days for brain lesions) before the first dose of study drug
- Intact uterus with a history of endometrial intraepithelial neoplasia (atypical endometrial hyperplasia or higher-grade lesion)
- Diagnosis of any other malignancy within 5 years before enrollment, except for adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or second primary breast cancer
- Note: Other protocol-defined inclusion/exclusion criteria may apply.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ElacestrantAdministered as an oral tablet | Drug | Elacestrant |
Primary outcome
Progression-free Survival as Assessed by the Imaging Review Committee
Time frame: Up to approximately 27 months
4 secondary outcomes
Number of Participants with Adverse Events
Time frame: Up to approximately 27 months
Plasma Concentration of Elacestrant
Time frame: Up to approximately 27 months
Progression-free Survival as Assessed by the Investigator
Time frame: Up to approximately 27 months
Overall Survival
Time frame: Up to approximately 27 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Nov 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Medical Director study director
Stemline Therapeutics, Inc.
26 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Elacestrant in people with Breast Cancer, run by Stemline Therapeutics, Inc. at 26 sites in Japan.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 5 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 26 sites in Japan. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Stemline Trials (1-877-332-7961, clinicaltrials@menarinistemline.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Progression-free Survival as Assessed by the Imaging Review Committee (time frame: Up to approximately 27 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Nov 2026; AzTrials last refreshed its copy on 6 Nov 2026.