A Phase 2 Bridging Study of Elacestrant Monotherapy in Advanced or Metastatic Breast Cancer

NCT07766018 | Recruiting Phase 2 DMC FDA Drug

• 2 other identifiers: STML-ELA-03262026-0020
• Study Type: interventional
• Target: 70
• Locations: 1 country
• Sites: 1

Brief 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 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

ER+/HER2- Advanced or Metastatic Breast Cancer

Keywords

Elacestrant; Bridging Study; Japan; ESR1-mutation; Breast Cancer; CDK4/6i

Outcome Measures

Primary Outcomes (1)

• Progression-free Survival as Assessed by the Imaging Review Committee

  Up to approximately 27 months

Secondary Outcomes (4)

• Number of Participants with Adverse Events

  Up to approximately 27 months

• Plasma Concentration of Elacestrant

  Up to approximately 27 months

• Progression-free Survival as Assessed by the Investigator

  Up to approximately 27 months

• Overall Survival

  Up to approximately 27 months

Study Arms (1)

Elacestrant

EXPERIMENTAL

Participants will receive elacestrant once daily.

Drug: Elacestrant

Interventions

Elacestrant DRUG

Administered as an oral tablet

Elacestrant

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Stemline Therapeutics, Inc.: lead

Study Sites (1)

Tokai University Hospital

Isehara, Japan

RECRUITING

MeSH Terms

Conditions

Breast Neoplasms

Interventions

elacestrant

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Study Officials

• Medical Director

  Stemline Therapeutics, Inc.

  STUDY DIRECTOR

Central Study Contacts

Stemline Trials

CONTACT

1-877-332-7961; clinicaltrials@menarinistemline.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 10, 2026
• First Posted: August 14, 2026
• Study Start: August 1, 2026
• Primary Completion (Estimated): October 1, 2028
• Study Completion (Estimated): October 1, 2028
• Last Updated: August 14, 2026

Record last verified: 2026-08

Locations

JP (1)