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Study identifier: NCT03781063 Synced from ClinicalTrials.gov · July 27, 2026
● Completed

Evaluation of Lasofoxifene Versus Fulvestrant in Advanced or Metastatic ER+/HER2- Breast Cancer With an ESR1 Mutation

Condition: Locally Advanced or Metastatic Breast Cancer  ·  Sponsor: Sermonix Pharmaceuticals Inc.

PhasePhase 2
Planned participants100
Who can joinFemale, 18 Years to no upper limit
Healthy volunteersNo

About this study

This is an open label, randomized, multicenter study evaluating the activity of lasofoxifene relative to fulvestrant for the treatment of pre- and postmenopausal women with locally advanced or metastatic ER+/HER2- breast cancer with an acquired ESR1 mutation and who have disease progression on an aromatase inhibitor (AI) in combination with a cyclin dependent kinase (CDK) 4/6 inhibitor. The primary objective is to evaluate the progression free survival (PFS) of 5 mg lasofoxifene relative to fulvestrant for the treatment of pre- and postmenopausal women with 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 secondary objectives are to evaluate: 1. Clinical benefit rate (CBR) and Objective Response Rate (ORR) 2. Duration of response 3. Time to response 4. Overall Survival (OS) 5. Pharmacokinetics of lasofoxifene 6. Quality of life (QoL): Quality of Life (QoL): vaginal assessment scale (VAS) and vulvar assessment scale (VuAS) questionnaires 7. Safety of lasofoxifene 8. Response to various ESR1 mutation (Y537S, Y537C, D538G, E380Q, S463P, V534E, P535H, L536H, L536P, L536R, L536Q, or Y537N).

This description comes directly from the study's public registry record.

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Contact details are listed per location below or on the registry record.

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Locations (51)

Mayo Clinic ArizonaPhoenix, Arizona, United States
Yuma Regional Medical Center (JIT)Yuma, Arizona, United States
City of Hope Comprehensive CancerDuarte, California, United States
Compassionate Care Research GroupFountain Valley, California, United States
UCSF Cancer CenterSan Francisco, California, United States
Rocky Mountain Cancer CentersLongmont, Colorado, United States
Mayo Clinic FloridaJacksonville, Florida, United States
Miami Cancer InstituteMiami, Florida, United States
Ocala Oncology Center (JIT)Oscala, Florida, United States
Florida Cancer SpecialistsTallahassee, Florida, United States
The Bond Clinic Cancer & Research Center.Winter Haven, Florida, United States
Emory UniversityAtlanta, Georgia, United States

+ 39 more locations — full list on the registry record.

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Source record: clinicaltrials.gov/study/NCT03781063