A Phase 3 interventional study of Elacestrant and Standard of Care in Breast Cancer, sponsored by Stemline Therapeutics, Inc.. Completed at 244 sites in 17 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-09-15.
Sponsored by Stemline Therapeutics, Inc. · Phase 3, Interventional, and Treatment
This Phase 3 clinical study compares the efficacy and safety of elacestrant to the standard of care (SoC) options of fulvestrant or an aromatase inhibitor (AI) in women and men with breast cancer whose disease has advanced on at least one endocrine therapy including a CDK4/6 inhibitor in combination with fulvestrant or an aromatase inhibitor (AI).
This is an international, multicenter, randomized, open-label, active-controlled, event-driven, Phase 3 clinical study comparing the efficacy and safety of elacestrant to the SoC options of fulvestrant or an aromatase inhibitor (AI) in postmenopausal women and in men with advanced or metastatic ER+/HER2- breast cancer, either in participants with tumors that harbor mutations in the ligand binding domain (LBD) of the estrogen receptor 1 (ESR1) gene (ESR1-mut participants) or in all participants regardless of ESR1 status (ESR1-mut and ESR1 wild type [ESR1-wt]) and whose disease has relapsed or progressed on at least one and no more than two prior lines of endocrine therapy (with documented progression), which must have included prior CDK4/6 inhibitor therapy in combination with fulvestrant or an aromatase inhibitor (AI) and for whom hormonal monotherapy with one of the SoC drugs (fulvestrant, anastrozole, letrozole, exemestane) is an appropriate treatment option.
12,544 studies on the registry are indexed under Breast Neoplasms; 2,892 are open to participants now.
This study's enrollment of 478 is above the median of 72 across 9,303 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →Stemline Therapeutics, Inc. is the lead sponsor of 22 studies on the registry; 7 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Critical Inclusion Criteria:
Critical Exclusion Criteria:
Prior anticancer or investigational drug treatment within the following windows:
Participants in Arm 1 will receive elacestrant.
Drug: Elacestrant
Participants in Arm 2 will receive investigator's choice of one of the standard-of-care drugs (fulvestrant, anastrozole, letrozole, or exemestane).
Drug: Standard of Care
400 mg/day once daily oral dosing
Also known as: RAD1901, ORSERDU
* Fulvestrant: 500 mg administered intramuscularly (IM) into the buttocks as two 5 mL injections on C1D1, C1D15 and C2D1 and Day 1 of every subsequent 28-day cycle * Anastrozole 1 mg/day on a continuous dosing schedule * Letrozole: 2.5 mg/day on a continuous dosing schedule * Exemestane: 25 mg/day on a continuous dosing schedule
Also known as: Faslodex, Arimidex, Femara, Aromasin
Progression-free Survival in ESR1-mut Participants
Progression-free survival based on blinded IRC assessment in ESR1-mut participants defined as the length of time from randomization until the date of objective disease progression per Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) as assessed by the blinded IRC or death from any cause. Progression is defined per RECIST v1.1 as a 20% increase in the sum of the longest diameter of target lesions, or a measurable increase in a non-target lesion, or the appearance of new lesions.
Time frame: From Date of Randomization until Disease Progression or Death Due to Any Cause (up to 12 Months)
Progression-free Survival in All Participants
Progression-free survival based on blinded imaging review committee (IRC) assessment in all (ESR1-mut and ESR1-wt) participants.
Time frame: From Date of Randomization until Disease Progression or Death Due to Any Cause (up to 12 Months)
Overall Survival in ESR1-mut Participants
Overall survival in ESR1-mut participants, where overall survival is defined as the length of time from randomization until the date of death from any cause.
Time frame: From Date of Randomization until Death Due to Any Cause (Estimated up to 24 Months)
Overall Survival in All Participants
Overall survival in all (ESR1-mut and ESR1-wt) participants.
Time frame: From Date of Randomization until Death Due to Any Cause (Estimated up to 24 Months)
| Milestone | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| Started | 239 | 239 |
| Intent-to-treat population | 239 | 239 |
| Safety population | 237 | 230 |
| Completed | 152 | 130 |
| Not completed | 87 | 109 |
| Withdrew: Withdrawal by subject | 12 | 25 |
| Withdrew: Physician decision | 1 | 3 |
| Withdrew: Participant noncompliance | 1 | 1 |
| Withdrew: Lost to follow-up | 4 | 1 |
| Withdrew: Death | 69 | 79 |
Progression-free survival based on blinded IRC assessment in ESR1-mut participants defined as the length of time from randomization until the date of objective disease progression per Response Evaluation Criteria In Solid Tumors Criteria (RECIST v1.1) as assessed by the blinded IRC or death from any cause. Progression is defined per RECIST v1.1 as a 20% increase in the sum of the longest diameter of target lesions, or a measurable increase in a non-target lesion, or the appearance of new lesions.
| months | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| Progression-free Survival in ESR1-mut Participants | 3.78 (2.17 to 7.26) | 1.87 (1.87 to 2.14) |
Progression-free survival based on blinded imaging review committee (IRC) assessment in all (ESR1-mut and ESR1-wt) participants.
| months | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| Progression-free Survival in All Participants | 2.79 (1.94 to 3.78) | 1.91 (1.87 to 2.10) |
Overall survival in ESR1-mut participants, where overall survival is defined as the length of time from randomization until the date of death from any cause.
| months | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| Overall Survival in ESR1-mut Participants | NA (18.60 to NA) | 16.95 (14.00 to NA) |
Overall survival in all (ESR1-mut and ESR1-wt) participants.
| months | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| Overall Survival in All Participants | NA (19.29 to NA) | NA (15.80 to NA) |
Collected over 24 months. Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Elacestrant | 70/239 (29.3%) | 29/237 (12.2%) | 215/237 (90.7%) |
| Standard of Care (SoC) | 80/239 (33.5%) | 25/230 (10.9%) | 195/230 (84.8%) |
| Event | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| PneumoniaInfections and infestations | 1/237 | 3/230 |
| NauseaGastrointestinal disorders | 3/237 | 0/230 |
| Abdominal painGastrointestinal disorders | 0/237 | 2/230 |
| Urinary tract infectionInfections and infestations | 0/237 | 2/230 |
| VomitingGastrointestinal disorders | 2/237 | 0/230 |
| Small intestinal obstructionGastrointestinal disorders | 2/237 | 0/230 |
| Back painMusculoskeletal and connective tissue disorders | 2/237 | 0/230 |
| Spinal cord compressionNervous system disorders | 2/237 | 0/230 |
| ColitisGastrointestinal disorders | 0/237 | 1/230 |
| DiarrhoeaGastrointestinal disorders | 0/237 | 1/230 |
| Event | Elacestrant | Standard of Care (SoC) |
|---|---|---|
| NauseaGastrointestinal disorders | 83/237 | 44/230 |
| FatigueGeneral disorders | 45/237 | 44/230 |
| VomitingGastrointestinal disorders | 45/237 | 20/230 |
| ArthralgiaMusculoskeletal and connective tissue disorders | 34/237 | 37/230 |
| Decreased appetiteMetabolism and nutrition disorders | 35/237 | 22/230 |
| DiarrhoeaGastrointestinal disorders | 33/237 | 22/230 |
| Back painMusculoskeletal and connective tissue disorders | 32/237 | 22/230 |
| Aspartate aminotransferase increasedInvestigations | 31/237 | 29/230 |
| ConstipationGastrointestinal disorders | 29/237 | 15/230 |
| HeadacheNervous system disorders | 29/237 | 26/230 |
| Age, Categorical(Participants) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| <=18 years | 0 | 0 | 0 |
| Between 18 and 65 years | 135 | 128 | 263 |
| >=65 years | 104 | 111 | 215 |
| Sex: Female, Male(Participants) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| Female | 233 | 238 | 471 |
| Male | 6 | 1 | 7 |
| Ethnicity (NIH/OMB)(Participants) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| Hispanic or Latino | 19 | 18 | 37 |
| Not Hispanic or Latino | 194 | 191 | 385 |
| Unknown or Not Reported | 26 | 30 | 56 |
| Height(cm) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| Mean | 162.27 ± 7.860 | 160.97 ± 7.149 | 161.62 ± 7.532 |
| Weight(kg) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| Mean | 72.70 ± 16.093 | 72.39 ± 16.390 | 72.55 ± 16.226 |
| Body Mass Index(kg/m^2) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| Mean | 27.58 ± 5.494 | 27.92 ± 5.853 | 27.75 ± 5.673 |
| Eastern Cooperative Oncology Group Performance Status(Participants) | Elacestrant | Standard of Care (SoC) | Total |
|---|---|---|---|
| 0: Fully active, able to carry on all pre-disease performance without restriction | 143 | 135 | 278 |
| 1: Restricted in physically strenuous activity but ambulatory & can carry out light, sedentary work | 96 | 103 | 199 |
| 2: Ambulatory and capable of all selfcare but unable to carry out any work activities | 0 | 1 | 1 |
Showing the first 100 of 244 sites across 17 countries.
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Stemline Therapeutics, Inc.