Medical Information Only. Consult your healthcare provider before considering clinical trial enrollment.
ER Positive Breast Cancer: early-phase trial registry
7 of 11 indexed ER Positive Breast Cancer trials are currently recruiting, with more weight in Phase 1-2.
Corpus placement: #1,577 of 28,707 conditions by registered trial count.
11 US clinical trials · 7 currently recruiting · #1,577 of 28,707 conditions by registered trial count
ER Positive Breast Cancer: 11 US clinical trials tracked, 7 recruiting.
ER Positive Breast Cancer is the subject of 11 registered US clinical trials on ClinicalTrials.gov, 7 of them currently open to new participants. 2 are in Phase 3-4 (later-stage) and 8 in Phase 1-2 (earlier-stage). The most active sponsor is Olema Pharmaceuticals, running 3 of these trials.
Enrollment posture brief
Registry condition er-positive-breast-cancer
OPEN 7 | RECR 64% | LATE 2 | EARLY 8 | RANK #1577 | SPON 3
Volume-matched condition peers
Nearest open-share peer: Advanced Melanoma (64% recruiting · 22 trials)
ER Positive Breast Cancer lists 7 open slots (64% of 11 indexed trials). Peers are matched on registered volume, not therapeutic-area browse lists. How peer matching works →
Key findings
What ClinicalTrials.gov does not surface for ER Positive Breast Cancer on its own pages , computed from the registry mirror as of 2026-08-08. Each line carries its own denominator so it can be quoted as it stands.
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ER Positive Breast Cancer is recruiting above its size-band peers.
7 of 11 indexed trials (63.6%) are open to enrollment, against a 46.5% average across 27,806 conditions with fewer than 20 trials. The peer set uses the same ClinicalTrials.gov-derived counts as this page.
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One sponsor concentrates ER Positive Breast Cancer research.
Olema Pharmaceuticals accounts for 3 of 11 trials (27.3%). 9 distinct sponsors appear on at least one study for this condition label.
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Typical ER Positive Breast Cancer enrolment sits around 134 participants.
Median target enrolment is 134 among the 11 trials that report a genuine target (sentinel values excluded). 5 of those (45.5%) plan for fewer than 100 participants.
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ER Positive Breast Cancer research is mostly interventional.
10 interventional and 1 observational studies make up this index (90.9% interventional). Study type is sponsor-reported on ClinicalTrials.gov.
Open and recent trials
11 total, page 1 of 1
Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer
Olema Pharmaceuticals
NCT07085767
OP-1250 (Palazestrant) vs. Standard of Care for the Treatment of ER+/HER2- Advanced Breast Cancer
Olema Pharmaceuticals
NCT06016738
Role of the Immune Environment in Response to Therapy in Breast Cancer
Abramson Cancer Center at Penn Medicine
NCT05396612
Phase 1b Study of OP-1250 (Palazestrant) in Combination With Ribociclib, Alpelisib, Everolimus, or Atirmociclib in ER+, HER2- Breast Cancer
Olema Pharmaceuticals
NCT05508906
DATO-BASE: DATOpotamab-deruxtecan for Breast Cancer Brain metAstaSEs
Sarah Sammons, MD
NCT06176261
Trial of Pre-operative Neratinib and Endocrine Therapy With Trastuzumab in ER-Positive, HER-2 Positive Breast Cancers
Ruth O'Regan
NCT04886531
Fulvestrant+Abemaciclib With Run-In of Fulvestrant in Er-Positive, Her2-Negative Metastatic Breast Cancer
The Methodist Hospital Research Institute
NCT05305924
Phase II Study of Neoadjuvant ArOMatase Inhibitor Therapy for ER+ Breast Cancer (NAOMI)
Dartmouth-Hitchcock Medical Center
NCT04568616
A Phase 1 Study of ATV-1601 in Patients With Advanced Cancer That Have AKT1 E17K Mutations
Atavistik Bio
NCT07038369
Levels of Circulating Tumor DNA as a Predictive Marker for Early Switch in Treatment for Patients With Metastatic (Stage IV) Breast Cancer
University of Miami
NCT05826964
Umbrella Trial of Subtype-Targeted Therapies in ER+/HER2- Breast Cancer
Jennifer Lee Caswell-Jin
NCT05101564
Phase Distribution
| Phase | Trial count |
|---|---|
| Phase 1 | 2 |
| Phase 2 | 6 |
| Phase 3 | 2 |
Top Sponsors
Named interventions
Most-linked intervention names on ER Positive Breast Cancer records (sponsor-reported on ClinicalTrials.gov). Counts are trial links, not unique products.
US sites by state
Facility locations filed on ER Positive Breast Cancer trials. A trial with sites in several states counts in each.
Source: ClinicalTrials.gov, National Library of Medicine. Data is informational only.
Related
What to do with this ER Positive Breast Cancer page
11 registered trials, 7 currently recruiting, is a starting point for a conversation, not a diagnosis or a recommendation.
- 7 ER Positive Breast Cancer trials are currently recruiting, check eligibility criteria before contacting a site. Browse recruiting trials
- Olema Pharmaceuticals sponsors the most ER Positive Breast Cancer trials on record, review their full trial history before evaluating a specific study. See Olema Pharmaceuticals's trials
- Bring the specific trial ID (NCT number) to your own doctor before enrolling, this page is a directory, not medical guidance. Read the trial-finding guide
Trial and recruiting counts reflect ClinicalTrials.gov registry status as of the data vintage above; individual trial eligibility and enrollment status can change.
Every figure on PlainTrial is rendered directly from the ClinicalTrials.gov registry, no number is typed in by an editor. This ER Positive Breast Cancer condition card totals 11 registered trials; most-linked intervention Palazestrant; top US site state Florida. See our editorial standards & corrections policy, the methodology behind these numbers, the data changelog, or report a data error.