{
  "api_version": "1",
  "request": {
    "url": "https://clinicaltrialsfind.com/api/v1/search.json?intervention=Estrogen+Receptor+Antagonist&page=4",
    "query": {
      "intervention": "Estrogen Receptor Antagonist",
      "page": 4
    },
    "page_size": 10
  },
  "pagination": {
    "page": 4,
    "page_size": 10,
    "total_count": 93,
    "total_pages": 10,
    "next_page_url": "https://clinicaltrialsfind.com/api/v1/search.json?intervention=Estrogen+Receptor+Antagonist&page=5&page_size=10",
    "previous_page_url": "https://clinicaltrialsfind.com/api/v1/search.json?intervention=Estrogen+Receptor+Antagonist&page=3&page_size=10"
  },
  "source": "remote",
  "last_synced_at": "2026-10-06T06:57:15.767Z",
  "attribution": "Data derived from public ClinicalTrials.gov records. The official record at https://clinicaltrials.gov/ remains the source of truth for current availability, contacts, and full study details.",
  "notes": [
    "This endpoint exposes only public summary fields — no participant contact emails, phone numbers, or scraped investigator contact details.",
    "For contact information and full protocol detail, follow each trial's `official_url` to the ClinicalTrials.gov record.",
    "This API is a navigational aid. It does not provide medical advice, eligibility determinations, or compensation guarantees."
  ],
  "trials": [
    {
      "nct_id": "NCT00044291",
      "title": "Phase III Study of Atamestane Plus Toremifene Versus Letrozole in Advanced Breast Cancer",
      "overall_status": "COMPLETED",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE3"
      ],
      "conditions": [
        "Breast Neoplasms",
        "Neoplasms, Hormone-dependent"
      ],
      "interventions": [
        {
          "name": "atamestane",
          "type": "DRUG"
        },
        {
          "name": "toremifene",
          "type": "DRUG"
        },
        {
          "name": "letrozole",
          "type": "DRUG"
        },
        {
          "name": "aromatase inhibition",
          "type": "DRUG"
        },
        {
          "name": "hormone therapy",
          "type": "PROCEDURE"
        },
        {
          "name": "endocrine therapy",
          "type": "PROCEDURE"
        },
        {
          "name": "antiestrogen therapy",
          "type": "PROCEDURE"
        }
      ],
      "intervention_types": [
        "DRUG",
        "PROCEDURE"
      ],
      "sponsor": "Intarcia Therapeutics",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "FEMALE",
        "summary": "18 Years and older · Female only"
      },
      "enrollment_count": 865,
      "start_date": "2002-06",
      "completion_date": "2006-01",
      "has_results": false,
      "last_update_posted_date": "2015-07-31",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 17,
      "location_summary": "Lake Havasu City, Arizona • Tucson, Arizona • Greenbrae, California + 14 more",
      "locations": [
        {
          "city": "Lake Havasu City",
          "state": "Arizona"
        },
        {
          "city": "Tucson",
          "state": "Arizona"
        },
        {
          "city": "Greenbrae",
          "state": "California"
        },
        {
          "city": "San Diego",
          "state": "California"
        },
        {
          "city": "Miami Shores",
          "state": "Florida"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT00044291"
    },
    {
      "nct_id": "NCT00005970",
      "title": "Doxorubicin Hydrochloride, Cyclophosphamide, and Pacltaxel With or Without Trastuzumab in Treating Women With HER2-Positive Node-Positive or High-Risk Node-Negative Breast Cancer",
      "overall_status": "COMPLETED",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE3"
      ],
      "conditions": [
        "Breast Adenocarcinoma",
        "HER2 Positive Breast Carcinoma",
        "Stage IA Breast Cancer AJCC v7",
        "Stage IB Breast Cancer AJCC v7",
        "Stage IIA Breast Cancer AJCC v6 and v7",
        "Stage IIB Breast Cancer AJCC v6 and v7",
        "Stage IIIA Breast Cancer AJCC v7"
      ],
      "interventions": [
        {
          "name": "Aromatase Inhibition Therapy",
          "type": "DRUG"
        },
        {
          "name": "Cyclophosphamide",
          "type": "DRUG"
        },
        {
          "name": "Doxorubicin Hydrochloride",
          "type": "DRUG"
        },
        {
          "name": "Laboratory Biomarker Analysis",
          "type": "OTHER"
        },
        {
          "name": "Paclitaxel",
          "type": "DRUG"
        },
        {
          "name": "Tamoxifen Citrate",
          "type": "DRUG"
        },
        {
          "name": "Trastuzumab",
          "type": "BIOLOGICAL"
        }
      ],
      "intervention_types": [
        "DRUG",
        "OTHER",
        "BIOLOGICAL"
      ],
      "sponsor": "National Cancer Institute (NCI)",
      "sponsor_class": "NIH",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "FEMALE",
        "summary": "18 Years and older · Female only"
      },
      "enrollment_count": 3436,
      "start_date": "2000-05-19",
      "completion_date": "2010-01-27",
      "has_results": false,
      "last_update_posted_date": "2020-08-14",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 154,
      "location_summary": "Birmingham, Alabama • Phoenix, Arizona • Scottsdale, Arizona + 119 more",
      "locations": [
        {
          "city": "Birmingham",
          "state": "Alabama"
        },
        {
          "city": "Phoenix",
          "state": "Arizona"
        },
        {
          "city": "Scottsdale",
          "state": "Arizona"
        },
        {
          "city": "Tucson",
          "state": "Arizona"
        },
        {
          "city": "Little Rock",
          "state": "Arkansas"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT00005970"
    },
    {
      "nct_id": "NCT06086340",
      "title": "Study to Compare Overall Survival in Medicare Patients With Metastatic Breast Cancer Treated With a Medicine Called Palbociclib in Combination With Aromatase Inhibitor and Aromatase Inhibitor by Itself.",
      "overall_status": "COMPLETED",
      "study_type": "OBSERVATIONAL",
      "phases": [],
      "conditions": [
        "Breast Cancer"
      ],
      "interventions": [
        {
          "name": "Palbociclib",
          "type": "DRUG"
        },
        {
          "name": "Aromatase Inhibitor",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Pfizer",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "65 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "65 Years and older"
      },
      "enrollment_count": 779,
      "start_date": "2023-09-29",
      "completion_date": "2024-01-24",
      "has_results": true,
      "last_update_posted_date": "2025-11-18",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 1,
      "location_summary": "New York, New York",
      "locations": [
        {
          "city": "New York",
          "state": "New York"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT06086340"
    },
    {
      "nct_id": "NCT03781063",
      "title": "Evaluation of Lasofoxifene Versus Fulvestrant in Advanced or Metastatic ER+/HER2- Breast Cancer With an ESR1 Mutation",
      "overall_status": "COMPLETED",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE2"
      ],
      "conditions": [
        "Locally Advanced or Metastatic Breast Cancer"
      ],
      "interventions": [
        {
          "name": "Lasofoxifene",
          "type": "DRUG"
        },
        {
          "name": "Fulvestrant",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Sermonix Pharmaceuticals Inc.",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "FEMALE",
        "summary": "18 Years and older · Female only"
      },
      "enrollment_count": 100,
      "start_date": "2019-09-20",
      "completion_date": "2025-05-08",
      "has_results": false,
      "last_update_posted_date": "2026-01-28",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 42,
      "location_summary": "Phoenix, Arizona • Yuma, Arizona • Duarte, California + 36 more",
      "locations": [
        {
          "city": "Phoenix",
          "state": "Arizona"
        },
        {
          "city": "Yuma",
          "state": "Arizona"
        },
        {
          "city": "Duarte",
          "state": "California"
        },
        {
          "city": "Fountain Valley",
          "state": "California"
        },
        {
          "city": "San Francisco",
          "state": "California"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT03781063"
    },
    {
      "nct_id": "NCT05361655",
      "title": "Real-World Effectiveness of Palbociclib in Combination With an Aromatase Inhibitor",
      "overall_status": "COMPLETED",
      "study_type": "OBSERVATIONAL",
      "phases": [],
      "conditions": [
        "Metastatic Breast Cancer"
      ],
      "interventions": [
        {
          "name": "Palbociclib + an aromatase inhibitor",
          "type": "DRUG"
        },
        {
          "name": "Aromatase inhibitor",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Pfizer",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "18 Years and older"
      },
      "enrollment_count": 2888,
      "start_date": "2021-09-01",
      "completion_date": "2021-09-01",
      "has_results": true,
      "last_update_posted_date": "2024-06-07",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 1,
      "location_summary": "New York, New York",
      "locations": [
        {
          "city": "New York",
          "state": "New York"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT05361655"
    },
    {
      "nct_id": "NCT04762979",
      "title": "Alpelisib (BYL719) in Combination With Continued Endocrine Therapy Following Progression on Endocrine Therapy in Hormone Receptor Positive, HER2 Negative, PIK3CA Mutant Metastatic Breast Cancer",
      "overall_status": "ACTIVE_NOT_RECRUITING",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE2"
      ],
      "conditions": [
        "Hormone Receptor Positive Breast Carcinoma",
        "HER2-negative Breast Cancer",
        "PIK3CA Mutant Metastatic Breast Cancer"
      ],
      "interventions": [
        {
          "name": "Alpelisib",
          "type": "DRUG"
        },
        {
          "name": "Fulvestrant",
          "type": "DRUG"
        },
        {
          "name": "Aromatase inhibitor",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Marina N Sharifi",
      "sponsor_class": "OTHER",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "18 Years and older"
      },
      "enrollment_count": 44,
      "start_date": "2021-02-12",
      "completion_date": "2026-05",
      "has_results": false,
      "last_update_posted_date": "2026-01-02",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 4,
      "location_summary": "Chicago, Illinois • Omaha, Nebraska • Hershey, Pennsylvania + 1 more",
      "locations": [
        {
          "city": "Chicago",
          "state": "Illinois"
        },
        {
          "city": "Omaha",
          "state": "Nebraska"
        },
        {
          "city": "Hershey",
          "state": "Pennsylvania"
        },
        {
          "city": "Madison",
          "state": "Wisconsin"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT04762979"
    },
    {
      "nct_id": "NCT05508906",
      "title": "Phase 1b Study of OP-1250 (Palazestrant) in Combination With Ribociclib, Alpelisib, Everolimus, or Atirmociclib in ER+, HER2- Breast Cancer",
      "overall_status": "ACTIVE_NOT_RECRUITING",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE1"
      ],
      "conditions": [
        "Metastatic Breast Cancer",
        "ER-positive Breast Cancer",
        "HER2-negative Breast Cancer",
        "Breast Cancer",
        "Locally Advanced Breast Cancer"
      ],
      "interventions": [
        {
          "name": "Palazestrant",
          "type": "DRUG"
        },
        {
          "name": "Ribociclib",
          "type": "DRUG"
        },
        {
          "name": "Alpelisib",
          "type": "DRUG"
        },
        {
          "name": "Everolimus",
          "type": "DRUG"
        },
        {
          "name": "Atirmociclib",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Olema Pharmaceuticals, Inc.",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "18 Years and older"
      },
      "enrollment_count": 190,
      "start_date": "2022-08-31",
      "completion_date": "2028-01-31",
      "has_results": false,
      "last_update_posted_date": "2026-09-15",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 14,
      "location_summary": "Gilbert, Arizona • San Francisco, California • Aurora, Colorado + 11 more",
      "locations": [
        {
          "city": "Gilbert",
          "state": "Arizona"
        },
        {
          "city": "San Francisco",
          "state": "California"
        },
        {
          "city": "Aurora",
          "state": "Colorado"
        },
        {
          "city": "Orlando",
          "state": "Florida"
        },
        {
          "city": "Iowa City",
          "state": "Iowa"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT05508906"
    },
    {
      "nct_id": "NCT03831711",
      "title": "68-Ga-RM2 PET/MRI in Imaging Patients With Estrogen Receptor-Positive Breast Cancer",
      "overall_status": "COMPLETED",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE1",
        "PHASE2"
      ],
      "conditions": [
        "Breast Carcinoma",
        "Estrogen Receptor Positive"
      ],
      "interventions": [
        {
          "name": "Gallium Ga 68-labeled GRPR Antagonist BAY86-7548",
          "type": "DRUG"
        },
        {
          "name": "Magnetic Resonance Imaging",
          "type": "PROCEDURE"
        },
        {
          "name": "Positron Emission Tomography",
          "type": "PROCEDURE"
        },
        {
          "name": "Investigational software and coils in PET/MR scan",
          "type": "DEVICE"
        }
      ],
      "intervention_types": [
        "DRUG",
        "PROCEDURE",
        "DEVICE"
      ],
      "sponsor": "Andrei Iagaru",
      "sponsor_class": "OTHER",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "18 Years and older"
      },
      "enrollment_count": 5,
      "start_date": "2019-03-19",
      "completion_date": "2021-11-15",
      "has_results": true,
      "last_update_posted_date": "2023-12-13",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 1,
      "location_summary": "Palo Alto, California",
      "locations": [
        {
          "city": "Palo Alto",
          "state": "California"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT03831711"
    },
    {
      "nct_id": "NCT06993844",
      "title": "Phase 1/2 Study of ETX-636 in Participants With Advanced Solid Tumors",
      "overall_status": "RECRUITING",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE1",
        "PHASE2"
      ],
      "conditions": [
        "Advanced Solid Tumors",
        "Advanced Breast Cancer"
      ],
      "interventions": [
        {
          "name": "ETX-636 dose escalation",
          "type": "DRUG"
        },
        {
          "name": "ETX-636 dose escalation in combination with fulvestrant",
          "type": "DRUG"
        },
        {
          "name": "ETX-636 dose expansion in combination with fulvestrant",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "Ensem Therapeutics",
      "sponsor_class": "INDUSTRY",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": null,
        "sex": "ALL",
        "summary": "18 Years and older"
      },
      "enrollment_count": 233,
      "start_date": "2025-06-10",
      "completion_date": "2027-12-30",
      "has_results": false,
      "last_update_posted_date": "2026-06-23",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 10,
      "location_summary": "Newport Beach, California • San Francisco, California • New Haven, Connecticut + 6 more",
      "locations": [
        {
          "city": "Newport Beach",
          "state": "California"
        },
        {
          "city": "San Francisco",
          "state": "California"
        },
        {
          "city": "New Haven",
          "state": "Connecticut"
        },
        {
          "city": "Boston",
          "state": "Massachusetts"
        },
        {
          "city": "Boston",
          "state": "Massachusetts"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT06993844"
    },
    {
      "nct_id": "NCT06701071",
      "title": "Evaluation of a Long Versus Short Clomid Protocol for Controlled Ovarian Stimulation",
      "overall_status": "RECRUITING",
      "study_type": "INTERVENTIONAL",
      "phases": [
        "PHASE4"
      ],
      "conditions": [
        "Infertility, Female"
      ],
      "interventions": [
        {
          "name": "Clomiphene Citrate",
          "type": "DRUG"
        }
      ],
      "intervention_types": [
        "DRUG"
      ],
      "sponsor": "University of Southern California",
      "sponsor_class": "OTHER",
      "healthy_volunteers": false,
      "eligibility": {
        "minimum_age": "18 Years",
        "maximum_age": "44 Years",
        "sex": "FEMALE",
        "summary": "18 Years to 44 Years · Female only"
      },
      "enrollment_count": 120,
      "start_date": "2025-06-01",
      "completion_date": "2028-06",
      "has_results": false,
      "last_update_posted_date": "2026-08-04",
      "last_synced_at": "2026-10-06T06:57:15.767Z",
      "location_count": 1,
      "location_summary": "Pasadena, California",
      "locations": [
        {
          "city": "Pasadena",
          "state": "California"
        }
      ],
      "official_url": "https://clinicaltrials.gov/study/NCT06701071"
    }
  ]
}