OP-1250 (Palazestrant) vs. Standard of Care for the Treatment of ER+/HER2- Advanced Breast Cancer (OPERA-01)

A Phase 3 Randomized, Open-Label Study of OP-1250 Monotherapy vs Standard of Care for the Treatment of ER+, HER2- Advanced or Metastatic Breast Cancer Following Endocrine and CDK 4/6 Inhibitor Therapy (OPERA-01)

This phase 3 clinical trial compares the safety and efficacy of palazestrant (OP-1250) to the standard-of-care options of fulvestrant or an aromatase inhibitor in women and men with breast cancer whose disease has advanced on one endocrine therapy in combination with a CDK4/6 inhibitor.

Study Overview

• Status: Recruiting
• Conditions: Breast Cancer; Advanced Breast Cancer; Metastatic Breast Cancer; HER2 Negative Breast Carcinoma; ER Positive Breast Cancer
• Intervention / Treatment: Drug: Fulvestrant; Drug: Anastrozole; Drug: Letrozole; Drug: Exemestane; Drug: Palazestrant

Detailed Description

This is an international, multicenter, randomized, open-label, active-controlled, phase 3 clinical trial. The purpose of this trial is to compare the safety and efficacy of palazestrant (OP-1250) as a single agent to the standard of care endocrine therapy: either fulvestrant or an aromatase inhibitor (anastrozole, letrozole, or exemestane).

This trial is seeking adult participants with ER+, HER2- advanced or metastatic breast cancer whose disease has relapsed or progressed on 1 or 2 prior lines of standard-of-care endocrine therapy for metastatic breast cancer. Prior lines of therapy must include one line of endocrine therapy in combination with a CDK 4/6 inhibitor. In the dose-selection part of the trial, approximately 120 participants will be randomized to one of the two doses of palazestrant or to the standard-of-care endocrine therapy. Thereafter, approximately 390 participants will be randomized to palazestrant at the selected dose or to the standard-of-care endocrine therapy.

• Study Type: Interventional
• Enrollment (Estimated): 510
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Olema Pharmaceuticals, Inc.; Phone Number: 415-651-7206; Email: OPERA-01@olema.com

Study Locations

• Argentina
  • Buenos Aires, Argentina, C14626ABP
    • Active, not recruiting
    • Clinical Trial Site
  • Buenos Aires
    • Bahía Blanca, Buenos Aires, Argentina, B8000HXM
      • Active, not recruiting
      • Clinical Trial Site
    • Mar del Plata, Buenos Aires, Argentina, B7600FZN
      • Active, not recruiting
      • Clinical Trial Site
    • Mar del Plata, Buenos Aires, Argentina
      • Active, not recruiting
      • Clinical Trial Site
  • Córdoba Province
    • Córdoba, Córdoba Province, Argentina, X5000HHW
      • Active, not recruiting
      • Clinical Trial Site
    • Córdoba, Córdoba Province, Argentina, X5008HHW
      • Active, not recruiting
      • Clinical Trial Site
  • Jujuy Province
    • San Salvador de Jujuy, Jujuy Province, Argentina, 4600
      • Active, not recruiting
      • Clinical Trial Site
  • La Rioja Province
    • La Rioja, La Rioja Province, Argentina, 5300
      • Active, not recruiting
      • Clinical Trial Site
  • Río Negro Province
    • Viedma, Río Negro Province, Argentina, R8500ACE
      • Active, not recruiting
      • Clinical Trial Site
  • Santa Fe Province
    • Rosario, Santa Fe Province, Argentina, S2013DTC
      • Active, not recruiting
      • Clinical Trial Site
    • Rosario, Santa Fe Province, Argentina, S2013KDS
      • Active, not recruiting
      • Clinical Trial Site
  • Tucumán Province
    • San Miguel de Tucumán, Tucumán Province, Argentina, 4000
      • Active, not recruiting
      • Clinical Trial Site
• Australia
  • New South Wales
    • Gosford, New South Wales, Australia, 2250
      • Recruiting
      • Clinical Trial Site
    • Westmead, New South Wales, Australia, 2145
      • Recruiting
      • Clinical Trial Site
  • South Australia
    • Adelaide, South Australia, Australia, 5000
      • Recruiting
      • Clinical Trial Site
  • Victoria
    • Ballarat Central, Victoria, Australia, 3355
      • Recruiting
      • Clinical Trial Site
    • Clayton, Victoria, Australia, 3168
      • Recruiting
      • Clinical Trial Site
    • Shepparton, Victoria, Australia, 3630
      • Recruiting
      • Clinical Trial Site
  • Western Australia
    • Nedlands, Western Australia, Australia, 6009
      • Recruiting
      • Clinical Trial Site
• Austria
  • Wels, Austria, 4600
    • Recruiting
    • Clinical Trial Site
  • Wiener Neustadt, Austria, 2700
    • Recruiting
    • Clinical Trial Site
• Belgium
  • Antwerpen
    • Edegem, Antwerpen, Belgium, 2650
      • Recruiting
      • Clinical Trial Site
    • Wilrijk, Antwerpen, Belgium, 2610
      • Recruiting
      • Clinical Trial Site
  • Brussels Capital
    • Woluwe-Saint-Lambert, Brussels Capital, Belgium, 1200
      • Recruiting
      • Clinical Trial Site
  • Hainaut
    • Charleroi, Hainaut, Belgium, 6060
      • Recruiting
      • Clinical Trial Site
  • Vlaams Brabant
    • Leuven, Vlaams Brabant, Belgium
      • Withdrawn
      • Clinical Trial Site
• Brazil
  • Porto Alegre, Brazil, 90470-340
    • Not yet recruiting
    • Clinical Trial Site
  • Rio de Janeiro, Brazil, 22281-100
    • Recruiting
    • Clinical Trial Site
  • Estado de Bahia
    • Salvador, Estado de Bahia, Brazil, 41253-190
      • Recruiting
      • Clinical Trial Site
  • Federal District
    • Brasília, Federal District, Brazil, 70.390-140
      • Recruiting
      • Clinical Trial Site
  • Maranhão
    • São Luís, Maranhão, Brazil, 65.060-645
      • Recruiting
      • Clinical Trial Site
  • Minas Gerais
    • Belo Horizonte, Minas Gerais, Brazil, 30150-221
      • Recruiting
      • Clinical Trial Site
  • Paraná
    • Curitiba, Paraná, Brazil, 81520-060
      • Recruiting
      • Clinical Trial Site
  • Pernambuco
    • Recife, Pernambuco, Brazil, 50070-480
      • Recruiting
      • Clinical Trial Site
  • Rio Grande do Sul
    • Porto Alegre, Rio Grande do Sul, Brazil, 90035-903
      • Recruiting
      • Clinical Trial Site
    • Porto Alegre, Rio Grande do Sul, Brazil, 90050-170
      • Recruiting
      • Clinical Trial Site
    • Porto Alegre, Rio Grande do Sul, Brazil, 91350-200
      • Recruiting
      • Clinical Trial Site
  • Santa Catarina
    • Itajaí, Santa Catarina, Brazil, 88301-220
      • Recruiting
      • Clinical Trial Site
  • São Paulo
    • Jaú, São Paulo, Brazil, 17210-080
      • Recruiting
      • Clinical Trial Site
    • Sorocaba, São Paulo, Brazil, 18052-775
      • Recruiting
      • Clinical Trial Site
• Bulgaria
  • Pazardzhik
    • Panagyurishte, Pazardzhik, Bulgaria, 4500
      • Recruiting
      • Clinical Trial Site
  • Sofia-Grad
    • Sofia, Sofia-Grad, Bulgaria, 1407
      • Recruiting
      • Clinical Trial Site
  • Vratsa
    • Vratsa, Vratsa, Bulgaria, 3000
      • Withdrawn
      • Clinical Trial Site
• Canada
  • Alberta
    • Calgary, Alberta, Canada, T2N 5G2
      • Recruiting
      • Clinical Trial Site
  • Ontario
    • London, Ontario, Canada, N6A 5W9
      • Recruiting
      • Clinical Trial Site
    • Toronto, Ontario, Canada, M5G 1X5
      • Recruiting
      • Clinical Trial Site
  • Quebec
    • Montreal, Quebec, Canada, H4A 3J1
      • Recruiting
      • Clinical Trial Site
• Czechia
  • Brno, Czechia, 625 00
    • Recruiting
    • Clinical Trial Site
  • Prague, Czechia, 140 59
    • Recruiting
    • Clinical Trial Site
  • Královéhradecký kraj
    • Hradec Králové, Královéhradecký kraj, Czechia, 500 12
      • Withdrawn
      • Clinical Trial Site
  • Moravskoslezský kraj
    • Nový Jičín, Moravskoslezský kraj, Czechia, 741 01
      • Recruiting
      • Clinical Trial Site
  • Olomoucký kraj
    • Olomouc, Olomoucký kraj, Czechia, 779 00
      • Recruiting
      • Clinical Trial Site
• France
  • Caen, France, 14000
    • Recruiting
    • Clinical Trial Site
  • Montpellier, France, 34070
    • Recruiting
    • Clinical Trial Site
  • Paris, France, 75014
    • Not yet recruiting
    • Clinical Trial Site
  • Ain
    • Bourg-en-Bresse, Ain, France, 01000
      • Recruiting
      • Clinical Trial Site
  • Doubs
    • Besançon, Doubs, France, 25030
      • Recruiting
      • Clinical Trial Site
  • Loire-Atlantique
    • Nantes, Loire-Atlantique, France, 44805
      • Recruiting
      • Clinical Trial Site
    • Nantes, Loire-Atlantique, France, 44277
      • Recruiting
      • Clinical Trial Site
  • Oise
    • Compiègne, Oise, France, 60200
      • Recruiting
      • Clinical Trial Site
  • Puy-de-Dôme
    • Clermont-Ferrand, Puy-de-Dôme, France, 63011
      • Recruiting
      • Clinical Trial Site
  • Sarthe
    • Le Mans, Sarthe, France, 7200
      • Recruiting
      • Clinical Trial Site
  • Val-de-Marne
    • Villejuif, Val-de-Marne, France, 94805
      • Recruiting
      • Clinical Trial Site
• Germany
  • Baden-Wurttemberg
    • Karlsruhe, Baden-Wurttemberg, Germany, 76135
      • Recruiting
      • Clinical Trial Site
  • North Rhine-Westphalia
    • Krefeld, North Rhine-Westphalia, Germany, 47805
      • Recruiting
      • Clinical Trial Site
    • Velbert, North Rhine-Westphalia, Germany, 42551
      • Recruiting
      • Clinical Trial Site
  • Saxony
    • Dresden, Saxony, Germany, 01307
      • Recruiting
      • Clinical Trial Site
  • Schleswig-Holstein
    • Kiel, Schleswig-Holstein, Germany, 24105
      • Recruiting
      • Clinical Trial Site
• Hong Kong
  • Hong Kong, Hong Kong, 999077
    • Recruiting
    • Clinical Trial Site
  • Hong Kong, Hong Kong, 999077
    • Recruiting
    • Clinical Trials Site
  • Hong Kong
    • Central, Hong Kong, Hong Kong, 100176
      • Withdrawn
      • Clinical Trial Site
    • Hong Kong, Hong Kong, Hong Kong, 999077
      • Recruiting
      • Clinical Trial Site
    • Kowloon, Hong Kong, Hong Kong, 999077
      • Recruiting
      • Clinical Trial Site
• Hungary
  • Baranya
    • Pécs, Baranya, Hungary, 7624
      • Recruiting
      • Clinical Trial Site
  • Bács-Kiskun county
    • Kecskemét, Bács-Kiskun county, Hungary, 6000
      • Recruiting
      • Clinical Trial Site
  • Hajdú-Bihar
    • Debrecen, Hajdú-Bihar, Hungary, 4032
      • Recruiting
      • Clinical Trial Site
• Italy
  • Ancona, Italy, 60126
    • Not yet recruiting
    • Clinical Trial Site
  • Genova, Italy, 16132
    • Recruiting
    • Clinical Trial Site
  • Naples, Italy, 80131
    • Not yet recruiting
    • Clinical Trial Site
  • Padua, Italy, 35128
    • Recruiting
    • Clinical Trial Site
  • Pavia, Italy, 27100
    • Recruiting
    • Clinical Trial Site
  • Campania
    • Avellino, Campania, Italy, 83100
      • Recruiting
      • Clinical Trial Site
  • Emilia-Romagna
    • Bologna, Emilia-Romagna, Italy, 40138
      • Recruiting
      • Clinical Trial Site
    • Meldola, Emilia-Romagna, Italy, 47014
      • Recruiting
      • Clinical Trial Site
    • Modena, Emilia-Romagna, Italy, 41124
      • Recruiting
      • Clinical Trial Site
    • Reggio Emilia, Emilia-Romagna, Italy, 42100
      • Recruiting
      • Clinical Trial Site
  • Friuli Venezia Giulia
    • Udine, Friuli Venezia Giulia, Italy, 33100
      • Withdrawn
      • Clinical Trial Site
  • Lazio
    • Rome, Lazio, Italy, 00144
      • Recruiting
      • Clinical Trial Site
    • Rome, Lazio, Italy, 00168
      • Recruiting
      • Clinical Trial Site
  • Lombardy
    • Milan, Lombardy, Italy, 20141
      • Recruiting
      • Clinical Trial Site
    • Rozzano, Lombardy, Italy, 20089
      • Recruiting
      • Clinical Trial Site
  • Piacenza
    • Piacenza, Piacenza, Italy, 29121
      • Not yet recruiting
      • Clinical Trial Site
  • Piedmont
    • Alessandria, Piedmont, Italy, 15121
      • Recruiting
      • Clinical Trial Site
  • Pordenone
    • Aviano, Pordenone, Italy, 33081
      • Recruiting
      • Clinical Trial Site
• Malaysia
  • Kedah
    • Sungai Petani, Kedah, Malaysia, 8000
      • Recruiting
      • Clinical Trials Site
  • Kelantan
    • Kota Bharu, Kelantan, Malaysia, 16150
      • Recruiting
      • Clinical Trial Site
  • Perak
    • Ipoh, Perak, Malaysia, 30450
      • Recruiting
      • Clinical Trial Site
  • Pulau Pinang
    • George Town, Pulau Pinang, Malaysia, 10450
      • Recruiting
      • Clinical Trial Site
  • Putramya
    • Putrajaya, Putramya, Malaysia, 62250
      • Recruiting
      • Clinical Trial Site
  • Sarawak
    • Kuching, Sarawak, Malaysia, 93586
      • Recruiting
      • Clinical Trial Site
  • Selangor
    • Petaling Jaya, Selangor, Malaysia, 46050
      • Recruiting
      • Clinical Trial Site
  • WP
    • Kuala Lumpur, WP, Malaysia, 59100
      • Recruiting
      • Clinical Trial Site
• Mexico
  • Monterrey, Mexico, 64460
    • Recruiting
    • Clinical Trial Site
  • Oaxaca City, Mexico, 68020
    • Recruiting
    • Clinical Trial Site
  • Sinaloa, Mexico, 80020
    • Recruiting
    • Clinical Trial Site
  • Jalisco
    • Guadalajara, Jalisco, Mexico, 44670
      • Recruiting
      • Clinical Trial Site
  • Mexico City
    • Mexico City, Mexico City, Mexico, 06760
      • Not yet recruiting
      • Clinical Trial Site
  • Puebla
    • Puebla City, Puebla, Mexico, 72530
      • Withdrawn
      • Clinical Trial Site
  • San Luis Potosí
    • San Luis Potosí City, San Luis Potosí, Mexico, 78209
      • Recruiting
      • Clinical Trial Site
• Netherlands
  • North Holland
    • Amsterdam, North Holland, Netherlands, 1081 HV
      • Recruiting
      • Clinical Trial Site
  • South Holland
    • Rotterdam, South Holland, Netherlands, 3083 AN
      • Recruiting
      • Clinical Trial Site
• Poland
  • Gdansk, Poland, 80-214
    • Not yet recruiting
    • Clinical Trial Site
  • Krakow, Poland, 31-501
    • Recruiting
    • Clinical Trial Site
  • Krakow, Poland, 31-115
    • Recruiting
    • Clinical Trial Site
  • Poznan, Poland, 60-192
    • Recruiting
    • Clinical Trial Site
  • Wroclaw, Poland, 50-450
    • Withdrawn
    • Clinical Trial Site
  • Lublin Voivodeship
    • Lublin, Lublin Voivodeship, Poland, 20-090
      • Recruiting
      • Clinical Trial Site
  • Lódzkie
    • Lodz, Lódzkie, Poland, 93-513
      • Recruiting
      • Clinical Trial Site
  • Masovian Voivodeship
    • Otwock, Masovian Voivodeship, Poland, 05-400
      • Recruiting
      • Clinical Trial Site
  • Podkarpackie Voivodeship
    • Brzozów, Podkarpackie Voivodeship, Poland, 36-200
      • Recruiting
      • Clinical Trial Site
    • Rzeszów, Podkarpackie Voivodeship, Poland, 35-021
      • Recruiting
      • Clinical Trial Site
  • Pomeranian Voivodeship
    • Gdynia, Pomeranian Voivodeship, Poland, 81-519
      • Recruiting
      • Clinical Trial Site
• Portugal
  • Coimbra District
    • Coimbra, Coimbra District, Portugal, 3000-075
      • Recruiting
      • Clinical Trial Site
  • Lisbon District
    • Lisbon, Lisbon District, Portugal, 1099-023
      • Recruiting
      • Clinical Trial Site
    • Lisbon, Lisbon District, Portugal, 1500-458
      • Recruiting
      • Clinical Trial Site
  • Porto District
    • Porto, Porto District, Portugal, 4200-072
      • Recruiting
      • Clinical Trial Site
    • Senhora da Hora, Porto District, Portugal, 4464-513
      • Recruiting
      • Clinical Trial Site
• Puerto Rico
  • Puerto Rico
    • Mayagüez, Puerto Rico, Puerto Rico, 00682-6391
      • Recruiting
      • Clinical Trial Site
• Romania
  • Bucharest, Romania, 030171
    • Not yet recruiting
    • Clinical Trial Site
  • Iași, Romania, 700451
    • Not yet recruiting
    • Clinical Trial Site
  • Bihor County
    • Oradea, Bihor County, Romania, 410469
      • Recruiting
      • Clinical Trial Site
  • Brașov County
    • Brasov, Brașov County, Romania, 500152
      • Recruiting
      • Clinical Trial Site
  • București
    • Bucharest, București, Romania, 014146
      • Recruiting
      • Clinical Trial Site
  • Cluj
    • Cluj-Napoca, Cluj, Romania, 400015
      • Recruiting
      • Clinical Trial Site
    • Cluj-Napoca, Cluj, Romania, 400132
      • Not yet recruiting
      • Clinical Trial Site
  • Dolj
    • Craiova, Dolj, Romania, 200542
      • Recruiting
      • Clinical Trial Site
  • Iaşi
    • Iași, Iaşi, Romania, 700106
      • Recruiting
      • Clinical Trial Site
  • Timiș County
    • Timișoara, Timiș County, Romania, 300239
      • Recruiting
      • Clinical Trial Site
• South Korea
  • Busan, South Korea, 49201
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 03722
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 03080
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 06591
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 02841
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 05505
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 06273
    • Recruiting
    • Clinical Trial Site
  • Seoul, South Korea, 08308
    • Recruiting
    • Clinical Trial Site
  • Suwon, South Korea, 16499
    • Recruiting
    • Clinical Trial Site
  • Gyeonggi-do
    • Suwon, Gyeonggi-do, South Korea, 16247
      • Recruiting
      • Clinical Trial Site
• Spain
  • Alicante, Spain, 03010
    • Recruiting
    • Clinical Trial Site
  • Barcelona, Spain, 08023
    • Not yet recruiting
    • Clinical Trial Site
  • Fuenlabrada, Spain, 28942
    • Recruiting
    • Clinical Trial Site
  • Madrid, Spain, 28033
    • Recruiting
    • Clinical Trial Site
  • Murcia, Spain, 30120
    • Not yet recruiting
    • Clinical Trial Site
  • Santa Cruz de Tenerife, Spain, 38320
    • Recruiting
    • Clinical Trial Site
  • Santiago de Compostela, Spain, 15706
    • Recruiting
    • Clinical Trial Site
  • Badajoz
    • Badajoz, Badajoz, Spain, 06080
      • Recruiting
      • Clinical Trial Site
  • Barcelona
    • Badalona, Barcelona, Spain, 08916
      • Not yet recruiting
      • Clinical Trial Site
    • Manresa, Barcelona, Spain, 08243
      • Not yet recruiting
      • Clinical Trial Site
  • Girona
    • Girona, Girona, Spain, 17007
      • Recruiting
      • Clinical Trial Site
  • León
    • León, León, Spain, 24071
      • Recruiting
      • Clinical Trial Site
  • Lleida
    • Lleida, Lleida, Spain, 25198
      • Recruiting
      • Clinical Trial Site
  • Madrid
    • Madrid, Madrid, Spain, 28050
      • Recruiting
      • Clinical Trial Site
  • Navarre
    • Pamplona, Navarre, Spain, 31008
      • Recruiting
      • Clinical Trial Site
  • Sevilla
    • Seville, Sevilla, Spain, 41009
      • Recruiting
      • Clinical Trial Site
  • Tarragona
    • Reus, Tarragona, Spain, 43204
      • Not yet recruiting
      • Clinical Trial Site
  • Valencia
    • Valencia, Valencia, Spain, 46010
      • Recruiting
      • Clinical Trial Site
• Taiwan
  • Changhua, Taiwan, 500
    • Recruiting
    • Clinical Trial Site
  • Kaohsiung City, Taiwan, 80756
    • Recruiting
    • Clinical Trial Site
  • Taichung, Taiwan, 40447
    • Recruiting
    • Clinical Trial Site
  • Taichung, Taiwan, 433
    • Recruiting
    • Clinical Trial Site
  • Tainan, Taiwan, 736
    • Recruiting
    • Clinical Trial Site
  • Taipei, Taiwan, 100
    • Recruiting
    • Clinical Trial Site
  • Taipei, Taiwan, 11217
    • Recruiting
    • Clinical Trial Site
  • Taipei, Taiwan, 111
    • Recruiting
    • Clinical Trial Site
  • Taipei, Taiwan, 114
    • Recruiting
    • Clinical Trial Site
• Thailand
  • Bangkok, Thailand, 10300
    • Recruiting
    • Clinical Trial Site
  • Bangkok, Thailand, 10330
    • Recruiting
    • Clinical Trial Site
  • Bangkok, Thailand, 10700
    • Recruiting
    • Clinical Trial Site
  • Chiang Mai, Thailand, 50180
    • Recruiting
    • Clinical Trial Site
  • Samut Sakhon, Thailand, 74120
    • Recruiting
    • Clinical Trial Site
  • Songkhla, Thailand, 90110
    • Recruiting
    • Clinical Trial Site
• United Kingdom
  • Bodelwyddan, United Kingdom, LL18 5UJ
    • Recruiting
    • Clinical Trial Site
  • London, United Kingdom, EC1A 7BE
    • Recruiting
    • Clinical Trial Site
  • Leicestershire
    • Leicester, Leicestershire, United Kingdom, LE1 5WW
      • Recruiting
      • Clinical Trial Site
  • Nottingham
    • Nottingham, Nottingham, United Kingdom, NG5 1PB
      • Recruiting
      • Clinical Trial Site
  • Somerset
    • Taunton, Somerset, United Kingdom, TA1 5DA
      • Recruiting
      • Clinical Trial Site
• United States
  • Arizona
    • Tucson, Arizona, United States, 85719
      • Recruiting
      • Clinical Trial Site
  • California
    • Fountain Valley, California, United States, 92708
      • Not yet recruiting
      • Clinical Trial Site
    • Glendale, California, United States, 91204
      • Not yet recruiting
      • Clinical Trial Site
    • La Jolla, California, United States, 92093
      • Completed
      • Clinical Trial Site
    • Los Alamitos, California, United States, 90720
      • Recruiting
      • Clinical Trial Site
    • Los Angeles, California, United States, 90027
      • Recruiting
      • Clinical Trial Site
    • Whittier, California, United States, 90602
      • Recruiting
      • Clinical Trial Site
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Recruiting
      • Clinical Trial Site
    • Denver, Colorado, United States, 80218
      • Recruiting
      • Clinical Trial Site
    • Golden, Colorado, United States, 80401
      • Recruiting
      • Clinical Trial Site
    • Grand Junction, Colorado, United States, 81505
      • Active, not recruiting
      • Clinical Trial Site
  • Connecticut
    • Danbury, Connecticut, United States, 06810
      • Recruiting
      • Clinical Trial Site
  • Delaware
    • Newark, Delaware, United States, 19713
      • Recruiting
      • Clinical Trial Site
  • Florida
    • Jacksonville, Florida, United States, 32223
      • Withdrawn
      • Clinical Trials Site
    • Margate, Florida, United States, 33063
      • Recruiting
      • Clinical Trial Site
    • Orlando, Florida, United States, 32804
      • Recruiting
      • Clinical Trial Site
    • Plantation, Florida, United States, 33324
      • Recruiting
      • Clinical Trial Site
    • Tamarac, Florida, United States, 33321
      • Recruiting
      • Clinical Trial Site
  • Georgia
    • Atlanta, Georgia, United States, 30322
      • Recruiting
      • Clinical Trial Site
  • Illinois
    • Chicago, Illinois, United States, 60637
      • Recruiting
      • Clinical Trial Site
    • Chicago, Illinois, United States, 60616-2315
      • Recruiting
      • Clinical Trial Site
    • Urbana, Illinois, United States, 61801
      • Recruiting
      • Clinical Trial Site
  • Louisiana
    • Baton Rouge, Louisiana, United States, 70809
      • Withdrawn
      • Clinical Trial Site
    • New Orleans, Louisiana, United States, 70112
      • Recruiting
      • Clinical Trial Site
  • Maryland
    • Baltimore, Maryland, United States, 21201
      • Recruiting
      • Clinical Trial Site
  • Massachusetts
    • Boston, Massachusetts, United States, 02111
      • Recruiting
      • Clinical Trial Site
  • Michigan
    • Detroit, Michigan, United States, 48202
      • Recruiting
      • Clinical Trial Site
  • Minnesota
    • Saint Louis Park, Minnesota, United States, 55426
      • Recruiting
      • Clinical Trial Site
    • Woodbury, Minnesota, United States, 55125
      • Recruiting
      • Clinical Trial Site
  • Nebraska
    • Lincoln, Nebraska, United States, 68516
      • Recruiting
      • Clinical Trial Site
  • New Mexico
    • Farmington, New Mexico, United States, 87401
      • Recruiting
      • Clinical Trial Site
  • New York
    • New York, New York, United States, 10032
      • Recruiting
      • Clinical Trial Site
    • Port Jefferson Station, New York, United States, 11776
      • Withdrawn
      • Clinical Trial Site
  • Ohio
    • Dayton, Ohio, United States, 45415
      • Recruiting
      • Clinical Trial Site
    • Toledo, Ohio, United States, 43623
      • Withdrawn
      • Clinical Trial Site
  • Oregon
    • Portland, Oregon, United States, 97239
      • Recruiting
      • Clinical Trial Site
  • Pennsylvania
    • Sayre, Pennsylvania, United States, 18840
      • Recruiting
      • Clinical Trial Site
  • Tennessee
    • Nashville, Tennessee, United States, 37203
      • Recruiting
      • Clinical Trial Site
    • Nashville, Tennessee, United States, 37232
      • Recruiting
      • Clinical Trial Site
    • Nashville, Tennessee, United States, 37208
      • Recruiting
      • Clinical Trial Site
  • Texas
    • Dallas, Texas, United States, 75390
      • Recruiting
      • Clinical Trial Site
    • Dallas, Texas, United States, 75246
      • Recruiting
      • Clinical Trial Site
    • Houston, Texas, United States, 77054
      • Recruiting
      • Clinical Trial Site
    • Webster, Texas, United States, 77598
      • Recruiting
      • Clinical Trial Site
  • Utah
    • Ogden, Utah, United States, 84405
      • Recruiting
      • Clinical Trial Site
  • Washington
    • Spokane, Washington, United States, 99204
      • Withdrawn
      • Clinical Trial Site
    • Spokane, Washington, United States, 99208
      • Recruiting
      • Clinical Trial Site

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Key inclusion criteria:

• Adult female or male participants.
• ER+, HER2- locally advanced or metastatic breast cancer that is not amenable to curative therapy.
• Evaluable disease (measurable disease or bone-only disease).
• Previously received a CDK4/6 inhibitor in combination with an endocrine therapy in the advanced setting. One additional line of ET as a monotherapy is allowed. Duration of the most recent prior ET must be at least 6 months.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Adequate hematologic, hepatic, and renal functions.
• Female participants can be pre-, peri- or postmenopausal.
• Male and pre- or peri-menopausal female participants must be willing to take a GnRH (or LHRH) agonist.

Key exclusion criteria:

• Symptomatic visceral disease, imminent organ failure, or any other reason that makes the participant ineligible for endocrine monotherapy.
• Previously received chemotherapy in the advanced/metastatic setting.
• Previously received treatment with elacestrant or an investigational estrogen receptor-directed therapy.
• History of allergic reactions to study treatment.
• Any contraindications to the selected standard-of-care endocrine therapy in the local prescribing information.
• Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require immediate treatment.
• Clinically significant comorbidities such as significant cardiac or cerebrovascular disease, gastrointestinal disorders that could affect absorption of study treatment.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Standard of Care Endocrine Therapy; Participants will receive Investigator's choice of one of the Standard of Care drugs (fulvestrant, anastrozole, letrozole, or exemestane)	Drug: Fulvestrant; Participants will be treated with fulvestrant on C1D1, C1D15, and then on Day 1 of every subsequent 4 week (28 day) cycle; Drug: Anastrozole; Participants will be treated with anastrozole once daily on a 4 week (28 day) cycle; Drug: Letrozole; Participants will be treated with letrozole once daily on a 4 week (28 day) cycle; Drug: Exemestane; Participants will be treated with exemestane once daily on a 4 week (28 day) cycle
Experimental: Palazestrant (OP-1250); Participants will receive Palazestrant	Drug: Palazestrant; Participants will be treated with palazestrant once daily on a 4 week (28 day) cycle. Doses evaluated in the dose-selection part will be 120 mg once daily and 90 mg once daily.; Other Names: OP-1250

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dose-Selection Part: Incidence of adverse events	To evaluate the number of participants with adverse events	From Date of Randomization up to 16 weeks
Dose-Selection Part: Incidence of dose reduction	To evaluate the number of participants reducing the dose of palazestrant	From Date of Randomization up to 16 weeks
Dose-Selection Part: Incidence of drug discontinuation	To evaluate the number of participants discontinuing palazestrant	From Date of Randomization up to 16 weeks
Trial: Progression-Free Survival (PFS)	To compare PFS, based on a Blinded Independent Review Committee (BIRC) assessment, between arms of OP-1250 and standard-of-care treatment. This will be assessed separately in populations of ESR1-mutation detected and ESR1-mutation not detected participants.	From Date of Randomization until Disease Progression or Death Due to Any Cause (estimated as up to 2 years)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Trial: Overall Survival (OS)	To compare OS between arms of OP-1250 and standard-of-care treatment. This will be assessed separately in populations of ESR1 mutation detected and ESR1 mutation not detected participants.	From Date of Randomization until Death Due to Any Cause (estimated as up to 4 years)

Collaborators and Investigators

• Sponsor: Olema Pharmaceuticals, Inc.
• Investigators: Study Director: Medical Director, MD, Olema Pharmaceuticals, Inc.

Publications and helpful links

General Publications

• Pistilli B, Bellet Ezquerra M, Del Mastro L, Sohn J, Schmid P, Meisel J, Chan A, Zheng L, de Kermadec E, McArthur H. OPERA-01: a phase III study of palazestrant for ER+, HER2- advanced breast cancer after CDK4/6 inhibitor therapy. Future Oncol. 2026 Jan;22(2):157-166. doi: 10.1080/14796694.2025.2608863. Epub 2025 Dec 29.

Helpful Links

• Olema Publications

Study record dates

Study Major Dates

• Study Start (Actual): November 16, 2023
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): September 30, 2027

Study Registration Dates

• First Submitted: August 17, 2023
• First Submitted That Met QC Criteria: August 29, 2023
• First Posted (Actual): August 30, 2023

Study Record Updates

• Last Update Posted (Actual): March 13, 2026
• Last Update Submitted That Met QC Criteria: March 11, 2026
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Organic Chemicals; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Azoles; Polycyclic Compounds; Steroids; Fused-Ring Compounds; Nitriles; Estradiol; Estrenes; Estranes; Estradiol Congeners; Gonadal Steroid Hormones; Gonadal Hormones; Triazoles; Letrozole; Fulvestrant; Anastrozole; exemestane
• Other Study ID Numbers: OP-1250-301; OPERA-01 (Other Identifier: Olema Pharmaceuticals, Inc.)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No