Breast CancerPhase 3OPERA-01NCT06016738

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

A Phase 3 study testing Palazestrant, Fulvestrant and Anastrozole in people with Breast Cancer and Advanced Breast Cancer, run by Olema Pharmaceuticals, Inc. at 233 sites in 26 countries.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record

Search all trials

Trial summary

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. Read more about this study

Who is it for?: Ages 18 years and older
Conditions the study is for: Breast Cancer, Advanced Breast Cancer, Metastatic Breast Cancer
What is being tested?: Palazestrant, Fulvestrant and Anastrozole
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 510 participants
Where: 233 sitesin 26 countries
Study dates: 16 Nov 2023to 29 Feb 2028
Phase: Phase 3
Are there results?: Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

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.

Who cannot join

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.

Trial locations and contacts

233 sites in 26 countries.

Country

City, postcode or hospital

233 sites in 26 countries

United States47 sites

Clinical Trial Site
Atlanta, Georgia, 30322
Clinical Trial Site
Aurora, Colorado, 80045
Clinical Trial Site
Baltimore, Maryland, 21201
Clinical Trial Site
Baton Rouge, Louisiana, 70809
Clinical Trial Site
Boston, Massachusetts, 02111
Clinical Trial Site
Chicago, Illinois, 60616-2315
Clinical Trial Site
Chicago, Illinois, 60637
Clinical Trial Site
Dallas, Texas, 75246
Clinical Trial Site
Dallas, Texas, 75390
Clinical Trial Site
Danbury, Connecticut, 06810
Clinical Trial Site
Dayton, Ohio, 45415
Clinical Trial Site
Denver, Colorado, 80218
Clinical Trial Site
Detroit, Michigan, 48202
Clinical Trial Site
Farmington, New Mexico, 87401
Clinical Trial Site
Fountain Valley, California, 92708
Clinical Trial Site
Glendale, California, 91204
Clinical Trial Site
Golden, Colorado, 80401
Clinical Trial Site
Grand Junction, Colorado, 81505
Clinical Trial Site
Houston, Texas, 77054
Clinical Trials Site
Jacksonville, Florida, 32223
Clinical Trial Site
La Jolla, California, 92093
Clinical Trial Site
Lincoln, Nebraska, 68516
Clinical Trial Site
Los Alamitos, California, 90720
Clinical Trial Site
Los Angeles, California, 90027
Clinical Trial Site
Margate, Florida, 33063
Clinical Trial Site
Nashville, Tennessee, 37203
Clinical Trial Site
Nashville, Tennessee, 37208
Clinical Trial Site
Nashville, Tennessee, 37232
Clinical Trial Site
New Orleans, Louisiana, 70112
Clinical Trial Site
New York, New York, 10032
Clinical Trial Site
Newark, Delaware, 19713
Clinical Trial Site
Ogden, Utah, 84405
Clinical Trial Site
Orlando, Florida, 32804
Clinical Trial Site
Plantation, Florida, 33324
Clinical Trial Site
Port Jefferson Station, New York, 11776
Clinical Trial Site
Portland, Oregon, 97239
Clinical Trial Site
Saint Louis Park, Minnesota, 55426
Clinical Trial Site
Sayre, Pennsylvania, 18840
Clinical Trial Site
Spokane, Washington, 99204
Clinical Trial Site
Spokane, Washington, 99208
Clinical Trial Site
Tamarac, Florida, 33321
Clinical Trial Site
Toledo, Ohio, 43623
Clinical Trial Site
Tucson, Arizona, 85719
Clinical Trial Site
Urbana, Illinois, 61801
Clinical Trial Site
Webster, Texas, 77598
Clinical Trial Site
Whittier, California, 90602
Clinical Trial Site
Woodbury, Minnesota, 55125

Other trials in United States

Italy18 sites

Clinical Trial Site
Alessandria, Piedmont, 15121
Clinical Trial Site
Ancona, 60126
Clinical Trial Site
Avellino, Campania, 83100
Clinical Trial Site
Aviano, Pordenone, 33081
Clinical Trial Site
Bologna, Emilia-Romagna, 40138
Clinical Trial Site
Genova, 16132
Clinical Trial Site
Meldola, Emilia-Romagna, 47014
Clinical Trial Site
Milan, Lombardy, 20141
Clinical Trial Site
Modena, Emilia-Romagna, 41124
Clinical Trial Site
Naples, 80131
Clinical Trial Site
Padova, 35128
Clinical Trial Site
Pavia, 27100
Clinical Trial Site
Piacenza, Piacenza, 29121
Clinical Trial Site
Reggio Emilia, Emilia-Romagna, 42100
Clinical Trial Site
Rome, Lazio, 00144
Clinical Trial Site
Rome, Lazio, 00168
Clinical Trial Site
Rozzano, Lombardy, 20089
Clinical Trial Site
Udine, Friuli Venezia Giulia, 33100

Other trials in Italy

Spain18 sites

Clinical Trial Site
Alicante, 03010
Clinical Trial Site
Badajoz, Badajoz, 06080
Clinical Trial Site
Badalona, Barcelona, 08916
Clinical Trial Site
Barcelona, 08023
Clinical Trial Site
Fuenlabrada, 28942
Clinical Trial Site
Girona, Girona, 17007
Clinical Trial Site
León, León, 24071
Clinical Trial Site
Lleida, Lleida, 25198
Clinical Trial Site
Madrid, Madrid, 28050
Clinical Trial Site
Madrid, 28033
Clinical Trial Site
Manresa, Barcelona, 08243
Clinical Trial Site
Murcia, 30120
Clinical Trial Site
Pamplona, Navarre, 31008
Clinical Trial Site
Reus, Tarragona, 43204
Clinical Trial site
Santa Cruz de Tenerife, 38320
Clinical Trial Site
Santiago de Compostela, 15706
Clinical Trial Site
Seville, Sevilla, 41009
Clinical Trial Site
Valencia, Valencia, 46010

Other trials in Spain

Brazil14 sites

Clinical Trial Site
Belo Horizonte, Minas Gerais, 30150-221
Clinical Trial Site
Brasília, Federal District, 70.390-140
Clinical Trial Site
Curitiba, Paraná, 81520-060
Clinical Trial Site
Itajaí, Santa Catarina, 88301-220
Clinical Trial Site
Jaú, São Paulo, 17210-080
Clinical Trial Site
Porto Alegre, Rio Grande do Sul, 90035-903
Clinical Trial Site
Porto Alegre, Rio Grande do Sul, 90050-170
Clinical Trial Site
Porto Alegre, Rio Grande do Sul, 91350-200
Clinical Trial Site
Porto Alegre, 90470-340
Clinical Trial Site
Recife, Pernambuco, 50070-480
Clinical Trial Site
Rio de Janeiro, 22281-100
Clinical Trial Site
Salvador, Estado de Bahia, 41253-190
Clinical Trial Site
São Luís, Maranhão, 65.060-645
Clinical Trial Site
Sorocaba, São Paulo, 18052-775

Other trials in Brazil

Argentina12 sites

Clinical Trial Site
Bahía Blanca, Buenos Aires, B8000HXM
Clinical Trial Site
Buenos Aires, C14626ABP
Clinical Trial Site
Córdoba, Córdoba Province, X5000HHW
Clinical Trial Site
Córdoba, Córdoba Province, X5008HHW
Clinical Trial Site
La Rioja, La Rioja Province, 5300
Clinical Trial Site
Mar del Plata, Buenos Aires, B7600FZN
Clinical Trial Site
Mar del Plata, Buenos Aires
Clinical Trial Site
Rosario, Santa Fe Province, S2013DTC
Clinical Trial Site
Rosario, Santa Fe Province, S2013KDS
Clinical Trial Site
San Miguel de Tucumán, Tucumán Province, 4000
Clinical Trial Site
San Salvador de Jujuy, Jujuy Province, 4600
Clinical Trial Site
Viedma, Río Negro Province, R8500ACE

Other trials in Argentina

France11 sites

Clinical Trial Site
Besançon, Doubs, 25030
Clinical Trial Site
Bourg-en-Bresse, Ain, 01000
Clinical Trial Site
Caen, 14000
Clinical Trial Site
Clermont-Ferrand, Puy-de-Dôme, 63011
Clinical Trial Site
Compiègne, Oise, 60200
Clinical Trial Site
Le Mans, Sarthe, 7200
Clinical Trial Site
Montpellier, 34070
Clinical Trial Site
Nantes, Loire-Atlantique, 44277
Clinical Trial Site
Nantes, Loire-Atlantique, 44805
Clinical Trial Site
Paris, 75014
Clinical Trial Site
Villejuif, Val-de-Marne, 94805

Other trials in France

Poland11 sites

Clinical Trial Site
Brzozów, Podkarpackie Voivodeship, 36-200
Clinical Trial Site
Gdansk, 80-214
Clinical Trial Site
Gdynia, Pomeranian Voivodeship, 81-519
Clinical Trial Site
Krakow, 31-115
Clinical Trial Site
Krakow, 31-501
Clinical Trial Site
Lodz, Lódzkie, 93-513
Clinical Trial Site
Lublin, Lublin Voivodeship, 20-090
Clinical Trial Site
Otwock, Masovian Voivodeship, 05-400
Clinical Trial Site
Poznan, 60-192
Clinical Trial Site
Rzeszów, Podkarpackie Voivodeship, 35-021
Clinical Trial Site
Wroclaw, 50-450

Other trials in Poland

Romania10 sites

Clinical Trial Site
Brasov, Brașov County, 500152
Clinical Trial Site
Bucharest, Bucharest, 014146
Clinical Trial Site
Bucharest, 030171
Clinical Trial Site
Cluj-Napoca, Cluj, 400015
Clinical Trial Site
Cluj-Napoca, Cluj, 400132
Clinical Trial Site
Craiova, Dolj, 200542
Clinical Trial Site
Iași, Iaşi, 700106
Clinical Trial Site
Iași, 700451
Clinical Trial Site
Oradea, Bihor County, 410469
Clinical Trial Site
Timișoara, Timiș County, 300239

Other trials in Romania

South Korea10 sites

Clinical Trial Site
Busan, 49201
Clinical Trial Site
Seoul, 02841
Clinical Trial Site
Seoul, 03080
Clinical Trial Site
Seoul, 03722
Clinical Trial Site
Seoul, 05505
Clinical Trial Site
Seoul, 06273
Clinical Trial Site
Seoul, 06591
Clinical Trial Site
Seoul, 08308
Clinical Trial Site
Suwon, Gyeonggi-do, 16247
Clinical Trial Site
Suwon, 16499

Other trials in South Korea

Taiwan9 sites

Clinical Trial Site
Changhua, 500
Clinical Trial Site
Kaohsiung City, 80756
Clinical Trial Site
Taichung, 40447
Clinical Trial Site
Taichung, 433
Clinical Trial Site
Tainan, 736
Clinical Trial Site
Taipei, 100
Clinical Trial Site
Taipei, 111
Clinical Trial Site
Taipei, 11217
Clinical Trial Site
Taipei, 114

Other trials in Taiwan

Malaysia8 sites

Clinical Trial Site
George Town, Pulau Pinang, 10450
Clinical Trial Site
Ipoh, Perak, 30450
Clinical Trial Site
Kota Bharu, Kelantan, 16150
Clinical Trial Site
Kuala Lumpur, WP, 59100
Clinical Trial Site
Kuching, Sarawak, 93586
Clinical Trial Site
Petaling Jaya, Selangor, 46050
Clinical Trial Site
Putrajaya, Putramya, 62250
Clinical Trials Site
Sungai Petani, Kedah, 8000

Other trials in Malaysia

Australia7 sites

Clinical Trial Site
Adelaide, South Australia, 5000
Clinical Trial Site
Ballarat Central, Victoria, 3355
Clinical Trial Site
Clayton, Victoria, 3168
Clinical Trial Site
Gosford, New South Wales, 2250
Clinical Trial Site
Nedlands, Western Australia, 6009
Clinical Trial Site
Shepparton, Victoria, 3630
Clinical Trial Site
Westmead, New South Wales, 2145

Other trials in Australia

Mexico7 sites

Clinical Trial Site
Guadalajara, Jalisco, 44670
Clinical Trial Site
Mexico City, Mexico City, 06760
Clinical Trial Site
Monterrey, 64460
Clinical Trial Site
Oaxaca City, 68020
Clinical Trial Site
Puebla City, Puebla, 72530
Clinical Trial Site
San Luis Potosí City, San Luis Potosí, 78209
Clinical Trial Site
Sinaloa, 80020

Other trials in Mexico

Thailand6 sites

Clinical Trial Site
Bangkok, 10300
Clinical Trial Site
Bangkok, 10330
Clinical Trial Site
Bangkok, 10700
Clinical Trial Site
Chiang Mai, 50180
Clinical Trial Site
Samut Sakhon, 74120
Clinical Trial Site
Songkhla, 90110

Other trials in Thailand

Belgium5 sites

Clinical Trial Site
Charleroi, Hainaut, 6060
Clinical Trial Site
Edegem, Antwerpen, 2650
Clinical Trial Site
Leuven, Vlaams Brabant
Clinical Trial Site
Wilrijk, Antwerpen, 2610
Clinical Trial Site
Woluwe-Saint-Lambert, Brussels Capital, 1200

Other trials in Belgium

Czechia5 sites

Clinical Trial Site
Brno, 625 00
Clinical Trial Site
Hradec Králové, Hradec Králové Region, 500 12
Clinical Trial Site
Nový Jičín, Moravian-Silesian Region, 741 01
Clinical Trial Site
Olomouc, Olomouc Region, 779 00
Clinical Trial Site
Prague, 140 59

Other trials in Czechia

Germany5 sites

Clinical Trial Site
Dresden, Saxony, 01307
Clinical Trial Site
Karlsruhe, Baden-Wurttemberg, 76135
Clinical Trial Site
Kiel, Schleswig-Holstein, 24105
Clinical Trial Site
Krefeld, North Rhine-Westphalia, 47805
Clinical Trial Site
Velbert, North Rhine-Westphalia, 42551

Other trials in Germany

Hong Kong5 sites

Clinical Trial Site
Central, Hong Kong, 100176
Clinical Trial Site
Hong Kong, Hong Kong, 999077
Clinical Trial Site
Hong Kong, 999077
Clinical Trials Site
Hong Kong, 999077
Clinical Trial Site
Kowloon, Hong Kong, 999077

Other trials in Hong Kong

Portugal5 sites

Clinical Trial Site
Coimbra, Coimbra District, 3000-075
Clinical Trial Site
Lisbon, Lisbon District, 1099-023
Clinical Trial Site
Lisbon, Lisbon District, 1500-458
Clinical Trial Site
Porto, Porto District, 4200-072
Clinical Trial Site
Senhora da Hora, Porto District, 4464-513

Other trials in Portugal

United Kingdom5 sites

Clinical Trial Site
Bodelwyddan, LL18 5UJ
Clinical Trial Site
Leicester, Leicestershire, LE1 5WW
Clinical Trial Site
London, EC1A 7BE
Clinical Trial Site
Nottingham, Nottingham, NG5 1PB
Clinical Trial Site
Taunton, Somerset, TA1 5DA

Other trials in United Kingdom

Canada4 sites

Clinical Trial Site
Calgary, Alberta, T2N 5G2
Clinical Trial Site
London, Ontario, N6A 5W9
Clinical Trial Site
Montreal, Quebec, H4A 3J1
Clinical Trial Site
Toronto, Ontario, M5G 1X5

Other trials in Canada

Bulgaria3 sites

Clinical Trial Site
Panagyurishte, Pazardzhik, 4500
Clinical Trial Site
Sofia, Sofia-Grad, 1407
Clinical Trial Site
Vratsa, Vratsa, 3000

Other trials in Bulgaria

Hungary3 sites

Clinical Trial Site
Debrecen, Hajdú-Bihar, 4032
Clinical Trial Site
Kecskemét, Bács-Kiskun county, 6000
Clinical Trial Site
Pécs, Baranya, 7624

Other trials in Hungary

Austria2 sites

Clinical Trial Site
Wels, 4600
Clinical Trial Site
Wiener Neustadt, 2700

Other trials in Austria

Netherlands2 sites

Clinical Trial Site
Amsterdam, North Holland, 1081 HV
Clinical Trial Site
Rotterdam, South Holland, 3083 AN

Other trials in Netherlands

Puerto Rico1 site

Clinical Trial Site
Mayagüez, Puerto Rico, 00682-6391

Other trials in Puerto Rico

About this study

Official title: 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)

Read the 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.

Conditions: Breast Cancer, Advanced Breast Cancer, Metastatic Breast Cancer, ER Positive Breast Cancer, HER2 Negative Breast Carcinoma
Being tested: Palazestrant, Fulvestrant, Anastrozole, Letrozole, Exemestane
Medical subject headings: Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

PalazestrantDrug
Also called OP-1250
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.
FulvestrantDrug
Participants will be treated with fulvestrant on C1D1, C1D15, and then on Day 1 of every subsequent 4 week (28 day) cycle
AnastrozoleDrug
Participants will be treated with anastrozole once daily on a 4 week (28 day) cycle
LetrozoleDrug
Participants will be treated with letrozole once daily on a 4 week (28 day) cycle
ExemestaneDrug
Participants will be treated with exemestane once daily on a 4 week (28 day) cycle

Study groups in NCT06016738
Study group	Role	What they receive
Palazestrant (OP-1250)	Experimental	Participants will receive Palazestrant Receives: Drug: Palazestrant
Standard of Care Endocrine Therapy	Active comparator	Participants will receive Investigator's choice of one of the Standard of Care drugs (fulvestrant, anastrozole, letrozole, or exemestane) Receives: Drug: Fulvestrant; Drug: Anastrozole; Drug: Letrozole; Drug: Exemestane

What is being measured

The primary outcome is the main question the study is designed to answer.

Dose-Selection Part: Incidence of adverse events
To evaluate the number of participants with adverse events
Measured: 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
Measured: From Date of Randomization up to 16 weeks
Dose-Selection Part: Incidence of drug discontinuation
To evaluate the number of participants discontinuing palazestrant
Measured: 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.
Measured: From Date of Randomization until Disease Progression or Death Due to Any Cause (estimated as up to 2 years)

Secondary outcomes (1)

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.
Measured: From Date of Randomization until Death Due to Any Cause (estimated as up to 4 years)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

16 Nov 202329 Feb 2028

First posted30 Aug 2023
Study start16 Nov 2023
Primary completion31 Oct 2026 (estimated)
Study completion29 Feb 2028 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Breast CancerStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 3
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Enrolment: 510 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06016738
Sponsor's protocol ID: OP-1250-301
Other IDs: OPERA-01
Acronym: OPERA-01
Status last verified: Aug 2025
First submitted: 17 Aug 2023
Last updated: 13 Aug 2026
Results posted: No
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No

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.
PubMed 41461598

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

Active, not recruiting
Streamlined Geriatric and Oncological Evaluation Based On IC Technology
Breast Cancer, Comorbidities and Coexisting Conditions
RecruitingPhase 2
Gene Signatures to Guide HR+MBC Therapy in a Diverse Cohort
Invasive Mammary Carcinoma, Metastatic Breast Cancer
Not yet recruitingObservational study
Comparison of Reliability, Time Cost, and Participant Comfort of Lymphedema Assessments in Upper Extremity
Lymphedema, Upper Extremity Lymphedema
RecruitingPhase 3
A Study of Camrelizumab Plus Chemotherapy in Combination With or Without Famitinib as Neoadjuvant Therapy in Participants With Triple Negative Breast Cancer (BCTOP-T-N01)
TNBC - Triple-Negative Breast Cancer
RecruitingPhase 3
Testing Whether Hormone Therapy With Ribociclib is as Effective as Chemotherapy Followed by Hormone Therapy With Ribociclib for the Treatment of High Anatomic Stage Breast Cancer With Low Recurrence Risk, The RxFINE-Low Trial
Anatomic Stage II Breast Cancer AJCC v8, Anatomic Stage IIIA Breast Cancer AJCC v8

All Breast Cancer trials

Study at a glance

From the registry record, last updated by the sponsor on 13 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: 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)
ClinicalTrials.gov ID: NCT06016738
Acronym / sponsor ID: OPERA-01 / OP-1250-301
Conditions: Breast Cancer, Advanced Breast Cancer, Metastatic Breast Cancer, ER Positive Breast Cancer, HER2 Negative Breast Carcinoma
Phase: Phase 3
Study type: Interventional
Recruitment status: Active, not recruiting
Enrolment: 510 participants (estimated)
Lead sponsor: Olema Pharmaceuticals, Inc.Industry (pharma, biotech, devices)
Study start: 16 Nov 2023 (actual)
Primary completion: 31 Oct 2026 (estimated)
Study completion: 29 Feb 2028 (estimated)
First posted: 30 Aug 2023 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Number of arms: 2

Arm	Type	Receives
Palazestrant (OP-1250)	Experimental	Drug: PalazestrantParticipants will receive Palazestrant
Standard of Care Endocrine Therapy	Active comparator	Drug: Fulvestrant, Drug: Anastrozole, Drug: Letrozole, Drug: ExemestaneParticipants will receive Investigator's choice of one of the Standard of Care drugs (fulvestrant, anastrozole, letrozole, or exemestane)

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (8 listed)

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.

Key exclusion criteria (7 listed)

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.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
PalazestrantAlso: OP-1250Participants 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.	Drug	Palazestrant (OP-1250)
FulvestrantParticipants will be treated with fulvestrant on C1D1, C1D15, and then on Day 1 of every subsequent 4 week (28 day) cycle	Drug	Standard of Care Endocrine Therapy
AnastrozoleParticipants will be treated with anastrozole once daily on a 4 week (28 day) cycle	Drug	Standard of Care Endocrine Therapy
LetrozoleParticipants will be treated with letrozole once daily on a 4 week (28 day) cycle	Drug	Standard of Care Endocrine Therapy
ExemestaneParticipants will be treated with exemestane once daily on a 4 week (28 day) cycle	Drug	Standard of Care Endocrine Therapy

Primary outcome

Dose-Selection Part: Incidence of adverse events
Time frame: From Date of Randomization up to 16 weeks
To evaluate the number of participants with adverse events
Dose-Selection Part: Incidence of dose reduction
Time frame: From Date of Randomization up to 16 weeks
To evaluate the number of participants reducing the dose of palazestrant
Dose-Selection Part: Incidence of drug discontinuation
Time frame: From Date of Randomization up to 16 weeks
To evaluate the number of participants discontinuing palazestrant
Trial: Progression-Free Survival (PFS)
Time frame: From Date of Randomization until Disease Progression or Death Due to Any Cause (estimated as up to 2 years)
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.

1 secondary outcome

Trial: Overall Survival (OS)
Time frame: From Date of Randomization until Death Due to Any Cause (estimated as up to 4 years)

Results and safety

This study is still under way. Results are not available in the source record yet.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 13 Aug 2026.
Derived from this study: PubMed 41461598Pistilli 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.
Olema PublicationsLink provided by the sponsor.
Individual participant dataSharing planned: No

Related trials for Breast Cancer

Active, not recruiting
Streamlined Geriatric and Oncological Evaluation Based On IC Technology
Breast Cancer, Comorbidities and Coexisting Conditions
RecruitingPhase 2
Gene Signatures to Guide HR+MBC Therapy in a Diverse Cohort
Invasive Mammary Carcinoma, Metastatic Breast Cancer
Not yet recruitingObservational study
Comparison of Reliability, Time Cost, and Participant Comfort of Lymphedema Assessments in Upper Extremity
Lymphedema, Upper Extremity Lymphedema
RecruitingPhase 3
A Study of Camrelizumab Plus Chemotherapy in Combination With or Without Famitinib as Neoadjuvant Therapy in Participants With Triple Negative Breast Cancer (BCTOP-T-N01)
TNBC - Triple-Negative Breast Cancer
RecruitingPhase 3
Testing Whether Hormone Therapy With Ribociclib is as Effective as Chemotherapy Followed by Hormone Therapy With Ribociclib for the Treatment of High Anatomic Stage Breast Cancer With Low Recurrence Risk, The RxFINE-Low Trial
Anatomic Stage II Breast Cancer AJCC v8, Anatomic Stage IIIA Breast Cancer AJCC v8

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Medical Director, MD study director

Olema Pharmaceuticals, Inc.

233 sites in 26 countries: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Palazestrant, Fulvestrant and Anastrozole in people with Breast Cancer and Advanced Breast Cancer, run by Olema Pharmaceuticals, Inc. at 233 sites in 26 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 8 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 13 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 233 sites in United States, Italy, Spain, Brazil, Argentina and 21 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Dose-Selection Part: Incidence of adverse events (time frame: From Date of Randomization up to 16 weeks). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06016738, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Aug 2026.