Clinical trials · California
ER Positive Breast Cancer clinical trials in California
We’re tracking 57 recruiting er positive breast cancer studies with a site in California — including Phase 1, Phase 1/Phase 2, Phase 2 and Phase 3 studies, each written for real people, not researchers.
Recruiting studies in California
- NCT05774951RecruitingPhase 3
Camizestrant for hormone-positive, HER2-negative early breast cancer
This trial tests camizestrant, a medicine that blocks estrogen signaling, to help prevent hormone-positive, HER2-negative early breast cancer from coming back. You may be eligible if your cancer has higher- or intermediate-risk features and you already completed at least 2 years of hormone therapy.
Anaheim, CaliforniaAges 18–130 - NCT05952557RecruitingPhase 3
Camizestrant after surgery for hormone-sensitive early breast cancer
This trial studies whether adding camizestrant (a hormone-blocking medicine) after breast cancer surgery can lower the chance the cancer returns in ER+/HER2− early breast cancer. It is designed for people who have had definitive local treatment and are being considered for additional “prevention” hormone therapy.
Duarte, CaliforniaAges 18–130 - NCT05989828RecruitingPhase 1
Engineered immune cells for advanced triple-negative breast cancer
This trial tests a personalized treatment where your own immune cells are modified to recognize and attack cancer cells that have a specific marker called NY-ESO-1. It is for people with triple-negative breast cancer that has not responded to at least two prior treatments.
Los Angeles, CaliforniaAges 18 years+ - NCT06016738RecruitingPhase 3
Palazestrant vs standard therapy for advanced breast cancer
This trial compares a new oral drug, palazestrant (OP-1250), to standard hormone therapies for people with ER+/HER2- advanced breast cancer that has worsened after prior hormone therapy. It tests whether palazestrant can better control the cancer.
Fountain Valley, CaliforniaAges 18 years+ - NCT06072612RecruitingPhase 3
Bria-IMT plus CPI vs standard care for advanced breast cancer
This trial tests a new combination of two immunotherapy drugs (Bria-IMT and a checkpoint inhibitor) against your doctor's choice of standard treatments. It is for people with advanced breast cancer that has spread and who have already tried several prior therapies.
Anaheim, CaliforniaAges 18 years+ - NCT06099769RecruitingPhase 2
Testing enzalutamide with or without mifepristone for AR-positive breast cancer
This trial tests if adding the drug mifepristone to the standard antiandrogen enzalutamide works better than enzalutamide alone or chemotherapy for people with a specific type of breast cancer that has androgen receptors. It aims to find a new targeted treatment option for triple-negative or ER-low breast cancer.
San Francisco, CaliforniaAges 18 years+ - NCT06224673RecruitingPhase 2
Testing ARX788 for HER2-low advanced breast cancer
This trial tests a new drug, ARX788, for people with HER2-low breast cancer that has spread or cannot be removed by surgery. The goal is to see if ARX788 helps shrink or control the cancer.
San Francisco, CaliforniaAges 18 years+ - NCT06260033RecruitingPhase 2
Radiation Therapy for Oligoprogressive ER+ Breast Cancer
This trial tests whether a precise radiation treatment (SBRT) can target a few growing spots of estrogen receptor-positive breast cancer that has spread to other parts of the body. It also uses a special PET scan (FES PET/CT) to see how well the cancer responds. The goal is to slow down the cancer and delay the need for stronger treatments.
Duarte, CaliforniaAges 18 years+ - NCT06263543RecruitingPhase 2
Sequencing antibody-drug conjugates in ER+, HER2-low breast cancer
This trial tests different sequences of antibody-drug conjugates (a type of targeted chemotherapy) for people with ER-positive, HER2-low or ultra-low metastatic breast cancer that has stopped responding to hormone therapy and has progressed on Enhertu. You must have had 1–4 prior chemotherapies for metastatic disease.
Los Angeles, CaliforniaAges 18 years+ - NCT07647328RecruitingPhase 3
Camizestrant and ribociclib for advanced hormone-receptor-positive breast cancer
This trial tests a combination of two drugs (camizestrant and ribociclib) for advanced breast cancer that is hormone-receptor-positive and HER2-negative. The study aims to see if this combination helps patients whose cancer cannot be surgically removed or treated with radiation alone.
Duarte, CaliforniaAges 18–130 - NCT06445738Recruiting
Can some women safely skip radiation after breast cancer surgery?
This trial is for women 50 and older with early-stage, hormone-positive or HER2-positive breast cancer. It tests whether it is safe to skip radiation therapy after a lumpectomy if an MRI before surgery shows the breast tissue looks a certain way.
San Francisco, CaliforniaAges 50 years+ - NCT06471673RecruitingPhase 1/Phase 2
BRIA-OTS cellular immunotherapy for metastatic breast cancer
This study tests an investigational cellular immunotherapy called BRIA-OTS for people with metastatic breast cancer that has spread and is no longer responding to standard treatments. It aims to help the immune system fight cancer cells.
Santa Monica, CaliforniaAges 18 years+ - NCT06533826RecruitingPhase 2
Testing two antibody drugs for HER2-low breast cancer
This trial tests two antibody-drug conjugates (Enhertu and Datroway) for breast cancer that is HER2-low or HER2-0. It aims to find the best treatment sequence for people whose cancer has stopped responding to prior therapy.
San Francisco, CaliforniaAges 18 years+ - NCT06568692RecruitingPhase 2
Study of PCS6422 with capecitabine for advanced breast cancer
This trial tests a new drug combination (PCS6422 plus capecitabine) for people with advanced or metastatic breast cancer that has not responded to other treatments. The goal is to see if adding PCS6422 can make the chemotherapy work better.
Oxnard, CaliforniaAges 18 years+ - NCT06492616RecruitingPhase 3
Elacestrant vs standard hormone therapy for high-risk early breast cancer
This trial tests a new hormone therapy pill (elacestrant) against standard hormone therapy for people with a common type of early breast cancer (ER+, HER2-) that has a higher chance of returning. You may qualify if you've already been on hormone therapy for 2 to 5 years and want to see if a different pill works better.
Bakersfield, CaliforniaAges 18 years+ - NCT06896474Recruiting
Breast cancer treatment choice help for women 70 and older
This study tests a decision aid to help women 70 and older with early stage breast cancer choose their treatment. It looks at whether the tool helps patients and their doctors make a confident treatment choice.
Los Angeles, CaliforniaAges 18 years+ - NCT06966453RecruitingPhase 1/Phase 2
Study of disitamab vedotin for HER2-positive advanced breast cancer
This study tests a new drug called disitamab vedotin for people with advanced breast cancer that has a certain amount of HER2 protein. Depending on your HER2 and hormone receptor status, you may be eligible for one of three groups, each with different prior treatment requirements.
Anaheim, CaliforniaAges 18 years+ - NCT07054190RecruitingPhase 2
Testing Inavolisib in early-stage breast cancer with PIK3CA mutation
This trial is testing a drug called Inavolisib (a type of targeted therapy) given before surgery for people with early-stage, hormone receptor-positive, HER2-negative breast cancer that has a specific genetic change (PIK3CA mutation). The goal is to see if adding Inavolisib to standard endocrine therapy can shrink the tumor more effectively.
Los Angeles, CaliforniaAges 18 years+ - NCT07214532Recruiting
Guiding CDK4/6 inhibitor use by a blood test in breast cancer
This trial is for women and men with early-stage, hormone-positive, HER2-negative breast cancer. It uses a blood test (Signatera) to detect tiny amounts of cancer DNA and only starts a CDK4/6 inhibitor (ribociclib or abemaciclib) if the test shows cancer DNA is present.
Greenbrae, CaliforniaAges 18 years+ - NCT01042379RecruitingPhase 2
Adaptive drug trial for newly diagnosed breast cancer
This study tests personalized, changing treatment plans (given before surgery) to find better options for your specific breast tumor. You may be asked for extra breast-tissue testing to help match you with the most suitable study drug(s).
San Francisco, CaliforniaAges 18 years+ - NCT01766297RecruitingPhase 2
Proton radiation after lumpectomy for early breast cancer
This trial studies a type of radiation made with protons to treat only part of the breast after surgery (lumpectomy) for early-stage breast cancer. It may help control the cancer while aiming to reduce radiation to surrounding tissues.
San Diego, CaliforniaAges 50 years+ - NCT06966700RecruitingPhase 3
Study of Sac-TMT in Early High-Risk Breast Cancer
This study tests a new drug called Sacituzumab Tirumotecan (Sac-TMT) for people with early-stage, high-risk breast cancer that hasn't spread. The drug is given before surgery to see if it can shrink tumors and improve outcomes.
Burbank, CaliforniaAges 18 years+ - NCT07287917RecruitingPhase 1/Phase 2
Testing a new drug combo for advanced breast cancer or melanoma
This trial tests a new combination of drugs (AMXT 1501, DFMO, and standard therapies) for people with advanced solid tumors, specifically breast cancer (ER+ HER2-) or melanoma that has progressed after other treatments. The goal is to see if this combination can help shrink tumors or slow their growth.
Los Angeles, CaliforniaAges 18 years+ - NCT07287098RecruitingPhase 2
Imlunestrant for premenopausal women with ER+/HER2- early breast cancer
This trial tests a new hormone-blocking pill (imlunestrant) in premenopausal women with early-stage ER+/HER2- breast cancer. Depending on whether you've had prior hormone therapy, the study will see if this treatment works better than standard options.
Duarte, CaliforniaAges 18 years+
Where these studies are running in California
Institutions with a site for the recruiting er positive breast cancer studies listed above.
- City of Hope Comprehensive Cancer Center · 5 studies
- University of California, San Francisco · 5 studies
- City of Hope Orange County Lennar Foundation Cancer Center · 4 studies
- Hoag Memorial Hospital Presbyterian · 4 studies
- Research Site · 4 studies
- Los Angeles Cancer Network · 3 studies
- USC / Norris Comprehensive Cancer Center · 3 studies
- Cancer and Blood Specialty Clinic · 2 studies
What taking part in a er positive breast cancer study involves
A screening visit first
Before anything else, the study team checks whether you fit — usually a visit with some tests. You can stop at any point, and screening is typically free.
Care at a nearby site
Study visits happen at a clinic or hospital taking part. Many studies cover the cost of the study treatment and related visits, and some reimburse travel.
You stay in control
Taking part is voluntary and you can leave a study at any time, for any reason, without affecting your regular care.
The team decides eligibility
Our fit check is a helpful first read, not a decision. The study team makes the final call after reviewing your health history.
ER Positive Breast Cancer trials in other states
Common questions
- Are there er positive breast cancer clinical trials in California?
- Yes. We're currently tracking 57 recruiting er positive breast cancer studies with a site in California, each rewritten in plain language so you can see what it's testing and who it's for.
- How do I find out if I qualify for a er positive breast cancer study in California?
- Each study lists its eligibility rules — age, diagnosis, prior treatments. On every trial page we explain these in plain language and offer a short, optional pre-screen for a fit read. The study team makes the final decision.
- Do I have to live in California to take part?
- Not necessarily. These studies have a site in California, but eligibility is about your health, not your address — some people travel to take part, and a few studies reimburse travel. The study team can tell you what's required.
- Does it cost anything to join a er positive breast cancer trial?
- Using Clin2 is always free. Many trials cover the study treatment and related visits; some reimburse travel. The study team explains exactly what's covered before you decide.
Not the right time?
New er positive breast cancer studies open in California regularly. Set up a health profile and we’ll quietly watch for studies that fit you and email you when one opens.
Clin2 helps you find and understand clinical trials and does not provide medical advice. Study data comes from ClinicalTrials.gov. Talk with your doctor about whether a specific trial is right for you.