Clinical trials · California
ER Positive Breast Cancer clinical trials in California
We’re tracking 54 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
- NCT05879926RecruitingPhase 3
Testing chemo after hormone therapy in premenopausal early breast cancer
This Phase 3 trial checks whether adding chemotherapy after standard hormone-blocking treatment works better for some premenopausal women with early-stage, ER-positive, HER2-negative breast cancer. It targets patients with limited lymph node spread and a lower-to-intermediate tumor “recurrence” risk score.
San Francisco, CaliforniaAges 18–60 - NCT05812807RecruitingPhase 3
Pembrolizumab versus monitoring after triple-negative breast cancer response
This trial checks whether giving pembrolizumab (an immunotherapy) after surgery helps people with triple-negative breast cancer reduce the chance of the cancer coming back, compared with close monitoring only. It’s for patients who had no remaining invasive cancer after neoadjuvant chemotherapy plus pembrolizumab.
San Jose, CaliforniaAges 18 years+ - 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 - NCT05696626RecruitingPhase 3
Test a new pill plus abemaciclib versus standard therapy
This Phase 3 study compares lasofoxifene plus abemaciclib versus fulvestrant plus abemaciclib for ER-positive, HER2-negative breast cancer that has an ESR1 mutation. It looks for better tumor control in people whose cancer has progressed on hormone therapy (an aromatase inhibitor) and who meet specific safety and testing requirements.
Santa Rosa, CaliforniaAges 18 years+ - NCT05524584RecruitingPhase 2
Anastrozole, fulvestrant, and abemaciclib for hormone-positive breast cancer
This trial tests whether combining three medicines can better control hormone-receptor–positive, HER2-negative metastatic breast cancer that cannot be cured with surgery or radiation. It may help shrink tumors and slow disease growth compared with standard hormone therapy approaches.
Orange, CaliforniaAges 18 years+ - NCT05491226RecruitingPhase 2
Pembrolizumab plus radiation and myeloid-targeting for high-risk breast cancer
This trial studies whether adding pembrolizumab (an immune “unlocking” drug) to radiation and another treatment that targets certain immune cells can improve outcomes for women with high-risk, early-stage triple negative breast cancer. You may be considered if your cancer has signs that it may respond less to immunotherapy on its own.
Los Angeles, CaliforniaAges 18 years+ - NCT05386108RecruitingPhase 1/Phase 2
Test abemaciclib plus elacestrant for breast cancer brain spread
This trial studies whether the combination of abemaciclib and elacestrant can slow or shrink ER-positive, HER2-negative breast cancer that has spread to the brain. It is designed for people whose cancer has progressed despite prior hormone (endocrine) treatment.
Fullerton, CaliforniaAges 18 years+ - NCT05304962RecruitingPhase 1
Test drug RGT-419B for advanced ER+ HER2- breast cancer
This Phase 1 study tests a new drug (RGT-419B), given alone or with hormone (endocrine) therapy, in people with advanced ER-positive, HER2-negative breast cancer that has progressed after standard treatments. It looks mainly at safety and early signs of how well the treatment may work.
Los Angeles, CaliforniaAges 18 years+ - NCT04893109RecruitingPhase 2
Study compares two HER2 breast cancer treatments after surgery
This Phase 2 study tests two different medicines given after breast surgery to reduce the risk of cancer coming back. It is only for people with early-stage HER2-positive breast cancer with limited or no lymph node spread.
San Francisco, CaliforniaAges 18 years+ - NCT04802759RecruitingPhase 1/Phase 2
Testing drug combinations for recurrent or advanced ER-positive breast cancer
This early-phase trial tests several combinations of cancer medicines to slow or control ER-positive breast cancer that has returned or progressed. It also checks safety and whether tumor or blood biomarkers can help match the right treatment to the right person.
Duarte, CaliforniaAges 18 years+ - NCT04768426RecruitingPhase 2
Watching DNA in blood while taking capecitabine after breast cancer
This trial checks how a blood test that looks for cancer DNA (ctDNA) changes during and after you take capecitabine after early triple-negative breast cancer. It aims to see whether these blood test results can help monitor the chance of the cancer coming back.
Stanford, CaliforniaAges 18 years+ - NCT04589468Recruiting
Exercise for cancer survivors at high risk
This study tests whether a structured exercise program can help prevent cancer from coming back in people who have been treated for certain solid tumors (colorectal, ovarian, lung, or breast cancer). If you've completed surgery and adjuvant therapy within the past 2 years and are currently not exercising much, you may be eligible. Participation involves following an exercise plan and regular check-ins.
Durate, CaliforniaAges 18 years+ - NCT04434040RecruitingPhase 2
Atezolizumab and sacituzumab to prevent breast cancer return
This trial tests two medicines after surgery and chemotherapy to help lower the risk that triple-negative breast cancer comes back. It’s for people whose cancer still showed “residual” invasive disease after neoadjuvant (before-surgery) chemotherapy, and whose blood test shows traces of tumor DNA.
San Francisco, CaliforniaAges 18 years+ - NCT03723928Recruiting
Blood test–guided monitoring for metastatic breast cancer treatment
This study checks whether specific blood “tumor marker” levels can help monitor how hormone receptor–positive, HER2-negative metastatic breast cancer responds to first-line therapy. It uses regular blood tests (and sometimes scans) to see if this marker-based monitoring is useful and reliable.
Carmichael, CaliforniaAges 18 years+ - NCT03606967RecruitingPhase 2
Individualized vaccine added to standard treatment for metastatic triple-negative breast cancer
This Phase 2 trial tests whether adding a personalized cancer vaccine to durvalumab (an immunotherapy), tremelimumab (another immunotherapy), and chemotherapy can improve outcomes for people with metastatic triple-negative breast cancer. It may help your immune system recognize your specific tumor features.
Orange, 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+ - 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).
Newport Beach, CaliforniaAges 18 years+ - NCT07701941RecruitingPhase 1/Phase 2
Combination treatment for advanced breast cancer
This trial tests two targeted drugs together for people with advanced breast cancer that is hormone receptor positive and has low levels of a protein called HER2. The goal is to see if this combination helps shrink tumors or slow the cancer's growth.
Los Angeles, 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+ - 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+ - 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+ - NCT05318469RecruitingPhase 1/Phase 2
Ivermectin with immunotherapy for metastatic triple-negative breast cancer
This trial studies whether ivermectin, given together with immunotherapy (balstilimab or pembrolizumab), can help treat metastatic triple-negative breast cancer. It mainly looks at safety first, and may also explore how well the treatment works for people whose cancer has spread.
Los Angeles, CaliforniaAges 18 years+ - NCT07017673RecruitingPhase 2
Ivonescimab with chemo for early-stage triple negative breast cancer
This trial tests a new drug, ivonescimab, combined with standard chemotherapy before surgery for people with high-risk early-stage triple negative breast cancer. The goal is to see if adding this drug improves treatment response.
Los Angeles, CaliforniaAges 18 years+ - NCT04852887RecruitingPhase 3
Testing shorter breast radiation after low-risk hormone breast cancer
This Phase 3 trial studies whether “less intense” radiation can work as well as standard radiation for certain early-stage hormone receptor–positive, HER2-negative breast cancers that have a low Oncotype DX score. It may help reduce treatment burden while keeping cancer control strong.
Auburn, CaliforniaAges 50–70
Where these studies are running in California
Institutions with a site for the recruiting er positive breast cancer studies listed above.
- Cedars-Sinai Medical Center · 7 studies
- City of Hope · 4 studies
- Mercy Cancer Center - Elk Grove · 4 studies
- Mercy Cancer Center - Rocklin · 4 studies
- Mercy Cancer Center - Sacramento · 4 studies
- Mercy San Juan Medical Center · 4 studies
- Mission Hope Medical Oncology - Arroyo Grande · 4 studies
- Mission Hope Medical Oncology - Santa Maria · 4 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 54 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.