Breast Cancer Trials / Trials in California
277 Recruiting Trials

Clinical Trials
for Breast Cancer in California

277 clinical trials for Breast Cancer are currently recruiting participants at study sites in California. Study-related care is provided at no cost.

277
Recruiting trials
636
Study sites
133
Cities
146
Industry-sponsored
97
Phase 2
44
Phase 3

Breast Cancer clinical trials in California: what to expect

Breast cancer trials are sorted first by subtype, because the treatments differ: hormone-receptor-positive, HER2-positive (including the newer HER2-low group) and triple-negative disease each have their own studies. Most recruiting trials test a new drug or combination, including targeted pills, antibody-drug conjugates and immunotherapy, either for metastatic cancer or before and after surgery for early-stage disease. Others study less surgery or radiation, ways to reduce recurrence, and screening for people at higher risk.

In California, recruiting breast cancer studies are concentrated in Los Angeles, San Francisco, Duarte and La Jolla, with sites in 129 other cities. 146 of the 277 are run by a drug or device company, which usually means a larger study with travel reimbursement; the rest are academic or hospital-led.

Who breast cancer trials usually look for

Listings name the subtype, the stage (early or metastatic) and how many treatments you may already have had. Early-stage trials often enroll between diagnosis and surgery, or in the months after surgery; metastatic trials usually enroll when a treatment has stopped working. Some specify menopausal status or a particular mutation (BRCA, PIK3CA, ESR1), which the site can test for. Nearly all require that you are well enough for daily activity and that recent blood work is adequate.

Your receptor status is on your pathology report; the site will confirm it from that report, so you do not need to know it by heart to ask.

What taking part involves

Screening reviews your pathology and scans and adds blood work, sometimes a biopsy. Treatment then runs in cycles, with infusions every two to three weeks or daily pills, and scans every two to three months to check the response. Early-stage trials follow you for years after treatment ends, usually with a visit or call every few months. Study drugs and study-specific tests are free; care you would receive anyway is billed to insurance as usual. Placebo, when used, is added to standard treatment.

Questions worth asking the study team

How the study treatment compares with what your oncologist would otherwise recommend; whether the trial is randomized and what the other arm receives; what happens if the cancer grows or returns; and how visits fit around work and family. Many trials now allow some visits at a local clinic.

Showing 20 of 277 recruiting Breast Cancer trials in California

A Study to Learn About the Study Medicine Called PF-07248144 in Combination With Fulvestrant in People With HR-positive, HER2-negative Advanced or Metastatic Breast Cancer Who Progressed After a Prior Line of Treatment.
PHASE3 Anchorage, Alaska +4 sites NCT07062965
This trial is looking for people with HR-positive, HER2-negative advanced breast cancer that has worsened after previous treatment. Participants will receive the study medicine PF-07248144 along with their normal treatment options to see how well they work together.
Recruiting
Phase 3 Study of Gedatolisib as First-Line Treatment for Patients With HR-Positive, HER2-Negative Advanced Breast Cancer (VIKTORIA-2)
PHASE3 Duarte, California +4 sites NCT06757634
This trial is looking for adults with advanced breast cancer that is HR-positive and HER2-negative. Participants will receive treatment involving gedatolisib along with other medications.
Recruiting
A Study Evaluating the Efficacy and Safety of Inavolisib Plus CDK4/6 Inhibitor and Letrozole vs Placebo + CDK4/6i and Letrozole in Participants With Endocrine-Sensitive PIK3CA-Mutated, Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer
PHASE3 Burbank, California +4 sites NCT06790693
This trial is looking for adults with a specific type of advanced breast cancer to test a new treatment combo. Participants will receive either the new treatment or a placebo along with standard care.
Recruiting
Conventionally Fractionated vs. Hypofractionated Comprehensive Nodal Irradiation for Breast Cancer Using Pencil Beam Scanning Proton Therapy
PHASE3 San Diego, California +4 sites NCT05856773
This trial is looking for women with breast cancer who need radiation therapy. Participants will receive either a shorter treatment course of 3 weeks or a standard course of 5 weeks using a specific type of radiation called proton therapy.
Recruiting
A Study Evaluating the Efficacy and Safety of Inavolisib Plus Fulvestrant Compared With Alpelisib Plus Fulvestrant in Participants With HR-Positive, HER2-Negative, PIK3CA Mutated, Locally Advanced or Metastatic Breast Cancer Post CDK4/6i and Endocrine Combination Therapy
PHASE3 Greenbrae, California +4 sites NCT05646862
This trial is looking for people with advanced breast cancer that has specific mutations and has not improved after certain treatments. Participants will compare two treatment combinations to see which is more effective and safe.
Recruiting
A Phase III Study of Dato-DXd With or Without Durvalumab Compared With Investigator's Choice of Chemotherapy in Combination With Pembrolizumab in Patients With PD-L1 Positive Locally Recurrent Inoperable or Metastatic Triple-negative Breast Cancer (TROPION-Breast05)
PHASE3 Duarte, California +4 sites NCT06103864
This trial is looking for patients with a specific type of breast cancer that is not treatable by surgery. Participants will receive a treatment called Dato-DXd, with or without another drug, or a standard chemotherapy treatment.
Recruiting
Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer
PHASE3 Beverly Hills, California +4 sites NCT07085767
This trial is looking for adults with advanced breast cancer that hasn’t been treated before. Participants will receive palazestrant with ribociclib or letrozole with ribociclib to see which treatment works better.
Recruiting
A Study of Elacestrant Versus Standard Endocrine Therapy in Women and Men With ER+,HER2-, Early Breast Cancer With High Risk of Recurrence
PHASE3 Daphne, Alabama +4 sites NCT06492616
This trial is looking for women and men with early breast cancer that has a high risk of coming back. Participants will compare the effects of elacestrant with standard treatment after being on another therapy for a while.
Recruiting
Evaluating the Addition of Adjuvant Chemotherapy to Ovarian Function Suppression Plus Endocrine Therapy in Premenopausal Patients With pN0-1, ER-Positive/HER2-Negative Breast Cancer and an Oncotype Recurrence Score Less Than or Equal to 25
PHASE3 Birmingham, Alabama +4 sites NCT05879926
This trial is looking for premenopausal women with early-stage breast cancer that is hormone receptor-positive. Participants will receive hormone therapy and may also get chemotherapy to see if it helps them live longer without cancer returning.
Recruiting
Study of the Bria-IMT Regimen and CPI vs Physicians' Choice in Advanced Metastatic Breast Cancer.
PHASE3 Anaheim, California +4 sites NCT06072612
This trial is looking for adults with advanced or locally recurrent breast cancer who have run out of treatment options. Participants will receive treatment with the Bria-IMT regimen and a checkpoint inhibitor to see how well it works compared to other standard treatments.
Recruiting
E-Mindfulness Approaches for Living After Breast Cancer
PHASE3 Anaheim, California +4 sites NCT06748222
This trial is looking for younger women who have survived breast cancer and are experiencing depression. Participants will try two different mindfulness programs, one led by an instructor via Zoom and the other through a mobile app.
Recruiting
Anastrazole, Fulvestrant & Abemaciclib for HR+HER2- Metastatic Breast Cancer
PHASE2 Orange, California NCT05524584
This trial is looking for women with stage IV hormone receptor-positive breast cancer. Participants will receive a combination of three medications as part of the treatment.
Recruiting
A Study to Evaluate the Effect of GDC-4198 Alone and in Combination With Giredestrant Versus Abemaciclib and Giredestrant in Participants With Locally Advanced or Metastatic Estrogen Receptor-Positive (ER+), Human Epidermal Growth Factor Receptor-Negative (HER2-) Breast Cancer
PHASE1 Duarte, California +4 sites NCT07100106
This trial is looking for people with advanced breast cancer that is hormone receptor positive and HER2 negative. Participants will receive GDC-4198 by itself or with another drug, Giredestrant, to see how well it works and compare it to another treatment option.
Recruiting
To Study the Effect of Inavolisib in Combination With Fulvestrant in Participants With Breast Cancer
PHASE2 Los Angeles, California +4 sites NCT07368998
This trial is looking for adults with a specific type of breast cancer who have had treatment before. Participants will take a combination of two medications and help researchers understand their effects.
Recruiting
A Phase II Study Evaluating the Efficacy and Safety of Inavolisib Plus Ribociclib Plus Fulvestrant Versus Placebo Plus Ribociclib Plus Fulvestrant in Participants With Advanced Breast Cancer
PHASE2 Anaheim, California +4 sites NCT07405801
This trial is looking for people with advanced breast cancer that has not responded to hormone treatments. Participants will receive a combination of medications to see how effective they are compared to a placebo.
Recruiting
A Phase 2 Neoadjuvant Study of Zanidatamab in Combination With Chemotherapy in Participants With HER2-positive Breast Cancer
PHASE2 Long Beach, California +4 sites NCT07102381
This trial is looking for people with early-stage HER2-positive breast cancer to see if zanidatamab combined with chemotherapy is safe and effective. Participants will need to undergo surgery after the treatment.
Recruiting
Phase II Protocol of Proton Therapy for Partial Breast Irradiation in Early Stage Breast Cancer
PHASE2 San Diego, California +4 sites NCT01766297
This trial is looking for women over 50 with early stage breast cancer. Participants will receive proton radiation therapy to see its effects on their cancer.
Recruiting
A Study to Test Inavolisib Treatments in Participants With Early-Stage, PIK3CA-Mutated Breast Cancer
PHASE2 Los Angeles, California +4 sites NCT07054190
This trial is looking for people with specific types of breast cancer who have not yet received treatment. Participants will take a combination of new therapies and may need to have surgery afterward.
Recruiting
TReatment of ADC-Refractory Breast CancEr With Dato-DXd or T-DXd: TRADE DXd
PHASE2 San Francisco, California +4 sites NCT06533826
This trial is looking for women with advanced breast cancer that is HER2-negative. Participants will take part in a treatment involving two investigational drugs to see how effective they are.
Recruiting
ATEMPT 2.0: Adjuvant T-DM1 vs TH
PHASE2 San Francisco, California +4 sites NCT04893109
This trial is looking for patients with early-stage breast cancer that tests positive for HER2. Participants will receive one of two treatment options after surgery to see how well they work.
Recruiting
See all 277 Breast Cancer trials in California

Where the Breast Cancer studies are in California

Research sites running the most studies
  • City of Hope, Duarte19 trials
  • City of Hope Medical Center, Duarte15 trials
  • Cedars-Sinai Medical Center, Los Angeles12 trials
  • UC San Diego Moores Cancer Center, La Jolla11 trials
  • USC / Norris Comprehensive Cancer Center, Los Angeles11 trials
  • University of California, San Francisco, San Francisco11 trials
By city

Counts are recruiting studies listing at least one site in California, from ClinicalTrials.gov, refreshed every two days.

Breast Cancer clinical trials in California: common questions

How many Breast Cancer clinical trials are recruiting in California?
TrialFinder currently lists 277 recruiting Breast Cancer clinical trials with study sites in California. Results are updated regularly from ClinicalTrials.gov, the official U.S. registry of clinical studies.
Where are Breast Cancer clinical trials located in California?
Study sites for the Breast Cancer trials listed on this page include Duarte, Burbank, San Diego, Greenbrae, Beverly Hills, Anaheim. Each trial page lists every participating site with contact details, so you can find the location closest to you.
Do I need insurance to join a Breast Cancer clinical trial in California?
No. Study-related care is covered by the trial sponsor at no cost to participants, including the study treatment, required lab tests and study visits. Many Breast Cancer trials in California also compensate participants for time and travel. Health insurance is not required to search or enroll.
How do I qualify for a Breast Cancer clinical trial in California?
Each study sets its own criteria based on age, Breast Cancer diagnosis details, prior treatments, current medications and general health. The fastest way to find out is to contact a research site directly — most will pre-screen you by phone in 10 to 15 minutes at no charge. You can also create a free TrialFinder profile to be matched automatically.
Do I need to know my receptor status to join a breast cancer trial?
It helps, because trials are organized by subtype, but the study site reads it from your pathology report. If a trial needs a test you have not had, such as HER2-low or a BRCA result, the site arranges it.
Are there trials for early-stage breast cancer?
Yes. Early-stage trials enroll before surgery, after surgery, or during the years of hormone therapy that follow, and test ways to lower the chance the cancer returns. The listing says which window it enrolls in.
Will a trial replace the treatment my oncologist planned?
Sometimes it is the plan, with a new drug added or compared; sometimes it is an alternative to discuss. Bring the trial page to your oncologist, who can refer you to the site or advise on timing.
Breast Cancer Trials in Other States
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Helpful Reading
Are Clinical Trials Safe? What Patients Should Know
How clinical trial safety works — phases, IRB oversight, informed consent, and your right to withdraw — plus the real risks and questions to ask.
How to Know If You Qualify for a Clinical Trial
Every trial has eligibility criteria based on diagnosis, age, and medical history. Here's how to tell if you qualify — and what to do if you're not sure.
Clinical Trials Without Insurance: What You Need to Know
Clinical trials cover the cost of study-related care, making them one of the few ways to access treatment without health insurance. Here's what's covered.
All guides →

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About Breast Cancer Trials

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