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Breast Cancer clinical trials in St. Louis, MO

64 studies for Breast Cancer are looking for participants at sites in and around St. Louis (within about 30 miles). Open a study to see who can join and how to contact the study team.

Recruiting for a study here? Feature it at the top of this page — $99 for 30 days →

The Vanguard Study: Testing a New Way to Screen for Cancer

RecruitingHealthy volunteers welcome

Washington University School of Medicine, St Louis

Ages 45 to 75 · All sexes · Updated Oct 5, 2026 · NCT06995898

Phase 3 Study of RLY-2608 + Fulvestrant vs Capivasertib + Fulvestrant as Treatment for Locally Advanced or Metastatic PIK3CA-mutant HR+/HER2- Breast Cancer

RecruitingPhase 3

Washington University School of Medicine- Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Oct 5, 2026 · NCT06982521

Collecting Blood Samples From Patients With and Without Cancer to Evaluate Tests for Early Cancer Detection

RecruitingObservational studyHealthy volunteers welcome

Mercy Infusion Center - Chippewa, St Louis
Mercy Hospital South, St Louis
Missouri Baptist Medical Center, St Louis
and 4 more

Ages 40 to 75 · All sexes · Updated Oct 2, 2026 · NCT05334069

A Study of HER3-DXd in Subjects With Locally Advanced or Metastatic Solid Tumors

RecruitingPhase 2

Washington University, School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Oct 1, 2026 · NCT06172478

A Study of Alisertib in Combination With Endocrine Therapy in Patients With HR-positive, HER2-negative Recurrent or Metastatic Breast Cancer

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Oct 1, 2026 · NCT06369285

Open-Label Study of BBO-10203 in Subjects With Advanced Solid Tumors

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Oct 1, 2026 · NCT06625775

An Investigational Study of BG-75202 Alone and in Combination With Other Therapeutic Agents in Adults With Advanced Solid Tumors

RecruitingPhase 1

Washington University in St Louis, St Louis

Ages 18 and older · All sexes · Updated Sep 28, 2026 · NCT07222267

A Study of Sacituzumab Tirumotecan (MK-2870) as a Single Agent and in Combination With Pembrolizumab (MK-3475) Versus Treatment of Physician's Choice in Participants With HR+/HER2- Unresectable Locally Advanced or Metastatic Breast Cancer (MK-2870-010)

RecruitingPhase 3

Washington University School of Medicine ( Site 0076), St Louis

Ages 18 and older · All sexes · Updated Sep 25, 2026 · NCT06312176

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)

RecruitingPhase 3

Research Site, St Louis

Ages 18 and older · All sexes · Updated Sep 25, 2026 · NCT06103864

ASPEN-09-03: A Study of Evorpacept in Combination With Trastuzumab and Chemotherapy in Metastatic HER2-Positive Breast Cancer

RecruitingPhase 2

Washington University School of Medicine- Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Sep 25, 2026 · NCT07007559

A Clinical Study of Sacituzumab Tirumotecan (Sac-TMT, MK-2870) in People With Breast Cancer (MK-2870-032)

RecruitingPhase 3

Washington University Siteman Cancer Center ( Site 0031), St Louis

Ages 18 and older · All sexes · Updated Sep 25, 2026 · NCT06966700

A Study to Evaluate the Safety, Tolerability, Drug Levels, and Preliminary Efficacy of BMS-986507 Combinations in Adult Participants With Advanced Solid Tumors

RecruitingPhase 1/2

Local Institution - 0140, St Louis

Ages 18 and older · All sexes · Updated Sep 23, 2026 · NCT06618287

Signatera-Guided CDK4/6 Inhibitor Therapy in Breast Cancer

Recruiting

Mercy Health - Sindelar Cancer Center, St Louis
Mercy Health - Pratt Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Sep 23, 2026 · NCT07214532

A Study of LY4257496 in Participants With Cancer (OMNIRAY)

RecruitingPhase 1

Washington University, St Louis

Ages 18 and older · All sexes · Updated Sep 22, 2026 · NCT07114601

A Study of LY4337713 in Participants With FAP-Positive Solid Tumors

RecruitingPhase 1

Washington University School of Medicine in St. Louis, St Louis

Ages 18 and older · All sexes · Updated Sep 22, 2026 · NCT07213791

A Study of Imlunestrant (LY3484356) in Premenopausal Women With Estrogen Receptor-Positive (ER+) Human Epidermal Growth Factor Receptor 2 Negative (HER2-) Early Breast Cancer

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 18 and older · Women · Updated Sep 22, 2026 · NCT07287098

A Clinical Study to Find the Optimal Dose of an Investigational Treatment Called BNT323 When Used in Combination With Another Investigational Treatment, BNT327, and to Test if That Combination Treatment is Safe and Beneficial for Patients With Advanced Breast Cancer

RecruitingPhase 1/2

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Sep 17, 2026 · NCT06827236

ROSETTA Breast-01: The Effects and Safety of Pumitamig in Patients With Triple-Negative Breast Cancer

RecruitingPhase 3

Cancer Care Specialists of Illinois, O'Fallon · 16 mi away

Ages 18 and older · All sexes · Updated Sep 17, 2026 · NCT07173751

A Phase 1/2 Trial of TER-2013 in Patients With Solid Tumors Harboring AKT/PI3K/PTEN Pathway Alterations

RecruitingPhase 1/2

Washington Univ. School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Sep 17, 2026 · NCT07109726

Precision Supplemental Imaging in Women With Dense Breasts

RecruitingHealthy volunteers welcome

Washington University School of Medicine, St Louis

Ages 25 to 55 · Women · Updated Sep 16, 2026 · NCT07277738

A Study of Elacestrant Versus Standard Endocrine Therapy in Women and Men With ER+,HER2-, Early Breast Cancer With High Risk of Recurrence

RecruitingPhase 3

Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Sep 15, 2026 · NCT06492616

A Phase I/IIa Study of AZD8205 Given Alone or Combined, in Participants With Advanced/Metastatic Solid Malignancies

RecruitingPhase 1/2

Research Site, St Louis

Ages 18 and older · All sexes · Updated Sep 11, 2026 · NCT05123482

A Phase 1/1b Study of IAM1363 in HER2 Cancers

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Sep 9, 2026 · NCT06253871

A Study to Evaluate Safety, Tolerability and Preliminary Activity of AGX101 in Participants With Advanced Solid Tumors

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Sep 9, 2026 · NCT06440005

A Study of LOXO-783 in Patients With Breast Cancer/Other Solid Tumors

RecruitingPhase 1

Washington University Medical School, St Louis

Ages 18 and older · All sexes · Updated Sep 8, 2026 · NCT05307705

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

RecruitingPhase 1/2

Washington University Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Sep 8, 2026 · NCT07100106

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

RecruitingPhase 3

Cancer Care Specialists of Central Illinois, O'Fallon · 16 mi away

Ages 18 and older · All sexes · Updated Sep 3, 2026 · NCT06790693

Evaluating Minimal Residual Disease (MRD) Through Longitudinal Circulating Tumor DNA (ctDNA) Profiling in Breast Malignancies

RecruitingObservational study

Cancer Care Specialist of Illinois, O'Fallon · 16 mi away

Ages 18 to 99 · All sexes · Updated Sep 3, 2026 · NCT07211178

Ovarian-Sparing Adaptive Radiotherapy in Young Adult Women

RecruitingObservational study

Washington University School of Medicine, St Louis

Ages 18 to 50 · Women · Updated Sep 2, 2026 · NCT06904365

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

RecruitingPhase 3

Mercy Infusion Center - Chippewa, St Louis
Washington University School of Medicine, St Louis
Mercy Hospital South, St Louis
and 9 more

Ages 18 to 60 · Women · Updated Sep 2, 2026 · NCT05879926

A Study With NKT5097 for Adults With Advanced/Metastatic Solid Tumors

RecruitingPhase 1

Washington University, St Louis

Ages 18 and older · All sexes · Updated Aug 28, 2026 · NCT07029399

Study of ECI830 Single Agent or in Combination in Patients With Advanced HR+/HER2- Breast Cancer and in Patients With Other Advanced Solid Tumors

RecruitingPhase 1/2

WA Uni School Of Med, St Louis

Ages 18 to 100 · All sexes · Updated Aug 27, 2026 · NCT06726148

A Study of Mutant Selective-Inhibitor (CGT6297), in Patients With Advanced Solid Tumors

RecruitingPhase 1

Washington University School of Medicine - Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Aug 26, 2026 · NCT07383506

A Phase 1 Study of LNCB74 in Advanced Solid Tumors

RecruitingPhase 1

Washington University, Siteman Cancer Center, St Louis

Ages 18 and older · All sexes · Updated Aug 21, 2026 · NCT06774963

Testing Proton Craniospinal Radiation Therapy Versus the Usual Radiation Therapy for Leptomeningeal Metastasis, RADIATE-LM Trial

RecruitingPhase 3

Washington University School of Medicine, St Louis
Mercy Hospital South, St Louis
Siteman Cancer Center-South County, St Louis
and 4 more

Ages 18 and older · All sexes · Updated Aug 17, 2026 · NCT06500481

FIH Study of RGT-419B Alone and With Endocrine Therapy in HR-Positive, HER2-Negative Advanced/Metastatic Breast Cancer

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Aug 12, 2026 · NCT05304962

Phase 3 Study to Evaluate the Efficacy and Safety of HER2/Neu Peptide GLSI-100 (GP2 + GM-CSF) in HER2/Neu Positive Subjects

RecruitingPhase 3

Siteman Cancer Center - Washington University Medical Campus, St Louis

Ages 18 to 100 · All sexes · Updated Aug 6, 2026 · NCT05232916

IDOV-Immune for Advanced Solid Tumors

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Aug 5, 2026 · NCT06910657

E-Mindfulness Approaches for Living After Breast Cancer

RecruitingPhase 3

Mercy Hospital South, St Louis
Missouri Baptist Medical Center, St Louis
Cancer Care Center of O'Fallon, O'Fallon · 16 mi away

Ages 18 to 50 · All sexes · Updated Aug 4, 2026 · NCT06748222

Endocrine Treatment Alone for Elderly Patients With Estrogen Receptor Positive Operable Breast Cancer and Low Recurrence Score

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 70 and older · Women · Updated Jul 27, 2026 · NCT02476786

Finding the Best Tamoxifen Dose for Breast Cancer Risk Reduction in Premenopausal Women, RENAISSANCE Trial

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 18 to 55 · Women · Updated Jul 27, 2026 · NCT06184750

Study of Orally Administered MOMA-313 in Participants With Advanced or Metastatic Solid Tumors

RecruitingPhase 1

Investigative Site #110, St Louis

Ages 18 and older · All sexes · Updated Jul 23, 2026 · NCT06545942

Testing the Safety of the Combination of Anti-Cancer Drugs CX-5461 (Pidnarulex) and Trastuzumab Deruxtecan (T-DXd) for Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Solid Tumors and Breast Cancer

RecruitingPhase 1

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Jul 13, 2026 · NCT07137416

First-in-Human Study of Tersolisib (STX-478) as Monotherapy and in Combination With Other Antineoplastic Agents in Participants With Advanced Solid Tumors

RecruitingPhase 1/2

Washington University, St Louis

Ages 18 and older · All sexes · Updated Jul 7, 2026 · NCT05768139

Treatment Monitoring of Patients Receiving CDK 4/6 Inhibitors for Hormone Receptor (HR) Positive, HER2 Negative Metastatic Breast Cancer (MBC) With or Without the Addition of DiviTum® Serum Thymidine Kinase 1 (TK1) Activity Testing

Recruiting

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Jul 6, 2026 · NCT04968964

Evaluation of Lasofoxifene Combined With Abemaciclib Compared With Fulvestrant Combined With Abemaciclib in Locally Advanced or Metastatic ER+/HER2- Breast Cancer With an ESR1 Mutation

RecruitingPhase 3

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Jun 22, 2026 · NCT05696626

ChatGPT & Surgeon Synergy: Redefining Breast Reconstruction Consultations for Enhanced Patient Engagement and Satisfaction

Recruiting

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Jun 10, 2026 · NCT06981208

Phase 3 Study of Gedatolisib as First-Line Treatment for Patients With HR-Positive, HER2-Negative Advanced Breast Cancer (VIKTORIA-2)

RecruitingPhase 3

Washington University School of Medicine in Saint Louis, St Louis

Ages 18 and older · All sexes · Updated May 18, 2026 · NCT06757634

COOL-IT-PRO: Cryoablation of Breast Cancer in Non-surgical Patients

RecruitingObservational study

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated May 7, 2026 · NCT05972343

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.

RecruitingPhase 3

Siteman Cancer Center, St Louis
Siteman Cancer Center - North County, Florissant · 13 mi away
Memorial Hospital., Shiloh · 17 mi away

Ages 18 and older · All sexes · Updated May 6, 2026 · NCT07062965

De-Escalation of Breast Radiation Trial for Hormone Sensitive, HER-2 Negative, Oncotype Recurrence Score Less Than or Equal to 18 Breast Cancer (DEBRA)

RecruitingPhase 3

Mercy Hospital South, St Louis
Missouri Baptist Medical Center, St Louis
Mercy Hospital Saint Louis, St Louis
and 3 more

Ages 50 to 70 · All sexes · Updated Apr 23, 2026 · NCT04852887

Zunsemetinib in Combination With Capecitabine in Patients With Hormone Receptor-Positive and HER2-Negative Metastatic Breast Cancer With Bone Metastasis

RecruitingPhase 1/2

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Apr 20, 2026 · NCT06374459

NeoTAILOR: ABiomarker-directed Approach to Guide Neoadjuvant Therapy for Patients With Stage II/III ER-positive, HER2-negative Breast Cancer

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 18 and older · Women · Updated Apr 13, 2026 · NCT05837455

Assessing Benefits and Harms of Cannabis/Cannabinoid Use Among Cancer Patients Treated in Community Oncology Clinics

RecruitingObservational study

Mercy Hospital South, St Louis
Missouri Baptist Medical Center, St Louis
Mercy Hospital Saint Louis, St Louis
and 4 more

Ages 18 and older · All sexes · Updated Mar 17, 2026 · NCT06418204

Cryoablation vs Lumpectomy in T1 Breast Cancers

Recruiting

Washington University School of Medicine, St Louis

Ages 50 and older · Women · Updated Feb 27, 2026 · NCT05505643

Circulating Tumor DNA (ctDNA) for Early Treatment Response Assessment of Solid Tumors

RecruitingObservational studyHealthy volunteers welcome

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Feb 20, 2026 · NCT04354064

Ultra-Hypofractionated vs. Hypofractionated Radiation for Node-Positive Breast Cancer

RecruitingPhase 2

Washington University School of Medicine, St Louis

Ages 18 and older · Women · Updated Jan 9, 2026 · NCT06559540

BettER: Biomarker Driven Early Therapeutic Selection in Patients With HR+ HER2- Metastatic or Unresectable Breast Cancer

Recruiting

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Dec 17, 2025 · NCT05977036

Effect of Neoadjuvant or Adjuvant Systemic Therapy on Breast Cancers, Bone Marrow Cancer Cells, and Circulating Cancer Cells

RecruitingObservational study

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Nov 28, 2025 · NCT00353483

WashU DIEP Flap Video and Patient Understanding Improvement

Recruiting

Washington University School of Medicine, St Louis

Ages 18 and older · Women · Updated Nov 24, 2025 · NCT06864754

SYNERGY-AI: Artificial Intelligence Based Precision Oncology Clinical Trial Matching and Registry

RecruitingObservational study

Massive Bio SYNERGY-AI site, St Louis

All ages · All sexes · Updated Oct 28, 2025 · NCT03452774

S1501 Dual Observational and Randomized Cohort Study of Patients With Metastatic HER-2+ Breast Cancer at Risk of Cardiac Toxicity

RecruitingPhase 3

Saint Louis Cancer and Breast Institute-South City, St Louis
Mercy Hospital South, St Louis
Missouri Baptist Medical Center, St Louis
and 2 more

Ages 18 and older · All sexes · Updated Oct 8, 2025 · NCT03418961

First-in-Human Study of Mutant-selective PI3Kα Inhibitor, RLY-2608, as a Single Agent in Patients With Advanced Solid Tumors and in Combination With Endocrine Therapy +/- a CDK4/6 or CDK4 Inhibitor in Patients With Advanced Solid Tumors or Advanced Breast Cancer

RecruitingPhase 1

Washington University School of Medicine St. Louis, St Louis

Ages 18 and older · All sexes · Updated Sep 22, 2025 · NCT05216432

MammaPrint, BluePrint, and Full-genome Data Linked With Clinical Data to Evaluate New Gene EXpression Profiles

RecruitingObservational study

Washington University School of Medicine, St Louis

Ages 18 and older · All sexes · Updated Aug 20, 2025 · NCT03053193

About Breast Cancer

Breast cancer is a cancer that starts in the breast tissue, when cells change and grow out of control. These extra cells can form a mass called a tumor.

More about Breast Cancer on MedlinePlus

Breast Cancer trials in other cities

Other studies in St. Louis

From ClinicalTrials.gov, data retrieved Oct 6, 2026. Each study sets its own eligibility; the study team decides who can join.