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Treatment for advanced breast cancer using RYZ101

Phase 1b/2 Open-label Trial of 225Ac-DOTATATE (RYZ101) in Subjects with Estrogen Receptor-positive (ER+), Human Epidermal Growth Factor Receptor 2 (HER2)-negative, Locally Advanced and Unresectable or Metastatic Breast Cancer Expressing Somatostatin Receptors (SSTRs) and Progressed After Antibody-drug Conjugates And/or Chemotherapy (TRACY-1).

Phase1; Phase2 Interventional RayzeBio, Inc. · NCT06590857

This study is testing a new treatment called RYZ101 for people with advanced breast cancer that can't be removed by surgery to see if it helps manage their condition.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment124 (estimated)
Ages18 Years and up
SexAll
SponsorRayzeBio, Inc. Industry-sponsored
Locations23 sites (Phoenix, Arizona and 22 other locations)
Trial IDNCT06590857 on ClinicalTrials.gov

What this trial studies

This is a Phase 1b/2 open-label trial evaluating the safety and efficacy of 225Ac-DOTATATE (RYZ101) in patients with ER+, HER2-negative unresectable or metastatic breast cancer that expresses somatostatin receptors (SSTRs). The study aims to enroll subjects who have measurable tumor lesions that are SSTR-PET positive and are not candidates for curative treatment. Participants will receive RYZ101 to assess its potential benefits in managing their condition.

Who should consider this trial

Good fit: Ideal candidates include individuals with ER+, HER2-negative metastatic breast cancer who have measurable SSTR-PET positive tumors.

Not a fit: Patients who have previously undergone radiopharmaceutical therapy or have significant toxicities from prior treatments may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients with advanced breast cancer that is currently difficult to treat.

How similar studies have performed: While this approach is innovative, it builds on existing research into targeted therapies for breast cancer, though specific prior successes with this exact treatment are not documented.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria

Subjects must meet all the following criteria for enrollment in the study:

* Eastern Cooperative Oncology Group performance status ≤2.
* Histologically confirmed, ER+, HER2-negative, locally advanced and unresectable or metastatic breast cancer not amenable to treatment with curative intent.
* At least one RECIST v1.1-measurable tumor lesion that is SSTR-PET positive (defined as maximum standard uptake value (SUVmax) higher than liver mean standard uptake value (SUVmean) on SSTR-PET imaging) and at least 80% of RECIST v1.1measurable tumor lesions are SSTR-PET positive
* Sufficient renal function, as evidenced by eGFR ≥60 mL/min/1.73m2 calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation
* Adequate hematologic and hepatic function

Exclusion Criteria

Subjects who meet any of the following criteria will be excluded from the study:

* Prior radiopharmaceutical therapy, including radioembolization.
* Any toxicities from prior treatments that have not recovered to CTCAE Grade ≤1, except for alopecia.
* Significant cardiovascular disease
* Known active uncontrolled or symptomatic central nervous system (CNS) metastases, carcinomatous meningitis, spinal cord compression, or leptomeningeal disease.
* History of hypersensitivity or allergy to 225Ac, 68Ga, 64Cu, octreotate, or any of the excipients of DOTATATE imaging agents.
* Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the study safety or efficacy assessments.
* Pregnancy or lactation.

Where this trial is running

Phoenix, Arizona and 22 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Metastatic Breast CancerHER2-negative Breast CancerER+ Breast CancerAdvanced Breast CancerActiniumAlpha-EmitterSSTR+ MBCER+, HER2-, MBC
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.