Tests RYZ101 in advanced ER-positive, HER2-negative breast cancer
Tests RYZ101, a radiation-carrying drug, in people with advanced breast cancer.
Plain-language title generated from the registry record
Registry title: Trial of 225Ac-DOTATATE (RYZ101) in Subjects With ER+, HER2-negative Unresectable or Metastatic Breast Cancer Expressing SSTRs.
Key facts
- Where
- Québec, Toronto, and Victoria, CanadaSee the 3 sites
- Phase
- Phase 1/2
AI summary: who the study is looking for
From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.
The trial is looking for people with ER+, HER2-negative breast cancer that has spread or cannot be removed by surgery, and whose tumours show somatostatin receptors on a special scan.
- Sex
- All sexes can join.
- Disease stage
- ER+, HER2-negative breast cancer that is locally advanced and cannot be removed by surgery, or has spread, and cannot be treated with treatment meant to remove all of the disease. One group needs measurable disease with at least 80% SSTR-positive lesions on SSTR-PET imaging. The hormone therapy combination groups need disease in the bones only or mostly in the bones, with at least 1 SSTR-positive bone lesion.
- Earlier treatment
- Single-drug group: the disease grew after at least 2 and no more than 4 earlier chemotherapy or ADC regimens for spread disease. Hormone therapy combination groups: earlier CDK4/6 inhibitor with hormone therapy for advanced or spread disease. Earlier radiopharmaceutical therapy, including radioembolization, is not allowed.
- Biomarker or test result
- SSTR-positive lesions on SSTR-PET imaging. For the hormone therapy combination groups, at least one bone lesion must be positive on both SSTR-PET and FDG-PET imaging.
Main reasons for not taking part
- Earlier radiopharmaceutical therapy, including radioembolization
- Pregnancy or breastfeeding
- Active uncontrolled or symptomatic brain or spinal cord spread, or cancer in the membranes around the brain
- Allergy to 225Ac, 68Ga, 64Cu, octreotate or the ingredients of DOTATATE imaging agents
- Hormone therapy combination groups: liver metastases, symptomatic organ spread, or earlier PARP inhibitor treatment
Read by machine on 9 November 2026.
Where in Canada
- Québec, QuebecHospital not named in the registryNot yet recruiting
- Toronto, OntarioHospital not named in the registryNot yet recruiting
- Victoria, British ColumbiaHospital not named in the registryNot yet recruiting
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Contact the study team: see the registry record → Contacts and Locations
Print a page for my doctorTrial details
- Who runs it
- RayzeBio, Inc.
- Trial code
- NCT06590857
- Record updated
- 6 October 2026
- Original description
Phase 1b/2 open-label trial of 225Ac-DOTATATE (RYZ101) in subjects with ER+, HER2-negative unresectable or metastatic breast cancer expressing SSTRs.Read full original descriptionShow less
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) (TRACY-1).
Phase 1b/2 open-label trial of 225Ac-DOTATATE (RYZ101) in subjects with ER+, HER2-negative unresectable or metastatic breast cancer expressing SSTRs.
Inclusion: Subjects must meet all the following criteria for enrollment in the study:; Histologically confirmed, ER+, HER2-negative, locally advanced and unresectable or metastatic breast cancer not amenable to treatment with curative intent; Adequate renal, hematologic, and hepatic function; Additional inclusion criteria for Monotherapy arm:; Measurable disease with at least 80% SSTR-positive lesions by SSTR-PET imaging; Eastern Cooperative Oncology Group (ECOG) performance status ≤2; Documented radiologic progression after at least 2 and no more than 4 prior chemotherapy or ADC regimens in the metastatic setting; Additional inclusion criteria for ET Combination arms:; Prior treatment with CDK4/6 inhibitors in combination with endocrine therapy in the advanced or metastatic setting; Eastern Cooperative Oncology Group (ECOG) performance status ≤1; Bone only or bone dominant disease. At least 1 bone lesion must be SSTR-positive on SSTR-PET imaging. For bone dominant disease, at least 50% of soft tissue measurable lesions must be SSTR-positive on SSTR-PET imaging. At least one bone lesion must be positive on both SSTR-PET and on FDG-PET imaging; Brain metastases are allowed if definitively treated and clinically stable as confirmed by interval imaging.
Exclusion: Prior radiopharmaceutical therapy, including radioembolization; Any toxicities from prior treatments that have not recovered to CTCAE Grade ≤1, except for alopecia; Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the study safety or efficacy assessments; Additional exclusion criteria for ET Combination arms:; Presence of liver metastases or symptomatic metastatic visceral disease; Prior PARPi exposure or are candidates for PARPi per local guidelines; 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; Subjects who meet any of the following criteria will be excluded from the study:; Pregnancy or breastfeeding.