A Phase 1/2 interventional study of RYZ101 and Standard of Care Endocrine Therapy in Metastatic Breast Cancer, HER2-negative Breast Cancer and ER+ Breast Cancer, sponsored by RayzeBio, Inc.. Recruiting at 31 sites in 3 countries. Per ClinicalTrials.gov, last updated 2026-11-12.
Sponsored by RayzeBio, Inc. (part of Bristol-Myers Squibb) · Phase 1/2, Interventional, and Treatment
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Among 44 studies in Breast Neoplasms by Bristol-Myers Squibb — 4 open to participants now, 4 under way, 1 of them phase 3. Breast Neoplasms · Bristol-Myers Squibb.
Among the 44 studies in Breast Neoplasms by Bristol-Myers Squibb, this one is the 23rd largest by planned enrollment of the 40 interventional ones that give a count, is the only one that started in 2024, is one of 6 in phase 1/2, and was the 41st registered.
14,832 studies on the registry are indexed under Breast Neoplasms; 3,320 are open to participants now.
Browse Breast Neoplasms studies →4 of the 44 studies in Breast Neoplasms by Bristol-Myers Squibb are open now, in 12 countries. Recruiting first, the newest first:
RayzeBio, Inc. · Sites in Australia, New Zealand, South Africa
Ages 18+
Bristol-Myers Squibb · Sites in United States, Argentina, Australia and 25 more countries
Ages 18+
Bristol-Myers Squibb · Sites in United States, Australia, Canada and 7 more countries
Ages 18+
By country, each count listing its studies:
Of the 2,399 Breast Neoplasms studies recruiting now, 1,570 (65%) set no upper age limit and 592 (25%) stop at 75 or younger; 103 take children under 18; 215 take healthy volunteers.
This study: all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
44 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 14 · Phase 2 31 · Phase 3 4
First in 2001; this study’s year is marked. 1 started in 2024.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 64 is below the median of 72 across 10,903 interventional studies indexed under Breast Neoplasms.
Median enrollment 73 across the 40 interventional studies, 149 across the 3 observational. Of the 39 that completed or were terminated, 20 (51%) have results posted.
This tab as a report to print or save as PDF → With an account.
This study is registered under RayzeBio, Inc., one of the names counted as Bristol-Myers Squibb. Under that name alone:
RayzeBio, Inc. is the lead sponsor of 8 studies on the registry; 6 are open to participants now.
1 of the studies in Breast Neoplasms by Bristol-Myers Squibb that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT07671092RayzeBio, Inc.Imaging Study in Metastatic UC, HR+ and HER2- Breast Cancer, TNBC, and NSCLC | 2027-08 |
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Among the 44 studies in Breast Neoplasms by Bristol-Myers Squibb, from their registry updates:
This tab as a report to print or save as PDF → With an account.
Phase 1b/2 open-label trial of 225Ac-DOTATATE (RYZ101) in subjects with ER+, HER2-negative unresectable or metastatic breast cancer expressing SSTRs.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subjects must meet all the following criteria for enrollment in the study:
Additional inclusion criteria for Monotherapy arm:
Additional inclusion criteria for ET Combination arms:
Exclusion Criteria
Subjects who meet any of the following criteria will be excluded from the study:
Additional exclusion criteria for ET Combination arms:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CTCAE grade
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Escalating doses of RYZ101 administered intravenously (IV)
Drug: RYZ101
RYZ101 in combination with investigator's choice of standard of care endocrine therapy
Drug: RYZ101 · Drug: Standard of Care Endocrine Therapy
Ac-225
Investigator's choice of endocrine therapy, such as, anastrozole, elacestrant, exemestane, fulvestrant, imlunestrant, letrozole, tamoxifen, or vepdegestrant
This study also gives Elacestrant, Imlunestrant, Fulvestrant, Vepdegestrant, Anastrozole, Exemestane. No intervention listed here names it: that was found by reading the record.
Dose Escalation
Incidence rate of DLTs during the first 6 weeks of RYZ101 treatment
Time frame: 6 weeks of RYZ101 treatment
Endocrine Therapy Combination Dose Escalation
Incidence rate of DLTs during the first 6 weeks of study treatment
Time frame: [Time Frame: 6 weeks of study treatment]
Endocrine Therapy Combination Dose Escalation
Incidence and severity of treatment emergent AEs by NCI-CTCAE v5.0
Time frame: Up to approximately 5 years after the last subject has completed RYZ101 treatment
Endocrine Therapy Combination Dose Escalation and Expansion
Progression Free Survival, defined as the time between first dose of study treatment and progression or death, as assessed by the investigator per RECIST v1.1 criteria
Time frame: Up to approximately 5 years after the last subject has completed RYZ101 treatment
Endocrine Therapy Combination Dose Escalation and Expansion
Time from the first dose of study treatment to first occurrence of Skeletal Related Events
Time frame: Up to approximately 5 years after the last subject has completed RYZ101 treatment
Not enrolling at this site — choose another above.
Not enrolling at this site — choose another above.
Started Jul 2024 (actual). Primary completion is estimated for Oct 2028, 51 months after the start.
Of 161 industry-sponsored phase 1/2 interventional studies under Breast Neoplasms, half reached primary completion within 59 months of starting (the median), counting those still running; a quarter within 44 and three quarters within 75. This study's planned 51 months is below that.
Counting every sponsor, half of 327 studies reached it within 61 months; a quarter within 45 and three quarters within 88.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Actinium AC-225 dotatate