Breast CancerPhase 1NCT05304962
FIH Study of RGT-419B Alone and With Endocrine Therapy in HR-Positive, HER2-Negative Advanced/Metastatic Breast Cancer
A Phase 1 study testing RGT-419B and RGT-419B in combination with hormonal therapy in people with Breast Cancer, run by Regor Pharmaceuticals Inc. at 8 sites in United States.
Trial summary
This is a phase I, First-in-Human (FIH), open-label study to evaluate the safety, tolerability, pharmacokinetic (PK) profile, and preliminary efficacy of RGT-419B administered orally as monotherapy OR in combination with Hormonal Therapy in subjects with HR+, HER2- locally advanced and unresectable (Stage III) or… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Breast Cancer
- What is being tested?
- RGT-419B and RGT-419B in combination with hormonal therapy
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 64 participants
- Where
- 8 sitesUnited States
- Study dates
- 4 Mar 2022to 31 Mar 2027
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Male or female >/= 18 years old
- ECOG Performance Status 0 to 1
- Subjects must have histologically or cytologically confirmed diagnosis of ER+, HER2- ABC consistent with ASCO CAP guidelines that is locally advanced and unresectable (Stage III) or metastatic (Stage IV) BC.
- Measurable AND evaluable lesions at baseline per RECIST v1.1.
- Eligible subjects must meet all of the following criteria:
- Progression after receiving 1 line of prior cyclin-dependent kinase 4 and 6 inhibitor (CDK4/6i) therapy combined with HT in the MBC setting (up to 1 additional line of CDK4/6i is permitted in the post-surgical adjuvant setting);
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- Subjects must have received therapy for ≥3 months in the MBC setting, or for ≥6 months in the adjuvant setting, prior to progression
- Progression after ≤3 lines of prior HT therapy (regardless of whether it is HT alone or in combination with other therapies)
- Prior HT combination agents, including SERD, SERM or AI, must have received formal approval by regulatory agency.
- ≤ 1 prior line of chemotherapy in the metastatic setting
- Adequate organ function
- Ability to understand and the willingness to sign a written informed consent document
Who cannot join
- Presence of visceral metastases with severe organ dysfunction as evidence by signs and symptoms, laboratory studies, lymphangitic spread and/or rapid progression of disease
- Pregnant or planning to become pregnant
- Prior irradiation to >25% of the bone marrow and/or inadequate bone marrow function or evidence of clinically significant end-organ damage
- Major surgery, chemotherapy, targeted therapy, experimental agents, or radiation within 14-28 days prior to Cycle 1, Day 1
- Active, serious medical condition that is not well controlled with locally approved medications allowed by the protocol
- History of allergic reactions attributed to compounds of similar chemical or biologic composition to the drugs used in the study
Trial locations and contacts
8 sites in 1 country. Contact the study team or a site near you to ask about taking part.
8 sites in 1 country
United States8 sites, 7 recruiting
- Recruiting
Emory University
Atlanta, Georgia, 30322
Ashley Trumbull, MS, 404-778-3969, Ashley.lynn.trumbull@emory.edu
Kathleen Coleman, 404.251.1278, kathleen.marie.coleman@emory.edu
- Recruiting
Massachusetts General Hospital
Boston, Massachusetts, 02142
Amber Newton, 617-726-1634, ANEWTON3@mgh.harvard.edu
Abigail Fessele, (P): 617-724-8305, afessele@mgh.harvard.edu
- Recruiting
University of California, San Diego
La Jolla, California, 92037
Sauntee Braddock, 858-534-8248, sbraddock@health.ucsd.edu
Rebecca Shatsky, MD
- Recruiting
University California, Los Angeles
Los Angeles, California, 90404
Monica Rocha, 310-998-4747 ext. 16910, mprocha@mednet.ucla.edu
Saeed Sadeghi, MD
- Recruiting
New York Cancer and Blood Specialists
Port Jefferson Station, New York, 11776
Laura Parisi, LPN, 631-675-5146, lparisi@nycancer.com
Lauren Gianelli-Bilka, LPN, 631-675-5256, lgianelli@nycancer.com
- Active, not recruiting
Hem-Onc Associates of the Treasure Coast
Port Saint Lucie, Florida, 34952
- Recruiting
Washington University School of Medicine
St Louis, Missouri, 63110
Sammie Ruzicka, LMSW, 314-747-5209, ruzicka@wustl.edu
Tracy Summa, CCRP, 314.362.0263, tracy.summa@wustl.edu
- Recruiting
Moffitt Cancer Center
Tampa, Florida, 33612
Taylor L Whann, 813-745-0824, Taylor.LewisWhann@moffitt.org
Heather Han, MD
About this study
Official title: First-in-Human, Escalating Oral Dose Study of RGT-419B Given Alone and With Endocrine Therapy in Subjects With Hormone Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative Advanced/Metastatic Breast Cancer
This is a phase I, First-in-Human (FIH), open-label study to evaluate the safety, tolerability, pharmacokinetic (PK) profile, and preliminary efficacy of RGT-419B administered orally as monotherapy OR in combination with Hormonal Therapy in subjects with HR+, HER2- locally advanced and unresectable (Stage III) or metastatic (Stage IV) breast cancer whose disease has progressed during prior therapy with an approved CDK4/6i plus hormonal therapy.
- Conditions
- Breast Cancer
- Being tested
- RGT-419B, RGT-419B in combination with hormonal therapy
- Keywords
- Breast Cancer
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RGT-419BDrug
oral capsules
RGT-419B in combination with hormonal therapyDrug
RGT-419B in combination with hormonal therapy (Selective Estrogen Receptor Degrader, Selective Estrogen Receptor Modulator, or Aromatase Inhibitor)
| Study group | Role | What they receive |
|---|---|---|
| Arm A | Experimental | RGT-419B given alone as monotherapy Receives: Drug: RGT-419B |
| Arm B | Experimental | RGT-419B in combination with Hormonal Therapy Receives: Drug: RGT-419B in combination with hormonal therapy |
What is being measured
The primary outcome is the main question the study is designed to answer.
Safety & Tolerability - Number of subjects with Dose-Limiting Toxicities (DLTs) at each cohort dose level in singlet and doublet therapy
Number of subjects who have a confirmed DLT at each cohort dose level in singlet and doublet study arms during the first 28-day cycle of RGT-419B treatment.
Measured: 4 weeks (1 cycle)
Secondary outcomes (10)
Safety & Tolerability - Incidence, Severity, and Causality of all Treatment Emergent Adverse Events (TEAEs)
Incidence, severity, and causality of all TEAEs will be assessed for all patient participating from Day 1 dosing through end of study.
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Cmax
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Area Under Concentration-Time Curve (AUC0-t)
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Area Under Concentration-Time Curve to Infinity (AUC0-inf)
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Plasma Decay Half-Life (t 1/2)
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Time to Reach Maximum Observed Plasma Concentration (Tmax)
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Accumulation rate after multiple doses
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Cumulative urinary excretion
Plasma and urine samples that are being collected for PK assessment may also be used for exploratory metabolite identification
Measured: through study completion, an average of 1 year
Tumor Response assessed by Investigator according to RECIST v1.1
Tumor response measured by radiologic imaging techniques at baseline and throughout the study
Measured: through study completion, an average of 1 year
QTc Interval - Changes in corrected QT interval
Number of subjects with a clinically significant increase from baseline in corrected QT (QTc) interval on repeated ECGs during RGT-419B monotherapy.
Measured: through study completion, an average of 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 Mar 2022
- Study start4 Mar 2022
- Primary completion30 Dec 2026 (estimated)
- Study completion31 Mar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Model description
- There will be two study arms opened sequentially to the same patient population. Arm A is RGT-419B alone (singlet). Arm B is RGT-419B + Hormonal Therapy (doublet) and will follow completion of Arm A.
- Masking
- None (open label)
- Enrolment
- 64 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Regor Pharmaceuticals Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05304962
- Sponsor's protocol ID
- RGT-419B_01-101
- Status last verified
- Aug 2026
- First submitted
- 24 Feb 2022
- Last updated
- 12 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 12 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- First-in-Human, Escalating Oral Dose Study of RGT-419B Given Alone and With Endocrine Therapy in Subjects With Hormone Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative Advanced/Metastatic Breast Cancer
- ClinicalTrials.gov ID
- NCT05304962
- Acronym / sponsor ID
- RGT-419B_01-101
- Conditions
- Breast Cancer
- Keywords
- Breast Cancer
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 64 participants (estimated)
- Lead sponsor
- Regor Pharmaceuticals Inc.Industry (pharma, biotech, devices)
- Study start
- 4 Mar 2022 (actual)
- Primary completion
- 30 Dec 2026 (estimated)
- Study completion
- 31 Mar 2027 (estimated)
- First posted
- 31 Mar 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a phase I, First-in-Human (FIH), open-label study to evaluate the safety, tolerability, pharmacokinetic (PK) profile, and preliminary efficacy of RGT-419B administered orally as monotherapy OR in combination with Hormonal Therapy in subjects with HR+, HER2- locally advanced and unresectable (Stage III) or metastatic (Stage IV) breast cancer whose disease has progressed during prior therapy with an approved CDK4/6i plus hormonal therapy.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- There will be two study arms opened sequentially to the same patient population. Arm A is RGT-419B alone (singlet). Arm B is RGT-419B + Hormonal Therapy (doublet) and will follow completion of Arm A.
| Arm | Type | Receives |
|---|---|---|
| Arm A | Experimental | Drug: RGT-419BRGT-419B given alone as monotherapy |
| Arm B | Experimental | Drug: RGT-419B in combination with hormonal therapyRGT-419B in combination with Hormonal Therapy |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (12 listed)
- Male or female >/= 18 years old
- ECOG Performance Status 0 to 1
- Subjects must have histologically or cytologically confirmed diagnosis of ER+, HER2- ABC consistent with ASCO CAP guidelines that is locally advanced and unresectable (Stage III) or metastatic (Stage IV) BC.
- Measurable AND evaluable lesions at baseline per RECIST v1.1.
- Eligible subjects must meet all of the following criteria:
Key exclusion criteria (6 listed)
- Presence of visceral metastases with severe organ dysfunction as evidence by signs and symptoms, laboratory studies, lymphangitic spread and/or rapid progression of disease
- Pregnant or planning to become pregnant
- Prior irradiation to >25% of the bone marrow and/or inadequate bone marrow function or evidence of clinically significant end-organ damage
- Major surgery, chemotherapy, targeted therapy, experimental agents, or radiation within 14-28 days prior to Cycle 1, Day 1
- Active, serious medical condition that is not well controlled with locally approved medications allowed by the protocol
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| RGT-419Boral capsules | Drug | Arm A |
| RGT-419B in combination with hormonal therapyRGT-419B in combination with hormonal therapy (Selective Estrogen Receptor Degrader, Selective Estrogen Receptor Modulator, or Aromatase Inhibitor) | Drug | Arm B |
Primary outcome
Safety & Tolerability - Number of subjects with Dose-Limiting Toxicities (DLTs) at each cohort dose level in singlet and doublet therapy
Time frame: 4 weeks (1 cycle)
Number of subjects who have a confirmed DLT at each cohort dose level in singlet and doublet study arms during the first 28-day cycle of RGT-419B treatment.
10 secondary outcomes
Safety & Tolerability - Incidence, Severity, and Causality of all Treatment Emergent Adverse Events (TEAEs)
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Cmax
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Area Under Concentration-Time Curve (AUC0-t)
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Area Under Concentration-Time Curve to Infinity (AUC0-inf)
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Plasma Decay Half-Life (t 1/2)
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Time to Reach Maximum Observed Plasma Concentration (Tmax)
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Accumulation rate after multiple doses
Time frame: through study completion, an average of 1 year
Day 1 and steady-state PK assessment of RGT-419B and major metabolites - Cumulative urinary excretion
Time frame: through study completion, an average of 1 year
Tumor Response assessed by Investigator according to RECIST v1.1
Time frame: through study completion, an average of 1 year
QTc Interval - Changes in corrected QT interval
Time frame: through study completion, an average of 1 year
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Aug 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
8 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing RGT-419B and RGT-419B in combination with hormonal therapy in people with Breast Cancer, run by Regor Pharmaceuticals Inc. at 8 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 12 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 12 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 8 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Joanna Dojillo, MSc (617-315-9070, joanna.dojillo@regor.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Safety & Tolerability - Number of subjects with Dose-Limiting Toxicities (DLTs) at each cohort dose level in singlet and doublet therapy (time frame: 4 weeks (1 cycle)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Aug 2026.