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BGB-21447 Combinations for HR+/HER2- Metastatic Breast Cancer

This study is testing new combinations of medicines for adults with hormone-receptor positive (HR+), HER2-negative metastatic breast cancer. Researchers want to see how safe and effective BGB-21447 (a drug that stops cancer cells from dying) is when given with fulvestrant (a hormone blocker), and sometimes with BGB-43395 (a drug that controls cell growth). You may be able to join if you have HR+/HER2- metastatic breast cancer and have already received at least one prior treatment for your advanced cancer, including endocrine therapy and a CDK4/6 inhibitor. The study will look at side effects and how well the tumors respond to treatment. The study plans to enroll 120 participants, but its current status is unclear.

Study design
This study is designed to find the right dose and then expand to test the effectiveness of BGB-21447 in combination with fulvestrant, with or without BGB-43395. It plans to enroll 120 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Your safety will be monitored for up to 30 days after your last dose of study drug, or up to approximately 6 months. Tumor response will be measured for approximately 12 months.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06756932

BGB-21447 (Bcl-2 Inhibitor) Combinations for Adults With Hormone-Receptor Positive (HR+)/Human Epidermal Growth Factor Receptor 2 Negative (HER2-) Metastatic Breast Cancer

Recruiting
PHASE1Ages 18+InterventionalTreatment
BeOne Medicines
~120 participants
Updated 2026-06-22 on ClinicalTrials.gov
What's tested:BGB-21447FulvestrantBGB-43395

At a glance

Recruiting sites
14 of 14 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Part 1: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)
Measured over From the first dose of study drug(s) to 30 days after the last dose; up to approximately 6 months
+2 more outcomes measured

Conditions

Hormone-receptor-positive Breast Cancer
HER2-negative Breast Cancer
Metastatic Breast Cancer

Explore related trials

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Where it's being run

14 sites across 12 states
New South Wales2
Victoria2
Iowa1
Texas1
Washington1
Queensland1
Western Australia1
Guangdong1

Study leadership

  • Study Director · STUDY_DIRECTOR · BeOne Medicines

Who to contact

Study Director
[email protected]
1.877.828.5568
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Histologically or cytologically confirmed HR+/HER2- metastatic breast cancer. Part 1A and 1B: Participants must have received ≥ 1 prior line(s) of treatment for advanced/metastatic disease, including prior endocrine therapy and CDK4/6 inhibitor in either the adjuvant or advanced/metastatic setting. Part 2: Participants must have received 1-3 prior line(s) of treatment for advanced/metastatic disease, including prior endocrine therapy and CDK4/6 inhibitor in either the adjuvant or advanced/metastatic setting.
Female participants will be required (either continue ongoing or initiate as soon as feasible) to have ovarian function suppression using gonadotropin-releasing hormone (GnRH) agonists (such as goserelin) or be postmenopausal.
Male participants may be required to use GnRH agonists when being treated with fulvestrant at the discretion of the investigator.
Participants must have a stable Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 1.
Adequate organ function.
Female participants of childbearing potential and nonsterile male participants with female partners of childbearing potential must be willing to use a highly effective method of birth control for the duration of the study and for 7 days after the last dose of BGB-21447, 6 months after the last dose of BGB-43395, and 2 years after the last dose of fulvestrant.
Food effect substudy only: Participants who are able and willing to fast overnight (≥ 10 hours) and consume a high-fat meal.

Exclusion

Prior Bcl-2 inhibitor exposure. For triplet combination cohorts only: Prior therapy selectively targeting CDK4.
Known leptomeningeal disease or uncontrolled, untreated brain metastases.
Any malignancy ≤ 3 years before the first dose of study treatment(s) except for the specific cancer under investigation in this study and any locally recurring cancer that has been treated with curative intent (eg, treated papillary thyroid carcinoma, resected basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix or breast).
For Part 1B: Uncontrolled diabetes.
History of hepatitis B or active Hepatitis C infection
China Only: Untreated chronic hepatitis B or chronic hepatitis B virus (HBV) carriers with HBV DNA \> 500 IU/ml (or \> 2500 copies/ml) at screening.

What this trial measures

  • Part 1: Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)From the first dose of study drug(s) to 30 days after the last dose; up to approximately 6 months

    Number of participants with AEs and SAEs, including findings from physical examinations, electrocardiograms (ECGs), laboratory assessments, and AEs that meet protocol-defined dose-limiting toxicity criteria.

  • Part 1: Recommended Dose for Expansion (RDFE) of BGB-21447 in combination with fulvestrant and in combination with fulvestrant and BGB-43395From first dose of the study drug(s) to 30 days after the last dose or initiation of a new anticancer therapy, whichever occurs first, up to approximately 6 to 9 months

    RDFE of BGB-21447 in combination with fulvestrant and in combination with fulvestrant and BGB-43395 will be determined based upon the maximum tolerated dose (MTD) or maximum administered dose (MAD).

  • Part 2: Objective Response Rate (ORR)Approximately 12 months

    ORR is defined as the percentage of participants who had confirmed complete response (CR) or partial response (PR) as assessed by the investigator per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.