A Phase 3 interventional study of BGB-43395 and Letrozole in HR+/HER2- Breast Cancer, sponsored by BeOne Medicines. Recruiting at 241 sites in 16 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-26.
Sponsored by BeOne Medicines · Phase 3, Interventional, and Treatment
The purpose of this study is to investigate the efficacy and safety of BGB-43395 in combination with letrozole compared with investigator's choice of cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) in combination with letrozole in patients with advanced or metastatic hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer (BC) who have not received prior systemic treatment for advanced or metastatic disease.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's planned enrollment of 1,056 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →BeOne Medicines is the lead sponsor of 68 studies on the registry; 48 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.
Counted across the registry records on this site, refreshed daily.
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.
Exclusion Criteria:
Note: Other protocol-defined inclusion/exclusion criteria may apply.
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.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
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.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
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.
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.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
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.
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.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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.
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.
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.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
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.
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.
Participants will receive BGB-43395 in combination with letrozole.
Drug: BGB-43395 · Drug: Letrozole
Participants will receive either abemaciclib, palbociclib, or ribociclib based on the Investigator's choice in combination with letrozole.
Drug: Letrozole · Drug: Abemaciclib · Drug: Palbociclib · Drug: Ribociclib
Administered orally.
Administered orally.
Administered orally.
Administered orally.
Administered orally.
Progression-Free Survival (PFS) Determined by Blinded Independent Central Review (BICR)
PFS is defined as the time from first dose until first documentation of progression or death, whichever comes first, as assessed by BICR per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.
Time frame: Up to approximately 4 years
Overall Survival (OS)
OS is defined as the time from the date of randomization until the date of death due to any cause.
Time frame: Up to approximately 11 years
Overall Response Rate (ORR)
ORR is defined as the percentage of participants who had a complete response (CR) or partial response (PR), as assessed by BICR per RECIST v1.1.
Time frame: Up to approximately 4 years
Duration of Response (DOR)
DOR is defined as the time from the first occurrence of a documented objective response to the time of disease progression or death from any cause, whichever occurs first, as assessed by BICR per RECIST v1.1.
Time frame: Up to approximately 4 years
PFS Determined by Investigator
PFS is defined as the time from first dose until first documentation of progression or death, whichever comes first, as assessed by the investigator per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.
Time frame: Up to approximately 4 years
Clinical Benefit Rate (CBR)
CBR is defined as the percentage of participants who have a CR, PR, or stable disease maintained for ≥ 24 weeks after randomization (without subsequent anticancer treatment) per RECIST v1.1 .
Time frame: Up to approximately 4 years
Time to Response (TTR)
TTR is defined as the time from treatment initiation to the first response confirmed by BICR per RECIST v1.1.
Time frame: Up to approximately 4 years
Number of Participants with Adverse Events (AEs)
Number of participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs), including laboratory values, vital signs, physical examination findings, and electrocardiogram results.
Time frame: From first dose of study drug up to 30 days after last dose, up to approximately 11 years
Change from Baseline in European Organisation for Research and Treatment of Cancer (EORTC)-Item Library (IL)454.
The EORTC-IL454 is a questionnaire that asks participants to rate their breast cancer symptoms and the impact of breast cancer on their quality of life (QoL). The EORTC-IL454 is an EORTC Item Library-derived scale set constructed using items from the validated EORTC Quality of Life Questionnaire-Core 30 (QLQ-C30) (a core measure of health-related QoL in cancer patients) and the QLQ-BR23 (its breast cancer-specific module) The EORTC-IL454 contains 26 questions, each answered on a 4-point scale (1 = Not at all; 4 = Very much), and includes 2 functional scales (physical functioning and role functioning), 2 symptom scales (Nausea/Vomiting and Diarrhea), and 1 Global Health Status (GHS)/Quality of Life (QoL) scale, 7 systemic side effects scales, 3 arm symptom scales, and 4 breast-specific symptom scales. The recall period is the past 7 days. Higher scores in GHS and functional scales and lower scores in symptom scales indicate better QoL.
Time frame: Baseline and up to approximately 4 years
Progression-Free Survival 2 (PFS2)
PFS2 is defined as the time from randomization until progression on the next line of treatment (ie, first subsequent therapy), as assessed by the investigator, or death due to any cause, whichever occurs first.
Time frame: Up to approximately 4 years
Showing the first 100 of 241 sites across 16 countries. Choose a country and city above to see the rest.
Plan to share: Yes — BeOne shares data on completed studies responsibly and provides qualified scientific and medical researchers access to data and supporting documentation for clinical trials in dossiers for medicines and indications after submission and approval in the United States, China, and Europe. Clinical trials supporting subsequent local approvals, new indications, or combination products are eligible for sharing once corresponding regulatory approvals are achieved. BeOne shares data only when permitted by applicable data privacy and security laws and regulations, when it is feasible to do so without compromising the privacy of study participants, and other considerations. Qualified researchers with appropriate competencies who are engaged in novel scientific research may submit a request for participant-level data with a research proposal for BeOne review. Research teams must include a biostatistician and sign a Data Sharing Agreement prior to receiving access to clinical trial data.
Supporting information: Study protocol, Statistical analysis plan, Clinical study report
Time frame: See plan description
Access criteria: See plan description
Data sharing details ↗ · beonemedicines.com
No publications or documents are linked to this record.
Started May 2026 (actual). Primary completion is estimated for Apr 2029, 35 months after the start.
Of 272 industry-sponsored phase 3 interventional studies under Breast Neoplasms, half reached primary completion within 40 months of starting (the median), counting those still running; a quarter within 28 and three quarters within 63. This study's planned 35 months is below that.
Counting every sponsor, half of 600 studies reached it within 59 months; a quarter within 36 and three quarters within 96.
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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Studies of the drug tested here: CDK4 Inhibitor BGB-43395