Tests BGB-43395 alone or with other drugs for advanced breast cancer
Tests a CDK4 inhibitor, alone or combined, in adults with hormone-positive breast cancer.
Key facts
- Who runs it
- BeOne Medicines
- Where
- Muang, ThailandSee the siteAlso in 10 other countries, 60 sites
- Trial code
- Registry title
- BGB-43395 Alone or as Part of Combination Therapies in Participants With Breast Cancer and Other Advanced Solid Tumors
- Status
- Recruiting
- Phase
- Phase 1
- People taking part
- 433 people, planned
- Started
- 1 Dec 2023
- Expected to end
- Dec 2029
- Type of study
- Interventional, 5 groups
- Treatments tested
- BGB-43395
- Fulvestrant
- Letrozole
- Elacestrant
- Anti-Diarrheal Agent
- Record updated
- 15 October 2026
Who can take part
AI summary
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 adults with advanced or metastatic solid tumors that depend on CDK4, including hormone receptor positive (HR+), HER2-negative breast cancer. It tests BGB-43395 alone or with fulvestrant, letrozole or elacestrant.
- Age
- 18 years or older
- Sex
- All sexes can join. Women with metastatic HR+/HER2- breast cancer must be postmenopausal or on ovarian function suppression treatment.
- Disease stage
- Advanced, metastatic or unresectable solid tumors (including HR+ breast cancer, ovarian, endometrial and non-small cell lung cancer). Breast cancer in the later part of the trial must be HR+/HER2-. No symptomatic visceral disease.
- Earlier treatment
- For the elacestrant or fulvestrant combinations: at least 1 prior line of treatment, including endocrine therapy and a CDK4/6 inhibitor. For the letrozole combination: no CDK4/6 inhibitor before and no earlier systemic treatment for advanced disease.
- Biomarker or test result
- Hormone receptor positive (HR+) and HER2-negative (HER2-) status is required for breast cancer.
Main reasons for not taking part
- Leptomeningeal disease or untreated or uncontrolled brain metastases
- Another cancer within 3 years before the first dose (with some exceptions)
- Uncontrolled diabetes
- Infection needing treatment within 28 days, active hepatitis C, or untreated chronic hepatitis B
- Earlier stem cell or organ transplant
The registry criteria, word for word
Show all 14 criteriaShow less
Who can take part
- Phase 1a (Dose Escalation): Participants with histologically or cytologically confirmed advanced, metastatic, or unresectable solid tumors associated with dependency on CDK4, including HR+ breast cancer, ovarian cancer, endometrial cancer, non-small cell lung cancer, and others. For combination with elacestrant, participants must have received at least 1 prior line of treatment for advanced/metastatic disease including prior endocrine therapy and CDK4/6 inhibitor in either the adjuvant or advanced/metastatic setting
- Phase 1a Safety Expansion: For combination with fulvestrant in regions where approved and available, participants with HR+ breast cancer must have received at least 1 prior line of treatment including endocrine therapy and a CDK4/6 inhibitor. For combination with letrozole, participants must be CDK4/6 inhibitor treatment naïve and have not received any previous systemic treatment for advanced disease
- Phase 1b: Participants with HR+/HER2- breast cancer
- Phase 1b: For combination with fulvestrant, participants with HR+/HER2- breast cancer enrolled in regions where CDK4/6 inhibitors are approved and available must have received 1-2 lines of therapy for advanced/metastatic disease including endocrine therapy and a CDK4/6 inhibitor. Participants can have received up to 2 lines of prior cytotoxic chemotherapy for advanced disease. For combination cohorts with letrozole, participants must be CDK4/6 inhibitor treatment naïve and have not received any previous systemic treatment for advanced disease
- Stable Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1
- Female participants with metastatic HR+/HER2- breast cancer must be postmenopausal or receiving ovarian function suppression treatment
- Adequate organ function without symptomatic visceral disease
Who cannot take part
- 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, resected basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix or breast)
- Infection requiring systemic antibacterial, antifungal, or antiviral therapy ≤ 28 days before the first dose of study drug(s), or symptomatic COVID-19 infection
- Prior allogeneic stem cell transplantation, or organ transplantation; Note: Other protocol defined Inclusion/Exclusion criteria may apply
- Known leptomeningeal disease or uncontrolled, untreated brain metastases
- Uncontrolled diabetes
- Participants with untreated chronic hepatitis B or chronic hepatitis B virus (HBV) carriers with HBV DNA ≥ 500 IU/mL (or ≥ 2500 copies/mL) at screening
- Participants with active hepatitis C infection
Where in Thailand
Also in 10 other countries, 60 sites
- Srinagarind Hospital (Khon Kaen University)Muang, ThailandContact: Study DirectorNo longer taking part
About the trial
What the trial wants to find out
This is a dose escalation and dose expansion study to compare how well BGB-43395, a selective cyclin-dependent kinase 4 (CDK4) inhibitor, works as monotherapy or in combination with fulvestrant, letrozole, or elacestrant in participants with hormone receptor positive (HR+) and human epidermal growth factor 2 negative (HER2-) breast cancer (BC) and other advanced solid tumors. The main purpose of this study is to explore the recommended dosing for BGB-43395.
The 5 groups in the trial
- Dose EscalationTreatment being tested
Phase 1a: Sequential cohorts of increasing dose levels of BGB-43395 will be evaluated as monotherapy and in combination with either fulvestrant, letrozole, or elacestrant to assess for safety and tolerability.
Treatment: BGB-43395, Fulvestrant, Letrozole, and Elacestrant
- Safety ExpansionTreatment being tested
Phase 1a: Cohorts of selected dose levels of BGB-43395 in combination with fulvestrant or letrozole in HR+/HER2 breast cancer.
Treatment: BGB-43395, Fulvestrant, and Letrozole
- Dose Expansion Cohort 1Treatment being tested
Phase 1b: The recommended dose for expansion (RFDE) for BGB-43395 (in combination with fulvestrant) from Phase 1a will be evaluated in HR+ breast cancer.
Treatment: BGB-43395 and Fulvestrant
- Dose Expansion Cohort 2Treatment being tested
Phase 1b: The recommended dose for expansion (RFDE) for BGB-43395 in combination with letrozole from Phase 1a will be evaluated in HR+ breast cancer.
Treatment: BGB-43395 and Letrozole
- Dose Expansion Cohort 3Treatment being tested
Phase 1b: The recommended dose for expansion (RFDE) for BGB-43395 in combination with letrozole from Phase 1a will be evaluated in HR+ breast cancer. Participants will also receive an anti-diarrheal agent for prophylaxis.
Treatment: BGB-43395, Letrozole, and Anti-Diarrheal Agent
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 doctorData and sources
- Registry record
- Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
- Official title
- A Phase 1a/1b Study Investigating the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Preliminary Antitumor Activity of the CDK4 Inhibitor BGB-43395, Alone or as Part of Combination Therapies in Patients With Metastatic HR+/HER2- Breast Cancer and Other Advanced Solid Tumors
- Plain-language title
- Tests BGB-43395 alone or with other drugs for advanced breast cancerGenerated from the registry record. The registry title is the official one.
- AI summary
- From the trial's eligibility criteria. Read by machine on 13 November 2026.
- Record updated
- 15 October 2026