Home › Trials › NCT06120283

BGB-43395 treatment for advanced breast cancer and other solid tumors

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

PHASE1 · BeOne Medicines · NCT06120283

This study is testing a new treatment called BGB-43395 for people with advanced breast cancer and other solid tumors to see if it works better alone or with other medications.

Quick facts

PhasePHASE1
Study typeInterventional
Enrollment399 (estimated)
Ages18 Years and up
SexAll
SponsorBeOne Medicines (industry)
Drugs / interventionschemotherapy
Locations63 sites (Denver, Colorado and 62 other locations)
Trial IDNCT06120283 on ClinicalTrials.gov

What this trial studies

This clinical trial evaluates the effectiveness of BGB-43395, a CDK4 inhibitor, either alone or in combination with fulvestrant or letrozole for patients with hormone receptor positive and HER2-negative breast cancer, as well as other advanced solid tumors. The study is designed in two phases: a dose escalation phase to determine the optimal dosing and a dose expansion phase focusing on specific tumor types. Participants must have advanced, metastatic, or unresectable tumors and have previously received standard therapies.

Who should consider this trial

Good fit: Ideal candidates include individuals with advanced, metastatic, or unresectable hormone receptor positive breast cancer who have received prior treatments.

Not a fit: Patients with early-stage breast cancer or those who have not received prior therapies may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for patients with advanced breast cancer and other solid tumors that are resistant to current therapies.

How similar studies have performed: Other studies involving CDK4 inhibitors have shown promise in treating similar conditions, indicating a potential for success in this approach.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* 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. Prior cytotoxic treatment is prohibited. 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.

Exclusion Criteria:

* 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, resected basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix or breast).
* Uncontrolled diabetes.
* Infection requiring systemic antibacterial, antifungal, or antiviral therapy ≤ 28 days before the first dose of study drug(s), or symptomatic COVID-19 infection.
* 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.
* Prior allogeneic stem cell transplantation, or organ transplantation.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Where this trial is running

Denver, Colorado and 62 other locations

+13 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Advanced Solid Tumor, Advanced Breast Cancer, Metastatic Breast Cancer, Hormone-receptor-positive Breast Cancer, Hormone Receptor Positive Breast Carcinoma, Hormone Receptor Positive Malignant Neoplasm of Breast, HER2-negative Breast Cancer, Hormone Receptor Positive HER-2 Negative Breast Cancer

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.