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Study of BBI-940 in Advanced or Metastatic Breast Cancer

This study is testing a new oral medication called BBI-940, either alone or with fulvestrant, for adults with advanced or metastatic breast cancer. BBI-940 is an investigational drug that targets kinesin, a protein involved in cell division. Fulvestrant is an approved drug that targets estrogen receptors. The study aims to find a safe dose and see how well BBI-940 works. You might be able to join if you have certain types of advanced or metastatic breast cancer, including those that are estrogen receptor-positive/HER2-negative or a specific subtype of triple-negative breast cancer. The study is currently recruiting participants.

Study design
This is an open-label, Phase 1 study, meaning you and your doctors will know which treatment you are receiving. It plans to enroll 96 participants and has two parts: a dose-escalation phase and a dose-expansion phase.
What's involved
Treatment is given in repeated 28-day cycles. You will have safety assessments throughout the study, and adverse events will be monitored from the first dose through 30 days after your last dose.
Compensation
Not stated in the trial record.
Follow-up
Adverse events will be monitored for 30 days after your last dose of study treatment.

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

NCT07408089

Study of the Kinesin Oral Molecular Degrader BBI-940 in Subjects With Advanced or Metastatic Breast Cancer

Terminated
PHASE1Ages 18+InterventionalTreatment
Boundless Bio, Inc.
~8 participants
Updated 2026-08-19 on ClinicalTrials.gov
What's tested:BBI-940Fulvestrant

At a glance

Recruiting sites
0 of 8 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Rate of dose limiting toxicities (DLTs) in each BBI-940 monotherapy dose escalation cohort.
Measured over First 28 days of study treatment (through end of Cycle 1).
+2 more outcomes measured

Conditions

Breast Cancer
Metastatic Breast Cancer
Advanced Breast Cancer

Explore related trials

Breast CarcinomaFGFR1 Gene

Where it's being run

8 sites across 4 states
Texas5
California1
New York1
Virginia1

Study leadership

  • Robert C. Doebele, MD, PhD · STUDY_DIRECTOR · Boundless Bio, Inc.

Who to contact

This trial hasn't published a contact. View it on ClinicalTrials.gov

Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Adults with locally advanced or metastatic breast cancer, including estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) disease or triple-negative breast cancer with luminal androgen receptor subtype (TNBC-LAR; androgen receptor expression ≥10% by immunohistochemistry), as applicable by study part.
Prior treatment with standard therapies known to provide clinical benefit, appropriate for disease subtype and study part, including endocrine therapy with CDK4/6 inhibition for ER+/HER2- disease.
Measurable disease per RECIST v1.1, except for participants enrolled in Part 1A.
Molecular eligibility as applicable by study part, including absence of an ESR1 mutation (Part 2A) or presence of FGFR1 amplification (Part 2B), based on prior local testing.
Availability of archival or newly obtained formalin-fixed, paraffin-embedded (FFPE) tumor tissue suitable for protocol-specified biomarker analyses.
Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
Adequate hematologic, hepatic, renal, and coagulation function per protocol-defined laboratory criteria.
Estimated life expectancy of at least 12 weeks.
Ability to swallow oral medication and provide written informed consent.

Exclusion

Prior exposure to an inhibitor or degrader of Kinesin.
Known hypersensitivity to study intervention(s) or excipients.
Receipt of recent anticancer therapy within protocol-defined washout periods.
Other active malignancy likely to interfere with study assessment.
Baseline QTcF \>470 msec or congenital long QT syndrome.
Clinically significant pulmonary embolism within 6 weeks prior to first dose.
Major surgery within 4 weeks or minor surgery within 2 weeks prior to first dose.
Active infection requiring systemic therapy within 2 weeks prior to first dose.
Pregnant or breastfeeding, or planning conception or gamete donation during the study or required post-treatment period.
Prior solid organ transplant or allogeneic stem cell transplant with protocol-defined exceptions.
Failure to recover to CTCAE Grade ≤1 (or baseline) from prior anticancer therapy, with protocol-specified exceptions.
Any serious or uncontrolled medical, laboratory, or psychiatric condition that could compromise safety or study integrity.

What this trial measures

  • Rate of dose limiting toxicities (DLTs) in each BBI-940 monotherapy dose escalation cohort.First 28 days of study treatment (through end of Cycle 1).

    DLTs will be assessed during the first 28 days of study treatment (Cycle 1) to establish the maximum tolerated dose (MTD) and the recommended dose for expansion (RDE) of BBI-940 as monotherapy.

  • Incidence of treatment emergent adverse events (TEAEs) in each dose group and overall as assessed by CTCAE version 5.0.First dose of study treatment through 30 days after the last dose of study treatment.

    Incidence of treatment emergent adverse events (TEAEs) will be assessed by maximum severity and maximum causality.

  • Incidence of study treatment discontinuation and/or interruption by dose group and overall.First dose of study treatment through 30 days after the last dose of study treatment.

    The incidence of study treatment discontinuation and/or interruption will be assessed.