NCT07408089

Brief Summary

This is a first-in-human, open-label, Phase 1 study evaluating BBI-940, an investigational kinesin oral molecular degrader, administered as monotherapy or in combination with fulvestrant in adults with advanced or metastatic breast cancer.

Trial Health

77
On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
96

participants targeted

Target at P75+ for phase_1 breast-cancer

Timeline
37mo left

Started Feb 2026

Geographic Reach
1 country

8 active sites

Status
recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

Study Progress7%
Feb 2026May 2029

First Submitted

Initial submission to the registry

January 22, 2026

Completed
21 days until next milestone

First Posted

Study publicly available on registry

February 12, 2026

Completed
13 days until next milestone

Study Start

First participant enrolled

February 25, 2026

Completed
3 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

February 28, 2029

Expected
3 months until next milestone

Study Completion

Last participant's last visit for all outcomes

May 31, 2029

Last Updated

April 13, 2026

Status Verified

February 1, 2026

Enrollment Period

3 years

First QC Date

January 22, 2026

Last Update Submit

April 9, 2026

Conditions

Breast CancerAdvanced Breast CancerMetastatic Breast Cancer

Keywords

Breast CancerMetastatic Breast CancerAdvanced Breast CancerPhase 1First in HumanBBI-940FulvestrantFGFR1

Outcome Measures

Primary Outcomes (3)

  • Rate of dose limiting toxicities (DLTs) in each BBI-940 monotherapy dose escalation cohort.

    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.

    First 28 days of study treatment (through end of Cycle 1).

  • Incidence of treatment emergent adverse events (TEAEs) in each dose group and overall as assessed by CTCAE version 5.0.

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

    First dose of study treatment through 30 days after the last dose of study treatment.

  • Incidence of study treatment discontinuation and/or interruption by dose group and overall.

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

    First dose of study treatment through 30 days after the last dose of study treatment.

Secondary Outcomes (6)

  • Objective response rate (ORR) per RECIST Version 1.1 by dose group and overall.

    From first dose of study treatment until disease progression per RECIST 1.1, death, withdrawal, loss to follow-up, or study completion; tumor assessments every 8 weeks (±7 days); assessed up to approximately 3 years.

  • Progression Free Survival (PFS) per RECIST Version 1.1 by dose group and overall.

    From first dose of study treatment until first documented disease progression per RECIST 1.1 or death from any cause, whichever occurs first; tumor assessments every 8 weeks (±7 days); assessed up to approximately 3 years.

  • Time of maximum plasma concentration (Tmax) of BBI-940.

    From 0 hours through up to 24 hours after BBI-940 dosing.

  • Maximum observed plasma concentration (Cmax) of BBI-940.

    From 0 hours through up to 24 hours after BBI-940 dosing.

  • Minimum observed plasma concentration (Ctrough) of BBI-940.

    From 0 hours through up to 24 hours after BBI-940 dosing.

  • +1 more secondary outcomes

Study Arms (4)

Parts 1A, 1B. BBI-940 Monotherapy Escalation

EXPERIMENTAL

Participants receive BBI-940 given alone in multiple sequential dose escalation cohorts. BBI-940 is given orally in repeated 28-day cycles.

Drug: BBI-940

Part 2A. BBI-940 in Combination with Fulvestrant (ER+/HER2- Breast Cancer without an ESR1 Mutation)

EXPERIMENTAL

Participants receive BBI-940 in combination with fulvestrant. BBI-940 is given orally in repeated 28-day cycles at one of multiple potential dose levels.

Drug: BBI-940Drug: Fulvestrant

Part 2B. BBI-940 Monotherapy Expansion (ER+/HER2- Breast Cancer with FGFR1 Amplification)

EXPERIMENTAL

Participants receive BBI-940 given alone at the recommended dose for expansion (RDE). BBI-940 is given orally in repeated 28-day cycles.

Drug: BBI-940

Part 2C. BBI-940 Monotherapy Expansion (TNBC-LAR)

EXPERIMENTAL

Participants receive BBI-940 given alone at the recommended dose for expansion (RDE). BBI-940 is given orally in repeated 28-day cycles.

Drug: BBI-940

Interventions

FulvestrantDRUG

Selective estrogen receptor degrader administered intramuscularly.

Part 2A. BBI-940 in Combination with Fulvestrant (ER+/HER2- Breast Cancer without an ESR1 Mutation)
BBI-940DRUG

Oral small molecule degrader targeting Kinesin.

Part 2A. BBI-940 in Combination with Fulvestrant (ER+/HER2- Breast Cancer without an ESR1 Mutation)Part 2B. BBI-940 Monotherapy Expansion (ER+/HER2- Breast Cancer with FGFR1 Amplification)Part 2C. BBI-940 Monotherapy Expansion (TNBC-LAR)Parts 1A, 1B. BBI-940 Monotherapy Escalation

Eligibility Criteria

Age18 Years+
Sexall
Healthy VolunteersNo
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • 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.

You may not qualify if:

  • 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.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Sites (8)

The START Center for Cancer Research

Los Angeles, California, 90025, United States

RECRUITING

The START Center for Cancer Research

Lake Success, New York, 11042, United States

RECRUITING

NEXT Oncology

Austin, Texas, 78758, United States

RECRUITING

University of Texas Southwestern Medical Center

Dallas, Texas, 75390, United States

RECRUITING

NEXT Oncology

Houston, Texas, 77054, United States

RECRUITING

NEXT Oncology

San Antonio, Texas, 78229, United States

RECRUITING

The START Center for Cancer Care

San Antonio, Texas, 78229, United States

RECRUITING

NEXT Oncology

Fairfax, Virginia, 22031, United States

RECRUITING

MeSH Terms

Conditions

Breast Neoplasms

Interventions

Fulvestrant

Condition Hierarchy (Ancestors)

Neoplasms by SiteNeoplasmsBreast DiseasesSkin DiseasesSkin and Connective Tissue Diseases

Intervention Hierarchy (Ancestors)

EstradiolEstrenesEstranesSteroidsFused-Ring CompoundsPolycyclic CompoundsEstradiol CongenersGonadal Steroid HormonesGonadal HormonesHormonesHormones, Hormone Substitutes, and Hormone Antagonists

Study Officials

  • Robert C. Doebele, MD, PhD

    Boundless Bio, Inc.

    STUDY DIRECTOR

Central Study Contacts

Angela Pietrofeso

CONTACT

1-619-821-1090clinicaltrials@boundlessbio.com

Rebecca Reynolds

CONTACT

1-619-821-1090clinicaltrials@boundlessbio.com

Study Design

Study Type
interventional
Phase
phase 1
Allocation
NON RANDOMIZED
Masking
NONE
Purpose
TREATMENT
Intervention Model
SEQUENTIAL
Model Details: BBI-940 single agent dose escalation and expansion, and BBI-940 dose expansion (at multiple potential dose levels) in combination with fulvestrant.
Sponsor Type
INDUSTRY
Responsible Party
SPONSOR

Study Record Dates

First Submitted

January 22, 2026

First Posted

February 12, 2026

Study Start

February 25, 2026

Primary Completion (Estimated)

February 28, 2029

Study Completion (Estimated)

May 31, 2029

Last Updated

April 13, 2026

Record last verified: 2026-02

Data Sharing

IPD Sharing
Will not share

Locations

US(8)