Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of BTX-9341 in Advanced and/or Metastatic Breast Cancer

NCT ID: NCT06515470

Last Updated: 2025-06-06

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

PHASE1

Total Enrollment

82 participants

Study Classification

INTERVENTIONAL

Study Start Date

2024-07-03

Study Completion Date

2027-12-31

Brief Summary

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The purpose of this study is to test BTX-9341 alone or in combination with fulvestrant (a currently marketed medication for breast cancer) in participants with advanced and/or metastatic hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer. The study includes a dose escalation part (Part A) where small groups of participants will receive increasing doses of BTX-9341 or BTX-9341 + fulvestrant followed by a dose expansion part (Part B) where participants will receive the dose of BTX-9341 selected in Part A + fulvestrant.

Detailed Description

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This first-in-human (FIH), Phase 1 study of BTX-9341 is multicenter, nonrandomized, and open-label to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of BTX-9341 in participants with advanced and/or metastatic HR+/HER2 breast cancer. The study will include a dose escalation part (Part A) followed by a dose expansion part (Part B). During Part A, BTX-9341 will initially be dose escalated alone and then in combination with fulvestrant. A single combination therapy cohort of BTX-9341 + fulvestrant will be further explored in Part B. BTX-9341 will be administered orally in 28-day treatment cycles.

Conditions

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Breast Cancer

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

SEQUENTIAL

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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BTX-9341 (Part A)

BTX-9341 capsule(s) administered orally once daily (QD) in 28-day cycles

Group Type EXPERIMENTAL

BTX-9341

Intervention Type DRUG

Daily oral dose in 28-day cycles until maximum tolerated dose (MTD) or maximum evaluable dose (MED) determined

BTX-9341 + fulvestrant (Part A)

BTX-9341 capsule(s) administered orally QD in 28-day cycles and fulvestrant intermuscular injections on Day 15 and then once every 28 days

Group Type EXPERIMENTAL

BTX-9341

Intervention Type DRUG

Daily oral dose in 28-day cycles until maximum tolerated dose (MTD) or maximum evaluable dose (MED) determined

Fulvestrant

Intervention Type DRUG

500 mg intramuscular injections on Day 15 and then every 28 days

BTX-9341 + fulvestrant (Part B)

BTX-9341 capsule(s) administered orally QD in 28-day cycles and fulvestrant intermuscular injections on Day 15 and then once every 28 days

Group Type EXPERIMENTAL

Fulvestrant

Intervention Type DRUG

500 mg intramuscular injections on Day 15 and then every 28 days

BTX-9341

Intervention Type DRUG

Daily oral dose in 28-day cycles using dose determined in Part A

Interventions

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BTX-9341

Daily oral dose in 28-day cycles until maximum tolerated dose (MTD) or maximum evaluable dose (MED) determined

Intervention Type DRUG

Fulvestrant

500 mg intramuscular injections on Day 15 and then every 28 days

Intervention Type DRUG

BTX-9341

Daily oral dose in 28-day cycles using dose determined in Part A

Intervention Type DRUG

Other Intervention Names

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Faslodex

Eligibility Criteria

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Inclusion Criteria

* Metastatic and/or locally advanced HR+/HER2- breast cancer (dose escalation: measurable disease and/or at least 1 lytic or mixed \[lytic + sclerotic\] bone lesion that can be assessed by CT or MRI or non-measurable disease \[including bone lesions\]; dose expansion: measurable disease)
* Dose escalation: (a) received not more than 1 chemotherapy in the metastatic/advanced setting; (b) no limit to the lines of endocrine therapy (monotherapy or combination therapy) in the metastatic setting; (c) received CDK4/6 inhibitor therapy
* Dose expansion: (a) received not more than 1 chemotherapy in metastatic/advanced setting; (b) received not more than 2 lines of endocrine therapy (monotherapy or combination therapy) and must have been on prior endocrine therapy for at least 6 months before progression; (c) received at most 2 lines of CDK4/6 inhibitor therapy (1 in the adjuvant setting and 1 in the metastatic setting) and must have been on prior CDK4/6 inhibitor therapy for at least 6 months
* Acceptable hematologic function

1. ANC ≥ 1500 per mL. Note: Use of growth-factors to maintain the ANC criterion is prohibited.
2. Platelet count ≥ 100,000 per mL. Note: Use of transfusions or thrombopoietic agents to achieve the baseline platelet count criterion is prohibited.
3. Hemoglobin ≥ 9.0 g/dL. Note: Packed red blood cell transfusion is allowed up to 14 days prior to trial entry.
* Acceptable liver function

1. Bilirubin ≤ 2.0 × institutional upper limit of normal (ULN) (or \< 3.0 × institutional ULN if Gilbert's disease is present)
2. Alanine transaminase (ALT)/aspartate aminotransferase (AST) ≤ 3.0 × institutional ULN (≤ 5.0 × institutional ULN if liver metastases present)
3. Alkaline phosphatase ≤ 2.5 × institutional ULN (≤ 5.0 × institutional ULN if bone or liver metastases present)
* Able and willing to sign informed consent
* Meets all study requirements in the opinion of the Investigator

Exclusion Criteria

* RB1 (retinoblastoma) gene mutation
* Symptomatic visceral disease
* Clinical evidence or history of central nervous system metastasis
* Abnormalities in coagulation, such as bleeding diathesis, or treatment with anticoagulants precluding injections of fulvestrant or luteinizing hormone-releasing hormone (LHRH) agonist
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Biotheryx, Inc.

INDUSTRY

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Jeremy Barton, MD

Role: STUDY_DIRECTOR

Chief Medical Officer

Locations

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Biotheryx Investigative Site

Rochester, Minnesota, United States

Site Status RECRUITING

Biotheryx Investigative Site

Omaha, Nebraska, United States

Site Status RECRUITING

Biotheryx Investigative Site

Houston, Texas, United States

Site Status RECRUITING

Biotheryx Investigative Site

San Antonio, Texas, United States

Site Status RECRUITING

Biotheryx Investigative Site

West Valley City, Utah, United States

Site Status RECRUITING

Biotheryx Investigative Site

Fairfax, Virginia, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Danette Powell

Role: CONTACT

858-354-1814

Facility Contacts

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Biotheryx Investigative Site

Role: primary

Biotheryx Investigative Site

Role: primary

Biotheryx Investigative Site

Role: primary

Biotheryx Investigative Site

Role: primary

Biotheryx Investigative Site

Role: primary

Biotheryx Investigative Site

Role: primary

Other Identifiers

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BTX-9341-101

Identifier Type: -

Identifier Source: org_study_id

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