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Purpose

The primary purpose of phase 1 portion of this study is to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of H3B-6545 in women with locally advanced or metastatic estrogen receptor (ER)-positive, human epidermal growth factor 2 (HER2)-negative breast cancer. The primary purpose of phase 2 portion of this study is to estimate the efficacy of H3B-6545 in terms of best overall response rate, duration of response (DoR), clinical benefit rate (CBR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) in all participants with ER-positive, HER2-negative breast cancer and in those with and without ER alpha mutation (including a clonal estrogen receptor 1 gene [ESR1] Y537S mutation).

Conditions

Eligibility

Eligible Ages
Over 18 Years
Eligible Genders
Female
Accepts Healthy Volunteers
No

Inclusion Criteria

  1. Pre- or post-menopausal women. 2. ER-positive, HER2-negative breast cancer that is advanced or metastatic. 3. Progressed on prior therapy. Multiple prior lines of therapy allowed in Phase 1 and 2. Participants under amendment 6 (or subsequent amendments) must have received prior cyclin-dependent kinase (CDK4/6) inhibitor therapy. Up to one prior chemotherapy in the metastatic setting is allowed. 4. A recent archival tumor tissue obtained within 6 months prior to enrollment or a fresh tumor biopsy must be provided. A second biopsy after initiating trial therapy is not required. 5. Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1. 6. Adequate bone marrow and organ function. 7. Participants under amendment 6 (or subsequent amendments) must have measurable disease at baseline as per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria. 8. Participants under amendment 6 (or subsequent amendments) must have ESR1 Y537S mutation in absence of ESR1 D538G mutation as per the results of a central laboratory from a Nucleic Acids Whole Blood sample.

Exclusion Criteria

  1. Participants must have at least one measurable lesion. 2. Participant with inflammatory breast cancer. 3. Participant has received more than one prior chemotherapy regimen for metastatic disease (Phase 2 only). 4. Females of childbearing potential who are unable or unwilling to follow adequate contraceptive measures.

Study Design

Phase
Phase 1/Phase 2
Study Type
Interventional
Allocation
Non-Randomized
Intervention Model
Sequential Assignment
Primary Purpose
Treatment
Masking
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Experimental
H3B-6545 Arm 1: Dose escalation
  • Drug: H3B-6545
    Oral capsules by mouth once daily
Experimental
H3B-6545 Arm 2: Phase 2
  • Drug: H3B-6545
    Oral capsules by mouth once daily

More Details

Status
Completed
Sponsor
Eisai Inc.

Study Contact

Notice

Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.