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Breast NeoplasmsPhase 1NCT04568902

Study of H3B-6545 in Japanese Women With Estrogen Receptor (ER)-Positive, Human Epidermal Growth Factor Receptor 2 (HER2)-Negative Breast Cancer

A Phase 1 study testing H3B-6545 and Antihistamine in people with Breast Neoplasms, run by Eisai Co., Ltd. at 2 sites in Japan.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

The purpose of study is to determine tolerability and safety profile of H3B-6545 in Japanese women with ER-positive, HER2-negative breast cancer, and also to confirm the dose applicability to Japanese. Read more about this study

Who is it for?
Ages 20 years and older, women only
Conditions the study is for
Breast Neoplasms
What is being tested?
H3B-6545 and Antihistamine
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
33 participants
Where
2 sitesJapan
Study dates
30 Sep 2020to 1 Oct 2025
Phase
Phase 1
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 20 years and older
  • Women only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Participant has a histologically and/or cytologically confirmed diagnosis of ER-positive, HER2-negative breast cancer.
  • Note: Status of ER and HER2 should be diagnosed by method approved by regulatory authority
  • Only females, age greater than or equal to (>=) 20 years at the time of informed consent.
  • Prior therapy for breast cancer in the adjuvant and/or advanced/metastatic setting must have included a minimum of:
  • two prior hormonal therapies, or
  • one prior hormonal therapy and one prior chemotherapy regimen, or
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  • one prior hormonal therapy and a cyclin-dependent kinase (CDK4/6) inhibitor.
  • Participant has an ECOG-PS of 0 or 1.
  • Participant has adequate bone marrow and organ function, as defined by the following laboratory values:
  • Absolute neutrophil count (ANC) >=1.5*10˄9/liter (L).
  • Platelets >=100*10˄9/L.
  • Hemoglobin >=9.0 gram per deciliter (g/dL).
  • Potassium, sodium, calcium (corrected for serum albumin) and magnesium less than or equal to (<=) Common Terminology Criteria for Adverse Events (CTCAE) Grade 1.
  • International normalized ratio (INR) <=1.5.
  • Serum creatinine <=1.5*upper limit of normal (ULN).
  • Serum albumin >=3.0 g/dL (>=30 gram per liter [g/L]).
  • Alanine aminotransferase (AST) and aspartate aminotransferase (ALT) <=3.0*ULN. If the participant has liver metastases, ALT and AST <=5.0*ULN.
  • Total serum bilirubin less than (<) 1.5*ULN.
  • Participants who are expected to survive for 3 months or longer after starting administration of the investigational drug.
  • Voluntary agreement to provide written informed consent and the willingness and ability to comply with all aspects of the protocol.

Who cannot join

  • Participant with inflammatory breast cancer.
  • Participant is currently receiving or has received systemic corticosteroids <=2 weeks prior to starting study drug, or has not fully recovered from side effects of such treatment.
  • Note: The following uses of corticosteroids are permitted: inhaled sprays (example- for obstructive airways diseases), eye drops or local injections (example- intra-articular).
  • Washout period required from the end of prior treatment to the first administration of study drug will be as follows.
  • Anti-cancer therapy
  • Antibody and other study drugs: greater than (>) 4 weeks (however, in the case where the half-life of other study drugs is known and 5*half-lives of that study drug is less than or equal to 4 weeks, participants can be eligible after >=5*half-lives of that study drug has passed).
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  • Prior chemotherapy (except small-molecule targeted therapy), surgical therapy, radiation therapy: >3 weeks.
  • Endocrine therapy, immunotherapy (except antibody drug), small-molecule targeted therapy: >2 weeks.
  • Supportive therapy • Blood/platelet transfusion, hematopoietic stimulating agent including granulocyte colony-stimulating factor (G-CSF) formulation: >2 weeks.
  • Participant has active cardiac disease or a history of cardiac dysfunction, including any of the following:
  • History of angina pectoris, symptomatic pericarditis, or myocardial infarction within 12 months prior to study entry.
  • History of documented congestive heart failure (New York Heart Association [NYHA] functional classification II to IV).
  • Documented cardiomyopathy.
  • Participant has a left ventricular ejection fraction (LVEF) <50 percent (%) as determined by multiple gated acquisition (MUGA) scan or echocardiogram (ECHO).
  • History of any cardiac arrhythmias, example- ventricular, supraventricular, nodal arrhythmias, or conduction abnormality in the previous 12 months.
  • Heart Rate <60 beats per minute (bpm) on the screening.
  • On screening, any of the following cardiac parameters: PR interval >220 millisecond (msec), QRS interval >10˄9 msec, or QT interval with Fridericia's correction (QTcF) >450 msec.
  • Systolic blood pressure (BP) not deemed clinically controlled by the investigator.
  • Participant has impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of H3B-6545.
  • Participant has a known hypersensitivity to any of the excipients of H3B-6545.
  • Known to be human immunodeficiency virus (HIV) positive.
  • Active viral hepatitis (B or C) as demonstrated by positive serology. Participants with chronic hepatitis B virus (HBV) infection is on antiviral therapy is eligible.
  • Participant has any other concurrent severe and/or uncontrolled medical condition that would, in the investigator's judgment, contraindicate participant participation in the clinical study (example- chronic pancreatitis, thyroid dysfunction etc).
  • Any adverse event related to previous therapies for breast cancer that has not resolved to <=Grade 1 (with exception of the alopecia).
  • Females who are breastfeeding or pregnant at Screening or Baseline (as documented by a positive beta-human chorionic gonadotropin [ß-hCG] or human chorionic gonadotropin [hCG] test). A separate baseline assessment is required if a negative screening pregnancy test was obtained more than 72 hours before the first dose of study drug.
  • Women of childbearing potential who don't agree that both the participant and her partner will use a medically effective method for contraception (as below) throughout the entire study period or for 28 days after study drug discontinuation.
  • Note: Condom, contraceptive sponge, foam, jelly, diaphragm, intrauterine device (IUD) , or use of oral contraception from at least 4 weeks before starting the study treatment (Approved drugs or certified medical devices in Japan, Non-approved drugs or certified medical devices in Japan) If a participant is on oral contraceptives, they should also be using some additional method.
  • Alcohol dependency within 6 months before study entry.
  • Participant has a concurrent malignancy or malignancy within 3 years of enrollment, with the exception of adequately treated basal or squamous cell carcinoma, non-melanomatous skin cancer, or curatively resected cervical cancer.
  • Psychological, familial, sociological, or geographical conditions that do not permit compliance with the protocol.
  • Diagnosed with meningeal carcinomatosis.
  • Participants with brain or subdural metastases are not eligible, unless they have completed local therapy and have discontinued the use of corticosteroids for this indication for at least 4 weeks before starting treatment in this study. Any signs (example- radiologic) or symptoms of brain metastases must be stable for at least 4 weeks before starting study treatment.
  • Participant has a known intolerability to any oral antihistamine drug (only for Antihistamine Prophylactic Administration Part and Randomization Part).
  • Participant needs to receive systemic or topical usage of either antihistamine or corticosteroid during Cycle 1 (only for Randomization Part).
  • Note: The following uses of corticosteroids are permitted: inhaled sprays (example, for obstructive airways diseases), eye drops or local injections (example, intra-articular).
  • Participants initiated to receive drugs may cause rash 7 days prior to starting study drug.

Trial locations and contacts

2 sites in 1 country.

Japan2 sites

  • Eisai Trial Site 2

    Chūōku

  • Eisai Trial Site 1

    Kōtoku

Other trials in Japan

About this study

Official title: A Phase 1 Study of H3B-6545 in Japanese Women With Estrogen Receptor-positive, HER2 Negative Breast Cancer

The purpose of study is to determine tolerability and safety profile of H3B-6545 in Japanese women with ER-positive, HER2-negative breast cancer, and also to confirm the dose applicability to Japanese.

Being tested
H3B-6545, Antihistamine
Keywords
H3B-6545, ER-positive, HER2-negative
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • H3B-6545Drug

    H3B-6545 oral tablets.

  • AntihistamineDrug

    Systemic antihistamine oral drug such as fexofenadine, loratadine and cetirizine.

Study groups in NCT04568902
Study groupRoleWhat they receive
Dose Escalation Part: H3B-6545 300 mgExperimentalParticipants will receive H3B-6545 300 milligram (mg) tablets, orally, once daily in 28 days cycle until disease progression, violation of study requirements, unable to continue study based on investigator opinion or withdrawal of consent.
Receives: Drug: H3B-6545
Dose Escalation Part: H3B-6545 450 mgExperimentalParticipants will receive H3B-6545 450 mg tablets, orally, once daily in 28 days cycle until disease progression, violation of study requirements, unable to continue study based on investigator opinion or withdrawal of consent.
Receives: Drug: H3B-6545
Antihistamine Prophylactic Administration PartExperimentalParticipants will receive prophylactic treatment with non-sedating systemic antihistamine, orally, once from Cycle 1 Day 1 until Cycle 1 Day 28, followed by H3B-6545 450 mg tablets, orally, once daily in 28 days cycle until disease progression, violation of study requirements, unable to continue study based on investigator opinion or withdrawal of consent.
Receives: Drug: H3B-6545; Drug: Antihistamine
Randomization PartExperimentalParticipants will be randomized in 1:1 ratio to receive H3B-6545 450 mg, tablets, orally, once daily in 28 days cycle either with non-sedating systemic antihistamine prophylactic administration from Day 1 until Day 28 of Cycle 1 OR without antihistamine prophylactic administration until disease progression, violation of study requirements, unable to continue study based on investigator opinion or withdrawal of consent.
Receives: Drug: H3B-6545; Drug: Antihistamine

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number of Participants With Dose-limiting Toxicities (DLTs)

    Toxicity will be assessed according to National Cancer Institute Common Terminology Criteria for Adverse Event (NCI CTCAE), v5.0. DLT is defined as any of the following events occurred within the Cycle 1 of the administration of H3B-6545: Febrile neutropenia, Grade 4 neutropenia that does not resolve to Grade<=2 within 7days, Grade 4 thrombocytopenia, Grade3 thrombocytopenia>=7days or requiring platelet transfusion, Grade3 thrombocytopenia associated with bleeding, Grade4 anemia or Grade3 anemia requiring erythrocyte transfusion; Grade3 or 4 bilirubin increase, AST or ALT>=10*ULN which does not resolve to Grade2 or less within 7days and/or else is clinically significant; Non-hematological toxicities Grade4 and Grade3 with exception of abnormal clinical laboratory values with no clinical significance and events which can be managed and controlled to Grade2 or less by maximal medical management within 7days, participant administered<70% of prescribed dose due to intolerable toxicity.

    Measured: Up to Cycle 1 (each cycle length is equal to [=] 28 days)

  2. Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs)

    Measured: Baseline up to 36 months

  3. Percentage of Participants With Incidence of Rash

    Measured: Baseline up to 36 months

  4. Number of Participants With Clinically Significant Change From Baseline in Laboratory Values

    Measured: Baseline up to 36 months

  5. Number of Participants With Clinically Significant Change From Baseline in Vital Sign Values

    Measured: Baseline up to 36 months

  6. Number of Participants With Clinically Significant Change From Baseline in Weight Values

    Measured: Baseline up to 36 months

  7. Number of Participants With Clinically Significant Change From Baseline in 12-lead Electrocardiogram (ECG) Findings

    Measured: Baseline up to 36 months

  8. Number of Participants With Clinically Significant Change From Baseline in Physical Examinations

    Measured: Baseline up to 36 months

  9. Number of Participants With Clinically Significant Change From Baseline in Eastern Cooperative Oncology Group Performance Status (ECOG-PS)

    ECOG performance score is measured on 6 point scale to assess participant's performance status, where: Grade 0: Fully active, able to carry on all pre-disease performance without restriction; Grade 1: Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work; Grade 2: Ambulatory and capable of all selfcare but unable to carry out any work activities. Up and about more than 50% of waking hours; Grade 3: Capable of only limited selfcare, confined to bed or chair more than 50% of waking hours; Grade 4: Completely disabled. Cannot carry on any selfcare. Totally confined to bed or chair; Grade 5: Dead.

    Measured: Baseline up to 36 months

Secondary outcomes (8)

  1. Cmax: Maximum Observed Plasma Concentration of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  2. Tmax: Time of Maximum Observed Plasma Concentration of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  3. AUC 0-t: Area Under the Concentration-time Curve From Zero (Pre-dose) to Time of Last Quantifiable Concentration of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  4. Rac: Accumulation Ratio of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  5. AUC 0-inf: Area Under the Concentration-time Curve From Zero (Pre-dose) Extrapolated to Infinite Time of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  6. T1/2: Terminal Half-life of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  7. CL/F: Apparent Total Body Clearance of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

  8. Vz/F: Apparent Volume of Distribution at Terminal Phase of H3B-6545

    Measured: Dose Escalation and Antihistamine Prophylactic Administration Part: Cycle 1 Days 1 and 15: 0-24 hours post dose; Randomization Part: Cycle 1 Days 1 and 15: 0-6 hours post dose (cycle length=28 days)

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted29 Sep 2020
  2. Study start30 Sep 2020
  3. Primary completion1 Oct 2025
  4. Study completion1 Oct 2025

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
33 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04568902
Sponsor's protocol ID
H3B-6545-J081-103
Status last verified
Jan 2025
First submitted
24 Sep 2020
Last updated
23 Oct 2025
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Eisai's data sharing commitment and further information on how to request data can be found on our website http://eisaiclinicaltrials.com/.

Publications

  • Furman C, Puyang X, Zhang Z, Wu ZJ, Banka D, Aithal KB, Albacker LA, Hao MH, Irwin S, Kim A, Montesion M, Moriarty AD, Murugesan K, Nguyen TV, Rimkunas V, Sahmoud T, Wick MJ, Yao S, Zhang X, Zeng H, Vaillancourt FH, Bolduc DM, Larsen N, Zheng GZ, Prajapati S, Zhu P, Korpal M. Covalent ERalpha Antagonist H3B-6545 Demonstrates Encouraging Preclinical Activity in Therapy-Resistant Breast Cancer. Mol Cancer Ther. 2022 Jun 1;21(6):890-902. doi: 10.1158/1535-7163.MCT-21-0378.

    PubMed 35642432

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing H3B-6545 and Antihistamine in people with Breast Neoplasms, run by Eisai Co., Ltd. at 2 sites in Japan.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 20 inclusion and 36 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 23 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in Japan. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants With Dose-limiting Toxicities (DLTs) (time frame: Up to Cycle 1 (each cycle length is equal to [=] 28 days)). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04568902, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Oct 2025.

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