An Open-label, Multicenter, Phase 2 Dose Optimization and Expansion Study to Evaluate the Safety and Efficacy of BB-1701, an Anti-human Epidermal Growth Factor Receptor 2 (Anti-HER2) Antibody-drug Conjugate (ADC), in Previously Treated Subjects With HER2-positive or HER2-low Unresectable or Metastatic Breast Cancer

Plain English Summary

A Study of BB-1701 in Previously Treated Participants With Human Epidermal Growth Factor Receptor 2 (HER2)-Positive or HER2-low Unresectable or Metastatic Breast Cancer is a Phase 2 clinical trial sponsored by Eisai Inc. studying Breast Cancer. This study tests a new drug called BB-1701, which is a type of targeted therapy for breast cancer. It is for adults with breast cancer that has spread or cannot be removed, and who have previously been treated with a drug called trastuzumab deruxtecan (T-DXd). Participants will receive BB-1701 as an intravenous infusion every three weeks. The study has two parts: one to find the best dose and another to evaluate how well the drug works. There are no direct alternatives mentioned in this summary, but standard treatments for advanced breast cancer include chemotherapy, hormone therapy, and other targeted therapies. The trial aims to enroll 135 participants.

Official Summary

The primary purpose of the Dose Optimization (Part 1) of this study is to assess the safety and tolerability of BB-1701 and to determine the recommended dose (RD) of BB-1701 for Dose Expansion (Part 2). The primary purpose of Dose Expansion (Part 2) is to assess the antitumor activity of BB-1701 at RD in the selected population(s) of breast cancer (BC).

Who Can Participate

Here is what you need to know about eligibility for this trial. Adults aged 18 and older with advanced or metastatic breast cancer. Patients must have previously received trastuzumab deruxtecan (T-DXd). The cancer must be confirmed as HER2-positive or HER2-low. Patients should have good general health and organ function, and not have active brain metastases or certain other serious medical conditions. This trial is studying Breast Cancer, so participants generally need a confirmed diagnosis.

What They're Measuring

The primary outcomes measure the safety and tolerability of BB-1701, meaning how often side effects occur and how severe they are, to determine the best dose for further study. The specific primary outcome measures are: Part 1, Dose Optimization: Number of Participants With Adverse Events (AEs) (Baseline up to 35 months); Part 1, Dose Optimization: Number of Participants With Clinically Significant Laboratory Values (Baseline up to 35 months); Part 1, Dose Optimization: Number of Participants With Clinically Significant Vital Sign Values (Baseline up to 35 months); Part 1, Dose Optimization: Number of Participants With Clinically Significant 12-lead ECGs Values (Baseline up to 35 months); Part 1, Dose Optimization: Number of Participants With Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) (Baseline up to 35 months). These endpoints are how researchers determine whether the treatment is effective and will form the basis of any future regulatory submissions.

About This Phase

This trial is in Phase 2, which tests whether the treatment actually works against the target condition. Phase 2 trials involve 100-300 patients and continue to monitor safety while evaluating effectiveness. This phase often tests different dosages to find the optimal amount. About 33% of Phase 2 drugs advance to Phase 3. If successful, the treatment will move to large-scale Phase 3 trials needed for FDA approval.

Why This Trial Matters

This trial is important because it explores a new treatment option for patients with advanced breast cancer who have already received T-DXd, addressing a need for further treatment strategies in this Phase 2 success would typically lead to larger Phase 3 trials needed for regulatory approval. This research targets Breast Cancer, where improved treatment options are needed.

Investor Insight

This trial targets a significant market of previously treated HER2-positive and HER2-low breast cancer patients, with BB-1701 representing a potential advancement in antibody-drug conjugate therapy, s Phase 2 trials have approximately a 15-20% chance of eventually gaining FDA approval.

Is This Trial Right for Me?

Ask your doctor if BB-1701 is a suitable option for you, considering your treatment history and overall health. Be prepared for regular intravenous infusions of the study drug every three weeks. You will have regular check-ups and tests to monitor your health and the drug's effects. The trial is being conducted at 20 sites. Always discuss clinical trial participation with your healthcare provider before making any decisions. This information is for educational purposes only and is not medical advice.

AI-generated analysis for educational purposes only. This is not medical advice. Discuss clinical trial participation with your doctor. Data sourced from ClinicalTrials.gov.

Study Design

• Study Type: INTERVENTIONAL
• Allocation: RANDOMIZED
• Model: PARALLEL
• Masking: NONE
• Enrollment: 135 participants

Interventions

• DRUG: BB-1701 — BB-1701 will be administered as an intravenous infusion, every 3 weeks (21-day cycle).

Primary Outcomes

• Part 1, Dose Optimization: Number of Participants With Adverse Events (AEs) (Baseline up to 35 months)
• Part 1, Dose Optimization: Number of Participants With Clinically Significant Laboratory Values (Baseline up to 35 months)
• Part 1, Dose Optimization: Number of Participants With Clinically Significant Vital Sign Values (Baseline up to 35 months)
• Part 1, Dose Optimization: Number of Participants With Clinically Significant 12-lead ECGs Values (Baseline up to 35 months)
• Part 1, Dose Optimization: Number of Participants With Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) (Baseline up to 35 months)

Secondary Outcomes

• Part 1, Dose Optimization: Duration of Response (DOR) (From the date of documented CR or PR to the date of PD or death, whichever occurs first (up to 35 months))
• Part 1, Dose Optimization: Progression-free Survival (PFS) (From the date of first dose to the date of the first documentation of PD or death, whichever occurs first (up to 35 months))
• Part 1, Dose Optimization: Overall Survival (OS) (From the date of first dose to the date of death (up to 35 months))
• Part 1, Dose Optimization: Disease Control Rate (DCR) (From the date of first dose until PD or death, whichever occurs first (up to 35 months))
• Part 1, Dose Optimization: Clinical Benefit Rate (CBR) (From the date of first dose until PD or death, whichever occurs first (up to 35 months))

Full Eligibility Criteria

Inclusion Criteria

* Male or female, aged \>=18 years at the time of informed consent.
* Metastatic or unresectable BC that is histologically confirmed to be either HER2-positive (defined as an immunohistochemistry \[IHC\] status of 3+, or a positive in situ hybridization \[ISH\] test \[fluorescence, chromogenic, or silver-enhanced ISH\] if IHC status is 2+) or HER2-low (defined as an IHC status of 1+, or 2+ and negative ISH) per the American Society of Clinical Oncology/College of American Pathology guidelines as documented prior to trastuzumab deruxtecan (T-DXd) treatment.
* Must have previously received T-DXd.
* Sufficient tumor tissue is required for HER2 status testing at a central laboratory.
* Measurable disease per RECIST 1.1 as assessed by the investigator. Participants with bone only disease may be eligible if there is a measurable soft tissue component associated with the bone lesion.
* Must have previously received at least 1 but no more than 3 prior chemotherapy-based regimes in the unresectable or metastatic setting. If recurrence occurred during or within 6 months of (neo) adjuvant chemotherapy, this would count as 1 line of chemotherapy.
* If HR-positive HER2-low BC, must have previously received endocrine therapy and is not expected to further benefit from it.
* ECOG PS 0 or 1.
* Life expectancy of at least 3 months.
* Adequate organ function and laboratory parameters.

Exclusion Criteria

* Presence of brain or subdural metastases, unless participant has completed local therapy and has discontinued the use of corticosteroids for this indication for at least 2 weeks prior to starting treatment in this study.
* Diagnosed with meningeal carcinomatosis.
* Received anticancer therapy (chemotherapy or other systemic anticancer therapies, immunotherapy, radiation therapy, etc) or an investigational drug or device within the past 28 days or 5 half-lives, whichever is shorter.
* Prior treatment with eribulin.
* Any prior allergic reactions of Grade \>=3 to monoclonal antibodies or contraindication to the receipt of corticosteroids or any of the excipients (investigators should refer to the prescribing information for the selected corticosteroid).
* Residual toxic effects of prior therapies or surgical procedures that is Grade \>=2 (except alopecia or anemia).
* Grade \>=2 peripheral neuropathy or history of Grade \>=3 peripheral neuropathy or discontinued any prior treatment due to peripheral neuropathy.
* Active pneumonitis/interstitial lung disease (ILD) or any clinically significant lung disease (example, chronic obstructive pulmonary disease), history of Grade \>=2 pneumonitis/ILD, or received radiotherapy to lung fields within 12 months of Cycle 1 Day 1 of study treatment.
* Congestive heart failure greater than (\>) New York Heart Association Class II or left ventricular ejection fraction (LVEF) less than (\<) 50 percent (%) measured by multigated acquisition scan (MUGA) or echocardiogram.
* Has a corrected QT interval prolongation per Fridericia formula (QTcF) \>470 millisecond (ms) (for both males and females) based on screening triplicate 12-lead ECG.
* Concomitant active infection requiring systemic treatment, except:

  * If known to be human immunodeficiency virus (HIV)-positive, must be on anti-HIV therapy for at least 4 weeks and have a clusters of differentiation 4+ T-cell (CD4+) count \>=350 cells per microliter (cells/mcL) and an HIV viral load \<400 copies per milliliter (copies/mL).
  * If meets the criteria for anti-hepatitis B virus (HBV) therapy, must agree to take anti-HBV therapy, if known to be HBV-positive as defined by positive hepatitis B surface antigen or hepatitis B core antibody. HBV viral load must be undetectable.
  * If known to be hepatitis C virus (HCV)-positive must have completed curative therapy for HCV. HCV viral load must be undetectable.
* Known history of active bacillus tuberculosis (TB).
* Any medical or other condition which, in the opinion of the investigator would preclude the participant's participation in the clinical study.

Trial Locations

• Cancer and Blood Specialty Clinic, Los Alamitos, California, United States
• UCLA Center for East-West Medicine, Los Angeles, California, United States
• UCSF, San Francisco, California, United States
• Yale New Haven Hospital, New Haven, Connecticut, United States
• AdventHealth Cancer Institute - Orlando, Orlando, Florida, United States
• Moffitt Cancer Center, Tampa, Florida, United States
• Fort Wayne Medical Oncology & Hematology, Fort Wayne, Indiana, United States
• Community Cancer Center South, Indianapolis, Indiana, United States
• Mission Blood and Cancer, Des Moines, Iowa, United States
• University of Michigan Hospital, Ann Arbor, Michigan, United States
• ...and 10 more locations

Frequently Asked Questions

Related Conditions

• Breast Cancer
• Metastatic Breast Cancer
• HER2-positive Breast Cancer
• HER2-low Breast Cancer
• Hormone Receptor-positive Breast Cancer
• Advanced Breast Cancer
• Unresectable Breast Cancer
• Trastuzumab Deruxtecan Resistance
• Oncology
• Targeted Therapy

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