This trial studies how well the drug tucatinib works when given with trastuzumab deruxtecan. It will also look at what side effects happen when these drugs are given together. A side effect is anything a drug does besides treating cancer. Participants in this trial have HER2-positive (HER2+) breast cancer that has either spread to other parts of the body (metastatic) or cannot be removed completely with surgery (unresectable). All participants will get both tucatinib and trastuzumab deruxtecan.



Eligible Ages
Over 18 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Have confirmed HER2+ breast cancer, as defined by the current American Society of Clinical Oncology - College of American Pathologists (ASCO/CAP) guidelines, previously determined at a Clinical Laboratory Improvements Amendments (CLIA)-certified or International Organization for Standardization (ISO)-accredited laboratory. - Have received 2 or more prior anti-HER2-based regimens in the metastatic setting - Have progression of unresectable LA/M breast cancer after last systemic therapy (as confirmed by investigator), or be intolerant of last systemic therapy - Have measurable disease assessable by RECIST v1.1 - Have Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 or 1 - Have a life expectancy of at least 6 months, in the opinion of the investigator - CNS Inclusion - Based on medical history and screening contrast brain magnetic resonance imaging (MRI), participants with a history of brain metastases must have one of the following: - Untreated brain metastases not needing immediate local therapy. For participants with untreated central nervous system (CNS) lesions >2.0 cm on screening contrast brain MRI, discussion with and approval from the medical monitor is required prior to enrollment - Previously treated brain metastases - Brain metastases previously treated with local therapy may either be stable since treatment or may have progressed since prior local CNS therapy, provided that there is no clinical indication for immediate re-treatment with local therapy in the opinion of the investigator - Participants treated with CNS local therapy for newly identified or previously treated progressing lesions found on contrast brain MRI performed during screening for this study may be eligible to enroll if all of the following criteria are met: - Time since whole brain radiation therapy (WBRT) is ≥14 days prior to first dose of study treatment, time since stereotactic radiosurgery (SRS) is ≥7 days prior to first dose of study treatment, or time since surgical resection is ≥28 days - Other sites of measurable disease by RECIST v1.1 are present - Relevant records of any CNS treatment must be available

Exclusion Criteria

  • Have previously been treated with: - Lapatinib or neratinib within 12 months of starting study treatment (except in cases where lapatinib or neratinib was given for ≤21 days and was discontinued for reasons other than disease progression or severe toxicity) - Tucatinib or enrolled on a tucatinib clinical trial - Any investigational HER2/epidermal growth factor receptor (EGFR) or HER2 tyrosine kinase inhibitor (TKI) (eg, afatinib) at any time previously - Trastuzumab deruxtecan or another antibody-drug conjugate (ADC) consisting of an exatecan derivative - Have received treatment with: - Any systemic anti-cancer therapy (including hormonal therapy) or experimental agent ≤21 days of first dose of study treatment or are currently participating in another interventional clinical trial. An exception for the washout of hormonal therapies is gonadotropin releasing hormone (GnRH) agonists used for ovarian suppression in premenopausal women, which are permitted concomitant medications - Treatment with non-CNS radiation ≤7 days prior to first dose of study treatment - Major surgery <28 days of first dose of study treatment - Have clinically significant cardiopulmonary disease (such as history of iterstitial lung disease (ILD)/pneumonitis that required systemic corticosteroids, or have current ILD/pneumonitis, or where suspected ILD /pneumonitis cannot be ruled out be imaging at screening) - Have known myocardial infarction or unstable angina within 6 months prior to first dose of study treatment - Known to be positive for hepatitis B by surface antigen expression. Known to be positive for hepatitis C infection. Participants who have been treated for hepatitis C infection are permitted if they have documented sustained virologic response of 12 weeks - Presence of known chronic liver disease - Known to be positive for human immunodeficiency virus (HIV) - Active or uncontrolled clinically serious infection - Are pregnant, breastfeeding, or planning a pregnancy - Have inability to swallow pills or significant gastrointestinal disease which would preclude the adequate oral absorption of medications

Study Design

Phase 2
Study Type
Intervention Model
Single Group Assignment
Primary Purpose
None (Open Label)

Arm Groups

ArmDescriptionAssigned Intervention
Single Arm
Tucatinib + trastuzumab deruxtecan
  • Drug: tucatinib
    300 mg orally twice daily
    Other names:
    • TUKYSA, ARRY-380, ONT-380
  • Drug: trastuzumab deruxtecan
    5.4 mg/kg via intravenous (into the vein; IV) infusion on Day 1 of each of 21-day cycle
    Other names:
    • Enhertu, DS-8201

Recruiting Locations

University of Alabama at Birmingham
Birmingham, Alabama 35249
Nazma Chowdhury

More Details

Seagen Inc.

Study Contact

Seagen Trial Information Support


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.