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RecruitingLast updated: 14 May 2024

HER2CLIMB-05: This phase III study is trying to understand whether targeted therapy (tucatinib) works better than placebo when given with other drugs (trastuzumab and pertuzumab) to treat people with HER2-positive breast cancer.A Randomized, Double-blind, Phase 3 Study of Tucatinib or Placebo in Combination With Trastuzumab and Pertuzumab as Maintenance Therapy for Metastatic HER2+ Breast Cancer (HER2CLIMB-05)

Clinical summary


Eligible participants will be randomly assigned to either the Experimental Arm or the Control Arm. In the Experimental Arm, participants will receive Tucatinib + trastuzumab + pertuzumab. Tucatinib (300mg) will be given by mouth (orally) twice daily. Tastuzumab will be given intravenously (via IV) at a dose of 6mg/kg or injected under the skin (subcutaneously) at a dose of 600mg, every 21 days. Pertuzumab (420mg) will be given via IV every 21 days. Alternatively, instead of receiving trastuzumab and pertuzumab individually, participants may receive a fixed dose combination of 600mg pertuzumab, 600mg trastuzumab, and 20,000 units hyaluronidase subcutaneously every 21 days. In the Control Arm, participants will receive Placebo + trastuzumab + pertuzumab. Placebo will be given orally, twice daily. Trastuzumab and Pertuzumab will be given as described in the Experimental Arm.


This trial is treating patients with HER2-Positive Breast Cancer


Breast Cancers Breast





Trial Acronym


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Trial Identifiers

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Trial sponsor

Seagen Inc.

Scientific Title

A Randomized, Double-blind, Phase 3 Study of Tucatinib or Placebo in Combination With Trastuzumab and Pertuzumab as Maintenance Therapy for Metastatic HER2+ Breast Cancer (HER2CLIMB-05)



  • Centrally confirmed HER2+ breast carcinoma according to the 2018 American Society of Clinical Oncologists (ASCO) College of American Pathologists (CAP) guidelines prior to randomization (defined as a 3+ score on immunohistochemistry (IHC) and/or 2+ IHC and concurrent positive by ISH).
  • Have unresectable locally advanced or metastatic disease.

    • If recurrent (after [neo]adjuvant therapy), must be at least 6 month treatment free from any trastuzumab and pertuzumab received in the early breast cancer setting for advanced HER2+ disease.
  • Have received 4-8 cycles of pre-study induction therapy including only trastuzumab, pertuzumab, and taxane as first-line of therapy for the treatment of advanced breast cancer prior to study enrollment. Participants are eligible provided they are without evidence of disease progression following completion of induction therapy.
  • Known hormone receptor status (per local guidelines; may be hormone receptor positive [HR+] or negative [HR-])
  • Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
  • CNS Inclusion - Based on screening contrast-enhanced brain magnetic resonance imaging (MRI), participants may have any of the following:

    • No evidence of brain metastases
    • Untreated brain metastases which are asymptomatic not needing immediate local treatment and, if identified on prior brain imaging, without evidence of progression since starting first-line induction therapy with trastuzumab, pertuzumab, and taxane
    • Previously treated brain metastases which are asymptomatic

      • Brain metastases previously treated with local therapy must not have progressed since treatment


  • Prior treatment with any tyrosine kinase inhibitor targeting HER2 and/or epidermal growth factor receptor (EGFR) including pyrotinib, lapatinib, tucatinib, neratinib, and afatinib (except neratinib if given in extended adjuvant setting and ≥ 12 months have elapsed since last neratinib dose prior to start of study drug)
  • Unable to undergo contrast-enhanced MRI of the brain
  • CNS Exclusion - Based on screening brain MRI and clinical assessment

    • Symptomatic brain metastasis after CNS-directed local therapy
    • Progression of brain metastases since starting first line trastuzumab, pertuzumab, and taxane
    • Ongoing use of systemic corticosteroids at a total daily dose of >2 mg of dexamethasone (or equivalent)
    • Any untreated brain lesion in an anatomic site which may pose risk to participant
    • Known or suspected leptomeningeal disease (LMD)
    • Poorly controlled (>1/week) seizures, or other persistent neurologic symptoms


  • You have had treatment, but your cancer has come back.
  • Your cancer has spread to other parts of the body.
  • Your cancer has not spread to other parts of the body.
  • You are able to swallow medication by mouth.
  • You have had a certain type of treatment or surgical procedure.


  • You have certain types of non-cancer medical conditions.
  • You have had certain treatments, surgical procedures or drugs.

Clinical trials have complex eligibility criteria.

Ask your doctor if this trial could be right for you.

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