Phase 2 Study of Tucatinib vs Placebo in Combination With Capecitabine & Trastuzumab in Patients With Advanced HER2+ Breast Cancer

Official Title

Phase 2 Randomized, Double-Blinded, Controlled Study of Tucatinib vs Placebo in Combination With Capecitabine and Trastuzumab in Patients With Pretreated Unresectable Locally Advanced or Metastatic HER2+ Breast Carcinoma (HER2CLIMB)


The purpose of this study is to assess the effect of tucatinib vs. placebo in combination with capecitabine and trastuzumab on progression-free survival (PFS) per RECIST 1.1 based on independent central review.

Trial Description

Primary Outcome:

  • Progression-free survival (PFS) per RECIST 1.1 based on independent central review
Secondary Outcome:
  • Effect of tucatinib in combination with capecitabine and trastuzumab on overall survival (OS)
  • Progression-free survival (PFS) in the subgroup of patients with baseline brain metastases per RECIST 1.1 based on central review
A randomized, international, multi-centre, double-blinded study in patients with pretreated unresectable locally advanced or metastatic HER2+ breast cancer who have had prior treatment with a taxane, trastuzumab, pertuzumab and T-DM1. Patients will be randomized in a 2:1 ratio to receive tucatinib or placebo in combination with capecitabine and trastuzumab. Stratification factors include presence or history of treated or untreated brain metastases (yes/no), Eastern Cooperative Oncology Group Performance Status (ECOG PS) (0 vs. 1), and region of world (US vs Canada vs Rest of World). No crossover from placebo to tucatinib will be allowed. Safety assessments will be performed at a minimum of once every three weeks throughout study treatment and 30 days after the last dose of study drugs. Laboratory assessments will be performed locally at sites. Cardiac ejection fraction will be assessed by MUGA/ECHO at screening and once every 12 weeks thereafter. Brain MRI will be performed at baseline in all patients. Efficacy assessments utilize RECIST 1.1 and should include measurement of all known sites of metastatic or locally advanced unresectable disease at baseline, every 6 weeks for the first 24 weeks, and then every 9 weeks thereafter. Repeat MRI of the brain will be required on this same schedule only in those patients with brain metastases. All treatment decisions will be made based upon investigator assessment of radiologic scans. All patients will undergo a repeat MRI of the brain within 30 days of the end of treatment. Patients in both arms of the study will continue to be followed for OS after completion of study treatment.

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