A Phase II Study of Tucatinib plus Trastuzumab in Patients with HER2-Positive Metastatic Colorectal Cancer


Full Title

MOUNTAINEER: A Phase II, Open Label Study of Tucatinib Combined with Trastuzumab in Patients with HER2+ Metastatic Colorectal Cancer


The purpose of this study is to assess the safety and effectiveness of the drug tucatinib given in combination with trastuzumab in patients with advanced colorectal cancer. Both drugs inhibit a protein called HER2, which can be found in large amounts in some cancers (including some colorectal cancers).

Tucatinib is taken orally (by mouth) and is used to treat breast cancer. Trastuzumab is already approved to treat breast and stomach cancers. The use of both drugs in this study is considered investigational. Trastuzumab is given intravenously (by vein).


To be eligible for this study, patients must meet several criteria, including but not limited to the following:

  • Patients must have inoperable or metastatic colorectal cancer that has persisted despite prior treatment that included 5-fluorouracil or capecitabine, oxaliplatin, irinotecan, and an anti-VEGF drug (bevacizumab, ramucirumab, or ziv-aflibercept).
  • Patients’ tumors must overproduce HER2 and may not contain mutated KRAS or NRAS.
  • At least 3 weeks must pass between the completion of prior therapies and entry into the study.
  • Patients must be able to walk and do routine activities for more than half of their normal waking hours.
  • This study is for patients age 18 and older.

For more information about this study and to inquire about eligibility, please contact Dr. Andrea Cercek at 646-888-4189.