Description and Target

Tucatinib is an orally bioavailable, small molecule tyrosine kinase inhibitor (TKI) that is highly selective for HER2, a growth factor receptor that is over-expressed in multiple cancers, including breast, colorectal, and gastric cancers. Between 15% and 20% of breast cancers cases worldwide are HER2-positive.

On October 21, 2019, Seattle Genetics announced positive topline results from the HER2CLIMB trial, a randomized, double-blind, placebo-controlled, active comparator pivotal trial evaluating tucatinib. The trial compared tucatinib in combination with trastuzumab and capecitabine to trastuzumab and capecitabine alone in patients with locally advanced unresectable or metastatic HER2-positive breast cancer.

See the Pipeline section for information on the ongoing clinical studies evaluating tucatinib in breast and colorectal cancer.


Tucatinib is an investigational agent, and its safety and efficacy have not yet been established.