Tucatinib is a small molecule kinase inhibitor that selectively targets human epidermal growth factor receptor 2 (HER2) and her family members. It blocks the activity of HER2 and HER3 by inhibiting the phosphorylation of tyrosine residues on these receptors, which leads to the inhibition of downstream signaling pathways that drive cancer cell proliferation and survival.
Tucatinib is approved for the treatment of advanced or metastatic breast cancer in patients with HER2-positive tumors who have received prior treatment with trastuzumab and taxane chemotherapy. It is typically used in combination with capecitabine and trastuzumab. Tucatinib has demonstrated activity in preclinical models of other HER2-positive cancers, including gastric, pancreatic, and ovarian cancer, but it is not approved for the treatment of these indications.