Tucatinib is tyrosine kinase inhibitor that targets the human epidermal growth factor receptor 2 (HER2) and is used in combination with other antineoplastic agents in the treatment of refractory, advanced or metastatic HER2 positive breast and colorectal cancer. Serum aminotransferase elevations are common during therapy with tucatinib, but it has not been linked to episodes of clinically apparent liver injury with jaundice.