Tucatinib: First Approval.

Tucatinib is an oral, small molecule, selective HER2 inhibitor initially developed by Array BioPharma (a subsidiary of Pfizer) and subsequently developed by Seattle Genetics for the treatment of HER2-positive solid tumours, including breast cancer and colorectal cancer. Tucatinib was approved in the USA in April 2020 and in Switzerland in May 2020 for the treatment of HER2-positive breast cancer, and is pending regulatory review in the EU, Australia, Canada and Singapore. This article summarizes the milestones in the development of tucatinib leading to this first approval in patients with advanced unresectable or metastatic HER2-positive breast cancer.