study procedures:
Patients will be managed by their treating clinician without any additional instructions. The study will require no additional treatment procedures during patient visits. Patients meeting the selection criteria will be invited to participate in the study. Before any study-specific data are recorded, patients will be provided with all the study details prior to their decision to participate and will be requested to sign an informed consent form (ICF) prior to their participation in the study. Patient's baseline data, safety, and PS (evaluation according to the Eastern Cooperative Oncology Group \[ECOG\] score) will be
collected during the observation period (treatment with tucatinib- trastuzumab-capecitabine). Response and survival assessments will
be collected during the study and include symptomatic response and best response by the treating clinician's assessment, according to investigator criteria and the local clinical practice procedures. Safety, response, and survival will be assessed during the follow-up period (18 months post tucatinib treatment). Previous and subsequent non-tucatinib treatments that the patient will receive since the follow-up period will also be described.
