The present observational study aims to collect data on long-term safety of trastuzumab deruxtecan, with a primary endpoint on trastuzumab deruxtecan related adverse drug reactions (ADRs) of interest. Data on patient profile, treatment history (before, during and after trastuzumab deruxtecan administration), effectiveness and health-related quality of life will also be collected in a real-life setting, to confirm and complement data from clinical trials. Patients will be recruited whether they have started trastuzumab deruxtecan treatment or will start it at the time of inclusion, whether they were prescribed compassionate trastuzumab deruxtecan or marketed Enhertu®, in order to rapidly collect a large set of data.
