Due to the exploratory nature of this study, the randomized PRO2 study (NCT05425550) is currently being conducted with the medidux app, the further-developed successor to the Consilium Care app, in which the incidence of high-grade adverse events (CTCAE >2) is being investigated in a better-defined patient population (patients with human epidermal growth factor receptor 2–positive breast cancer) under controlled conditions to support the results of this exploratory analysis. The gene discussed is ERBB2; the disease is breast cancer.