Gastrointestinal disorders was the commonest SOC for AEs leading to dose reductions, for the monotherapy breast cancer safety analysis set, in particular diarrhoea. In study 3004, an AE of diarrhoea led to dose reductions for 26.4% of patients in the neratinib arm compared to 0.6% in the placebo arm. The next commonest AE leading to dose reduction was nausea (2.8% of patients in the neratinib arm).