Although gastrointestinal toxicities are a class effect of EGFR TKIs, the very high incidence of diarrhoea is a particular safety concern of neratinib treatment. Diarrhoea can affect quality of life, but can also lead to complications including dehydration and renal failure, particularly in older patients. Based on available data from study 6201, it is uncertain at this time whether the diarrhoea can be adequately managed by anti-diarrhoeal prophylaxis.