ACE and endothelial dysfunction: We hypothesized that perindopril, an angiotensin-converting enzyme (ACE) inhibitor, indicated for the treatment of hypertension (Ceconi et al., in Cardiovasc Res 73:237–246, 2007), and which plays a role in preventing endothelial dysfunction, may help to prevent or reduce the severity of regorafenib-induced HFSR.