Melanoma patients with a KIT mutation affecting a recurrent hot spot, such as the L576 or K642E mutation, had better clinical outcomes than those without a hotspot mutation, whereas those with a V654A or D820Y mutation, which are known to be associated with imatinib resistance in gastrointestinal stromal tumors, had early disease progression. In addition, melanoma patients with a mutant/wild-type allelic ratio of >1 had a higher response rate.