In a few particular cancers, treatment with immunotherapeutics or tyrosine kinase inhibitors, tailored to the individual, are possible, for example, trastuzumab in human epidermal growth factor receptor 2 (HER2)-positive breast cancer or gastric cancer, imatinib in philadelphia chromosome positive chronic myelogenous leukaemia (Ph + CML) or in KIT+ gastrointestinal stromal tumour (GIST), pazopanib and sunitinib in advanced renal cell carcinoma (RCC), or BRAF-directed therapy with vemurafenib or dabrafenib/trametinib in melanoma6–8. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.