It was also recently approved in the United States for the treatment of adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) harboring platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutations at a recommended starting dose of 300 mg once daily (QD), based on dose-escalation and dose-expansion trials that evaluated efficacy and safety in this setting27,28. The gene discussed is PDGFRA; the disease is gastrointestinal stromal tumor.